1. Reference for Oracle GoldenGate
  2. Oracle GoldenGate Common Components
  3. Oracle GoldenGate Parameters
  4. COMPRESSUPDATES | NOCOMPRESSUPDATES

1.34 COMPRESSUPDATES | NOCOMPRESSUPDATES

Valid For

Extract

Description

Use the COMPRESSUPDATES and NOCOMPRESSUPDATES parameters for Extract to control the way columns are written to the trail record for UPDATE operations.

COMPRESSUPDATES and NOCOMPRESSUPDATES apply globally for all TABLE statements in a parameter file or they can be used as on-off switches for individual TABLE statements.

GETUPDATEBEFORES is used to decide whether to get before images or not, and COMPRESSUPDATES decides if you want all columns or selected columns. By default, only the after images of update operations are written to the trail, but by using NOCOMPRESSUPDATES along with GETUPDATEBEFORES writes the before image changes as well, which can be used when implementing Conflict Detection and Resolution rules.

These parameters support the following databases:

  • DB2 LUW

  • DB2 z/OS

  • DB2 for i

  • MySQL

  • SQL Server

  • PostgreSQL

For Oracle, refer to the LOGALLSUPCOLS parameter.

Default

COMPRESSUPDATES

Syntax

COMPRESSUPDATES | NOCOMPRESSUPDATES
COMPRESSUPDATES

Causes Extract to write only the primary key and the changed columns of a row to the trail for update operations, and is the default value. This provides enough information to update the correct target record (unless conflict resolution is required), while restricting the amount of data that must be processed.

Additionally, if a substitute key is defined with the KEYCOLS option of the TABLE parameter, those columns are written to the trail, whether or not a primary or unique key is defined. See "KEYCOLS (columns)" for more information.

NOCOMPRESSUPDATES

Sends all of the columns to the trail. This becomes the default when a table definition does not include a primary key or unique index. NOCOMPRESSUPDATES also is required when using the Conflict Detection and Resolution (CDR) feature. See Administering Oracle GoldenGate for more information about CDR.

For PostgreSQL, when using NOCOMPRESSUPDATES, LOB column data will only be written in the after image of the record if the column was modified.

Parent topic: Oracle GoldenGate Parameters