On Mon, Aug 19, 2013 at 1:41 PM, Tom Lane <t...@sss.pgh.pa.us> wrote: > Andres Freund <and...@2ndquadrant.com> writes: >> ISTM that we shouldn't use GetTransactionSnapshot() in enum.c but >> GetLatestSnapshot() in <= 9.3 and NULL/GetCatalogSnapshot() > 9.3. > >> typecache.c's usage was converted to GetLatestSnapshot() but enum.c's >> was not. > > That was intentional, see the comments for commit > 9ad45c18b6c8d03ce18a26223eb0d15e900c7a2c. > > Possibly we should rethink this in HEAD given that we don't do SnapshotNow > scans anymore, but I'm disinclined to do so in back branches. > > BTW, I notice that the MVCC-catalog-scans patch summarily asserts that > RenumberEnumType no longer poses any concurrency hazards. I doubt that's > true: isn't it still possible that pg_enum rows acquired through the > syscaches will have inconsistent enumsortorder values, if they were > read at different times? If you want to examine enumsortorder, you really > need to be comparing rows you know were read with the *same* snapshot.
Good point, I missed that. Here's a proposed comment patch. -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company
pg_enum_now.patch
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