From: | fearless_fool <rdpoor(at)gmail(dot)com> |
---|---|
To: | pgsql-general(at)postgresql(dot)org |
Subject: | multiple SAVEPOINTs without RELEASE SAVEPOINT |
Date: | 2012-07-13 21:05:00 |
Message-ID: | 1342213500675-5716594.post@n5.nabble.com |
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Thread: | |
Lists: | pgsql-general |
Is there any penalty for repeatedly doing
SAVEPOINT eugene
without a corresponding
RELEASE SAVEPOINT
?
In my case, I have a table with a unique index constraint. Multiple
processes will be trying to "create or lookup" a record, so trapping the
unique index constraint seems the most robust way to detect if the record
already exists. The overall structure I'm using (in pseudo-Ruby syntax):
begin
response = execute("SAVEPOINT eugene;
INSERT INTO symbols (name) VALUES
('#{name}') RETURNING id")
rescue
# arrive here on a constraint violation if the name already existed
response = execute("ROLLBACK TO SAVEPOINT eugene;
SELECT id FROM symbols WHERE symbols.name =
'#{name}'")
ensure
# is this RELEASE strictly required?
execute("RELEASE SAVEPOINT eugene")
end
(On a related note, would I be better off using advisory locks? And would
that be sufficient in the face of multiple processes?)
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