2.117 DST_UPGRADE_INSERT_CONV

DST_UPGRADE_INSERT_CONV specifies whether internal operators will be allocated on top of TIMESTAMP WITH TIME ZONE (TSTZ) columns of tables which have not been upgraded during the upgrade window of daylight saving time patching for TIMESTAMP WITH TIME ZONE data.

Property Description

Parameter type

Boolean

Default value

true

Modifiable

ALTER SESSION, ALTER SYSTEM

Modifiable in a PDB

Yes

Range of values

true | false

Basic

No

Values

  • true

    Internal operators will be allocated on top of TSTZ columns of tables which have not been upgraded. This is the default.

  • false

    Internal operators will not be allocated on top of TSTZ columns of tables which have not been upgraded.

When DST_UPGRADE_INSERT_CONV is set to true during the upgrade window of the daylight saving time patching process:

  • SELECT queries on tables with TSTZ data which have not been upgraded will use internal operators on top of TSTZ columns to present TSTZ data as if they were recorded using the new time zone translation rules.

  • DML on tables with TSTZ data which have not been upgraded will use internal operators on top of TSTZ columns to ensure that the TSTZ data is recorded using the old time zone translation rules in order to be consistent with the existing TSTZ data in the same tables.

Note:

Oracle strongly recommends that this parameter is set to true throughout the upgrade window of the daylight saving time patching process. This parameter reduces the performance impact since indexes on TSTZ columns will be disabled whenever internal operators are allocated. If the parameter is set to false, then indexes will be used and this may affect performance of queries against TSTZ data during the DST upgrade window. Turning off this parameter during the upgrade window may corrupt data on disk when DMLs occur for tables with TSTZ data which have not yet been upgraded.

See Also:

Oracle Database Globalization Support Guide for more information about this parameter