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Oracle® Database JDBC Developer's Guide and Reference,
11g Release 1 (11.1)

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6 Features Specific to JDBC OCI Driver

This chapter introduces the features specific to the Java Database Connectivity (JDBC) Oracle Call Interface (OCI) driver. It also describes the OCI Instant Client. This chapter contains the following sections:

OCI Connection Pooling

The OCI connection pooling feature is an Oracle-designed extension. The connection pooling provided by the JDBC OCI driver enables applications to have multiple logical connections, all of which are using a small set of physical connections. Each call on a logical connection is routed on to the physical connection that is available at the given time.

Client Result Cache

Client result cache feature enables client-side caching of SQL query result sets in client memory. In this way, OCI applications can use client memory to take advantage of the client result cache to improve response times of repetitive queries.

Usage Guidelines in JDBC

You must annotate a query with a /*+ result_cache */ hint to indicate that results are to be stored in the client result cache. For example, look at the following code snippet:

String  query  = "select /*+ result_cache */ * from emp where empno < : 1";
   ((oracle.jdbc.OracleConnection)conn).setImplicitCachingEnabled(true);
   ((oracle.jdbc.OracleConnection)conn).setStatementCacheSize(10);
   PreparedStatement  pstmt;
   ResultSet rs;
     
    for (int j = 0 ; j < 10 ; j++ )
    {
       pstmt  = conn.prepareStatement (query);
       pstmt.setInt(1,7500);
       rs  = pstmt.executeQuery();
         while (rs.next( ) )
        {     // see the values  }
          rs.close;
          pstmt.close( ) ;
        }
    } 

In the preceding example, the client result cache hint /*+ result_cache */ is annotated to the actual query, that is, select * from emp where empno < : 1. So, the first execution of the query goes to the database and the result set is cached for the remaining nine executions of the query. This improves the performance of your application significantly.

You must use JDBC statement caching or cache statements at the application level when using the JDBC OCI client result cache.

See Also:

"Statement and Result Set Caching" for more information on JDBC statement caching

Validation of the Client Result Cache

Validation of the JDBC OCI client result cache can be achieved in the following ways:

Client Cache Statistics Verification

JDBC OCI driver periodically sends statistics related to the client result cache to the server. These statistics that contain information such as the number of result sets successfully cached, number of cache hits, and number of cached result sets invalidated are stored in CLIENT_RESULT_CACHE_STATS$.

Timing Measurement

First, you measure the time taken to run the queries without the /*+ result_cache */ hints. Then add the /*+ result_cache */ hints to the query and measure the time again. You will see the performance gain.

Transparent Application Failover

The Transparent Application Failover feature of JDBC OCI driver enables you to automatically reconnect to a database if the database instance to which the connection is made goes down. The new database connection, though created by a different node, is identical to the original.

OCI Native XA

The JDBC OCI driver also provides a feature called Native XA.

See Also:

"OCI Native XA"

OCI Instant Client

This section covers the following topics:

Overview of Instant Client

The Instant Client feature makes it extremely easy to deploy OCI, Oracle C++ Call Interface (OCCI), Open Database Connectivity (ODBC), and JDBC-OCI based customer applications, by eliminating the need for an Oracle home. The storage space requirement of a JDBC OCI application running in the Instant Client mode is significantly reduced compared to the same application running on a full client-side installation. The Instant Client shared libraries occupy only about one-fourth the disk space used by a full client installation.

Table 6-1 shows the Oracle client-side files required to deploy a JDBC OCI application. Library names of release 11.1 are used in the table. The number part of library names will change in future releases to agree with the release.

Table 6-1 OCI Instant Client Shared Libraries

Linux and UNIX Systems Description for Linux and UNIX Systems Microsoft Windows Description for Microsoft Windows

libclntsh.so.11.1

Client Code Library

oci.dll

Forwarding functions that applications link with

libociei.so

OCI Instant Client Data Shared Library

oraociei11.dll

Data and code

libnnz11.so

Security Library

orannzsbb11.dll

Security Library

libocijdbc11.so

OCI Instant Client JDBC Library

ocijdbc11.dll

OCI Instant Client JDBC Library

ALL JDBC Java Archive (JAR) files

See Also: "Check the Environment Variables"

All JDBC JAR files

See Also: "Check the Environment Variables"


Note:

To provide Native XA functionality, you must copy the JDBC XA class library. On UNIX systems, this library, libheteroxa11.so, is located in the ORACLE_HOME/jdbc/lib directory. On Microsoft Windows, this library, heteroxa11.dll, is located in the ORACLE_HOME\bin directory.

Benefits of Instant Client

The benefits of Instant Client are the following:

  • Installation involves copying a small number of files.

  • The number of required files and the total disk storage on the Oracle client-side are significantly reduced.

  • There is no loss of functionality or performance for applications deployed with the Instant Client.

  • It is simple for independent software vendors to package applications.

JDBC OCI Instant Client Installation Process

The Instant Client libraries can be installed by choosing the Instant Client option from Oracle Universal Installer. The Instant Client libraries can also be downloaded from the Oracle Technology Network Web site. The installation process is as follows:

  1. Download and install the Instant Client shared libraries and Oracle JDBC class libraries to a directory, such as instantclient.

  2. Set the library path environment variable to the directory from Step 1. For example, on UNIX systems, set the LD_LIBRARY_PATH environment variable to instantclient. On Microsoft Windows, set the PATH environment variable to locate the instantclient directory.

  3. Add the full path names of the JDBC class libraries to the CLASSPATH environment variable.

After completing these steps you are ready to run the JDBC OCI application.

The JDBC OCI application operates in the Instant Client mode when the OCI and JDBC shared libraries are accessible through the library path environment variable. In the Instant Client mode, there is no dependency on the ORACLE_HOME and none of the other code and data files provided in ORACLE_HOME is needed by JDBC OCI, except for the tnsnames.ora file.

Instant Client can be also installed from Oracle Universal Installer by selecting the Instant Client option. The Instant Client files should always be installed in an empty directory. As with the OTN installation, you must set the LD_LIBRARY_PATH environment variable to the Instant Client directory to operate in the Instant Client mode.

If you have done a complete client installation by choosing the Admin option, then the Instant Client shared libraries are also installed. The location of the Instant Client shared libraries and JDBC class libraries in a full client installation is:

On Linux or UNIX systems:

  • libociei.so library is in $ORACLE_HOME/instantclient

  • libclnstsh.so.11.1, libocijdbc11.so, and libnnz11.so are in $ORACLE_HOME/lib

  • The JDBC class libraries are in $ORACLE_HOME/jdbc/lib

On Microsoft Windows:

  • oraociei11.dll library is in ORACLE_HOME\instantclient

  • oci.dll, ocijdbc11.dll, and orannzsbb11.dll are in ORACLE_HOME\bin

  • The JDBC class libraries are in ORACLE_HOME\jdbc\lib

By copying these files to a different directory, setting the library path to locate this directory, and adding the path names of the JDBC class libraries to the CLASSPATH environment variable, you can enable running the JDBC OCI application in the Instant Client mode.

Note:

  • To provide Native XA functionality, you must copy the JDBC XA class library. On UNIX, this library, libheteroxa11.so, is located in ORACLE_HOME/jdbc/lib. On Windows, this library, heteroxa11.dll, is located in ORACLE_HOME\bin.

  • All the libraries must be copied from the same ORACLE_HOME and must be placed in the same directory.

  • On hybrid platforms, such as Sparc64, if the JDBC OCI driver needs to be operated in the Instant Client mode, then you must copy the libociei.so library from the ORACLE_HOME/instantclient32 directory. You must copy all other Sparc64 libraries needed for the JDBC OCI Instant Client from the ORACLE_HOME/lib32 directory.

  • Only one set of Oracle libraries should be specified in the library path environment variable. That is, if you have multiple directories containing Instant Client libraries, then only one such directory should be specified in the library path environment variable.

  • If you have an Oracle home on your computer, then you should not have the ORACLE_HOME/lib and Instant Client directories in the library path environment variable simultaneously, regardless of the order in which they appear in the variable. That is, only one of ORACLE_HOME/lib directory (for non-Instant Client operation) or Instant Client directory (for Instant Client operation) should be specified in the library path environment variable.

  • Oracle recommends that you download Instant Client from Oracle Technology Network (OTN)

    http://www.oracle.com/technology/tech/oci/instantclient/instantclient.html

Usage of Instant Client

Instant Client is a deployment feature and should be used for running production applications. For development, a full installation is necessary to access demonstration programs and so on. In general, all JDBC OCI functionality is available to an application being run in the Instant Client mode, except that the Instant Client mode is for client-side operation only. Therefore, server-side external procedures cannot operate in the Instant Client mode.

Patching Instant Client Shared Libraries

Because Instant Client is a deployment feature, the emphasis has been on reducing the number and size of files required to run a JDBC OCI application. Therefore, all files needed to patch Instant Client shared libraries are not available in an Instant Client deployment. An ORACLE_HOME based full client installation is needed to patch the Instant Client shared libraries. The opatch utility will take care of patching the Instant Client shared libraries.

Note:

On Microsoft Windows, you cannot patch the shared libraries.

After applying the patch in an ORACLE_HOME environment, copy the files listed in Table 6-1, "OCI Instant Client Shared Libraries" to the instant client directory as described in "JDBC OCI Instant Client Installation Process".

Instead of copying individual files, you can generate Instant Client ZIP files for OCI, OCCI, JDBC, and SQL*Plus as described in "Regeneration of Data Shared Library and ZIP files". Then, you can copy the ZIP files to the target computer and unzip them as described in "JDBC OCI Instant Client Installation Process".

The opatch utility stores the patching information of the ORACLE_HOME installation in libclnstsh.so.11.1. This information can be retrieved by the following command:

genezi -v

Note that if the computer from where Instant Client is deployed does not have the genezi utility, then it must be copied from the ORACLE_HOME/bin directory on the computer that has the ORACLE_HOME installation.

Regeneration of Data Shared Library and ZIP files

The OCI Instant Client Data Shared Library, libociei.so, can be regenerated by performing the following steps in an Administrator Installation of ORACLE_HOME:

mkdir -p $ORACLE_HOME/rdbms/install/instantclient/light
cd $ORACLE_HOME/rdbms/lib
make -f ins_rdbms.mk ilibociei

A new version of the libociei.so Data Shared Library based on the current files in the ORACLE_HOME is then placed in the ORACLE_HOME/rdbms/install/instantclient directory.

Note that the location of the regenerated Data Shared Library, libociei.so, is different from that of the original Data Shared Library, libociei.so, which is located in the ORACLE_HOME/instantclient directory.The preceding steps also generate Instant Client ZIP files for OCI, OCCI, JDBC, and SQL*Plus.

Regeneration of data shared library and ZIP files is not available on Microsoft Windows platforms.

Database Connection Names for OCI Instant Client

All Oracle Net naming methods that do not require the ORACLE_HOME or TNS_ADMIN environment variables to locate configuration files, such as tnsnames.ora or sqlnet.ora, work in the Instant Client mode. In particular, the connection string can be specified in the following formats:

  • A Thin-style connection string of the form:

     host:port:service_name
    

    For example:

    url="jdbc:oracle:oci:@//example.com:5521:bjava21"
    
  • A SQL connection URL string of the form:

    //host:[port][/service name]
    

    For example:

    url="jdbc:oracle:oci:@//example.com:5521/bjava21
    
  • As an Oracle Net keyword-value pair. For example:

    url="jdbc:oracle:oci:@(DESCRIPTION=(ADDRESS=(PROTOCOL=tcp) 
      (HOST=dlsun242) (PORT=5521))
      (CONNECT_DATA=(SERVICE_NAME=bjava21)))"
    

Naming methods that require TNS_ADMIN to locate configuration files continue to work if the TNS_ADMIN environment variable is set.

See Also:

Oracle Database Net Services Administrator's Guide for more information about connection formats

If the TNS_ADMIN environment variable is not set and TNSNAMES entries, such as inst1, are used, then the ORACLE_HOME environment variable must be set and the configuration files are expected to be in the $ORACLE_HOME/network/admin directory.

Note:

In this case, the ORACLE_HOME environment variable is used only for locating Oracle Net configuration files. No other component of Client Code Library uses the value of the ORACLE_HOME environment variable.

The empty connection string is not supported. However, an alternate way to use the empty connection string is to set the TWO_TASK environment variable on UNIX systems, or the LOCAL variable on Microsoft Windows, to either a tnsnames.ora entry or an Oracle Net keyword-value pair. If TWO_TASK or LOCAL is set to a tnsnames.ora entry, then the tnsnames.ora file must be loaded by the TNS_ADMIN or ORACLE_HOME setting.

Example

Consider that the listener.ora file on the database server contains the following information:

LISTENER = (ADDRESS_LIST=(ADDRESS=(PROTOCOL=tcp)(HOST=server6)(PORT=1573)))

SID_LIST_LISTENER = (SID_LIST=
                     (SID_DESC=(SID_NAME=rdbms3)
                     (GLOBAL_DBNAME=rdbms3.server6.us.alchemy.com)
                     (ORACLE_HOME=/home/dba/rdbms3/oracle)))

You can connect to this server in one of the following ways:

url = "jdbc:oracle:oci:@(DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)
                     (HOST=server6)(PORT=1573))
                     (CONNECT_DATA=(SERVICE_NAME=rdbms3.server6.us.alchemy.com)))"

or:

url = "jdbc:oracle:oci:@//server6:1573/rdbms3.server6.us.alchemy.com"

Alternatively, you can set the TWO_TASK environment variable to any of the connection strings and connect to the database server without specifying the connection string along with the sqlplus command. For example, set the TWO_TASK environment in one of the following ways:

setenv TWO_TASK "(DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=server6)(PORT=1573))
                 (CONNECT_DATA=(SERVICE_NAME=rdbms3.server6.us.alchemy.com)))"

or:

setenv TWO_TASK //server6:1573/rdbms3.server6.us.alchemy.com

Now, you can connect to the database server using the following URL:

url = "jdbc:oracle:oci:@"

The connection string can also be stored in the tnsnames.ora file. For example, consider that the tnsnames.ora file contains the following:

conn_str = (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=server6)(PORT=1573))
                (CONNECT_DATA=(SERVICE_NAME=rdbms3.server6.us.alchemy.com)))

If this tnsnames.ora file is located in the /home/webuser/instantclient directory, then you can set the TNS_ADMIN environment variable (or LOCAL on Microsoft Windows) as follows:

setenv TNS_ADMIN /home/webuser/instantclient

Now, you can connect as follows:

url = "jdbc:oracle:oci:@conn_str"

Note:

The TNS_ADMIN environment variable specifies the directory where the tnsnames.ora file is located. However, TNS_ADMIN does not specify the full path of the tnsnames.ora file, instead it specifies the directory.

If this tnsnames.ora file is located in the /network/server6/home/dba/oracle/network/admin directory in the Oracle home, then instead of using TNS_ADMIN to locate the tnsnames.ora file, you can set the ORACLE_HOME environment variable as follows:

setenv ORACLE_HOME /network/server6/home/dba/oracle

Now, you can connect with either of the conn_str connection strings, as specified previously.

If tnsnames.ora can be located by TNS_ADMIN or ORACLE_HOME, then TWO_TASK can be set to:

setenv TWO_TASK conn_str

You can then connect with the following URL:

url = "jdbc:oracle:oci:@"

Environment Variables for OCI Instant Client

The ORACLE_HOME environment variable no longer determines the location of the Globalization Support files and error message files. An OCI-only application does not require the ORACLE_HOME environment variable to be set. However, if the variable is set, then it does not have an impact on the operation of the OCI driver. OCI will always obtain its data from the Data Shared Library. If the Data Shared Library is not available, only then is the ORACLE_HOME environment variable used and a full client installation is assumed. Even though the ORACLE_HOME environment variable is not required to be set, if it is set, then it must be set to a valid operating system path name that identifies a directory.

Environment variables ORA_NLS10 and ORA_NLSPROFILES33 are ignored in the Instant Client mode.

In the Instant Client mode, if the ORA_TZFILE variable is not set, then the smaller, default, timezone.dat file from the Data Shared Library is used. If the larger timezlrg.dat file is to be used from the Data Shared Library, then set the ORA_TZFILE environment variable to the name of the file without any absolute or relative path names. That is:

On UNIX systems:

setenv ORA_TZFILE timezlrg.dat

On Microsoft Windows:

set ORA_TZFILE timezlrg.dat

If the driver is not operating in the Instant Client mode, then the ORA_TZFILE variable, if set, names a complete path name, as it does in previous Oracle Database releases.

If TNSNAMES entries are used, then, as mentioned earlier, the TNS_ADMIN directory must contain the TNSNAMES configuration files, and if TNS_ADMIN is not set, then the ORACLE_HOME/network/admin directory must contain Oracle Net Services configuration files.

Instant Client Light (English)

The lightweight version of Instant Client is called Instant Client Light (English). Instant Client Light is the short name. Instant Client Light is a significantly smaller version of Instant Client. This reduces the disk space requirements of the client installation by about 63 MB. This is achieved by the lightweight Data Shared Library, libociicus.so on UNIX systems, which is 4 MB in size and a subset of the data shared library, libociei.so, which is 67 MB in size.

The lightweight data shared library supports only a few character sets and error messages that are only in English. Therefore, the name Instant Client Light (English). Instant Client Light is designed for applications that require English-only error messages and use either US7ASCII, WE8DEC, or one of the Unicode character sets.

Table 6-2 lists the names of the data shared libraries for Instant Client and Instant Client Light (English) on different platforms. The table also specifies the size of each data shared library in parentheses following the library file name.

Table 6-2 Data Shared Library for Instant Client and Instant Client Light (English)

Platform Instant Client Instant Client Light (English)

Sun Solaris

libociei.so (67 MB)

libociicus.so (4 MB)

Linux

libociei.so (67 MB)

libociicus.so (4 MB)

Microsoft Windows

oraociei11.dll (85 MB)

oraociicus11.dll (15 MB)


This section covers the following topics:

Globalization Settings

The NLS_LANG setting determines the language, territory, and character set as language_territory.characterset. In Instant Client Light, language can only be American, territory can be any that is supported, and characterset can be any one of the following:

  • Single-byte

    • US7ASCII

    • WE8DEC

    • WE8MSWIN1252

    • WE8ISO8859P1

  • Unicode

    • UTF8

    • AL16UTF16

    • AL32UTF8

Specifying character set or national character set other than those listed as the client or server character set or setting the language in NLS_LANG on the client will throw one of the following errors:

  • ORA-12734

  • ORA-12735

  • ORA-12736

  • ORA-12737

With Instant Client Light, the error messages obtained are only in English. Therefore, the valid values for the NLS_LANG setting are of the type:

American_territory.characterset

where, territory can be any valid and supported territory and characterset can be any one the previously listed character sets.

Instant Client Light can operate with the OCI environment handles created in the OCI_UTF16 mode.

See Also:

Oracle Database Globalization Support Guide for more information about NLS settings.

Operation

To operate in the Instant Client Light mode, an application must set the LD_LIBARARY_PATH environment variable in UNIX systems or the PATH environment variable in Microsoft Windows to a location containing the client and data shared libraries. OCI applications by default look for the OCI Data Shared Library, libociei.so in the LD_LIBRARY_PATH environment variable in UNIX systems or the oraociei11.dll Data Shared Library in the PATH environment variable in Microsoft Windows, to determine if the application should operate in the Instant Client mode. In case this library is not found, then OCI tries to load the Instant Client Light Data Shared Library, libociicus.so in UNIX systems or libociicus11.dll in Microsoft Windows. If this library is found, then the application operates in the Instant Client Light mode. Otherwise, a non-Instant Client mode is assumed.

Installation

Instant Client Light can be installed in one of the following ways:

  • From OTN

    You can download the required file from

    http://www.oracle.com/technology/tech/oci/instantclient/instantclient.html

    For Instant Client Light, instead of downloading and expanding the Basic package, download and unzip the Basic Light package. The instantclient_11_1 directory in which the lightweight libraries are unzipped should be empty before unzipping the files.

  • From Client Admin Install

    Instead of copying libociei.so or oraociei11.dll from the ORACLE_HOME/instantclient directory, copy libociicus.so or oraociic10.dll from the ORACLE_HOME/instantclient/light directory. That is, the Instant Client directory on the LD_LIBRARY_PATH environment variable, in UNIX systems, should contain the Instant Client Light Data Shared Library, libociicus.so, instead of the larger OCI Instant Client Data Shared Library, libociei.so. In Microsoft Windows, the PATH environment variable should contain oraociicus11.dll instead of oraociei11.dll.

  • From Oracle Universal Installer

    If the Instant Client option is selected from Oracle Universal Installer, then libociei.so (or oraociei11.dll on Microsoft Windows) is installed in the base directory of the installation which is going to be placed on the LD_LIBRARY_PATH environment variable. This is so that Instant Client Light is not enabled by default. The Instant Client Light Data Shared Library, libociicus.so (or oraociicus11.dll on Microsoft Windows), is installed in the light subdirectory of the base directory. Therefore, to operate in the Instant Client Light mode, the OCI Data Shared Library, libociei.so (or oraociei11.dll on Windows) must be deleted or renamed and the Instant Client Light Data Shared Library must be copied from the light subdirectory to the base directory of the installation.

    For example, if Oracle Universal Installer has installed the Instant Client in my_oraic_11_1 directory on the LD_LIBRARY_PATH environment variable, then one would need to do the following to operate in the Instant Client Light mode:

    cd my_oraic_11_1
    rm libociei.so
    mv light/libociicus.so .
    

    Note:

    All the Instant Client files should always be copied or installed in an empty directory. This is to ensure that no incompatible binaries exist in the installation.