Re: GiST index performance
От | Matthew Wakeling |
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Тема | Re: GiST index performance |
Дата | |
Msg-id | alpine.DEB.2.00.0904201503570.22330@aragorn.flymine.org обсуждение исходный текст |
Ответ на | Re: GiST index performance (Matthew Wakeling <matthew@flymine.org>) |
Ответы |
Re: GiST index performance
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Список | pgsql-performance |
On Fri, 17 Apr 2009, Matthew Wakeling wrote: > I have done a bit of investigation, and I think I might have found the > smoking gun I was looking for. I have found a bug in the contrib package seg, which has been copied into the bioseg data type as well. It causes the index to be created with horribly bad unselective trees, so that when a search is performed many of the branches of the tree need to be followed. This explanation does not extend to btree_gist, so I will have to further investigate that. Apply the following patch to contrib/seg/seg.c: *** seg.c 2006-09-10 18:36:51.000000000 +0100 --- seg.c_new 2009-04-20 15:02:52.000000000 +0100 *************** *** 426,432 **** else { datum_r = union_dr; ! size_r = size_alpha; *right++ = i; v->spl_nright++; } --- 426,432 ---- else { datum_r = union_dr; ! size_r = size_beta; *right++ = i; v->spl_nright++; } Matthew -- The early bird gets the worm. If you want something else for breakfast, get up later.
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