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When (re) loading the typcache comparison cache for an enum type's values, use an up-to-date MVCC snapshot, not the transaction's existing snapshot. This avoids problems if we encounter an enum OID that was created since our transaction started. Per report from Andres Freund and diagnosis by Robert Haas. To ensure this is safe even if enum comparison manages to get invoked before we've set a transaction snapshot, tweak GetLatestSnapshot to redirect to GetTransactionSnapshot instead of throwing error when FirstSnapshotSet is false. The existing uses of GetLatestSnapshot (in ri_triggers.c) don't care since they couldn't be invoked except in a transaction that's already done some work --- but it seems just conceivable that this might not be true of enums, especially if we ever choose to use enums in system catalogs. Note that the comparable coding in enum_endpoint and enum_range_internal remains GetTransactionSnapshot; this is perhaps debatable, but if we changed it those functions would have to be marked volatile, which doesn't seem attractive. Back-patch to 9.1 where ALTER TYPE ADD VALUE was added. |
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PostgreSQL Database Management System ===================================== This directory contains the source code distribution of the PostgreSQL database management system. PostgreSQL is an advanced object-relational database management system that supports an extended subset of the SQL standard, including transactions, foreign keys, subqueries, triggers, user-defined types and functions. This distribution also contains C language bindings. PostgreSQL has many language interfaces, many of which are listed here: http://www.postgresql.org/download See the file INSTALL for instructions on how to build and install PostgreSQL. That file also lists supported operating systems and hardware platforms and contains information regarding any other software packages that are required to build or run the PostgreSQL system. Changes between all PostgreSQL releases are recorded in the file HISTORY. Copyright and license information can be found in the file COPYRIGHT. A comprehensive documentation set is included in this distribution; it can be read as described in the installation instructions. The latest version of this software may be obtained at http://www.postgresql.org/download/. For more information look at our web site located at http://www.postgresql.org/.