From: | "Igor Neyman" <ineyman(at)perceptron(dot)com> |
---|---|
To: | "Yang Zhang" <yanghatespam(at)gmail(dot)com>, "Richard Broersma" <richard(dot)broersma(at)gmail(dot)com> |
Cc: | "Frank Heikens" <frankheikens(at)mac(dot)com>, <pgsql-general(at)postgresql(dot)org> |
Subject: | Re: Sorting performance vs. MySQL |
Date: | 2010-02-22 22:31:58 |
Message-ID: | F4C27E77F7A33E4CA98C19A9DC6722A205932548@EXCHANGE.corp.perceptron.com |
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Thread: | |
Lists: | pgsql-general |
When in doubt - test.
Why not remove index in MySQL (or create index in PostgreSQL) and see
what happens.
Why trying compare "apples and oranges"?
Igor Neyman
> -----Original Message-----
> From: Yang Zhang [mailto:yanghatespam(at)gmail(dot)com]
> Sent: Monday, February 22, 2010 1:37 PM
> To: Richard Broersma
> Cc: Frank Heikens; pgsql-general(at)postgresql(dot)org
> Subject: Re: Sorting performance vs. MySQL
>
> On Mon, Feb 22, 2010 at 1:30 PM, Richard Broersma
> <richard(dot)broersma(at)gmail(dot)com> wrote:
> > On Mon, Feb 22, 2010 at 10:17 AM, Frank Heikens
> <frankheikens(at)mac(dot)com> wrote:
> >
> >> There is no index on the column transactionid in your
> >> PostgreSQL-table, as there is in your MySQL-table. This
> explains the difference.
> >>
> >> CREATE INDEX i_transactionid ON public.metarelcloud_transactionlog
> >> (transactionid);
> >
> > Does an index help a sort operation in PostgreSQL?
>
> I also share the same doubt. An external merge-sort needs to
> make complete passes over the entire dataset, with no
> index-directed accesses.
> --
> Yang Zhang
> http://www.mit.edu/~y_z/
>
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