Re: [HACKERS] vacuum process size - Mailing list pgsql-hackers

Tom, you already handled this, right?


> >Tatsuo Ishii <t-ishii@sra.co.jp> writes:
> >> Just for a testing I made a huge table (>2GB and it has 10000000
> >> tuples).  copy 10000000 tuples took 23 minutes. This is not so
> >> bad. Vacuum analyze took 11 minutes, not too bad. After this I created
> >> an index on int4 column. It took 9 minutes. Next I deleted 5000000
> >> tuples to see how long delete took. I found it was 6
> >> minutes. Good. Then I ran into a problem. After that I did vacuum
> >> analyze, and seemed it took forever!  (actually took 47 minutes). The
> >> biggest problem was postgres's process size. It was 478MB! This is not
> >> acceptable for me.  Any idea?
> >
> >Yeah, I've complained about that before --- it seems that vacuum takes
> >a really unreasonable amount of time to remove dead tuples from an index.
> >It's been like that at least since 6.3.2, probably longer.
>
> Hiroshi came up with a work around for this(see included
> patches). After applying it, the process size shrinked from 478MB to
> 86MB! (the processing time did not descrease, however). According to
> him, repalloc seems not very effective with large number of calls. The
> patches probably descreases the number to 1/10.
> --
> Tatsuo Ishii
>
> -------------------------------------------------------------------------
> *** vacuum.c.orig    Sat Jul  3 09:32:40 1999
> --- vacuum.c    Thu Aug 19 17:34:18 1999
> ***************
> *** 2519,2530 ****
>   static void
>   vc_vpinsert(VPageList vpl, VPageDescr vpnew)
>   {
>
>       /* allocate a VPageDescr entry if needed */
>       if (vpl->vpl_num_pages == 0)
> !         vpl->vpl_pagedesc = (VPageDescr *) palloc(100 * sizeof(VPageDescr));
> !     else if (vpl->vpl_num_pages % 100 == 0)
> !         vpl->vpl_pagedesc = (VPageDescr *) repalloc(vpl->vpl_pagedesc, (vpl->vpl_num_pages + 100) *
sizeof(VPageDescr));
>       vpl->vpl_pagedesc[vpl->vpl_num_pages] = vpnew;
>       (vpl->vpl_num_pages)++;
>
> --- 2519,2531 ----
>   static void
>   vc_vpinsert(VPageList vpl, VPageDescr vpnew)
>   {
> + #define PG_NPAGEDESC 1000
>
>       /* allocate a VPageDescr entry if needed */
>       if (vpl->vpl_num_pages == 0)
> !         vpl->vpl_pagedesc = (VPageDescr *) palloc(PG_NPAGEDESC * sizeof(VPageDescr));
> !     else if (vpl->vpl_num_pages % PG_NPAGEDESC == 0)
> !         vpl->vpl_pagedesc = (VPageDescr *) repalloc(vpl->vpl_pagedesc, (vpl->vpl_num_pages + PG_NPAGEDESC) *
sizeof(VPageDescr));
>       vpl->vpl_pagedesc[vpl->vpl_num_pages] = vpnew;
>       (vpl->vpl_num_pages)++;
>
>
> ************
> Check out "PostgreSQL Wearables" @ http://www.pgsql.com
>
>


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