Hi there,

seems I have a serious problem with vacuuming of rather big table
(500,000,000 rows) on dual Intel(R) Xeon(TM) CPU 2.40GHz, 1Gb RAM,
running Linux 2.6.7. I have PostgreSQL 8.0 release installed with
slightly changed postgresql.conf:

shared_buffers = 24576 # min 16, at least max_connections*2, 8KB each
maintenance_work_mem = 65536 # 16384 # min 1024, size in KB
checkpoint_segments = 12 #3 # in logfile segments, min 1, 16MB each

I tried run 'vacuumdb -v -z -f wsdb > vacuum-wsdb.log 2>&1&'
with default value of maintenance_work_mem but it was
too small for big table and I increased its value as Tom recommended.
But this change causes huge memory consumption - rather quickly memory
grew to 1Gb and after almost 42 hours of running (yes, it's still running)
postmaster eats more than 2Gb of RAM

20458 postgres 15 0 2462m 646m 204m D 37.5 63.9 744:38.74 postmaster

There are no messages in log file since start (just pg_* tables), so it's
difficult to say if there is some useful activity

The only non-standard action was installing 8.0 in neighbour with running
7.4.6 version. I run configure with different prefix and pgport specified
and use PGPORT, PGLIB, PGDATA, PATH modified to work with new postmaster.
I don't see any problem here.

Does anybody have experience vacuuming large database with 8.0 ?


table is very simple:

Table "public.usno"
Column | Type | Modifiers
--------+--------+-----------
ra | real |
dec | real |
bmag | real |
rmag | real |
ipix | bigint |
Indexes:
"ipix_ind" btree (ipix)
"radec_idx1" btree (ra, "dec")

Regards,
Oleg
__________________________________________________ ___________
Oleg Bartunov, sci.researcher, hostmaster of AstroNet,
Sternberg Astronomical Institute, Moscow University (Russia)
Internet: oleg@sai.msu.su, http://www.sai.msu.su/~megera/
phone: +007(095)939-16-83, +007(095)939-23-83

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On Sun, 30 Jan 2005, Oleg Bartunov wrote:

> On Sun, 30 Jan 2005, Tom Lane wrote:
>
>> Oleg Bartunov <oleg@sai.msu.su> writes:
>>> On Sun, 30 Jan 2005, Tom Lane wrote:
>>>> I'm confused. The log trace you showed us before appeared to be from
>>>> a non-FULL vacuum, but here you're saying it's VACUUM FULL. Which is
>>>> it ... or did you change?
>>
>>> Yes, first time I tried vacuum from withing psql, next time I decided
>>> to run vacuumdb and seems changed option.
>>
>> Um. Well, a VACUUM FULL is going to build in-memory data structures
>> that represent *all* of the usable free space in a table. I don't
>> actually think that VACUUM FULL is useful on an enormous table ... you
>> want to keep after it with routine plain VACUUMs, instead.
>
> ok. I'll try without FULL, but if memory does not fail me postmaster was
> also greedy. Let's see

Seems, postmaster eats expected amount of memory now ! Will see how long
it will proceeded. Probably, my case should be documented somewhere.

>
>>
>> Another possibility is to use CLUSTER or a rewriting ALTER TABLE to
>> shrink the space, but be aware that this requires a transient second
>> copy of the table and indexes.

I aware, but I don't so much free space

Is there TODO for scaling VACUUM FULL ?



>>
>> regards, tom lane
>>
>
> Regards,
> Oleg
> __________________________________________________ ___________
> Oleg Bartunov, sci.researcher, hostmaster of AstroNet,
> Sternberg Astronomical Institute, Moscow University (Russia)
> Internet: oleg@sai.msu.su, http://www.sai.msu.su/~megera/
> phone: +007(095)939-16-83, +007(095)939-23-83
>
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>

Regards,
Oleg
__________________________________________________ ___________
Oleg Bartunov, sci.researcher, hostmaster of AstroNet,
Sternberg Astronomical Institute, Moscow University (Russia)
Internet: oleg@sai.msu.su, http://www.sai.msu.su/~megera/
phone: +007(095)939-16-83, +007(095)939-23-83

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TIP 9: the planner will ignore your desire to choose an index scan if your
joining column's datatypes do not match

On Sun, 30 Jan 2005, Oleg Bartunov wrote:

>
> Seems, postmaster eats expected amount of memory now ! Will see how long
> it will proceeded. Probably, my case should be documented somewhere.

just to inform - vacuum took almost 48 hours !

>
>>
>>>
>>> Another possibility is to use CLUSTER or a rewriting ALTER TABLE to
>>> shrink the space, but be aware that this requires a transient second
>>> copy of the table and indexes.
>
> I aware, but I don't so much free space

I run
wsdb=# create table c_usno as select * from usno order by ipix;
to cluster table and notice that disk usage changing in discontinuous manner.
After some reduction I see no changes. postmaster is doing something

PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
12723 postgres 18 0 207m 196m 204m D 21.6 19.4 52:17.12 postmaster

I see that pgsql_tmp/ contains files, looks like clustered table.
What postmaster is doing if disk usage doesn't changed ?



>
> Is there TODO for scaling VACUUM FULL ?
>
>
>
>>>
>>> regards, tom lane
>>>
>>
>> Regards,
>> Oleg
>> __________________________________________________ ___________
>> Oleg Bartunov, sci.researcher, hostmaster of AstroNet,
>> Sternberg Astronomical Institute, Moscow University (Russia)
>> Internet: oleg@sai.msu.su, http://www.sai.msu.su/~megera/
>> phone: +007(095)939-16-83, +007(095)939-23-83
>>
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>>
>> http://www.postgresql.org/docs/faq
>>
>
> Regards,
> Oleg
> __________________________________________________ ___________
> Oleg Bartunov, sci.researcher, hostmaster of AstroNet,
> Sternberg Astronomical Institute, Moscow University (Russia)
> Internet: oleg@sai.msu.su, http://www.sai.msu.su/~megera/
> phone: +007(095)939-16-83, +007(095)939-23-83
>
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> TIP 9: the planner will ignore your desire to choose an index scan if your
> joining column's datatypes do not match
>

Regards,
Oleg
__________________________________________________ ___________
Oleg Bartunov, sci.researcher, hostmaster of AstroNet,
Sternberg Astronomical Institute, Moscow University (Russia)
Internet: oleg@sai.msu.su, http://www.sai.msu.su/~megera/
phone: +007(095)939-16-83, +007(095)939-23-83

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TIP 9: the planner will ignore your desire to choose an index scan if your
joining column's datatypes do not match

On Tue, 1 Feb 2005, Tom Lane wrote:

> Oleg Bartunov <oleg@sai.msu.su> writes:
>> I see that pgsql_tmp/ contains files, looks like clustered table.
>> What postmaster is doing if disk usage doesn't changed ?
>
> Most likely doing a disk-based merge sort ...
>

just interesting - multiway, in-place or just place merge sort ?

> regards, tom lane
>

Regards,
Oleg
__________________________________________________ ___________
Oleg Bartunov, sci.researcher, hostmaster of AstroNet,
Sternberg Astronomical Institute, Moscow University (Russia)
Internet: oleg@sai.msu.su, http://www.sai.msu.su/~megera/
phone: +007(095)939-16-83, +007(095)939-23-83

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