66ec01dc41
After commit fe8192a95, compress_zstd.c tends to produce data block sizes around 128K, and we don't really have any control over that unless we want to overrule ZSTD_CStreamOutSize(). Which seems like a bad idea. But let's try to align the other compression modes to produce block sizes roughly comparable to that, so that pg_restore's skip-data performance isn't enormously different for different modes. gzip compression can be brought in line simply by setting DEFAULT_IO_BUFFER_SIZE = 128K, which this patch does. That increases some unrelated buffer sizes, but none of them seem problematic for modern platforms. lz4's idea of appropriate block size is highly nonlinear: if we just increase DEFAULT_IO_BUFFER_SIZE then the output blocks end up around 200K. I found that adjusting the slop factor in LZ4State_compression_init was a not-too-ugly way of bringing that number roughly into line. With compress = none you get data blocks the same sizes as the table rows, which seems potentially problematic for narrow tables. Introduce a layer of buffering to make that case match the others. Comments in compress_io.h and 002_pg_dump.pl suggest that if we increase DEFAULT_IO_BUFFER_SIZE then we need to increase the amount of data fed through the tests in order to improve coverage. I've not done that here, leaving it for a separate patch. Author: Tom Lane <tgl@sss.pgh.pa.us> Discussion: https://postgr.es/m/3515357.1760128017@sss.pgh.pa.us
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.
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