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In selectnewtape(), use 'nOutputTapes' rather than 'nOutputRuns' in the check for whether to start a new tape or to append a new run to an existing tape. Until 'maxTapes' is reached, nOutputTapes is always equal to nOutputRuns, so it doesn't change the logic, but it seems more logical to compare # of tapes with # of tapes. Also, currently maxTapes is never modified after the merging begins, but written this way, the code would still work if it was. (Although the nOutputRuns == nOutputTapes assertion would need to be removed and using nOutputRuns % nOutputTapes to distribute the runs evenly across the tapes wouldn't do a good job anymore). Similarly in mergeruns(), change to USEMEM(state->tape_buffer_mem) to account for the memory used for tape buffers. It's equal to availMem currently, but tape_buffer_mem is more direct and future-proof. For example, if we changed the logic to only allocate half of the remaining memory to tape buffers, USEMEM(state->tape_buffer_mem) would still be correct. Coverity complained about these. Hopefully this patch helps it to understand the logic better. Thanks to Tom Lane for initial analysis.
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/.