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From: kenfar on 9 Apr 2010 12:24 It's not clear from the db2 9.7 documentation whether or not to perform runstats before or after a partition is attached: http://publib.boulder.ibm.com/infocenter/db2luw/v9r7/index.jsp?topic=/com.ibm.db2.luw.admin.partition.doc/doc/t0021577.html In a nutshell, it appears that: 1. runstats on the detached partition will be kept associated with that partition after attachment 2. runstats for the table itself will not be incrementally updated - and so require a table-level runstats My table has 400 daily partitions with 130+ million rows per day. I'd really rather avoid performing runstats on 50 billion rows every day. So, I'm wondering if I can do runstats during loads into the detached partition, include them automatically at attach time, but then only do runstats on the entire table once a week. What are the implications of this? How about if my stats were more detailed at the partition level, but more general at the table level? Any chance we'll see a new feature to update table-level stats from attached partitions in a pending update? Thanks in advance for advise and recommendations! Ken
From: Naresh Chainani on 12 Apr 2010 00:49 On Apr 9, 9:24 am, kenfar <ken...(a)gmail.com> wrote: > It's not clear from the db2 9.7 documentation whether or not to > perform runstats before or after a partition is attached: > > http://publib.boulder.ibm.com/infocenter/db2luw/v9r7/index.jsp?topic=.... > > In a nutshell, it appears that: > 1. runstats on the detached partition will be kept associated with > that partition after attachment > 2. runstats for the table itself will not be incrementally updated - > and so require a table-level runstats > > My table has 400 daily partitions with 130+ million rows per day. I'd > really rather avoid performing runstats on 50 billion rows every > day. So, I'm wondering if I can do runstats during loads into the > detached partition, include them automatically at attach time, but > then only do runstats on the entire table once a week. > > What are the implications of this? How about if my stats were more > detailed at the partition level, but more general at the table > level? Any chance we'll see a new feature to update table-level > stats from attached partitions in a pending update? > > Thanks in advance for advise and recommendations! > > Ken The InfoCenter link in your post has the following: "Execute a runstats operation after the completion of an attach operation, because the statistics that are carried over will not affect the aggregated statistics in SYSINDEXES and SYSTABLES." You seem to be asking for ATTACH to aggregate table level stats based on stats from the partition being attached. I think your feature request is reasonable. Can you work with your IBM Account team to gets this request along with brief business justification into the DB2 feature request database so that it can be evaluated and prioritized for upcoming releases? Naresh
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