On 08/16/2010 08:44 AM, Greg Smith wrote:
> Mario Splivalo wrote:
>> I understand that VACUUM FULL in 9.0 copies all the data, but is it OK
>> that plain vacuum in 9.0 is slower than in 8.4?
>
> It should be faster for tables with a lot of junk in them, but the new
> VACUUM FULL is likely to be slower for ones that are already clean.
> Note that one thing to be aware of is that depending on where you got
> your 9.0 from, it may be compiled with debugging and assertion calls
> that can slow certain operations down quite a bit. If you try this at a
> command prompt:
>
> postgres=# show debug_assertions;
> debug_assertions
> ------------------
> on
>
> And that's on, you can expect that copy of 9.0 to be significantly
> slower at a number of things than a similar 8.4.
I downloaded source and compiled it myself, this is excerpt from the
config.log:
enable_debug='no'
enable_dtrace='no'
enable_nls='no'
enable_profiling='no'
postgres=# show debug_assertions;
debug_assertions
------------------
off
(1 row)
Yes, I run the tests on clean tables. I run VACUUM FULL, and after that
I mesured how long it takes for VACUUM ANALYZE and VACUUM ANALYZE FULL.
So, it is ok for VACUUM FULL (on clean tables) on 9.0b4 to be six times
slower than on 8.4. But is it ok for plain VACUUM to be two times slower?
Mike
