Oct 18, 2010

DBMS_WM.CompressWorkspace

DBMS_WM.Compress Workspace

 If   you version enabled the tables with  DBMS_WM.EnableVersioning ('TABLE_NAME', 'VIEW_WO_OVERWRITE')   API  THEN your  Oracle Workspace  database WILL  GET SLOW  WHEN SO MANY DATA COMES ; use DBMS_WM.CompressWorkspace API  TO MAKE IT FASTER; There is a scenario to check  whether your Workspace  is getting slow or Workspace database is to be Compressed or not ,execute this  workspace API
DBMS_WM.SetDiffVersions('LIVE',wksp2) . and  then  pick a version enabled table having highest record count   , issue command select count(*) from tablename_diff ; if it takes more than a minute to GET RESULT THEN YOU CAN MAKE SURE THAT YOU NEED TO COMPRESS YOUR WORKSPACE ;here u want to use the   statement  (1) , using statement (2) will not give better result because your table is version enabled  with DBMS_WM.EnableVersioning ('TABLE_NAME', 'VIEW_WO_OVERWRITE')  .

(1) exec DBMS_WM.CompressWorkspace('LIVE',compress_view_wo_overwrite => true);

(2) exec DBMS_WM.CompressWorkspace('LIVE')



VIEW_WO_OVERWRITE: The without overwrite (WO_OVERWRITE) option. A view named _HIST  is created to contain history information, and it will show all modifications to the same version of the table. A history of modifications to the version is maintained; that is, subsequent changes to a row in the same version do not overwrite earlier changes.

compress_view_wo_overwrite        A Boolean value (TRUE or FALSE).

TRUE causes history information between the affected savepoints to be deleted even if VIEW_WO_OVERWRITE was specified when versioning was enabled.

FALSE causes history information (between the affected savepoints) for a table not to be deleted if VIEW_WO_OVERWRITE was specified when versioning was enabled. (If VIEW_WO_OVERWRITE was not specified for a table, history information for the table is deleted regardless of the parameter value.) FALSE is assumed if the procedure format without this parameter is used.


Advantage
------------
1  Run-time performance for Workspace Manager operations is improved.
2  Less disk storage is used for Workspace Manager structures

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