Re: [HACKERS] pgbench -i order of vacuum

2012-07-23 Thread Robert Haas
On Fri, Jul 20, 2012 at 12:26 PM, Tom Lane t...@sss.pgh.pa.us wrote:
 Jeff Janes jeff.ja...@gmail.com writes:
 On Fri, Jul 20, 2012 at 7:57 AM, Amit Kapila amit.kap...@huawei.com wrote:
 The command it executes is vacuum analyze .., so it will do analyze also
 on table which means
 it will collect stats corresponding to table and index.

 Are there stats collected on indexes?

 Only for expression indexes, which there aren't any of in the standard
 pgbench scenario.  I don't see a reason not to change the ordering
 as you suggest.

OK, done.

-- 
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company

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Re: [HACKERS] pgbench -i order of vacuum

2012-07-20 Thread Amit Kapila
 From: pgsql-hackers-ow...@postgresql.org
[mailto:pgsql-hackers-ow...@postgresql.org] On Behalf Of Jeff Janes
 Sent: Friday, July 20, 2012 5:36 AM


 Is there a reason to vacuum the pgbench_* tables after the indexes on them
are built, rather than before?

 Since the indexes are on fresh tables, they can't have anything that needs
to be cleaned.

The command it executes is vacuum analyze .., so it will do analyze also
on table which means
it will collect stats corresponding to table and index. So if you do it
before creation of index pgbench might behave 
different.
In specific, from function do_analyze_rel(), it will not call
compute_index_stats() if you execute the command before
Creation of index.

With Regards,
Amit Kapila.



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Re: [HACKERS] pgbench -i order of vacuum

2012-07-20 Thread Jeff Janes
On Fri, Jul 20, 2012 at 7:57 AM, Amit Kapila amit.kap...@huawei.com wrote:
 From: pgsql-hackers-ow...@postgresql.org
 [mailto:pgsql-hackers-ow...@postgresql.org] On Behalf Of Jeff Janes
 Sent: Friday, July 20, 2012 5:36 AM


 Is there a reason to vacuum the pgbench_* tables after the indexes on them
 are built, rather than before?

 Since the indexes are on fresh tables, they can't have anything that needs
 to be cleaned.

 The command it executes is vacuum analyze .., so it will do analyze also
 on table which means
 it will collect stats corresponding to table and index.

Are there stats collected on indexes?  I thought all stats were on
tables only, and the only reason to visit the index was to remove
all-visible-dead entries.

Cheers,

Jeff

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Re: [HACKERS] pgbench -i order of vacuum

2012-07-20 Thread Tom Lane
Jeff Janes jeff.ja...@gmail.com writes:
 On Fri, Jul 20, 2012 at 7:57 AM, Amit Kapila amit.kap...@huawei.com wrote:
 The command it executes is vacuum analyze .., so it will do analyze also
 on table which means
 it will collect stats corresponding to table and index.

 Are there stats collected on indexes?

Only for expression indexes, which there aren't any of in the standard
pgbench scenario.  I don't see a reason not to change the ordering
as you suggest.

regards, tom lane

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[HACKERS] pgbench -i order of vacuum

2012-07-19 Thread Jeff Janes
Is there a reason to vacuum the pgbench_* tables after the indexes on
them are built, rather than before?

Since the indexes are on fresh tables, they can't have anything that
needs to be cleaned.

I don't think the current order accomplishes anything, except to slow
down large initializations by ~25%.

The attached patch moves the vacuums up.

I also made -n skip the vacuums altogether.  Since -n is allowed under
-i, it would be nice if it did something, and there is only one
intuitive thing for it to do.  I don't know what the use case for is,
but I think I've heard grumbling about it before.

Cheers,

Jeff


pgbench_vacuum_order_v1.patch
Description: Binary data

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