Skip site navigation (1) Skip section navigation (2)

Performance penalty of visibility info in indexes?

From: Jim Nasby <decibel(at)decibel(dot)org>
To: PostgreSQL Development <pgsql-hackers(at)postgresql(dot)org>
Subject: Performance penalty of visibility info in indexes?
Date: 2007-02-02 05:57:41
Message-ID: 9835AE6B-7A50-480A-99C5-F325DDB12BBC@decibel.org (view raw or flat)
Thread:
Lists: pgsql-hackers
Has anyone actually measured the performance overhead of storing  
visibility info in indexes? I know the space overhead sounds  
daunting, but even if it doubled the size of the index in many cases  
that'd still be a huge win over having to scan the heap as well as  
the index (esp. for things like count(*)). There would also be  
overhead from having to update the old index tuple, but for the case  
of updates you're likely to need that page for the new index tuple  
anyway.

I know this wouldn't work for all cases, but ISTM there are many  
cases where it would be a win.
--
Jim Nasby                                            jim(at)nasby(dot)net
EnterpriseDB      http://enterprisedb.com      512.569.9461 (cell)



Responses

pgsql-hackers by date

Next:From: Jim NasbyDate: 2007-02-02 06:03:09
Subject: Re: Estimation error in n_dead_tuples
Previous:From: Bruce MomjianDate: 2007-02-02 05:43:04
Subject: Re: column ordering, was Re: [PATCHES] Enums patch v2

Privacy Policy | About PostgreSQL
Copyright © 1996-2014 The PostgreSQL Global Development Group