Results 1 to 2 of 2
  1. #1
    Join Date
    Dec 2003
    Posts
    1

    Question Unanswered: Incremental refresh of AST in DB2 V7

    Hi!

    Is incremental refresh of AST supported in DB2 V7 REFRESH TABLE command ?

    DB2 V8 REFRESH TABLE command for MQT allows both INCRMENTAL and NOT INCRMENTAL refresh of MQT.
    MQT with REFRESH IMMEDIATE option allows INCRMENTAL refresh by default, whereas REFRESH DEFERRED option allows only when staging table is prepared.

    To the contrary, DB2 V7 (specifically V7.2.9 on Windows) doesn't seem to allow INCRMENTAL refresh of AST by REFRESH TABLE command even when it is defined with REFRESH IMMEDIATE option.

    Here is my simple experiment result. The procedure is as follows.
    1. Create AST with "DATA INITIALLY DEFERRED REFRESH IMMEDIATE" option.
    2. Issue "REFRESH TABLE" statement.
    3. Issue "REFRESH TABLE" statement again.
    (please not that no action is made between step 2 and 3)

    After AST was generated with the base tables, even if no change is applied to the base tables, "REFRESH TABLE"statement requires the same time as it required first time in DB2 V7. This means that full refresh of AST is carried out in the step 3 above.
    To the contrary, "REFRESH TABLE" statement on DB2 V8 finishes in no time in the same step 3 above.

    Is this a specification of DB2 V7 or specific symptom in V7.2 Fixpack 9 ?
    I have been completely ignorant of this change since DB2 V8 MQT was announced.
    Anyway, this is a big hit from the view point of table maintenance.
    Any opnion is highly appreciated.

    Environment:
    Windows 2000 Professional SP4
    DB2 UDB V7.2.9
    Attached Files Attached Files

  2. #2
    Join Date
    Apr 2003
    Posts
    191

    Re: Incremental refresh of AST in DB2 V7

    Hi,

    the problem described is typical of REFRESH DEFERRED tables in version 7. Are you positiv you defined your test table with REFRESH IMMEDIATE?

    Johann

    Originally posted by Masya
    Hi!

    Is incremental refresh of AST supported in DB2 V7 REFRESH TABLE command ?

    DB2 V8 REFRESH TABLE command for MQT allows both INCRMENTAL and NOT INCRMENTAL refresh of MQT.
    MQT with REFRESH IMMEDIATE option allows INCRMENTAL refresh by default, whereas REFRESH DEFERRED option allows only when staging table is prepared.

    To the contrary, DB2 V7 (specifically V7.2.9 on Windows) doesn't seem to allow INCRMENTAL refresh of AST by REFRESH TABLE command even when it is defined with REFRESH IMMEDIATE option.

    Here is my simple experiment result. The procedure is as follows.
    1. Create AST with "DATA INITIALLY DEFERRED REFRESH IMMEDIATE" option.
    2. Issue "REFRESH TABLE" statement.
    3. Issue "REFRESH TABLE" statement again.
    (please not that no action is made between step 2 and 3)

    After AST was generated with the base tables, even if no change is applied to the base tables, "REFRESH TABLE"statement requires the same time as it required first time in DB2 V7. This means that full refresh of AST is carried out in the step 3 above.
    To the contrary, "REFRESH TABLE" statement on DB2 V8 finishes in no time in the same step 3 above.

    Is this a specification of DB2 V7 or specific symptom in V7.2 Fixpack 9 ?
    I have been completely ignorant of this change since DB2 V8 MQT was announced.
    Anyway, this is a big hit from the view point of table maintenance.
    Any opnion is highly appreciated.

    Environment:
    Windows 2000 Professional SP4
    DB2 UDB V7.2.9

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •