Many-To-Many Bridge Table Index - Mailing list pgsql-general

From Sergei Dubov
Subject Many-To-Many Bridge Table Index
Date
Msg-id 433C4409.9090007@gmail.com
Whole thread Raw
Responses Re: Many-To-Many Bridge Table Index
Re: Many-To-Many Bridge Table Index
List pgsql-general
Hi guys,

I'd really appreciate if you could clarify this to me. Let's say I have
a table named TABLE_A that is a bridge to many-to-many relationship
between TABLE_B and TABLE_C, as such here is my declaration:

CREATE TABLE table_a (
      table_b_id    INT4        NOT NULL
    REFERENCES table_b ON DELETE CASCADE ON UPDATE CASCADE,

    table_c_id    INT4        NOT NULL
    REFERENCES table_c ON DELETE RESTRICT ON UPDATE CASCADE,

    CONSTRAINT table_a_pkey
    PRIMARY KEY (table_b_id, table_c_id)
);

This will automatically create a unique index on the primary key.

Well, if I do a query later like:

select * from table_a where table_b_id=1,

will the query use an index? Will this be true when I do join on this table?

Thanks so much,

Serge

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