From: | Stephan Szabo <sszabo(at)megazone(dot)bigpanda(dot)com> |
---|---|
To: | Benjamin Smith <lists(at)benjamindsmith(dot)com> |
Cc: | pgsql-general(at)postgresql(dot)org |
Subject: | Re: Performance woes |
Date: | 2005-12-10 19:50:04 |
Message-ID: | 20051210114807.D66479@megazone.bigpanda.com |
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Thread: | |
Lists: | pgsql-general |
On Sat, 10 Dec 2005, Benjamin Smith wrote:
> A few questions:
>
> 1) Let's assume that I have some multipile foreign keys, and I join on three
> values. For example:
>
> Create table gangsters (
> name varchar not null,
> birthdate integer not null,
> shirtnumber integer not null,
> primary key (name, birthdate, shirtnumber);
>
> create table children (
> father_name varchar not null,
> father_bd integer not null,
> father_shirtnumber integer not null,
> birthdate integer not null,
> name varchar not null,
> foreign key (father_name, father_bd, father_shirtnumber) REFERENCES
> gangsters(name, birthdate, shirtnumber)
> );
>
> We have two table declarations, each with implicit indexes:
> 1) table gangsters has a primary_key index on name, birthdate, shirtnumber.
> 2) children has an implicit index on father_name, father_bd,
> father_shirtnumber. (right?)
AFAIK, not unless you create one.
Explain analyze output for the query would probably be useful as well.
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