In response to Alvaro Herrera <[EMAIL PROTECTED]>: > Bill Moran wrote: > > In response to Tom Lane <[EMAIL PROTECTED]>: > > > > > "Bill Moran" <[EMAIL PROTECTED]> writes: > > > > Issuing a statement like: > > > > CREATE TABLE table2 AS SELECT * FROM table1; > > > > simultaneously in two separate sessions should result in an error like > > > > "ERROR: relation "table2" already exists" (in one or the other of the > > > > sessions, depending on the exact timing of things). > > > > > > This isn't really fixable, or at least the cure would be worse than the > > > disease. The "already exists" message is just a pre-check and it cannot > > > detect an uncommitted concurrent attempt to insert the same table name. > > > The place where the rubber really meets the road is during unique index > > > insertion. We might be able to fix things so that you get a unique > > > index complaint about pg_class.relname instead of pg_type, but that > > > would be about it. > > > > I figured it was something along those lines, otherwise it would have > > already been "fixed". > > > > I haven't had time to look at the code, so I'm speaking from a position > > of ignorance, but would it be terribly difficult to catch the unique > > constraint error, then re-run the pre-check to determine if it's > > occurring as a result of trying to create an existing table, and > > translate the error to a friendlier one before reporting to the client? > > The problem we have with that is that unique index violations are not > separable from the elog(ERROR) they generate, so yes, it is terribly > difficult. > > Maybe it would work to have a PG_TRY block around that code and compare > the error code with the one for unique index violation, in which case > the error is turned into "relation already exists".
That was my hope, but I'm hoping from a position of ignorance, as I've yet to have a chance to look at the code, and doubt I'll get a chance for at least a week. -- Bill Moran Collaborative Fusion Inc. http://people.collaborativefusion.com/~wmoran/ [EMAIL PROTECTED] Phone: 412-422-3463x4023 ---------------------------(end of broadcast)--------------------------- TIP 7: You can help support the PostgreSQL project by donating at http://www.postgresql.org/about/donate
