Re: Finding referecing and referenced tables, adaptation from David Fetter's solution

On 30 Jul 2011, at 13:49, Gavin Flower wrote:

> On 30/07/11 10:45, bricklen wrote:
>> [...]
>> CREATE OR REPLACE VIEW table_dependencies AS (
>> WITH RECURSIVE t AS (
>> SELECT
>> c.oid AS origin_id,
>> c.oid::regclass::text AS origin_table,
>> c.oid AS referencing_id,
>> c.oid::regclass::text AS referencing_table,
>> c2.oid AS referenced_id,
>> c2.oid::regclass::text AS referenced_table,
>> ARRAY[c.oid::regclass,c2.oid::regclass] AS chain
>> FROM pg_catalog.pg_constraint AS co
>> INNER JOIN pg_catalog.pg_class AS c
>> ON c.oid = co.conrelid
>> INNER JOIN pg_catalog.pg_class AS c2
>> ON c2.oid = co.confrelid
>> [...]
> I am curious about the explicit use of INNER JOINs, I find them cumbersome, so I rewrote the code to remove them, I know in some situations that they can improve performance - but was this the case here, or is there some other subtlety that I have missed?

Explicit inner joins provide a means to separate the join conditions from other result filtering conditions. Each join is kept with its relevant conditions even, so it's immediately clear which conditions pertain to which joins.

I find in general explicit inner joins improve readability of queries over implicit joins, especially when the joins get a little more complicated.

Perhaps what you find cumbersome about them is just a matter of formatting?

Alban Hertroys

--
The scale of a problem often equals the size of an ego.

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