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c7b849a896
plpgsql likes to cache query plans and simple-expression execution state trees across calls. This is a considerable win for multiple executions of the same function. However, it's useless for DO blocks, since by definition those are executed only once and discarded. Nonetheless, we were allowing a DO block's expression execution trees to survive until end of transaction, resulting in a significant intra-transaction memory leak, as reported by Yeb Havinga. Worse, if the DO block exited with an error, the compiled form of the block's code was leaked till end of session --- along with subsidiary plancache entries. To fix, make DO blocks keep their expression execution trees in a private EState that's deleted at exit from the block, and add a PG_TRY block to plpgsql_inline_handler to make sure that memory cleanup happens even on error exits. Also add a regression test covering error handling in a DO block, because my first try at this broke that. (The test is not meant to prove that we don't leak memory anymore, though it could be used for that with a much larger loop count.) Ideally we'd back-patch this into all versions supporting DO blocks; but the patch needs to add a field to struct PLpgSQL_execstate, and that would break ABI compatibility for third-party plugins such as the plpgsql debugger. Given the small number of complaints so far, fixing this in HEAD only seems like an acceptable choice. |
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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/.