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Problem IT31200
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Status: Closed |
IN-PLACE ALTER CAN TAKE LONG, CONSUMING A FULL CPU VP, WHEN CLEANING UP MANY (AND SOME LARGE) OLD ALTERS
|
| product: |
INFORMIX SERVER / 5725A3900 / C10 - IDS 12.10 |
| Problem description: |
An ALTER TABLE, when executed as an in-place alter (IPA), is the
point in time where oldest in-place alter versions get cleaned
up if there are no more rows for these versions. Such clean-up
can be time and cpu consuming if there are many such old
versions to remove and esp. some later versions in the IPA
history involve large alters (e.g. multiple hundreds of columns
added in one version). With fragmented tables this process had
to occur for every fragment's IPA history, and while processing
one partition, no other thread could be running on the current
cpu vp.
This is independent from any rows in such table and also has
nothing to do with 'outstanding in-place alters' (rows still in
old versions' schemas). No table data is being modified in this
process. |
| Problem Summary: |
****************************************************************
* USERS AFFECTED: *
* Users of Informix Server prior to 12.10.xC15 and 14.10.xC5. *
****************************************************************
* PROBLEM DESCRIPTION: *
* See Error Description *
****************************************************************
* RECOMMENDATION: *
* Upgrade to Informix Server 12.10.xC15 (when available) or *
* 14.10.xC5. *
**************************************************************** |
| Local Fix: |
To anticipate and avoid this problem, find tables with very high
(> couple thousands) sysmaster.sysptnhdr.pta_opems_filled values
and rebuild them before their next ALTER TABLE. |
| Solution |
|
| Workaround |
****************************************************************
* USERS AFFECTED: *
* Users of Informix Server prior to 12.10.xC15 and 14.10.xC5. *
****************************************************************
* PROBLEM DESCRIPTION: *
* See Error Description *
****************************************************************
* RECOMMENDATION: *
* Upgrade to Informix Server 12.10.xC15 (when available) or *
* 14.10.xC5. *
**************************************************************** |
| Comment |
Fixed in Informix Server 12.10.xC15 and 14.10.xC5. |
| Timestamps |
Date - problem reported :
Date - problem closed :
Date - last modified :
| 09.12.2019
10.12.2020
10.12.2020 |
| Problem solved at the following versions (IBM BugInfos) |
|
| Problem solved according to the fixlist(s) of the following version(s) |
