b5810de3f4
Previously, exec_simple_query always ran parse analysis, rewrite, and planning in MessageContext, allowing all the data generated thereby to persist until the end of processing of the whole query string. That's fine for single-command strings, but if a client sends many commands in a single simple-Query message, this strategy could result in annoying memory bloat, as complained of by Andreas Seltenreich. To fix, create a child context to do this work in, and reclaim it after each command. But we only do so for parsetrees that are not last in their query string. That avoids adding any memory management overhead for the typical case of a single-command string. Memory allocated for the last parsetree would be freed immediately after finishing the command string anyway. Similarly, adjust extension.c's execute_sql_string() to reclaim memory after each command. In that usage, multi-command strings are the norm, so it's a bit surprising that no one has yet complained of bloat --- especially since the bloat extended to whatever data ProcessUtility execution might leak. Amit Langote, reviewed by Julien Rouhaud Discussion: https://postgr.es/m/87ftp6l2qr.fsf@credativ.de |
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README
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: https://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. 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 https://www.postgresql.org/download/. For more information look at our web site located at https://www.postgresql.org/.