In pg_dump, avoid doing per-table queries for RLS policies.
For no particularly good reason, getPolicies() queried pg_policy
separately for each table. We can collect all the policies in
a single query instead, and attach them to the correct TableInfo
objects using findTableByOid() lookups. On the regression
database, this reduces the number of queries substantially, and
provides a visible savings even when running against a local
server.
Per complaint from Hubert Depesz Lubaczewski. Since this is such
a simple fix and can have a visible performance benefit, back-patch
to all supported branches.
Discussion: https://postgr.es/m/
20210826084430.GA26282@depesz.com