pgsql: Avoid unnecessary catalog updates in ALTER SEQUENCE

Started by Peter Eisentrautabout 9 years ago1 messagescomitters

peter_e@gmx.net

about 9 years ago

Avoid unnecessary catalog updates in ALTER SEQUENCE

ALTER SEQUENCE can do nontransactional changes to the sequence (RESTART
clause) and transactional updates to the pg_sequence catalog (most other
clauses). When just calling RESTART, the code would still needlessly do
a catalog update without any changes. This would entangle that
operation in the concurrency issues of a catalog update (causing either
locking or concurrency errors, depending on how that issue is to be
resolved).

Fix by keeping track during options parsing whether a catalog update is
needed, and skip it if not.

Reported-by: Jason Petersen <jason@citusdata.com>

Branch
------
master

Details
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https://git.postgresql.org/pg/commitdiff/3d092fe5409b98272ddd6e623b657308a3c5f004

Modified Files
--------------
src/backend/commands/sequence.c | 51 ++++++++++++++++++++++++++++++++++-------
1 file changed, 43 insertions(+), 8 deletions(-)

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