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Oracle® TimesTen In-Memory Database C Developer's Guide
11g Release 2 (11.2.2)

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9 XLA Reference

This chapter provides reference information for the Transaction Log API (XLA) described in Chapter 5, "XLA and TimesTen Event Management". It includes the following topics:

About XLA functions

This section provides general information about XLA functions.

About return codes

All of the XLA API functions described in this chapter return a value of type SQLRETURN, which is defined by ODBC to have one of the following values:

  • SQL_SUCCESS

  • SQL_SUCCESS_WITH_INFO

  • SQL_NO_DATA_FOUND

  • SQL_ERROR

See "Handling XLA errors" for information on handling XLA errors.

About parameter types (input, output, input/output)

In the function descriptions:

  • All parameters are input-only unless otherwise indicated.

  • Output parameters are prefixed with OUT.

  • Input/output parameters are prefixed with IN OUT.

About results output by functions

Most routines in this API copy results to application buffers. Those few routines that produce pointers to buffers containing results are guaranteed as valid only until the next call with the same XLA handle.

Exceptions to this rule include the following.

  • Buffers remain valid across calls to the ttXlaError function that supplies diagnostic information.

  • Results returned by ttXlaNextUpdate remain valid until the next call to ttXlaNextUpdate.

  • For ttXlaAcknowledge, if the application must retain access to the buffers for a longer time, it must copy the information from the buffer returned by XLA to an application-owned buffer.

Character string values in XLA are null-terminated, except for actual column values. Fixed-length CHAR columns are space-padded to their full length. VARCHAR columns have an explicit length encoded.

XLA uses the same data structures for both 32-bit and 64-bit platforms. The types SQLUINTEGER and SQLUBIGINT are used to refer to 32-bit and 64-bit integers unambiguously. Issues of alignment and padding are addressed by filling the type definition so that each SQLUINTEGER value is on a four-byte boundary and each SQLUBIGINT value is on an eight-byte boundary. For a description of storage requirements for other TimesTen data types, see "Understanding rows" in Oracle TimesTen In-Memory Database Operations Guide.

About required privileges

"Access control impact on XLA" introduces the effects of TimesTen access control features on XLA functionality. Any XLA functionality requires the system privilege XLA.

Summary of XLA functions by category

As described in Chapter 5, "XLA and TimesTen Event Management", TimesTen XLA can be used to detect updates on a database or as a toolkit to build your own replication solution.

This section categorizes the XLA functions based on their use and provides a brief description of each function. It includes the following categories:

XLA core functions

The following table lists all the XLA functions used in typical XLA operations, aside from data conversion functions which are listed separately below.

Function Description
ttXlaAcknowledge Acknowledges receipt of one or more transaction update records from the transaction log.
ttXlaClose Closes the XLA handle opened by ttXlaPersistOpen.
ttXlaConvertCharType Converts column data into the connection character set.
ttXlaDeleteBookmark Deletes a transaction log bookmark.
ttXlaError Retrieves error information.
ttXlaErrorRestart Resets error stack information.
ttXlaGetColumnInfo Retrieves information about all the columns in the table.
ttXlaGetLSN Retrieves the log record identifier of the current bookmark for a database.
ttXlaGetTableInfo Retrieves information about a table.
ttXlaGetVersion Retrieves the current version of XLA.
ttXlaNextUpdate Retrieves a batch of updates from TimesTen.
ttXlaNextUpdateWait Retrieves a batch of updates from TimesTen. Waits for a specified time if no updates are available in the transaction log.
ttXlaPersistOpen Initializes a handle to a database to access the transaction log.
ttXlaSetLSN Sets the log record identifier of the current bookmark for a database.
ttXlaSetVersion Sets the XLA version to be used.
ttXlaTableByName Finds the system and user table identifiers for a table given the table owner and name.
ttXlaTableStatus Sets and retrieves XLA status for a table.
ttXlaTableVersionVerify Checks whether the cached table definitions are compatible with the XLA record being processed.
ttXlaVersionColumnInfo Retrieves information about the columns in a table for which a change update record must be processed.
ttXlaVersionCompare Compares two XLA versions.

See "Writing an XLA event-handler application" for a discussion on how to use most of these functions.

XLA data type conversion functions

The following table lists data type conversion functions.

Function Description
ttXlaDateToODBCCType Converts a TTXLA_DATE_TT value to an ODBC C value usable by applications.
ttXlaDecimalToCString Converts a TTXLA_DECIMAL_TT value to a character string usable by applications.
ttXlaNumberToBigInt Converts a TTXLA_NUMBER value to a SQLBIGINT C value usable by applications.
ttXlaNumberToCString Converts a TTXLA_NUMBER value to a character string usable by applications.
ttXlaNumberToDouble Converts a TTXLA_NUMBER value to a long floating point number value usable by applications.
ttXlaNumberToInt Converts a TTXLA_NUMBER value to an integer usable by applications.
ttXlaNumberToSmallInt Converts a TTXLA_NUMBER value to a SQLSMALLINT C value usable by applications.
ttXlaNumberToTinyInt Converts a TTXLA_NUMBER value to a SQLCHAR C value usable by applications.
ttXlaNumberToUInt Converts a TTXLA_NUMBER value to an unsigned integer usable by applications.
ttXlaOraDateToODBCTimeStamp Converts a TTXLA_DATE value to an ODBC timestamp usable by applications.
ttXlaOraTimeStampToODBCTimeStamp Converts a TTXLA_TIMESTAMP value to an ODBC timestamp usable by applications.
ttXlaRowidToCString Converts a ROWID value to a character string value usable by applications.
ttXlaTimeToODBCCType Converts a TTXLA_TIME value to an ODBC C value usable by applications.
ttXlaTimeStampToODBCCType Converts a TTXLA_TIMESTAMP_TT value to an ODBC C value usable by applications.

For more information about XLA data types, see "About XLA data types".

XLA replication functions

TimesTen replication as described in Oracle TimesTen In-Memory Database Replication Guide is sufficient for most customer needs; however, it is also possible to use XLA functions to replicate updates from one database to another. Implementing your own replication scheme on top of XLA in this way is fairly complicated, but can be considered if TimesTen replication is not feasible for some reason.

The following table lists functions used exclusively for XLA as a replication mechanism. (Reference information for these functions is in a separate section from other XLA functions, "XLA replication function reference".)

Function Description
ttXlaApply Applies the update to the database associated with the XLA handle.
ttXlaCommit Commits a transaction.
ttXlaGenerateSQL Generates a SQL statement that expresses the effect of an update record.
ttXlaLookup Looks for an update record for a table with a specific key value.
ttXlaRollback Rolls back a transaction.
ttXlaTableCheck Verifies that the named table in the table description received from the sending database is compatible with the receiving database.

See "Using XLA as a replication mechanism" for a discussion on how to use these functions.


XLA function reference

This section provides reference information for XLA core functions and XLA data type conversion functions. The functions are listed in alphabetical order.

Note:

Functions used exclusively for XLA as a replication mechanism are documented in a separate section, "XLA replication function reference".

ttXlaAcknowledge

Description

This function is used to acknowledge that one or more records have been read from the transaction log by the ttXlaNextUpdate or ttXlaNextUpdateWait function.

After you make this call, the bookmark is reset so that you cannot reread any of the previously returned records. Call ttXlaAcknowledge only when messages have been completely processed.

Notes:

  • The bookmark is only reset for the specified handle. Other handles in the system may still be able to access those earlier transactions.

  • The bookmark is reset even if there are no relevant update records to acknowledge.

Note that ttXlaAcknowledge is an expensive operation that should be used only as necessary. Calling ttXlaAcknowledge more than once per reading of the transaction log file does not reduce the volume of the transaction log since XLA only purges transaction logs a file at a time. To detect when a new transaction log file is generated, you can find out which log file a bookmark is in by examining the purgeLSN (represented by the PURGELSNHIGH and PURGELSNLOW values) for the bookmark in the system table SYS.TRANSACTION_LOG_API. You can then call ttXlaAcknowledge to purge the old transaction log files. (Note that you must have ADMIN or SELECT ANY TABLE privilege to view this table.)

The second purpose of ttXlaAcknowledge is to ensure that the XLA application does not see the acknowledged records if it were to connect to a previously used bookmark by calling the ttXlaPersistOpen function with the XLAREUSE option. If you intend to reuse a bookmark, call ttXlaAcknowledge to reset the bookmark position to the current record before calling ttXlaClose.

See "Retrieving update records from the transaction log" for a discussion about using this function.

Required privilege

XLA

Syntax

SQLRETURN ttXlaAcknowledge(ttXlaHandle_h handle)

Parameters

Parameter Type Description
handle ttXlaHandle_h Transaction log handle

Returns

Returns SQL_SUCCESS if call is successful. Otherwise, use ttXlaError to report the error.

Example

rc = ttXlaAcknowledge(xlahandle);

See also


ttXlaNextUpdate
ttXlaNextUpdateWait

ttXlaClose

Description

Closes an XLA handle that was opened by ttXlaPersistOpen. See "Terminating an XLA application" for a discussion about using this function.

Required privilege

XLA

Syntax

SQLRETURN ttXlaClose(ttXlaHandle_h handle)

Parameters

Parameter Type Description
handle ttXlaHandle_h ODBC handle for the database

Returns

Returns SQL_SUCCESS if call is successful. Otherwise, use ttXlaError to report the error.

To close the XLA handle opened in the previous example, use the following call:

rc = ttXlaClose(xlahandle);

See also


ttXlaPersistOpen

ttXlaConvertCharType

Description

Converts the column data indicated by the colinfo and tup parameters into the connection character set associated with the transaction log handle and places the result in a buffer.

Required privilege

XLA

Syntax

SQLRETURN ttXlaConvertCharType (ttXlaHandle_h handle,
                                ttXlaColDesc_t*  colinfo,
                                void* tup,
                                void* buf,
                                size_t buflen)

Parameters

Parameter Type Description
handle ttXlaHandle_h Transaction log handle for the database
colinfo ttXlaColDesc_t* Pointer to the buffer that holds the column descriptions
tup void* Data to be converted
buf void* Location where the converted data is placed
buflen size_t Size of the buffer where the converted data is placed

Returns

Returns SQL_SUCCESS if call is successful. Otherwise, use ttXlaError to report the error.


ttXlaDateToODBCCType

Description

Converts a TTXLA_DATE_TT value to an ODBC C value usable by applications. See "Converting complex data types" for a discussion about using this function.

Call this function only on a column of data type TTXLA_DATE_TT. The data type can be obtained from the ttXlaColDesc_t structure returned by the ttXlaGetColumnInfo function.

Required privilege

XLA

Syntax

SQLRETURN ttXlaDateToODBCCType(void* fromData,
                               out DATE_STRUCT* returnData)

Parameters

Parameter Type Description
fromData void* Pointer to the date value returned from the transaction log
returnData DATE_STRUCT* Pointer to storage allocated to hold the converted date

Returns

Returns SQL_SUCCESS if call is successful. Otherwise, use ttXlaError to report the error.


ttXlaDecimalToCString

Description

Converts a TTXLA_DECIMAL_TT value to a string usable by applications. The scale and precision values can be obtained from the ttXlaColDesc_t structure returned by the ttXlaGetColumnInfo function. The scale parameter specifies the maximum number of digits after the decimal point. If the decimal value is larger than 1, the precision parameter should specify the maximum number of digits before and after the decimal point. If the decimal value is less than 1, precision equals scale.

Call this function only for a column of type TTXLA_DECIMAL_TT. The data type can be obtained from the ttXlaColDesc_t structure returned by the ttXlaGetColumnInfo function.

See "Converting complex data types" for a discussion about using this function.

Required privilege

XLA

Syntax

SQLRETURN ttXlaDecimalToCString(void* fromData,
                                out char* returnData,
                                SQLSMALLINT precision,
                                SQLSMALLINT scale)

Parameters

Parameter Type Description
fromData void* Pointer to the decimal value returned from the transaction log
returnData char* Pointer to storage allocated to hold the converted string
precision SQLSMALLINT If fromData is greater than 1, the maximum number of digits before and after the decimal point

If fromData is less than 1, same as scale

scale SQLSMALLINT Maximum number of digits after the decimal point

Returns

Returns SQL_SUCCESS if call is successful. Otherwise, use ttXlaError to report the error.

Example

This example assumes you have obtained the offset, precision, and scale values from a ttXlaColDesc_t structure and used the offset to obtain a decimal value, pColVal, in a row returned in a transaction log record.

char decimalData[50];
static ttXlaColDesc_t colDesc[255];

rc = ttXlaDecimalToCString(pColVal, (char*)&decimalData,
                                     colDesc->precision, 
                                     colDesc->scale);

ttXlaDeleteBookmark

Description

Deletes the bookmark associated with the specified transaction log handle. After the bookmark has been deleted, it is no longer accessible and its identifier may be reused for another bookmark. The deleted bookmark is no longer associated with the database handle and the effect is the same as having opened the connection with the XLANONE option.

If the bookmark is in use, it cannot be deleted until it is no longer in use.

See "Deleting bookmarks" for a discussion about using this function.

Notes:

  • Do not confuse this with the TimesTen built-in procedure ttXlaBookmarkDelete, documented in "ttXlaBookmarkDelete" in Oracle TimesTen In-Memory Database Reference.

  • You cannot delete replicated bookmarks while the replication agent is running.

Required privilege

XLA

Syntax

SQLRETURN ttXlaDeleteBookmark(ttXlaHandle_h handle)

Parameters

Parameter Type Description
handle ttXlaHandle_h Transaction log handle

Returns

Returns SQL_SUCCESS if call is successful. Otherwise, use ttXlaError to report the error.

Example

Delete the bookmark for xlahandle:

rc = ttXlaDeleteBookmark(xlahandle);

See also


ttXlaPersistOpen
ttXlaGetLSN
ttXlaSetLSN

ttXlaError

Description

Reports details of any errors encountered from the previous call on the given transaction log handle. Multiple errors may be returned through subsequent calls to ttXlaError. The error stack is cleared following each call to a function other than ttXlaError itself and ttXlaErrorRestart.

See "Handling XLA errors" for a discussion about using this function.

Required privilege

XLA

Syntax

SQLRETURN ttXlaError(ttXlaHandle_h handle,
                     out SQLINTEGER* errCode,
                     out char* errMessage,
                     SQLINTEGER maxLen,
                     out SQLINTEGER* retLen)

Parameters

Parameter Type Description
handle ttXlaHandle_h Transaction log handle for the database
errCode SQLINTEGER* Code of the error message to be copied into the errMessage buffer
errMessage char* Buffer to hold the error text
maxLen SQLINTEGER Maximum length of the errMessage buffer
retLen SQLINTEGER* Actual size of the error message

Returns

Returns SQL_SUCCESS if error information is returned, or SQL_NO_DATA_FOUND if no more errors are found in the error stack. If the errMessage buffer is not large enough, ttXlaError returns SQL_SUCCESS_WITH_INFO.

Example

There can be multiple errors on the error stack. This example shows how to read them all.

char message[100];
SQLINTEGER code;

for (;;) {
  rc = ttXlaError(xlahandle, &code, message, sizeof (message), &retLen);
  if (rc == SQL_NO_DATA_FOUND)
      break;
  if (rc == SQL_ERROR) {
      printf("Error in fetching error message\n");
      break;
  }
  else {
      printf("Error code %d: %s\n", code, message);
  }
}

Note

If you use multiple threads to access a TimesTen transaction log over a single XLA connection, TimesTen creates a latch to control concurrent access. If for some reason the latch cannot be acquired by a thread, the XLA function returns SQL_INVALID_HANDLE.

See also

ttXlaErrorRestart


ttXlaErrorRestart

Description

Resets the error stack so that an application can reread the errors. See "Handling XLA errors" for a discussion about using this function.

Required privilege

XLA

Syntax

SQLRETURN ttXlaErrorRestart(ttXlaHandle_h handle)

Parameters

Parameter Type Description
handle ttXlaHandle_h Transaction log handle for the database

Returns

Returns SQL_SUCCESS if call is successful. Otherwise, use ttXlaError to report the error.

Example

rc = ttXlaErrorRestart(xlahandle);

See also

ttXlaError


ttXlaGetColumnInfo

Description

Retrieves information about all the columns in the table. Normally, the output parameter for number of columns returned, nreturned, is set to the number of columns returned in colinfo. The systemTableID or userTableID parameter describes the desired table. This call is serialized with respect to changes in the table definition.

See "Obtaining column descriptions" for a discussion about using this function.

Required privilege

XLA

Syntax

SQLRETURN ttXlaGetColumnInfo(ttXlaHandle_h handle,
                             SQLUBIGINT systemTableID,
                             SQLUBIGINT userTableID,
                             out ttXlaColDesc_t* colinfo,
                             SQLINTEGER maxcols,
                             out SQLINTEGER* nreturned)

Parameters

Parameter Type Description
handle ttXlaHandle_h Transaction log handle for the database
systemTableID SQLUBIGINT System ID of table
userTableID SQLUBIGINT User ID of table
colinfo ttXlaColDesc_t* Pointer to the buffer large enough to hold a separate description for maxcols columns
maxcols SQLINTEGER Maximum number of columns that can be stored in the colInfo buffer

If the table contains more than maxcols columns, an error is returned.

nreturned SQLINTEGER* Number of columns returned

Returns

Returns SQL_SUCCESS if call is successful. Otherwise, use ttXlaError to report the error.

Example

For this example, assume the following definitions:

ttXlaColDesc_t colinfo[20];
SQLUBIGINT systemTableID, userTableID;
SQLINTEGER ncols;

To get the description of up to 20 columns using the system table identifier, issue the following call.

rc = ttXlaGetColumnInfo(xlahandle, systemTableID, 0, colinfo, 20, &ncols);

Likewise, the user table identifier can be used:

rc = ttXlaGetColumnInfo(xlahandle, 0, userTableID, colinfo, 20, &ncols);

See "ttXlaColDesc_t" for details and an example on how to access the column data in a returned row.

See also


ttXlaGetTableInfo
ttXlaDecimalToCString
ttXlaDateToODBCCType
ttXlaTimeToODBCCType
ttXlaTimeStampToODBCCType

ttXlaGetLSN

Description

Returns the Current Read log record identifier for the connection specified by the transaction log handle. See "How bookmarks work" for a discussion about using this function.

Required privilege

XLA

Syntax

SQLRETURN ttXlaGetLSN(ttXlaHandle_h handle,
                      out tt_XlaLsn_t* LSN)

Parameters

Parameter Type Description
handle ttXlaHandle_h Transaction log handle for the database
LSN tt_XlaLsn_t* Current Read log record identifier for the handle

Note:

Be aware that tt_XlaLsn_t, particularly the logFile and logOffset fields, is used differently than in earlier releases, referring to log record identifiers rather than sequentially increasing LSNs. See the note in "tt_XlaLsn_t".

Returns

Returns SQL_SUCCESS if call is successful. Otherwise, use ttXlaError to report the error.

Example

This example returns the Current Read log record identifier, CurLSN.

tt_XlaLsn_t CurLSN;

rc = ttXlaGetLSN(xlahandle, &CurLSN);

See also

ttXlaSetLSN


ttXlaGetTableInfo

Description

Retrieves information about the rows in the table (refer to the description of the ttXlaTblDesc_t data type.) If the userTableID parameter is nonzero, then it is used to locate the desired table. Otherwise, the systemTableID value is used to locate the table. If both are zero, an error is returned. The description is stored in the output parameter tblinfo. This call is serialized with respect to changes in the table definition.

Required privilege

XLA

Syntax

SQLRETURN ttXlaGetTableInfo(ttXlaHandle_h handle,
                            SQLUBIGINT systemTableID,
                            SQLUBIGINT userTableID,
                            out ttXlaTblDesc_t* tblinfo)

Parameters

Parameter Type Description
handle ttXlaHandle_h Transaction log handle for the database
systemTableID SQLUBIGINT System table ID
userTableID SQLUBIGINT User table ID
tblinfo ttXlaTblDesc_t* Row information

Returns

Returns SQL_SUCCESS if call is successful. Otherwise, use ttXlaError to report the error.

Example

For this example, assume the following definitions:

ttXlaTblDesc_t tabinfo; 
SQLUBIGINT systemTableID, userTableID;

To get table information using a system identifier, find the system table identifier using ttXlaTableByName or other means and issue the following call:

rc = ttXlaGetTableInfo(xlahandle, systemTableID, 0, &tabinfo);

Alternatively, the table information can be retrieved using a user table identifier:

rc = ttXlaGetTableInfo(xlahandle, 0, userTableID, &tabinfo);

See also

ttXlaGetColumnInfo


ttXlaGetVersion

Description

This function is used in combination with ttXlaSetVersion to ensure XLA applications written for older versions of XLA operate on a new version. The configured version is typically the older version, while the actual version is the newer one.

The function retrieves the currently configured XLA version and stores it into configuredVersion parameter. The actual version of the underlying XLA is stored in actualVersion. Due to calls on ttXlaSetVersion, the results in configuredVersion may vary from one call to the next, but the results in actualVersion remain the same.

See "XLA basics" for a discussion about using this function.

Required privilege

XLA

Syntax

SQLRETURN ttXlaGetVersion(ttXlaHandle_h handle,
                          out ttXlaVersion_t* configuredVersion,
                          out ttXlaVersion_t* actualVersion)

Parameters

Parameter Type Description
handle ttXlaHandle_h Transaction log handle for the database
configuredVersion ttXlaVersion_t* Configured version of XLA
actualVersion ttXlaVersion_t* Actual version of XLA

Returns

Returns SQL_SUCCESS if call is successful. Otherwise, use ttXlaError to report the error.

Example

Assume the following directions for this example:

ttXlaVersion_t configured, actual;

To determine the current version configuration, use the following call:

rc = ttXlaGetVersion(xlahandle, &configured, &actual);

See also


ttXlaVersionCompare
ttXlaSetVersion

ttXlaNextUpdate

Description

This function fetches up to a specified maximum number of update records from the transaction log and returns the records associated with committed transactions to a specified buffer. The actual number of returned records is reported in the nreturned output parameter. This function requires a bookmark to be present in the database and to be associated with the connection used by the function.

Each call to ttXlaNextUpdate resets the bookmark to the last record read to enable the next call to ttXlaNextUpdate to return the next list of records.

See "Retrieving update records from the transaction log" for a discussion about using this function.

Required privilege

XLA

Syntax

SQLRETURN ttXlaNextUpdate(ttXlaHandle_h handle,
                          out ttXlaUpdateDesc_t*** records,
                          SQLINTEGER maxrecords,
                          out SQLINTEGER* nreturned)

Parameters

Parameter Type Description
handle ttXlaHandle_h Transaction log handle for the database
records ttXlaUpdateDesc_t*** Buffer to hold the completed transaction records
maxrecords SQLINTEGER Maximum number of records to be fetched
nreturned SQLINTEGER* Actual number of returned records, where 0 is returned if no update data is available

Returns

Returns SQL_SUCCESS if call is successful. Otherwise, use ttXlaError to report the error.

Example

This example retrieves up to 100 records and describes a loop in which each record can be processed:

ttXlaUpdateDesc_t** records;
SQLINTEGER nreturned;
SQLINTEGER i;

rc = ttXlaNextUpdate(xlahandle, &records, 100, &nreturned);
/* Check for errors; if none, process the records */
for (i = 0; i < nreturned; i++) {
  process(records[i]);
}

Notes

Updates are generated for all data definition statements, regardless of tracking status. Updates are generated for data update operations for all tracked tables associated with the bookmark.

In addition, updates are generated for certain special operations, including assigning application-level identifiers for tables and columns and changing the tracking status of a table.

See also


ttXlaNextUpdateWait
ttXlaAcknowledge

ttXlaNextUpdateWait

Description

This is similar to the ttXlaNextUpdate function, with the addition of a seconds parameter that specifies the number of seconds to wait if no records are available in the transaction log. The actual number of seconds of wait time can be up to two seconds more than the specified seconds value.

Also see "Retrieving update records from the transaction log".

Required privilege

XLA

Syntax

SQLRETURN ttXlaNextUpdateWait(ttXlaHandle_h handle,
                              out ttXlaUpdateDesc_t*** records,
                              SQLINTEGER maxrecords,
                              out SQLINTEGER* nreturned,
                              SQLINTEGER seconds)

Parameters

Parameter Type Description
handle ttXlaHandle_h Transaction log handle for the database
records ttXlaUpdateDesc_t*** Buffer to hold completed transaction records
maxrecords SQLINTEGER Maximum number of records to be fetched

Note: The largest effective value is 1000 records.

nreturned SQLINTEGER* Actual number of records returned, where 0 is returned if no update data is available within the seconds wait period
seconds SQLINTEGER Number of seconds to wait if the log is empty

Returns

Returns SQL_SUCCESS if call is successful. Otherwise, use ttXlaError to report the error.

Example

This example retrieves up to 100 records and waits for up to 60 seconds if there are no records available in the transaction log.

ttXlaUpdateDesc_t** records;
SQLINTEGER nreturned;
SQLINTEGER i;

rc = ttXlaNextUpdateWait(xlahandle, &records, 100, &nreturned, 60);
/* Check for errors; if none, process the records */
for (i = 0; i < nreturned; i++) {
  process(records[i]);
}

See also


ttXlaNextUpdate
ttXlaAcknowledge

ttXlaNumberToBigInt

Description

Converts a TTXLA_NUMBER value to a SQLBIGINT value usable by an application.

Call this function only for a column of type TTXLA_NUMBER. The data type can be obtained from the ttXlaColDesc_t structure returned by the ttXlaGetColumnInfo function.

Required privilege

XLA

Syntax

SQLRETURN ttXlaNumberToBigInt(void* fromData,
                              SQLBIGINT* bint)

Parameters

Parameter Type Description
fromData void* Pointer to the number value returned from the transaction log
bint SQLBIGINT* The SQLBIGINT value converted from the XLA number value

Returns

Returns SQL_SUCCESS if call is successful. Otherwise, use ttXlaError to report the error.


ttXlaNumberToCString

Description

Converts a TTXLA_NUMBER value to a character string usable by an application.

Call this function only for a column of type TTXLA_NUMBER. The data type can be obtained from the ttXlaColDesc_t structure returned by the ttXlaGetColumnInfo function.

Required privilege

XLA

Syntax

SQLRETURN ttXlaNumberToCString(ttXlaHandle_h handle,
                               void* fromData,
                               char* buf,
                               int buflen
                               int* reslen)

Parameters

Parameter Type Description
fromData void* Pointer to the number value returned from the transaction log
buf char* Location where the converted data is placed
buflen int Size of the buffer where the converted data is placed
reslen int* Number of bytes that were written, assuming buflen is large enough (otherwise, the number of bytes that would have been written)

Returns

Returns SQL_SUCCESS if call is successful. Otherwise, use ttXlaError to report the error.


ttXlaNumberToDouble

Description

Converts a TTXLA_NUMBER value to a long floating point number value usable by applications.

Call this function only for a column of type TTXLA_NUMBER. The data type can be obtained from the ttXlaColDesc_t structure returned by the ttXlaGetColumnInfo function.

Required privilege

XLA

Syntax

SQLRETURN ttXlaNumberToDouble(void* fromData,
                              double* dbl)

Parameters

Parameter Type Description
fromData void* Pointer to the number value returned from the transaction log
dbl double* The long floating point number value converted from the XLA number value

Returns

Returns SQL_SUCCESS if call is successful. Otherwise, use ttXlaError to report the error.


ttXlaNumberToInt

Description

Converts a TTXLA_NUMBER value to a SQLINTEGER value usable by an application.

Call this function only for a column of type TTXLA_NUMBER. The data type can be obtained from the ttXlaColDesc_t structure returned by the ttXlaGetColumnInfo function.

Required privilege

XLA

Syntax

SQLRETURN ttXlaNumberToInt(void* fromData,
                           SQLINTEGER* ival)

Parameters

Parameter Type Description
fromData void* Pointer to the number value returned from the transaction log
ival SQLINTEGER* The SQLINTEGER value converted from the XLA number value

Returns

Returns SQL_SUCCESS if call is successful. Otherwise, use ttXlaError to report the error.


ttXlaNumberToSmallInt

Description

Converts a TTXLA_NUMBER value to a SQLSMALLINT value usable by an application.

Call this function only for a column of type TTXLA_NUMBER. The data type can be obtained from the ttXlaColDesc_t structure returned by the ttXlaGetColumnInfo function.

Required privilege

XLA

Syntax

SQLRETURN ttXlaNumberToSmallInt(void* fromData,
                                SQLSMALLINT* smint)

Parameters

Parameter Type Description
fromData void* Pointer to the number value returned from the transaction log
smint SQLSMALLINT* The SQLSMALLINT value converted from the XLA number value

Returns

Returns SQL_SUCCESS if call is successful. Otherwise, use ttXlaError to report the error.


ttXlaNumberToTinyInt

Description

Converts a TTXLA_NUMBER value to a tiny integer value usable by an application.

Call this function only for a column of type TTXLA_NUMBER. The data type can be obtained from the ttXlaColDesc_t structure returned by the ttXlaGetColumnInfo function.

Required privilege

XLA

Syntax

SQLRETURN ttXlaNumberToTinyInt(void* fromData,
                               SQLCHAR* tiny)

Parameters

Parameter Type Description
fromData void* Pointer to the number value returned from the transaction log
tiny SQLCHAR* The tiny integer value converted from the XLA number value

Returns

Returns SQL_SUCCESS if call is successful. Otherwise, use ttXlaError to report the error.


ttXlaNumberToUInt

Description

Converts a TTXLA_NUMBER value to an unsigned integer value usable by an application.

Call this function only for a column of type TTXLA_NUMBER. The data type can be obtained from the ttXlaColDesc_t structure returned by the ttXlaGetColumnInfo function.

Required privilege

XLA

Syntax

SQLRETURN ttXlaNumberToInt(void* fromData,
                           SQLUINTEGER* ival)

Parameters

Parameter Type Description
fromData void* Pointer to the number value returned from the transaction log
ival SQLUINTEGER* The integer value converted from the XLA number value

Returns

Returns SQL_SUCCESS if call is successful. Otherwise, use ttXlaError to report the error.


ttXlaOraDateToODBCTimeStamp

Description

Converts a TTXLA_DATE value to an ODBC timestamp.

Call this function only for a column of type TTXLA_DATE. The data type can be obtained from the ttXlaColDesc_t structure returned by the ttXlaGetColumnInfo function.

Required privilege

XLA

Syntax

SQLRETURN ttXlaOraDateToODBCTimeStamp(void* fromData,
                                      TIMESTAMP_STRUCT* returnData)

Parameters

Parameter Type Description
fromData void* Pointer to the number value returned from the transaction log
returnData TIMESTAMP_STRUCT* ODBC timestamp value converted from the XLA Oracle Database DATE value

Returns

Returns SQL_SUCCESS if call is successful. Otherwise, use ttXlaError to report the error.


ttXlaOraTimeStampToODBCTimeStamp

Description

Converts a TTXLA_TIMESTAMP value to an ODBC timestamp.

Call this function only for a column of type TTXLA_TIMESTAMP. The data type can be obtained from the ttXlaColDesc_t structure returned by the ttXlaGetColumnInfo function.

Syntax

SQLRETURN ttXlaOraTimeStampToODBCTimeStamp(void* fromData,
                                           TIMESTAMP_STRUCT* returnData)

Required privilege

XLA

Parameters

Parameter Type Description
fromData void* Pointer to the number value returned from the transaction log
returnData TIMESTAMP_STRUCT* ODBC timestamp value converted from the XLA Oracle Database TIMESTAMP value

Returns

Returns SQL_SUCCESS if call is successful. Otherwise, use ttXlaError to report the error.


ttXlaPersistOpen

Description

Initializes a transaction log handle to a database to enable access to the transaction log. The hdbc parameter is an ODBC connection handle to a database. Create only one XLA handle for each ODBC connection. After you have created an XLA handle on an ODBC connection, do not issue any other ODBC calls over the ODBC connection until it is closed by ttXlaClose.

The tag is a string that identifies the XLA bookmark (see "About XLA bookmarks"). The tag can identify a new bookmark, either non-replicated or replicated, or one that exists in the system, as specified by the options parameter. The handle parameter is initialized by this call and must be provided on each subsequent call to XLA.

Some actions can be done without a bookmark. When performing these types of actions, you can use the XLANONE option to access the transaction log without a bookmark. Actions that cannot be done without a bookmark are the following:

Multiple applications can concurrently read from the transaction log. See "Initializing XLA and obtaining an XLA handle" for a discussion about using this function.

When this function is successful, XLA sets the autocommit mode to off.

If this function fails but still creates a handle, the handle must be closed to prevent memory leaks.

Note:

Space is allocated by this call. Call ttXlaClose to free space when you are done.

Required privilege

XLA

Syntax

SQLRETURN ttXlaPersistOpen(SQLHDBC hdbc,
                           SQLCHAR* tag,
                           SQLUINTEGER options,
                           out ttXlaHandle_h* handle)

Parameters

Parameter Type Description
hdbc SQLHDBC ODBC handle for the database
tag SQLCHAR* Identifier for the XLA bookmark

This can be null, in which case options should be set to XLANONE. Maximum allowed length is 31.

options SQLUINTEGER Bookmark options:
  • XLANONE: Connect without a bookmark. The tag field is ignored.

  • XLACREAT: Create a new non-replicated bookmark. Fails if a bookmark already exists.

  • XLAREPL: Create a new replicated bookmark. Fails if a bookmark already exists.

  • XLAREUSE: Associate with an existing bookmark (non-replicated or replicated). Fails if the bookmark does not exist.

handle ttXlaHandle_h* Transaction log handle returned by this call

Returns

Returns SQL_SUCCESS if call is successful. Otherwise, use ttXlaError to report the error.

Example

This example opens a transaction log, returns a handle named xlahandle, and creates a new non-replicated bookmark named mybookmark:

SQLHDBC hdbc;
ttXlaHandle_h xlahandle;

rc = ttXlaPersistOpen(hdbc, ( SQLCHAR*)mybookmark,
                      XLACREAT, &xlahandle);

Alternatively, create a new replicated bookmark as follows:

SQLHDBC hdbc;
ttXlaHandle_h xlahandle;

rc = ttXlaPersistOpen(hdbc, ( SQLCHAR*)mybookmark,
                      XLAREPL, &xlahandle);

Note

Multithreaded applications should create a separate XLA handle for each thread. If multiple threads must use the same XLA handle, use a mutex to serialize thread access to that XLA handle so that only one thread can execute an XLA operation at a time.

See also


ttXlaClose
ttXlaDeleteBookmark
ttXlaGetLSN
ttXlaSetLSN

ttXlaRowidToCString

Description

Converts a ROWID value to a string value usable by applications.

Required privilege

XLA

Syntax

SQLRETURN ttXlaRowidToCString(void* fromData, char* buf, int buflen)

Parameters

Parameter Type Description
fromData void* Pointer to the ROWID value returned from the transaction log
buf char* Pointer to storage allocated to hold the converted string
buflen int Length of the converted string

Returns

Returns SQL_SUCCESS if call is successful. Otherwise, use ttXlaError to report the error.

Example

char charbuf[18];
void* rowiddata;
/* ... */
rc = ttXlaRowidToCString(rowiddata, charbuf, sizeof(charbuf));

ttXlaSetLSN

Description

Sets the Current Read log record identifier for the database specified by the transaction handle. The specified LSN value should be returned from ttXlaGetLSN. It cannot be a user-created value and cannot be earlier than the current bookmark Initial Read log record identifier.

See "About XLA bookmarks" for a discussion about using this function.

Required privilege

XLA

Syntax

SQLRETURN ttXlaSetLSN(ttXlaHandle_h handle,
                      tt_XlaLsn_t* LSN)

Parameters

Parameter Type Description
handle ttXlaHandle_h Transaction log handle for the database
LSN tt_XlaLsn_t* New log record identifier for the handle

Note:

Be aware that tt_XlaLsn_t, particularly the logFile and logOffset fields, is used differently than in earlier releases, referring to log record identifiers rather than sequentially increasing LSNs. See the note in "tt_XlaLsn_t".

Returns

Returns SQL_SUCCESS if call is successful. Otherwise, use ttXlaError to report the error.

Example

This example sets the Current Read log record identifier to CurLSN.

tt_XlaLsn_t CurLSN;

rc = ttXlaSetLSN(xlahandle, &CurLSN);

See also

ttXlaGetLSN


ttXlaSetVersion

Description

Sets the version of XLA to be used by the application. This version must be either the same as the version received from ttXlaGetVersion or from an earlier version.

See "XLA basics" for a discussion about using this function.

Required privilege

XLA

Syntax

SQLRETURN ttXlaSetVersion(ttXlaHandle_h handle,
                          ttXlaVersion_t* version)

Parameters

Parameter Type Description
handle ttXlaHandle_h Transaction log handle for the database
version ttXlaVersion_t* Desired version of XLA

Returns

Returns SQL_SUCCESS if call is successful. Otherwise, use ttXlaError to report the error.

Example

To set the configured version to the value specified in requestedVersion, issue the following call:

rc = ttXlaSetVersion(xlahandle, &requestedVersion);

See also


ttXlaVersionCompare
ttXlaGetVersion

ttXlaTableByName

Description

Finds the system and user table identifiers for a table or materialized view by providing the owner and name of the table or view. See "Specifying which tables to monitor for updates" for a discussion about using this function.

Required privilege

XLA

Syntax

SQLRETURN ttXlaTableByName(ttXlaHandle_h handle,
                           char* owner,
                           char* name,
                           out SQLUBIGINT* sysTableID,
                           out SQLUBIGINT* userTableID)

Parameters

Parameter Type Description
handle ttXlaHandle_h Transaction log handle for the database
owner char* Owner for the table or view as a string
name char* Name of the table or view
sysTableID SQLUBIGINT* System table ID
userTableID SQLUBIGINT* User table ID

Returns

Returns SQL_SUCCESS if call is successful. Otherwise, use ttXlaError to report the error.

Example

To get the system and user table IDs associated with the table PURCHASING.INVOICES, use the following call:

SQLUBIGINT sysTableID;
SQLUBIGINT userTableID;

rc = ttXlaTableByName(xlahandle, "PURCHASING", "INVOICES", 
                      &sysTableID, &userTableID);

See also

ttXlaTableStatus


ttXlaTableStatus

Description

Returns the update status for a table. Identify the table by specifying either a user ID (userTableID) or a system ID (systemTableID). If userTableID is nonzero, it is used to locate the table. Otherwise systemTableID is used. If both are zero, an error is returned.

Specifying a value for newstatus sets the update status to *newstatus. A nonzero status means the table specified by systemTableID is available through XLA. Zero means the table is not tracked. Changes to table update status are effective immediately.

Updates to a table are tracked only if update tracking was enabled for the table at the time the update was performed. This call is serialized with respect to updates to the underlying table. Therefore, transactions that update the table run either completely before or completely after the change to table status.

To use ttXlaTableStatus, the user must be connected to a bookmark. The function reports inserts, updates, and deletes only to the bookmark that has subscribed to the table. It reports DDL events to all bookmarks. DDL events include CREATAB, DROPTAB, CREAIND, DROPIND, CREATVIEW, DROPVIEW, CREATSEQ, DROPSEQ, CREATSYN, DROPSYN, ADDCOLS, DRPCOLS, TRUNCATE, SETTBL1, and SETCOL1 transactions. See "ttXlaUpdateDesc_t" for information about these event types.

See "Specifying which tables to monitor for updates" for a discussion about using this function.

Note:

DML updates to a table being tracked through XLA do not prevent ttXlaTableStatus from running. However, DDL updates to the table being tracked, which take a lock on SYS.TABLES, do delay ttXlaTableStatus from running in serializable isolation against SYS.TABLES.

Required privilege

XLA

Syntax

SQLRETURN ttXlaTableStatus(ttXlaHandle_h handle,
                           SQLUBIGINT systemTableID,
                           SQLUBIGINT userTableID,
                           out SQLINTEGER* oldstatus,
                           SQLINTEGER* newstatus)

Parameters

Parameter Type Description
handle ttXlaHandle_h Transaction log handle for the database
systemTableID SQLUBIGINT System ID of table
userTableID SQLUBIGINT User ID of table
oldstatus SQLINTEGER* XLA old status:
  • 1: On

  • 0: Off

newstatus SQLINTEGER* XLA new status:
  • 1: On

  • 0: Off


Returns

Returns SQL_SUCCESS if call is successful. Otherwise, use ttXlaError to report the error.

Example

The following examples assume that the system or user table identifiers are found using ttXlaTableByName or some other means.

Assume these declarations for the example:

SQLUBIGINT systemTableID;
SQLUBIGINT userTableID;
SQLINTEGER currentStatus, requestedStatus;

To find the status of a table given its system table identifier, use the following call:

/* Get system table identifier into systemTableID, then ... */
rc = ttXlaTableStatus(xlahandle, systemTableID, 0,
                      &currentStatus, NULL);

The currentStatus value is nonzero if update tracking for the table is enabled, or zero otherwise.

To enable update tracking for a table given a system table identifier, set the requested status to 1 as follows:

requestedStatus = 1;

rc = ttXlaTableStatus(xlahandle, systemTableID, 0,
                      NULL, &requestedStatus);

You can set a new update tracking status and retrieve the current status in a single call, as in the following example:

requestedStatus = 1;

rc = ttXlaTableStatus(xlahandle, systemTableID, 0,
                      &currentStatus, &requestedStatus);

The above call enables update tracking for a table by system table identifier and retrieves the prior update tracking status in the variable currentStatus.

All of these examples can be done using user table identifiers as well. To retrieve the update tracking status of a table through its user table identifier, use the following call:

/* Get system table identifier into userTableID, then ... */

rc = ttXlaTableStatus(xlahandle, 0, userTableID,
                      &currentStatus, NULL);

See also

ttXlaTableByName


ttXlaTableVersionVerify

Description

Verifies that the cached table definitions are compatible with the XLA record being processed. Table definitions change only when the ALTER TABLE statement is used to add or remove columns.

You can monitor the XLA stream for XLA records of transaction type ADDCOLS and DRPCOLS to avoid the overhead of using this function. When an XLA record of transaction type ADDCOLS or DROPCOLS is encountered, refresh the table and column definitions. See "Inspecting record headers and locating row addresses" for information about monitoring XLA records for transaction type.

Required privilege

XLA

Syntax

SQLRETURN ttXlaTableVersionVerify(ttXlaHandle_h handle
                                  ttXlaTblVerDesc_t* table,
                                  ttXlaUpdateDesc_t* record
                                  out SQLINTEGER* compat)

Parameters

Parameter Type Description
handle ttXlaHandle_h Transaction log handle for the database
table ttXlaTblVerDesc_t* A cached table description
record ttXlaUpdateDesc_t* XLA record to be processed
compat SQLINTEGER* Compatibility information:
  • 1: Tables are compatible.

  • 0: Tables are not compatible.


Returns

Returns SQL_SUCCESS if cached table definition is compatible with the XLA record being processed. Otherwise, use ttXlaError to report the error.

Example

This example checks the compatibility of a table.

SQLINTEGER compat;
ttXlaTbVerDesc_t table;
ttXlaUpdateDesc_t* record;
/*
 * Get the desired table definitions into the variable "table"
 */
rc = ttXlaTableVersionVerify(xlahandle, &table, record, &compat);
if (compat) {
/*
 * Compatible
 */
}
else {
/*
 * Not compatible or some other error occurred
 * If not compatible, issue a call to ttXlaVersionTableInfo and
 * ttXlaVersionColumnInfo to get the new definition.
 */
}

See also


ttXlaVersionColumnInfo
ttXlaVersionTableInfo

ttXlaTimeToODBCCType

Description

Converts a TTXLA_TIME value to an ODBC C value usable by applications. See "Converting complex data types" for a discussion about using this function.

Call this function only for a column of type TTXLA_TIME. The data type can be obtained from the ttXlaColDesc_t structure returned by the ttXlaGetColumnInfo function.

Required privilege

XLA

Syntax

SQLRETURN ttXlaTimeToODBCCType (void* fromData,
                                out TIME_STRUCT* returnData)

Parameters

Parameter Type Description
fromData void* Pointer to the time value returned from the transaction log
returnData TIME_STRUCT* Pointer to storage allocated to hold the converted time

Returns

Returns SQL_SUCCESS if call is successful. Otherwise, use ttXlaError to report the error.

Example

This example assumes you have used the offset value returned in a ttXlaColDesc_t structure to obtain a time value, pColVal, from a row returned in a transaction log record.

TIME_STRUCT time;

rc = ttXlaTimeToODBCCType(pColVal, &time);

ttXlaTimeStampToODBCCType

Description

Converts a TTXLA_TIMSTAMP_TT value to an ODBC C value usable by applications. See "Converting complex data types" for a discussion about using this function.

Call this function only for a column of type TTXLA_TIMSTAMP_TT. The data type can be obtained from the ttXlaColDesc_t structure returned by the ttXlaGetColumnInfo function.

Required privilege

XLA

Syntax

SQLRETURN ttXlaTimeStampToODBCCType(void* fromData,
                                    out TIMESTAMP_STRUCT* returnData)

Parameters

Parameter Type Description
fromData void* Pointer to the timestamp value returned from the transaction log
returnData TIMESTAMP_STRUCT* Pointer to storage allocated to hold the converted timestamp

Returns

Returns SQL_SUCCESS if call is successful. Otherwise, use ttXlaError to report the error.

Example

This example assumes you have used the offset value returned in a ttXlaColDesc_t structure to obtain a timestamp value, pColVal, from a row returned in a transaction log record.

TIMESTAMP_STRUCT timestamp;

rc = ttXlaTimeStampToODBCCType(pColVal, &timestamp);

ttXlaVersionColumnInfo

Description

Retrieves information about the columns in a table for which a change update XLA record must be processed.

Required privilege

XLA

Syntax

SQLRETURN ttXlaVersionColumnInfo(ttXlaHandle_h handle,
                                 ttXlaUpdateDesc_t* record,
                                 out ttXlaColDesc_t* colinfo,
                                 SQLINTEGER maxcols,
                                 out SQLINTEGER* nreturned)

Parameters

Parameter Type Description
handle ttXlaHandle_h Transaction log handle for the database
record ttXlaUpdateDesc_t* XLA record to be processed
colinfo ttXlaColDesc_t* A pointer to the buffer large enough to hold a description for maxcols columns
maxcols SQLINTEGER Maximum number of columns the table can have

Note: If the table contains more than maxcols columns, an error is returned.

nreturned SQLINTEGER* Number of columns returned

Returns

Returns SQL_SUCCESS if call is successful. Otherwise, use ttXlaError to report the error.

Example

For this example, assume the following definitions:

ttXlaHandle_h xlahandle
ttXlaUpdateDesc_t* record;
ttXlaColDesc_t colinfo[20];
SQLINTEGER ncols;

The following call retrieves the description of up to 20 columns:

rc = ttXlaVersionColumnInfo(xlahandle, record, colinfo, 20, &ncols);

ttXlaVersionCompare

Description

Compares two XLA versions and returns the result.

Required privilege

XLA

Syntax

SQLRETURN ttXlaVersionCompare(ttXlaHandle_h handle,
                              ttXlaVersion_t* version1,
                              ttXlaVersion_t* version2,
                              out SQLINTEGER* comparison)

Parameters

Parameter Type Description
handle ttXlaHandle_h Transaction log handle for the database
version1 ttXlaVersion_t* Version of XLA to compare with version2
version2 ttXlaVersion_t* Version of XLA to compare with version1
comparison SQLINTEGER* Comparison result:
  • 0: Indicates version1 and version2 match.

  • -1: Indicates version1 is earlier than version2.

  • +1: Indicates version1 is later than version2.


Returns

Returns SQL_SUCCESS if call is successful. Otherwise, use ttXlaError to report the error.

Example

To compare the configured version against the actual version of XLA, issue the following call:

ttXlaVersion_t configured, actual;
SQLINTEGER comparision;

rc = ttXlaGetVersion (xlahandle, &configured, &actual);
rc = ttXlaVersionCompare (xlahandle, &configured, &actual,
                          &comparison);

Notes

When connecting two systems with XLA-based replication, use the following protocol:

  1. At the primary site, retrieve the XLA version using ttXlaGetVersion. Send this version information to the standby site.

  2. At the standby site, retrieve the XLA version using ttXlaGetVersion. Use ttXlaVersionCompare to determine which version is earlier. The earlier version number must be used to ensure proper operation between the two sites. Use ttXlaSetVersion to specify the version of the interface to use at the standby site. Send the earlier version number back to the primary site.

  3. When the chosen version is received at the primary site, use ttXlaSetVersion to specify the version of XLA to use.

See also


ttXlaGetVersion
ttXlaSetVersion

ttXlaVersionTableInfo

Description

Retrieves the table definition for the change update record that must be processed. The table description is stored in the tableinfo output parameter.

Required privilege

XLA

Syntax

SQLRETURN ttXlaVersionTableInfo(ttXlaHandle_h handle,
                                ttXlaUpdateDesc_t* record,
                                out ttXlaTblVerDesc_t* tblinfo)

Parameters

Parameter Type Description
handle ttXlaHandle_h Transaction log handle for the database
record ttXlaUpdateDesc_t* XLA record to be processed
tableinfo ttXlaTblVerDesc_t* Information about table definition

Returns

Returns SQL_SUCCESS if call is successful. Otherwise, use ttXlaError to report the error.

Example

For this example, assume the following definitions:

ttXlaHandle_h xlahandle;
ttXlaUpdateDesc_t* record;
ttXlaTblVerDesc_t tabinfo;

The following call retrieves a table definition:

rc = ttXlaVersionTableInfo(xlahandle, record, &tabinfo);

XLA replication function reference

TimesTen replication as described in Oracle TimesTen In-Memory Database Replication Guide is sufficient for most customer needs; however, it is also possible to use XLA functions to replicate updates from one database to another. Implementing your own replication scheme on top of XLA in this way is fairly complicated, but can be considered if TimesTen replication is not feasible for some reason.

This section documents the functions that are exclusive to using XLA as a replication mechanism. Functions are listed in alphabetical order.


ttXlaApply

This function is part of XLA replication functionality and is not appropriate for use in a typical XLA application.

Description

Applies an update to the database associated with the transaction log handle. The return value indicates whether the update was successful. The return also shows if the update encountered a persistent problem. (To see whether the update encountered a transient problem such as a deadlock or timeout, you must call ttXlaError and check the error code.)

If the ttXlaUpdateDesc_t record is a transaction commit, the underlying database transaction is committed. No other transaction commits are performed by ttXlaApply. If the parameter test is true, the "old values" in the update description are compared against the current contents of the database for record updates and deletions. If the old value in the update description does not match the corresponding row in the database, this function rejects the update and returns an sb_ErrXlaTupleMismatch error.

See "Using XLA as a replication mechanism" for a discussion about using this function.

Note:

ttXlaApply cannot be used if the table definition was updated since it was originally written to the transaction log. Unique key and foreign key constraints are checked at the row level rather than at the statement level.

Required privilege

ADMIN

Additional privileges may be required on the target database for the ttXlaApply operation. For example, to apply a CREATETAB (create table) record to the target database, you must have CREATE TABLE or CREATE ANY TABLE privilege, as appropriate.

Syntax

SQLRETURN ttXlaApply(ttXlaHandle_h handle,
                     ttXlaUpdateDesc_t* record,
                     SQLINTEGER test)

Parameters

Parameter Type Description
handle ttXlaHandle_h Transaction log handle for the database
record ttXlaUpdateDesc_t* Transaction to generate SQL statement
test SQLINTEGER Test for old values:
  • 1: Test on

  • 0: Test off


Returns

Returns SQL_SUCCESS if call is successful. Otherwise, use ttXlaError to report the error.

If test is 1 and ttXlaApply detects an update conflict, an sb_ErrXlaTupleMismatch error is returned.

Example

This example applies an update to a database without testing for the previous value of the existing record:

ttXlaUpdateDesc_t record;
rc = ttXlaApply(xlahandle, &record, 0);

Note

When calling ttXlaApply, it is possible for the update to timeout or deadlock with concurrent transactions. In such cases, it is the application's responsibility to roll the transaction back and reapply the updates.

See also


ttXlaCommit
ttXlaRollback
ttXlaLookup
ttXlaTableCheck
ttXlaGenerateSQL

ttXlaCommit

This function is part of XLA replication functionality and is not appropriate for use in a typical XLA application.

Description

Commits the current transaction being applied on the transaction log handle. This routine commits the transaction regardless of whether the transaction has completed. You can call this routine to respond to transient errors (timeout or deadlock) reported by ttXlaApply, which applies the current transaction if it does not encounter an error.

See "Handling timeout and deadlock errors" for a discussion about using this function.

Required privilege

XLA

Syntax

SQLRETURN ttXlaCommit(ttXlaHandle_h handle)

Parameters

Parameter Type Description
handle ttXlaHandle_h Transaction log handle for the database

Returns

Returns SQL_SUCCESS if call is successful. Otherwise, use ttXlaError to report the error.

Example

rc = ttXlaCommit(xlahandle);

See also


ttXlaApply
ttXlaRollback
ttXlaLookup
ttXlaTableCheck
ttXlaGenerateSQL

ttXlaGenerateSQL

This function is part of XLA replication functionality and is not appropriate for use in a typical XLA application.

Note:

This function does not currently work with LOB locators.

Description

Generates a SQL DML or DDL statement that expresses the effect of the update record. The generated statement is not applied to any database. Instead, the statement is returned in the given buffer, whose maximum size is specified by the maxLen parameter. The actual size of the buffer is returned in actualLen. For update and delete records, ttXlaGenerateSQL requires a primary key or a unique index on a non-nullable column to generate the correct SQL.

The generated SQL statement is encoded in the connection character set that is associated with the ODBC connection of the XLA handle.

Also see "Replicating updates to a non-TimesTen database".

Required privilege

XLA

Syntax

SQLRETURN ttXlaGenerateSQL(ttXlaHandle_h handle,
                           ttXlaUpdateDesc_t* record,
                           out char* buffer,
                           SQLINTEGER maxLen,
                           out SQLINTEGER* actualLen)

Parameters

Parameter Type Description
handle ttXlaHandle_h Transaction log handle for the database
record ttXlaUpdateDesc_t* Record to be translated into SQL
buffer char* Location of the translated SQL statement
maxLen SQLINTEGER Maximum length of the buffer, in bytes
actualLen SQLINTEGER* Actual length of the buffer, in bytes

Returns

Returns SQL_SUCCESS if call is successful. Otherwise, use ttXlaError to report the error.

Example

This example generates the text of a SQL statement that is equivalent to the UPDATE expressed by an update record:

ttXlaUpdateDesc_t record;
char buffer[200];
/*
 * Get the desired update record into the varable record.
 */

SQLINTEGER actualLength;

rc = ttXlaGenerateSQL(xlahandle, &record, buffer, 200,
                      &actualLength);

Note

The ttXlaGenerateSQL function cannot generate SQL statements for update records associated with a table that has been dropped or altered since the record was generated.

See also


ttXlaApply
ttXlaCommit
ttXlaRollback
ttXlaLookup
ttXlaTableCheck

ttXlaLookup

This function is part of XLA replication functionality and is not appropriate for use in a typical XLA application.

Description

This function looks for a record in the given table with key values according to the keys parameter. The formats of the keys and result records are the same as for ordinary rows. This function requires a primary key on the underlying table.

Required privilege

XLA

Syntax

SQLRETURN ttXlaLookup(ttXlaHandle_h handle,
                      ttXlaTableDesc_t* table,
                      void* keys,
                      out void* result,
                      SQLINTEGER maxsize,
                      out SQLINTEGER* retsize)

Parameters

Parameter Type Description
handle ttXlaHandle_h Transaction log handle for the database
table ttXlaTblDesc_t* Table to search
keys void* A record in the defined structure for the table

Only those columns of the keys record that are part of the primary key for the table are examined.

result void* Where the located record is copied

If no record exists with the matching key columns, an error is returned.

maxsize SQLINTEGER Size of the largest record that can fit into the result buffer
retsize SQLINTEGER* Actual size of the record

Returns

Returns SQL_SUCCESS if call is successful. Otherwise, use ttXlaError to report the error.

Example

This example looks up a record given a pair of integer key values. Before this call, table should describe the desired table and keybuffer contains a record with the key columns set.

char keybuffer[100];
char recbuffer[2000];
ttXlaTableDesc_t table;
SQLINTEGER recordSize;

rc = ttXlaLookup(xlahandle, &table, keybuffer, recbuffer,
                 sizeof (recbuffer), &recordSize);

See also


ttXlaApply
ttXlaCommit
ttXlaRollback
ttXlaTableCheck
ttXlaGenerateSQL

ttXlaRollback

This function is part of XLA replication functionality and is not appropriate for use in a typical XLA application.

Description

Rolls back the current transaction being applied on the transaction log handle. You can call this routine to respond to transient errors (timeout or deadlock) reported by ttXlaApply.

See "Handling timeout and deadlock errors" for a discussion about using this function.

Required privilege

XLA

Syntax

SQLRETURN ttXlaRollback(ttXlaHandle_h handle)

Parameters

Parameter Type Description
handle ttXlaHandle_h Transaction log handle for the database

Returns

Returns SQL_SUCCESS if call is successful. Otherwise, use ttXlaError to report the error.

Example

rc = ttXlaRollback(xlahandle);

See Also


ttXlaApply
ttXlaCommit
ttXlaLookup
ttXlaTableCheck
ttXlaGenerateSQL

ttXlaTableCheck

This function is part of XLA replication functionality and is not appropriate for use in a typical XLA application.

Description

When using XLA as a replication mechanism, this function verifies that the named table in the ttXlaTblDesc_t structure received from a master database is compatible with a subscriber database or database associated with the transaction log handle. The compat parameter indicates whether the tables are compatible.

See "Checking table compatibility between databases" for a discussion about using this function.

Required privilege

XLA

Syntax

SQLRETURN ttXlaTableCheck(ttXlaHandle_h handle,
                          ttXlaTblDesc_t* table,
                          ttXlaColDesc_t* columns,
                          out SQLINTEGER* compat)

Parameters

Parameter Type Description
handle ttXlaHandle_h Transaction log handle for the database
table ttXlaTblDesc_t* Table description
columns ttXlaColDesc_t* Column description for the table
compat SQLINTEGER* Compatibility information:
  • 1: Tables are compatible.

  • 0: Tables are not compatible.


Returns

Returns SQL_SUCCESS if call is successful. Otherwise, use ttXlaError to report the error.

Example

This example checks the compatibility of a table:

SQLINTEGER compat;
ttXlaTblDesc_t table;
ttXlaColDesc_t columns[20];
/*
 * Get the desired table and column definitions into
 * the variables "table" and "columns"
 */
rc = ttXlaTableCheck(xlahandle, &table, columns, &compat);
if (compat) {
    /* Compatible */
}
else {
    /*
     * Not compatible or some other error occurred
     */
}

See also


ttXlaApply
ttXlaCommit
ttXlaRollback
ttXlaLookup
ttXlaGenerateSQL

C data structures used by XLA

This section describes the C data structures used by the XLA functions described in this chapter. These structures are defined in the following file:

install_dir/include/tt_xla.h

You must include this file when building your XLA application.

Table 9-1 Summary of C data structures

C data structure Description

ttXlaNodeHdr_t

Describes the record type. Used at the beginning of records returned by XLA.

ttXlaUpdateDesc_t

Describes an update record.

ttXlaVersion_t

Describes XLA version information returned by ttXlaGetVersion.

ttXlaTblDesc_t

Describes table information returned by ttXlaGetTableInfo.

ttXlaTblVerDesc_t

Describes table version returned by ttXlaVersionTableInfo.

ttXlaColDesc_t

Describes table column information returned by ttXlaGetColumnInfo.

tt_LSN_t

Describes a log record identifier used by bookmarks. This structure is used by the ttXlaUpdateDesc_t structure.

tt_XlaLsn_t

Describes a log record identifier used by an XLA bookmark.



ttXlaNodeHdr_t

Most C data structures begin with a standard header that describes the data record type and length. The standard header has the type ttXlaNodeHdr_t.

This header has the following fields.

Field Type Description
nodeType char The type of record:
  • TTXLANHVERSION: Version

  • TTXLANHUPDATE: Update

  • TTXLANHTABLEDESC: Table description

  • TTXLANHCOLDESC: Column description

  • TTXLANHSTATUS: Status

  • TTXLANHINVALID: Invalid

byteOrder char Byte order of the record:
  • "1": Big-endian

  • "2": Little-endian

length SQLUINTEGER Total length of record, including all attachments


ttXlaUpdateDesc_t

This structure describes an update operation to a single row (or tuple) in the database. Each update record returned by a ttXlaNextUpdate or ttXlaNextUpdateWait function begins with a fixed length ttXlaUpdateDesc_t header followed by zero to two rows from the database. The row data differs depending on the record type reported in the ttXlaUpdateDesc_t header:

The flags field is a bit-map of special options for the record update.

The connID field identifies the ODBC connection handle that initiated the update. This value can be used to determine if updates came from the same connection.

A separate commit XLA record is generated when a call to the ttApplicationContext procedure is not followed by an operation that generates an XLA record. See "Passing application context" for a description of the ttApplicationContext procedure.

Note

XLA cannot receive notification of the following:

The only XLA records that can be generated from an ALTER TABLE operation are of the following types:

While sequence creates (CREATESEQ) and drops (DROPSEQ) are visible through XLA, sequence increments are not.

All deletes resulting from cascading deletes and aging are visible through XLA. The flags value (discussed in the following table) indicates when deletes are due to cascading or aging.

The fields of the update header defined by ttXlaUpdateDesc_t are as follows.

Field Type Description
header ttXlaNodeHdr_t Standard data header
type SQLUSMALLINT Record type:
  • CREATAB: Create table.

  • DROPTAB: Drop table.

  • CREAIND: Create index.

  • DROPIND: Drop index.

  • CREATVIEW: Create view.

  • DROPVIEW: Drop view.

  • CREATSEQ: Create sequence.

  • DROPSEQ: Drop sequence.

  • CREATSYN: Create synonym.

  • DROPSYN: Drop synonym.

  • ADDCOLS: Add columns.

  • DRPCOLS: Drop columns.

  • TRUNCATE: Truncate table.

  • INSERTTUP: Insert.

  • UPDATETUP: Update.

  • DELETETUP: Delete.

  • COMMITONLY: Commit.

flags SQLUSMALLINT Special options on record update:
  • TT_UPDCOMMIT: Indicates that the update record is the last record for the transaction. (Implied commit.)

  • TT_UPDFIRST: Indicates that the update record is the first record for the transaction.

  • TT_UPDREPL: Indicates that this update was the result of a non-XLA TimesTen replicated update from another database.

  • TT_UPDCOLS: Indicates the presence of a list following the last returned row that specifies which columns in the row were updated. The list consists of an array of SQLUSMALLINT values, the first of which is the number of columns that were updated, followed by the column numbers of the updated columns. For example, if the first and third columns are updated, the array is (2, 1, 3) or (2, 3, 1), depending on the UPDATE statement used. This array is in all UPDATETUP records.

  • TT_UPDDEFAULT: Indicates that the update record (either a CREATAB or ADDCOLS) contains default column values. If set, the default columns are presented as an array of SQLUSMALLINT values followed by a string with all the default values concatenated. The number of SQLUSMALLINT values in the array equals the number of columns in the CREATAB or ADDCOLS record.

  • TT_CASCDEL: Indicates that the XLA update was generated as part of a cascade delete operation.

  • TT_AGING: Indicates that the XLA update was generated as part of an aging operation.

If the value of a specific column is 0, it indicates that column does not have a default value. The defaults for all nonzero values are concatenated in a string and are presented in order, with the array value indicating the length of the default value. For example, three columns with defaults 1 of type INTEGER, no default, and "apple" of type VARCHAR2(10) is (1,0,5)"1apple".

Decimal values for each of these flags bits is as follows. (Note that some flag values are for internal use only.)

TT_UPDCOMMIT     1
TT_UPDFIRST      2
TT_UPDREPL       4
TT_UPDCOLS       8
TT_UPDDEFAULT   64
TT_CASCDEL     256
TT_AGING       512
contextOffset SQLUINTEGER Offset to application-provided context value

This value is 0 if there is no context. A nonzero value indicates the location of the context relative to the beginning of the XLA record.

connID SQLUBIGINT Connection ID owning the transaction
sysTableID SQLUBIGINT System-provided identifier of the affected table
userTableID SQLUBIGINT Application-defined table ID of the affected table
tranID SQLUBIGINT Read-only, system-provided transaction identifier
LSN tt_LSN_t Transaction log record identifier of this operation, used for diagnostics
tuple1 SQLUINTEGER Length of first row (tuple), or zero
tuple2 SQLUINTEGER Length of second row (tuple), or zero

Note:

Be aware that tt_LSN_t, particularly the logFile and logOffset fields, is used differently than in earlier releases, referring to log record identifiers rather than sequentially increasing LSNs. See the note in "tt_LSN_t".

Special update data formats

The data contained in an update record follows the ttXlaTblDesc_t header. This section describes the data formats for the special update records related to specific SQL operations.

CREATE TABLE

For a CREATE TABLE operation, the special row value consists of the ttXlaTblDesc_t record describing the new table, followed by the ttXlaColDesc_t records that describe each column.


ALTER TABLE

For an ALTER TABLE operation, the special row value consists of a ttXlaDropTableTup_t or ttXlaAddColumnTup_t value, followed by a ttXlaColDesc_t record that describes the column.


ttXlaDropTableTup_t

For a DROP TABLE operation, the row value is as follows.

Field Type Description
tblName char(31) Name of the dropped table
tblOwner char(31) Owner of the dropped table


ttXlaTruncateTableTup_t

For a TRUNCATE TABLE operation, the row value is as follows.

Field Type Description
tblName char(31) Name of the truncated table
tblOwner char(31) Owner of the truncated table


ttXlaCreateIndexTup_t

For a CREATE INDEX operation, the row value is as follows.

Field Type Description
tblName char(31) Name of the table on which the index is defined
tblOwner char(31) Owner of the table on which the index is defined
ixName char(31) Name of the new index
flag char(31) Index flag:
  • "P": Primary key

  • "F": Foreign key

  • "R": Regular

nixcols SQLUINTEGER Number of indexed columns
ixColsSys SQLUINTEGER(16) Indexed column numbers using system numbers
ixColsUser SQLUINTEGER(16) Indexed column numbers using user-defined column IDs
ixType char Type of index:
  • "T": Range

  • "H": Hash

  • "B": Bit map

ixUnique char Uniqueness of index:
  • "U": Unique

  • "N": Non-unique

pages SQLUINTEGER Number of pages for hash indexes


ttXlaDropIndexTup_t

For a DROP INDEX operation, the row value is as follows.

Field Type Description
tblName char(31) Name of the table on which the index was dropped
tblOwner char(31) Owner of the table on which the index was dropped
ixName char(31) Name of the dropped index


ttXlaAddColumnTup_t

For an ADD COLUMN operation, the row value is as follows.

Field Type Description
ncols SQLUINTEGER Number of additional columns

Following this special row are the ttXlaColDesc_t records describing the new columns.


ttXlaDropColumnTup_t

For a DROP COLUMN operation, the row value is as follows.

Field Type Description
ncols SQLUINTEGER Number of dropped columns

Following this special row is an array of ttXlaColDesc_t records describing the columns that were dropped.


ttXlaCreateSeqTup_t

For a CREATE SEQUENCE operation, the row value is as follows.

Field Type Description
sqName char(31) Name of sequence
sqOwner char(31) Owner of sequence
cycle char Cycle flag

Indicates whether the sequence number generator continues to generate numbers after it reaches the maximum or minimum value:

  • "1": Yes

  • "0": No

minval SQLBIGINT Minimum value of sequence
maxval SQLBIGINT Maximum value of sequence
incr SQLBIGINT Increment between sequence numbers

Positive numbers indicate an ascending sequence and negative numbers indicate a descending sequence. In a descending sequence, the range goes from maxval to minval. In an ascending sequence, the range goes from minval to maxval.



ttXlaDropSeqTup_t

For a DROP SEQUENCE operation, the row value is as follows.

Field Type Description
sqName char(31) Name of sequence
sqOwner char(31) Owner of sequence


ttXlaViewDesc_t

For a CREATE VIEW operation, the row value is as follows.

Note:

This applies to either materialized or non-materialized views.
Field Type Description
vwName char(31) Name of view
vwOwner char(31) Owner of view
sysTableID SQLUBIGINT System table ID stored in SYS.TABLES


ttXlaDropViewTup_t

For a DROP VIEW operation, the row value is as follows.

Note:

This applies to either materialized or non-materialized views.
Field Type Description
vwName char(31) Name of view
vwOwner char(31) Owner of view


ttXlaCreateSynTup_t

For a CREATE SYNONYM operation, the row value is as follows.

Field Type Description
synName char(31) Name of synonym
synOwner char(31) Owner of synonym
objName char(31) Name of object the synonym points to
objOwner char(31) Owner of object the synonym points to
isPublic char Indicates whether the synonym is public:
  • "1": True

  • "0": False

isReplace char Indicates whether the synonym was created using CREATE OR REPLACE:
  • "1": True

  • "0": False



ttXlaDropSynTup_t

For a DROP SYNONYM operation, the row value is as follows.

Field Type Description
synName char(31) Name of synonym
synOwner char(31) Owner of synonym
isPublic char Indicates whether the synonym is public:
  • "1": True

  • "0": False



ttXlaSetTableTup_t

The description of the SET TABLE ID operation uses the previously assigned application table identifier in the main part of the update record and provides the new value of the application table identifier in the following special row.

Field Type Description
newID SQLUBIGINT New user-defined table ID


ttXlaSetColumnTup_t

The description of the SET COLUMN ID operation provides the following special row:

Field Type Description
oldUserColID SQLUINTEGER Previous user-defined column ID value
newUserColID SQLUINTEGER New user-defined column ID value
sysColID SQLUINTEGER System column ID


ttXlaSetStatusTup_t

A change in a table's replication status provides the following special row:

Field Type Description
oldStatus SQLUINTEGER Previous replication status
newStatus SQLUINTEGER New replication status


Locating the row data following a ttXlaUpdateDesc_t header

See "Retrieving update records from the transaction log" and "Inspecting record headers and locating row addresses" for a detailed discussion on obtaining update records and inspecting the contents of ttXlaUpdateDesc_t headers. Below is a summary of these procedures.

The update header is immediately followed by the row data. The row data is stored in an internal format with the offsets given in the ttXlaColDesc_t structure returned by ttXlaGetColumnInfo.

You can locate the address of the row data by adding the address of the update header to its size.

For example:

char* Row = (char*)&ttXlaUpdateDesc_t +
             sizeof(ttXlaUpdateDesc_t);

For UPDATETUP records, there are two rows of data following the ttXlaUpdateDesc_t header. The first row contains the data before the update, and the second row the data after the update.

Since the new row is right after the old row, you can calculate its address by adding the address of the old row to its length (tuple1).

For example:

char* oldRow = (char*)&ttXlaUpdateDesc_t +
                sizeof(ttXlaUpdateDesc_t);
char* newRow = oldRow + ttXlaUpdateDesc_t.tuple1;

See "ttXlaColDesc_t" for details on how to access the column data in a returned row.


ttXlaVersion_t

To permit future extensions to XLA, a version structure ttXlaVersion_t describes the current XLA version and structure byte order. This structure is returned by the ttXlaGetVersion function.

This structure has the following fields:

Field Type Description
header ttXlaNodeHdr_t Standard data header
hardware char(16) Name of hardware platform
wordSize SQLUINTEGER Native word size (32 or 64)
TTMajor SQLUINTEGER TimesTen major version
TTMinor SQLUINTEGER TimesTen minor version
TTPatch SQLUINTEGER TimesTen point release number
OS char(16) Name of operating system
OSMajor SQLUINTEGER Operating system major version
OSMinor SQLUINTEGER Operating system minor version


ttXlaTblDesc_t

Table information is portrayed through the ttXlaTblDesc_t structure. This structure is returned by the ttXlaGetTableInfo function.

This structure has the following fields:

Field Type Description
header ttXlaNodeHdr_t Standard data header
tblName char(31) Name of the table, null-terminated
tblOwner char(31) Owner of the table, null-terminated
sysTableID SQLUBIGINT Unique system-defined table identifier
userTableId SQLUBIGINT User-defined table identifier
columns SQLUINTEGER Number of columns
width SQLUINTEGER Inline row size
nPrimCols SQLUINTEGER Number of primary columns
primColsSys SQLUINTEGER(16) System primary key column numbers
primColsUser SQLUINTEGER(16) User-defined primary key column numbers

The inline row size includes space for all fixed-width columns, null column flags, and pointer information for variable-length columns. Each varying-length column occupies four bytes of inline row space.

Note the following if the table has a declared primary key:


ttXlaTblVerDesc_t

This data structure contains the table version number and ttXlaTblDesc_t. It is returned by ttXlaVersionTableInfo. This structure has the following fields:

Field Type Description
tblDesc ttXlaTblDesc_t Table description
tblVer SQLBIGINT System-generated table version number


ttXlaColDesc_t

Column information is given through this structure, which is returned by the ttXlaGetColumnInfo function.

The structure has the following fields:

Field Type Description
header ttXlaNodeHdr_t Standard data header
colName [tt_NameLenMax] char Name of the column
pad0 SQLUINTEGER Pad to four-byte boundary
sysColNum SQLUINTEGER Ordinal number of the column as determined when the table is created or subsequently altered

This is the same as the corresponding COLNUM value in SYS.COLUMNS. (See "SYS.COLUMNS" in Oracle TimesTen In-Memory Database System Tables and Views Reference.)

userColNum SQLUINTEGER Ordinal number of the column if optionally specified by the user

This is zero or a column number specified through the ttSetUserColumnID TimesTen built-in procedure. (See "ttSetUserColumnID" in Oracle TimesTen In-Memory Database Reference.)

dataType SQLUINTEGER Structure in ODBC TTXLA_* code

See "About XLA data types".

size SQLUINTEGER Maximum or basic size of column
offset SQLUINTEGER Offset to fixed-length part of column
nullOffset SQLUINTEGER Offset to null byte, or zero if not nullable
precision SQLSMALLINT Numeric precision for decimal types
scale SQLSMALLINT Numeric scale for decimal types
flags SQLUINTEGER Column flag:
  • TT_COLPRIMKEY: Column is primary key.

  • TT_COLVARYING: Column is stored out of line.

  • TT_COLNULLABLE: Column is nullable.

  • TT_COLUNIQUE: Column has a unique attribute defined on it.


The procedures for obtaining a ttXlaColDesc_t structure and inspecting its contents are described in "Inspecting column data". Below is a summary of these procedures.

The ttXlaColDesc_t structure is returned by the ttXlaGetColumnInfo function. This structure contains the metadata needed to access column information in a particular table. For example, you can use the offset field to locate specific column data in the row or rows returned in an update record after the ttXlaColDesc_t structure. By adding the offset to the address of a returned row, you can locate the address to the column value. You can then cast this value to the corresponding C types according to the dataType field, or pass it to one of the conversion routines described in "Converting complex data types".

TimesTen row data consists of fixed-length data followed by any variable-length data.

For columns that can have null values, nullOffset points to a null byte in the record. This value is 1 if the column is null, or 0 if it is not null. See "Detecting null values" for a discussion.

The flags bits define whether the column is nullable, part of a primary key, or stored out of line.

The sysColNum value is the system column number to assign to the column. This value begins with 1 for the first column.

Note:

LOB support in XLA is limited, as follows:
  • You can subscribe to tables containing LOB columns, but information about the LOB value itself is unavailable.

  • ttXlaGetColumnInfo returns information about LOB columns.

  • Columns containing LOBs are reported as empty (zero length) or null (if the value is actually NULL). In this way, you can tell the difference between a null column and a non-null column.

Example 9-1 Copying and printing a VARCHAR2 string

For fixed-length column data, the address of a column is the offset value in the ttXlaColDesc_t structure, plus the address of the row as follows:

ttXlaColDesc_t colDesc;

void* pColVal = colDesc->offset + row;

The value of the column can be obtained by dereferencing this pointer using a type pointer that corresponds to the data type. For example, for SQL_INTEGER, the ODBC type is SQLINTEGER and the value of the column can be obtained by the following:

*((SQLINTEGER*) pColVal))

In the case of variable-length column data, the pColVal calculated above is the address of a four-byte offset value. Adding this offset value to the address of pColVal provides a pointer to the beginning of the variable-length column data. Assuming the operation is performed on a 64-bit platform, the first eight bytes at this location is the length of this data (var_len), followed by the actual data (var_data).

In this example, a VARCHAR string is copied and printed.

tt_ptrint* var_len = (tt_ptrint*)((char*)pColVal +
                    *((int*)pColVal));
char* var_data = (char*)(var_len+1);
char* buffer = malloc(*var_len+1);
memcpy(buffer,var_data,*var_len);
buffer[*var_len] = (char)NULL; /* NULL terminate the string */
printf("%s\n",buffer);
free(buffer);

tt_LSN_t

Description of log record identifier used by bookmarks. This structure is used by the ttXlaUpdateDesc_t structure.

Field Type Description
logFile SQLUBIGINT Higher order portion of log record identifier
logOffset SQLUBIGINT Lower order portion of log record identifier

Note:

The logFile and logOffset field names are retained for backward compatibility, although their usage has changed. In previous releases the values referred to LSNs, which increased sequentially, and the values had very specific meanings, indicating the log file number plus byte offset. Now they refer to log record identifiers, which are more abstract and do not have a direct relationship to the log file number and byte offset. All you can assume about a sequence of log record identifiers is that a log record identifier B read at a later time than a log record identifier A has a higher value.

tt_XlaLsn_t

Description of a log record identifier used by bookmarks. This structure is returned by the ttXlaGetLSN function and used by the ttXlaSetLSN function.

The checksum is specific to an XLA handle to ensure that every log record identifier is related to a known XLA connection.

Field Type Description
checksum SQLUINTEGER Checksum used to ensure that it is a valid log record identifier handle
xid SQLUSMALLINT Transaction ID
logFile SQLUBIGINT Higher order portion of log record identifier
logOffset SQLUBIGINT Lower order portion of log record identifier

Note:

The logFile and logOffset field names are retained for backward compatibility, although their usage has changed. In previous releases the values referred to LSNs, which increased sequentially, and the values had very specific meanings, indicating the log file number plus byte offset. Now they refer to log record identifiers, which are more abstract and do not have a direct relationship to the log file number and byte offset. All you can assume about a sequence of log record identifiers is that a log record identifier B read at a later time than a log record identifier A has a higher value.