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Problem IC84583
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Status: Closed |
WRONG PREFETCH SIZE CALCULATION FOR AUTOMATIC STORAGE |
| product: |
DB2 FOR LUW / DB2FORLUW / A10 - DB2 |
| Problem description: |
In case you use PREFETCHSIZE AUTOMATIC with AUTOMATIC STORAGE,
there could be a miscalculation of the PREFETCH SIZE used.
The intention of this APAR is to fix the the prefetch size
calculation.
However, there is a more subtle and complex issue here. In our
design, each table has a packed descriptor and the packed
descriptor contains a bunch of information including the
tablespace's prefetch size. When the tablespace's prefetch size
changes, we need to update the packed descriptors of ALL the
tables and indexes within this tablespace. This is a complex
issue because the packed descriptors are stored in the system
catalog. This is how it's done in the ALTER TABLESPACE
PREFETCHSIZE codepath. However, the automatic storage codepath
does not have the infrastructure to do all these. Fixing this is
too risky to be done in an APAR fix. There is a simple
workaround available:
1. ALTER TABLESPACE PREFETCHSIZE <some number>
2. ALTER TABLESPACE PREFETCHSIZE AUTOMATIC " |
| Problem Summary: |
****************************************************************
* USERS AFFECTED: *
* All *
****************************************************************
* PROBLEM DESCRIPTION: *
* See Error Description *
****************************************************************
* RECOMMENDATION: *
* Upgrade to DB2 Version 10.1 Fix Pack 1. *
**************************************************************** |
| Local Fix: |
1. ALTER TABLESPACE PREFETCHSIZE <some number>
2. ALTER TABLESPACE PREFETCHSIZE AUTOMATIC "
NOTE: Workaround is good till new stripe set is not created.
Once containers get filled and new stripe set needs to be
created, then prefetch size will be miscalculated again. |
| available fix packs: |
DB2 Version 10.1 Fix Pack 1 for Linux, UNIX, and Windows
DB2 Version 10.1 Fix Pack 2 for Linux, UNIX, and Windows
DB2 Version 10.1 Fix Pack 3 for Linux, UNIX, and Windows
DB2 Version 10.1 Fix Pack 4 for Linux, UNIX, and Windows
DB2 Version 10.1 Fix Pack 3a for Linux, UNIX, and Windows
DB2 Version 10.1 Fix Pack 6 for Linux, UNIX, and Windows
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| Solution |
First fixed in DB2 Version 10.1 Fix Pack 1. |
| Workaround |
not known / see Local fix |
| Timestamps |
Date - problem reported :
Date - problem closed :
Date - last modified :
| 14.06.2012
07.11.2012
07.11.2012 |
| Problem solved at the following versions (IBM BugInfos) |
|
| Problem solved according to the fixlist(s) of the following version(s) |
| 10.1.0.1
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| 10.5.0.1
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