ALTER SESSION v16

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Name

ALTER SESSION — Change a runtime parameter.

Synopsis

ALTER SESSION SET <name> = <value>

Description

The ALTER SESSION command changes runtime configuration parameters. ALTER SESSION affects only the value used by the current session. Some of these parameters are provided solely for compatibility with Oracle syntax and have no effect on the runtime behavior of EDB Postgres Advanced Server. Others alter a corresponding EDB Postgres Advanced Server database server runtime configuration parameter.

Parameters

name

Name of a settable runtime parameter.

value

New value of parameter.

Configuration parameters

You can modify the following configuration parameters using the ALTER SESSION command:

  • NLS_DATE_FORMAT (string)

    Sets the display format for date and time values as well as the rules for interpreting ambiguous date input values. Has the same effect as setting the EDB Postgres Advanced Server datestyle runtime configuration parameter.

  • NLS_LANGUAGE (string)

    Sets the message-display language. Has the same effect as setting the EDB Postgres Advanced Server lc_messages runtime configuration parameter.

  • NLS_LENGTH_SEMANTICS (string)

    Valid values are BYTE and CHAR. The default is BYTE. This parameter is provided only for syntax compatibility and has no effect in the EDB Postgres Advanced Server.

  • OPTIMIZER_MODE (string)

    Sets the default optimization mode for queries. Valid values are ALL_ROWS, CHOOSE, FIRST_ROWS, FIRST_ROWS_10, FIRST_ROWS_100, and FIRST_ROWS_1000. The default is CHOOSE. This parameter is implemented in EDB Postgres Advanced Server.

  • QUERY_REWRITE_ENABLED (string)

    Valid values are TRUE, FALSE, and FORCE. The default is FALSE. This parameter is provided only for syntax compatibility and has no effect in EDB Postgres Advanced Server.

  • QUERY_REWRITE_INTEGRITY (string)

    Valid values are ENFORCED, TRUSTED, and STALE_TOLERATED. The default is ENFORCED. This parameter is provided only for syntax compatibility and has no effect in EDB Postgres Advanced Server.

Examples

Set the language to U.S. English in UTF-8 encoding. In this example, the value en_US.UTF-8 is in the format for EDB Postgres Advanced Server. This form isn't compatible with Oracle databases.

ALTER SESSION SET NLS_LANGUAGE = 'en_US.UTF-8';

Set the date display format:

ALTER SESSION SET NLS_DATE_FORMAT = 'dd/mm/yyyy';
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