Idea is to reduce lock level of ADD/DROP COLUMN from AccessExclusiveLock
down to ShareRowExclusiveLock.
To make it work, we need to recognise that we are adding a column
without rewriting the table. That's a simple test at post parse analysis
stage, but what I can't do is work out whether the column name used is a
domain name which contains a constraint.
So if we want this, then it seems we need to add a separate subcommand,
so we can then throw an error if a domain is specified.
ALTER TABLE foo
ADD [COLUMN] colname CONCURRENTLY;
Or other ideas? Do we really care?
DROP ... RESTRICT works fine at reduced lock level, assuming I'm not
missing anything...
ALTER TABLE foo
DROP [COLUMN] colname RESTRICT;
Patch needs docs, tests and a check for the domain, so just a quick hack
just to get my dev muscles back in shape after Christmas. (Jokes
please).
Comments?
--
Simon Riggs http://www.2ndQuadrant.com/books/
PostgreSQL Development, 24x7 Support, Training and Services
