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Arjen Visser

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The following settings and configurations maybe optimized in high volume transactions to achieve higher performance.

VariableDescription
STATUS_BEAT_LCRThis determines how often a log message is written showing number of processed LCRs (in LCR count) (use 0 to disable). As of Dbvisit Replicate 2.3.14 the default is 10,000. For high volume configurations consider increasing to higher number.
OCI_COMMIT_MODE = NOWAIT BATCHThis may improve apply processing speed. Only set for non RAC target systems. See Configuration Variable Reference for more information.
_ENABLE_5_19_PARSE = NO

Disables processing of auditing information. This information is used by CDC/Audit function or by querying the DBRSAPPLY_PKG package on the target database (e.g. in triggers).

This information includes source sid, serial#, transaction id, os user, os machine, login name. If this information is not required, then this can be disabled.

Please Internal Variables for more information

 

Improving performance

 

Following settings/tips can be applied to improve Replicate performance. Please test them first on a test system before implementing in a production environment

 

Mine

 

No CDC/AUDIT

 

Disable maintaining of session information. This information is needed only if CDC/Audit is in use to populate auxiliary fields such as source user login, program, module, action and so on.

 

If  _MINE_PRINT_OPEN_TRANSACTIONS is used, this feature populates the sid/serial info.

 

_ENABLE_5_19_PARSE = NO

 

No trace files

 

Disable keeping of past debug messages. So the trace files will not contain this information

 

This is only recommended in a tested environment.

 

_DISABLE_DBGPRINTF = YES

 

No redo log checksums

 

Disable checking of redolog checksums. This is recommended only if

  • fetcher not is used
  • on a local filesystem, no ASM
  • if the replication has been running fine for some time

 

_MINE_CHECK_ORACHECKSUM = NO

 

No error logging to database

 

Do not log errors to DBRSCOMMON_ERRORLOG. 

 

Note that this decreases the table size and not performance.

 

_LOG_ERRORS_TO_DATABASE = NO

 

Less frequent updates of table names in list progress

 

This setting only updates table names in list progress when a log switch occurs. Note that new tables are added on the fly even with this setting.

 

The setting can confuse if there is a lot of DDL, table renames etc. Then list progress may show stale information until next log switch happens.

 

_MINE_UPDATE_TABLIST_ON_SWITCH_ONLY = YES

 

Apply

 

No trace files

 

see Mine.

 

No error logging to database

 

see Mine.

 

Commit Nowait

 

Change default commit settings. Use only if target is not RAC, otherwise data loss can occur.

 

OCI_COMMIT_MODE = NOWAIT BATCH

 

No audit info, no triggers

 

If DBRSAPPLY_PKG is used at all, apply can stop populating it's variables.

 

It's used for:

 

  • CDC/Audit auxiliary columns like source login, sid, serial, program, module, action, ...
  • To determine whether current session is a replicate session (used in triggers to disable double-firing)

 

_SET_APPPLY_PKG_AUDIT NO (on login)

 

_SET_APPPLY_PKG_CONFLICT NO (on conflict)

 

_SET_APPPLY_PKG_ALWAYS NO (on each change; NO is the default)

 

 

 

Examples:

This shows an example of how to change the settings to further improve the performance:

Please add these settings to your MINE ddc file on the source server:

Column
width95%
Panel
bgColorCCC
memory_set _ENABLE_5_19_PARSE NO -- this disables auxiliary data like action, module, osprog, osproc etc. available on apply with CDC/Audit or using the DBRSAPPLY_PKG package
memory_set _DISABLE_DBGPRINTF YES -- this disables most of the contents of trace files
memory_set _MINE_CHECK_ORACHECKSUM NO -- disable checking of redo log checksums
memory_set _LOG_ERRORS_TO_DATABASE NO -- disables logging of errors to DBRSCOMMON_ERRORLOG table
memory_set _MINE_UPDATE_TABLIST_ON_SWITCH_ONLY YES -- updates table names in list progress only on log switch; so if you rename a table, you won't see the change until a log switch

Please add these settings to your APPLY ddc file on the target server:

Column
width95%
Panel
bgColorCCC
memory_set _DISABLE_DBGPRINTF YES 
memory_set _LOG_ERRORS_TO_DATABASE NO