Re: How to hint 2 coulms IS NOT DISTINCT FROM each other

From: Kim Rose Carlsen <krc(at)hiper(dot)dk>
To: Merlin Moncure <mmoncure(at)gmail(dot)com>
Cc: Scott Marlowe <scott(dot)marlowe(at)gmail(dot)com>, "pgsql-general(at)postgresql(dot)org" <pgsql-general(at)postgresql(dot)org>
Subject: Re: How to hint 2 coulms IS NOT DISTINCT FROM each other
Date: 2016-10-29 12:55:25
Message-ID: AM4PR0501MB26104BB0436C438D94D92249C7AC0@AM4PR0501MB2610.eurprd05.prod.outlook.com
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> try this :-D

> create or replace function indf(anyelement, anyelement) returns anyelement as
> $$
> select $1 = $2 or ($1 is null and $2 is null);
> $$ language sql;
>
> CREATE VIEW view_circuit_with_status AS (
> SELECT r.*,
> s.circuit_status,
> s.customer_id AS s_customer_id,
> p.line_speed,
> p.customer_id AS p_customer_id
> FROM view_circuit r
> JOIN view_circuit_product_main s
> ON r.circuit_id = s.circuit_id
> AND indf(r.customer_id, s.customer_id)
> JOIN view_circuit_product p
> ON r.circuit_id = p.circuit_id
> AND indf(r.customer_id, s.customer_id)
>
> merlin

This doesn't do much good. This doesn't tell the planner that the 3 customer_ids are actually of same value, and it therefore can't filter them as it sees fit.

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