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Make min_wal_size/max_wal_size use MB internally

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Previously they were defined using multiples of XLogSegSize.
Remove GUC_UNIT_XSEGS. Introduce GUC_UNIT_MB

Extracted from patch series on XLogSegSize infrastructure.

Beena Emerson
This commit is contained in:
Simon Riggs
2017-04-04 18:00:01 -04:00
parent cd740c0dbf
commit 9a3215026b
4 changed files with 30 additions and 28 deletions
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22
src/backend/access/transam/xlog.c
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@ -86,8 +86,8 @@ extern uint32 bootstrap_data_checksum_version;
/* User-settable parameters */
int max_wal_size = 64; /* 1 GB */
int min_wal_size = 5; /* 80 MB */
int max_wal_size_mb = 1024; /* 1 GB */
int min_wal_size_mb = 80; /* 80 MB */
int wal_keep_segments = 0;
int XLOGbuffers = -1;
int XLogArchiveTimeout = 0;
@ -738,6 +738,10 @@ static ControlFileData *ControlFile = NULL;
#define UsableBytesInPage (XLOG_BLCKSZ - SizeOfXLogShortPHD)
#define UsableBytesInSegment ((XLOG_SEG_SIZE / XLOG_BLCKSZ) * UsableBytesInPage - (SizeOfXLogLongPHD - SizeOfXLogShortPHD))
/* Convert min_wal_size_mb and max wal_size_mb to equivalent segment count */
#define ConvertToXSegs(x) \
(x / (XLOG_SEG_SIZE / (1024 * 1024)))
/*
* Private, possibly out-of-date copy of shared LogwrtResult.
* See discussion above.
@ -2200,7 +2204,7 @@ AdvanceXLInsertBuffer(XLogRecPtr upto, bool opportunistic)
}
/*
* Calculate CheckPointSegments based on max_wal_size and
* Calculate CheckPointSegments based on max_wal_size_mb and
* checkpoint_completion_target.
*/
static void
@ -2210,14 +2214,14 @@ CalculateCheckpointSegments(void)
/*-------
* Calculate the distance at which to trigger a checkpoint, to avoid
* exceeding max_wal_size. This is based on two assumptions:
* exceeding max_wal_size_mb. This is based on two assumptions:
*
* a) we keep WAL for two checkpoint cycles, back to the "prev" checkpoint.
* b) during checkpoint, we consume checkpoint_completion_target *
* number of segments consumed between checkpoints.
*-------
*/
target = (double) max_wal_size / (2.0 + CheckPointCompletionTarget);
target = (double) ConvertToXSegs(max_wal_size_mb) / (2.0 + CheckPointCompletionTarget);
/* round down */
CheckPointSegments = (int) target;
@ -2229,7 +2233,7 @@ CalculateCheckpointSegments(void)
void
assign_max_wal_size(int newval, void *extra)
{
max_wal_size = newval;
max_wal_size_mb = newval;
CalculateCheckpointSegments();
}
@ -2253,12 +2257,12 @@ XLOGfileslop(XLogRecPtr PriorRedoPtr)
XLogSegNo recycleSegNo;
/*
* Calculate the segment numbers that min_wal_size and max_wal_size
* Calculate the segment numbers that min_wal_size_mb and max_wal_size_mb
* correspond to. Always recycle enough segments to meet the minimum, and
* remove enough segments to stay below the maximum.
*/
minSegNo = PriorRedoPtr / XLOG_SEG_SIZE + min_wal_size - 1;
maxSegNo = PriorRedoPtr / XLOG_SEG_SIZE + max_wal_size - 1;
minSegNo = PriorRedoPtr / XLOG_SEG_SIZE + ConvertToXSegs(min_wal_size_mb) - 1;
maxSegNo = PriorRedoPtr / XLOG_SEG_SIZE + ConvertToXSegs(max_wal_size_mb) - 1;
/*
* Between those limits, recycle enough segments to get us through to the