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stevetheski
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oracle DBMS_STATS slow

All I am wondering why the following gather stats command will take 24hrs on serverA however if i export the table and import it (including indexes) to serverB the stats are collected in 10 minutes.

ServerA and Server are identical vm's on the same metal box

EXECUTE DBMS_STATS.GATHER_TABLE_STATS( 
ownname =>  'SIEBEL', 
tabname => 'S_OPTY',  
block_sample => FALSE,  
method_opt => 'FOR ALL COLUMNS  size SKEWONLY', 
granularity => 'ALL', 
 cascade => FALSE, 
degree => DBMS_STATS.DEFAULT_DEGREE);

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also with the above stats should index stats be run also?

Thanks
Oracle Database

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johnsone

8/22/2022 - Mon
slightwv (䄆 Netminder)

You might have a lot more extents on ServerA.  They might be all over the place in the files.

The blocks in the extents on serverA might be all jumbled around (scientific term) with a lot of chained rows etc...

All that said, I wouldn't expect the 24 hour to 10 minute difference.  You might want to also open an SR with Oracle Support on this one.

>>also with the above stats should index stats be run also?

The docs have this info:
http://docs.oracle.com/cd/E11882_01/appdev.112/e25788/d_stats.htm#i1036461

GATHER_TABLE_STATS Procedure
 
This procedure gathers table and column (and index) statistics.
sventhan

How big the table is? Are you running the same DBMS_STATS on both the server?

Is your table partitioned?  Try estimate percent 20%

EXECUTE DBMS_STATS.GATHER_TABLE_STATS(
ownname =>  'SIEBEL',
tabname => 'S_OPTY',  
estimate_percent => 20,  
 cascade => FALSE,
degree => DBMS_STATS.DEFAULT_DEGREE);
stevetheski

ASKER
slightwv
I have read the docs and other blogs the cascade=false to me has to do with partitioning however some where i read that it pertains to indexes also. Just looking for clarification.

I agree with the blocks/extents all over the place especially considering the table has 276 columns and the imported table is mostly organized due to the import re-org.
If I move the table to a new tablespace/datafile the size of the table on disk will most likely shrink. will that also help with performance? I came from a DW/DSS role to a relational role on this project (which i have no real access) and 2 or 3 times a year we migrated tables. The tables that were updated a lot got smaller but the performance pretty much stayed the same. Once again this was a heavily partitioned DW with mostly bulk inserts other than a few of the "smaller" tables. Just thinking out loud if the table is less fragmented it should be faster. but tom kyte says indexes see little to no performance when they are reorganized so thats why i am asking your opinion.

sventhan
the table is about 3g and has a millions of rows. How many to be exact well i can't say. I am the development DBA and do not have access to the prod server. I have noticed a lot of things I would have done differently based on AWR reports.  I also suggested changing the % to 20 but that really doesn't answer the question. The table is not partitioned this is something i have been looking into for both an archiving and performance enhancements.

The worst part is i do not know and haven't received the answer to "what is the DEFAULT_DEGREE on each server" knowing these guys it may be serial on the prod server :-o

would either of you ever use method_opt => 'FOR ALL COLUMNS  size SKEWONLY' on a table with 276 columns. I know if you had your way you wouldn't have a table with 276 rows, neither would I. :)
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slightwv (䄆 Netminder)

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stevetheski

ASKER
Thanks for all the info so far. especially considering we are all on the same page. Who created the table? only one thing can be worse than old main frame folks. THE DEVELOPERS.

I have a lot of proposals to "clean up" the database. One of the funny things i did was suggested a few bitmap indexes on the DSS db. the queries wwent from hours to about a minute. however it increased load time from 2 hrs to 2.5 hrs. and they said no. so to save about 100 processing hours a day running reports they would rather save less than 30 mins loading data.

Yeah it's GOVT contracting at it's best. do nothing blame everyone else.
slightwv (䄆 Netminder)

>>so to save about 100 processing hours a day running reports they would rather save less than 30 mins loading data.

WOW!!!!  Did you try to force them to justify that position?   Aside from 'job security'...

TRUST me:  I've had my share of dealing with Gov't contractors on both sides of the fence.

There is always enough time to do it wrong but never enough time to correct previous mistakes!  NEVER go backwards!!! ALWAYS forwards!!!
stevetheski

ASKER
im trying being the new guy on the block i am also trying to not ruffle feathers.
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stevetheski

ASKER
going to leave this open for another week or so to see if anyone else chimes in about the  method_opt => 'FOR ALL COLUMNS  size SKEWONLY', or anything else.
slightwv (䄆 Netminder)

You might ask about methind_opt as a new question.  Most Experts that monitor Oracle questions have probably already seen this one and didn't feel they had anythig to offer on the performance.
johnsone

Are we sure it is really taking that much time?  What is it waiting for, if anything?  I have seen this before, and the issue was that the stats process is waiting for a lock on the table.  Some careless interactive user left an uncommitted transaction on the table and the lock could not be acquired to do the stats.
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