David G Johnston <david.g.johnston@xxxxxxxxx> writes: > In the end the two questions are: > 1) does adding a length restriction cause a table rewrite? Yes. In principle the restriction could be checked with just a scan, not a rewrite, but ALTER TABLE doesn't currently understand that --- and in any case a scan would still be potentially a long time. > 2) what level of locking occurs while the length check is resolving? AccessExclusiveLock. This would be necessary in any case for a data type change. regards, tom lane -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
