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Support long distance matching for zstd compression

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zstd compression supports a special mode for finding matched in distant
past, which may result in better compression ratio, at the expense of
using more memory (the window size is 128MB).

To enable this optional mode, use the "long" keyword when specifying the
compression method (--compress=zstd:long).

Author: Justin Pryzby
Reviewed-by: Tomas Vondra, Jacob Champion
Discussion: https://postgr.es/m/20230224191840.GD1653@telsasoft.com
Discussion: https://postgr.es/m/20220327205020.GM28503@telsasoft.com
This commit is contained in:
Tomas Vondra
2023-04-06 17:18:38 +02:00
parent 983ec23007
commit 2820adf775
12 changed files with 127 additions and 6 deletions
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12
src/backend/backup/basebackup_zstd.c
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@@ -118,6 +118,18 @@ bbsink_zstd_begin_backup(bbsink *sink)
compress->workers, ZSTD_getErrorName(ret)));
}
if ((compress->options & PG_COMPRESSION_OPTION_LONG_DISTANCE) != 0)
{
ret = ZSTD_CCtx_setParameter(mysink->cctx,
ZSTD_c_enableLongDistanceMatching,
compress->long_distance);
if (ZSTD_isError(ret))
ereport(ERROR,
errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("could not set compression flag for %s: %s",
"long", ZSTD_getErrorName(ret)));
}
/*
* We need our own buffer, because we're going to pass different data to
* the next sink than what gets passed to us.