| From: | Claudio Freire <klaussfreire(at)gmail(dot)com> |
|---|---|
| To: | Merlin Moncure <mmoncure(at)gmail(dot)com> |
| Cc: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com>, Peter Geoghegan <peter(at)2ndquadrant(dot)com>, Stefan Keller <sfkeller(at)gmail(dot)com>, pgsql-performance(at)postgresql(dot)org |
| Subject: | Re: Hash index use presently(?) discouraged since 2005: revive or bury it? |
| Date: | 2011-09-16 01:04:58 |
| Message-ID: | CAGTBQpanG5vXJctZ42Qz9F9=+pqQjrYyjM6emZio6brh4xQELw@mail.gmail.com |
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| Lists: | pgsql-performance |
On Fri, Sep 16, 2011 at 3:00 AM, Merlin Moncure <mmoncure(at)gmail(dot)com> wrote:
>
> c:\Program Files\PostgreSQL\9.0\data>dir/s | grep 16525
> 09/15/2011 07:46 PM 224,641,024 16525
>
> c:\Program Files\PostgreSQL\9.0\data>dir/s | grep 16526
> 09/15/2011 07:49 PM 268,451,840 16526
That's not surprising at all.
Hashes need to be bigger to avoid collisions.
What's more interesting than index creation, is index maintainance and
access costs.
In my experience, btree beats hash.
I haven't tried with 9.1, though.
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