Quick question

On Fri, 3 Oct 2003, Christopher Kings-Lynne wrote:

Hi guys,

If someone could help me with this, it would be cool. How do I query
the catalogs to find the underlying index for a constraint? (Assuming
the constraint is primary or unique)

For a primary key you can do:

SELECT cls.relname AS index_name
FROM pg_class cls, pg_constraint con, pg_index i
WHERE cls.oid = i.indexrelid AND con.conrelid = i.indrelid AND
i.indisprimary AND con.conname='<constraint name>';

This is not possible for a unique constraint because you can have multiple
unique constraints per table. So you are left trying to match
pg_constraint.conkey to pg_index.indkey (for which no default operator
exists), but even this can fail if you have the unlikely situation of two
unique indexes covering the same columns.

Kris Jurka

Christopher Kings-Lynne <chriskl@familyhealth.com.au> writes:

If someone could help me with this, it would be cool. How do I query
the catalogs to find the underlying index for a constraint? (Assuming
the constraint is primary or unique)

A first approximation is that the constraint and the index have the same
name, but I suppose someone could break that association by renaming the
index. Look in pg_depend for an internal dependency entry from the
index to the constraint if you want to be sure.

regards, tom lane

Thanks - that's what I ended up doing. Hooray for CLUSTER indexes and
constraints in phpPgAdmin CVS now!

Chris

Tom Lane wrote: