functional indices with functions taking row as argument - Mailing list pgsql-general

Hi.

I have a table which represents clients' sessions / orders.

CREATE TABLE sessions (
    id              INTEGER NOT NULL DEFAULT nextval('sessions_seq'),
    ...
    finished        TIMESTAMP,
    bl_confirmed    BOOL NOT NULL DEFAULT false,
    bl_sent         BOOL NOT NULL DEFAULT false,
    bl_paid         BOOL NOT NULL DEFAULT false,
    bl_ok           BOOL NOT NULL DEFAULT false,
    PRIMARY KEY (id)
);

bl_* fields define state of the session. I define some conditions based on
those booleans and other fields. Example:

   CREATE FUNCTION is_session_to_be_sent (SESSIONS) RETURNS BOOL AS '
       SELECT ($1.bl_ok) AND ($1.bl_confirmed) AND (NOT $1.bl_sent)
   ' LANGUAGE 'sql';

I don't want to explicitly pass those three arguments to the function, because
there may be more of them in the future. So I pass SESSIONS type arg.

It would be nice, if I could create functional index on this table. Then the
following query might be faster.

   SELECT * FROM sessions s WHERE is_session_to_be_sent(s) = true;

Unfortunately, it seems that there is no appropriate syntax for creating such
an index.

Hope I'm wrong ;)

(I see a workaround - additional boolean field updated in triggers)

greetings,
Tom

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