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

Re: Probable faq: need some benchmarks of pgsql vr.s mysql

From: Josh Berkus <josh(at)agliodbs(dot)com>
To: pgsql-advocacy(at)postgresql(dot)org
Subject: Re: Probable faq: need some benchmarks of pgsql vr.s mysql
Date: 2010-11-08 18:02:01
Message-ID: 4CD83B19.1070806@agliodbs.com (view raw or flat)
Thread:
Lists: pgsql-advocacy
> It isn't that simple as I described earlier in this thread. InnoDB has
> the insert buffer:
> http://www.google.com/search?hl=en&q=insert+buffer+innodb
>
> InnoDB can do a disk seek for each PK/unique index on a table during
> an insert. It does not do disk seeks for each secondary index.

How does InnoDB make sure that sessions see the buffered inserts if they 
should transactionally be visible?

Postgres doesn't have a concept of "primary" vs. "secondary" indexes, 
since unlike InnoDB, table rows are not btree-ordered on disk.  This 
means that, for example, it takes a much larger table before we hit the 
"won't fit in memory" limit where the indexes become expensive to 
update.  It also makes insert buffering much less valuable, since when a 
table gets busy we can just start tacking stuff onto the end.

Not that I wouldn't love to have someone working on "fractal indexes" in 
Postgres.  Maybe I need to find a Postgres-based business model for 
Tokutek.  ;-)

-- 
                                   -- Josh Berkus
                                      PostgreSQL Experts Inc.
                                      http://www.pgexperts.com

In response to

Responses

pgsql-advocacy by date

Next:From: Peter EisentrautDate: 2010-11-08 18:47:44
Subject: Re: Postgres References
Previous:From: Martin Farach-ColtonDate: 2010-11-08 16:23:18
Subject: Re: Probable faq: need some benchmarks of pgsql vr.s mysql

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