Home > mailing lists

Re: procost for to_tsvector - Mailing list pgsql-hackers

From	Jeff Janes
Subject	Re: procost for to_tsvector
Date	March 12, 2015 01:22:31
Msg-id	CAMkU=1xX_EMv2OXqM=_fA9mTFwZA-L8qrn1onFvYE_toVtG+KA@mail.gmail.com Whole thread Raw
In response to	Re: procost for to_tsvector (Andrew Gierth <andrew@tao11.riddles.org.uk>)
List	pgsql-hackers

On Wed, Mar 11, 2015 at 2:54 PM, Andrew Gierth <andrew@tao11.riddles.org.uk> wrote:

Seq Scan on comments (cost=0.00..2406.18 rows=4140 width=792) (actual time=0.601..3946.589 rows=4056 loops=1)

Bitmap Heap Scan on comments (cost=204.09..2404.30 rows=4140 width=792) (actual time=2.401..11.564 rows=4056 loops=1)

...

(strangely, the seqscan plan is picked despite having a cost more than a
point higher? what's up with that?)

It is probably this, from src/backend/optimizer/util/pathnode.c :

costcmp = compare_path_costs_fuzzily(new_path, old_path, 1.01,

parent_rel->consider_startup);

Cheers,

Jeff

From: Kevin Grittner
Date: 12 March 2015, 01:19:50
Subject: Re: Precedence of standard comparison operators

From: Peter Geoghegan
Date: 12 March 2015, 01:57:57
Subject: Re: Documentation of bt_page_items()'s ctid field