Re: PostgreSQL Indexing versus MySQL

Jan,

Thanks for the reply. Is there anyway to control your index file locations?
Can I place my Postgres indexes on different mount points?

I haven't put Postgres to the full test yet for importing/indexing but I was
concerned on the time it took to perform some sample queries that MySQL
seemed to handle more efficiently.

I would like view support but let me know if you have any insight into my
first question.

Thanks for the reply.

Chris.

-----Original Message-----
From: Jan Wieck [mailto:JanWieck(at)Yahoo(dot)com]
Sent: Sunday, February 15, 2004 4:23 PM
To: Chris Fossenier
Cc: pgsql-general(at)postgresql(dot)org
Subject: Re: [GENERAL] PostgreSQL Indexing versus MySQL

Chris Fossenier wrote:

> I currently have a client with a database that must hold 125 million
> records and all tallied about 250 fields.
>
> The database has been normalized and indexed appropriately.
>
> If any of you have worked with MySQL, you will have discovered that
> indexing is very limited. You can only have one index file per table.
> The indexing process actuallly creates a full copy of the original
> table and once you get above 2 indexes with 125million records, it is
> extremely slow.
>
> Should I even bother trying PostgreSQL to resolve this issue?
>
> We can generate the same indexes in MS SQL and Oracle in a fraction of
> the amount of time when held up to MySQL.

This is a known MySQL specific problem. I know of no other database that
handles index creation in such an inefficient way.

Creating an index in PostgreSQL requires scanning the entire main table
and sorting the resulting key set ... don't see how to do it better.
Every index is stored in its own (set of) file(s). During index
creation, an exclusive lock on the table is required by create index, so
reindexing your entire DB is not your preferred operation during peak
access times of your webserver. But I think professional DBA's don't
torture Oracle that way either.

Jan

>
> Thanks
>
> Chris.
>

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