Overview of TimesTen Support for Pro*C/C++

TimesTen support for the Oracle Pro*C/C++ Precompiler depends on TimesTen OCI. TimesTen OCI depends on the Oracle client library and the TimesTen ODBC libraries.

See Figure 3-1 to see where OCI and Pro*C/C++ fit in the TimesTen architecture.

This chapter contains information specific to using the Oracle Pro*C/C++ Precompiler with TimesTen. The syntax and usage of the Oracle Pro*C/C++ Precompiler with TimesTen is essentially the same as with Oracle Database.

The rest of this section includes the following topics.

Overview of the Oracle Pro*C/C++ Precompiler

The Oracle Pro*C/C++ Precompiler enables you to embed SQL statements or PL/SQL blocks directly into C or C++ code. Further, you can use your C or C++ program host variables in your embedded SQL or PL/SQL.

You use a precompilation step to convert the Pro*C/C++ source file into a C or C++ source file. The precompiler accepts the Pro*C/C++ file as input, translates embedded SQL statements into standard Oracle Database runtime library calls, and generates a modified source code file that you can then compile and link. Pro*C/C++ code is linked against the Oracle Database precompiler SQLLIB library, which is included in the TimesTen distribution as part of the Oracle Instant Client.

TimesTen OCI Support With Respect to Pro*C/C++

TimesTen support of the Oracle Pro*C/C++ Precompiler depends on TimesTen OCI support. Because of this, restrictions for TimesTen OCI apply to Pro*C/C++ applications.

In addition, TimesTen does not support OCI calls that are related to functionality that does not exist in TimesTen.

See TimesTen Support for OCI. Much of the information there applies to Pro*C/C++ applications as well.

Restrictions in TimesTen Support for Pro*C/C++

There are restrictions when using TimesTen support for Pro*C/C++.

Embedded SQL Support and Restrictions

The TimesTen Pro*C/C++ Precompiler does not support embedded SQL for functionality that TimesTen does not support.

See TimesTen Restrictions and Limitations.

TimesTen provides the following support for SQLLIB functions:

SQLErrorGetText (sqlglmt) is supported.
SQLRowidGet() is supported following only SELECT FOR UPDATE statements.

In addition, TimesTen support for the Oracle Pro*C/C++ Precompiler has the following restrictions:

REGISTER CONNECT is not supported.
Stored Java subprograms are not supported.

Semantic Checking Restrictions

TimesTen support for the Oracle Pro*C/C++ Precompiler does not provide semantic checking during precompilation. A SQLCHECK precompiler option setting that specifies semantic checking is permissible but has no effect.

It is important to be aware, however, that a setting of SEMANTICS results in a database connection even though precompilation semantic checking is not performed. Therefore, a setting of SEMANTICS requires the following during precompilation:

The database must be running.
The USERID precompiler option must be set, either on the command line or in the pcscfg.cfg configuration file. You must provide the user name and password for an existing TimesTen user, and a TNS name that points to the database. In the following example, you are prompted for the password:
```
USERID=user1@my_tnsname
```
Alternatively, you can enter USERID=user1/password@my_tnsname, but for security reasons it is not advisable to specify a password on a command line or in a configuration file.

See Connecting to a TimesTen Database From Pro*C/C++ for information about usage and syntax for TNS names.

See the next section, Embedded PL/SQL Restrictions, for related information about Pro*C/C++ programs that use PL/SQL.

Embedded PL/SQL Restrictions

In TimesTen, if a Pro*C/C++ application contains PL/SQL blocks, then Pro*C/C++ acts as though the SQLCHECK setting is SEMANTICS. It is important to be aware that this results in a database connection even though precompilation semantic checking is not performed.

Therefore, using PL/SQL in a Pro*C/C++ application requires the following during precompilation:

The database must be running.
The USERID precompiler option must be set, specifying an existing TimesTen user. See the preceding section, Semantic Checking Restrictions.

Transaction Restrictions

Regarding transactions, TimesTen support for the Oracle Pro*C/C++ Precompiler has some restrictions.

The following is not supported:

SAVEPOINT SQL statement
SET TRANSACTION SQL statement

You can still have transactions with commit and rollback, just not the SET TRANSACTION SQL statement.
Fetch across commits
Distributed transactions

Connection Restrictions

Regarding connections, TimesTen support for the Oracle Pro*C/C++ Precompiler does not provide certain features.

ALTER AUTHORIZATION clause
Automatic connections to the database
Making connections to the database with SYSDBA or SYSOPER privilege, given that these privileges do not exist in TimesTen
Implicit connections (dblinks) to a TimesTen or Oracle Database

For information about supported connection syntax, see Connecting to a TimesTen Database From Pro*C/C++.

Summary of Unsupported or Restricted Executable Commands and Clauses

Given TimesTen restrictions, including those noted in the preceding sections, this section summarizes the Pro*C/C++ EXEC SQL executable commands, categories of commands, and command clauses that TimesTen does not support or supports only partially.

ALTER AUTHORIZATION
CACHE FREE ALL
CALL

This is supported only for calling PL/SQL. To call TimesTen built-in procedures, use dynamic SQL statements.
Any "COLLECTION..." command
COMMIT FORCE 'some text'
COMMIT WORK COMMENT 'some text' RELEASE

The COMMENT clause is not supported.
CONNECT BY
CONTEXT OBJECT OPTION GET
CONTEXT OBJECT OPTION SET
DECLARE CURSOR

The WITH HOLD clause is not supported.
DECLARE TABLE

Only Oracle Database data types are supported.
DECLARE TYPE
EXPLAIN PLAN
IN SYSDBA MODE
IN SYSOPER MODE
LOCK TABLE
Any "OBJECT..." command
PARTITION
REGISTER CONNECT
RETURN
RETURNING
SAVEPOINT
SET DESCRIPTOR

You cannot set CHARACTER_SET_NAME.
SET TRANSACTION
START WITH
TO SAVEPOINT