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Don't waste the last segment of each 4GB logical log file.

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The comments claimed that wasting the last segment made it easier to do
calculations with XLogRecPtrs, because you don't have problems representing
last-byte-position-plus-1 that way. In my experience, however, it only made
things more complicated, because the there was two ways to represent the
boundary at the beginning of a logical log file: logid = n+1 and xrecoff = 0,
or as xlogid = n and xrecoff = 4GB - XLOG_SEG_SIZE. Some functions were
picky about which representation was used.

Also, use a 64-bit segment number instead of the log/seg combination, to
point to a certain WAL segment. We assume that all platforms have a working
64-bit integer type nowadays.

This is an incompatible change in WAL format, so bumping WAL version number.
This commit is contained in:
Heikki Linnakangas
2012-06-24 18:06:38 +03:00
parent 47c7365e79
commit dfda6ebaec
12 changed files with 413 additions and 554 deletions
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20
src/backend/replication/basebackup.c
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@ -221,10 +221,8 @@ perform_base_backup(basebackup_options *opt, DIR *tblspcdir)
* We've left the last tar file "open", so we can now append the
* required WAL files to it.
*/
uint32 logid,
logseg;
uint32 endlogid,
endlogseg;
XLogSegNo logsegno;
XLogSegNo endlogsegno;
struct stat statbuf;
MemSet(&statbuf, 0, sizeof(statbuf));
@ -236,8 +234,8 @@ perform_base_backup(basebackup_options *opt, DIR *tblspcdir)
statbuf.st_size = XLogSegSize;
statbuf.st_mtime = time(NULL);
XLByteToSeg(startptr, logid, logseg);
XLByteToPrevSeg(endptr, endlogid, endlogseg);
XLByteToSeg(startptr, logsegno);
XLByteToPrevSeg(endptr, endlogsegno);
while (true)
{
@ -245,7 +243,7 @@ perform_base_backup(basebackup_options *opt, DIR *tblspcdir)
char fn[MAXPGPATH];
int i;
XLogFilePath(fn, ThisTimeLineID, logid, logseg);
XLogFilePath(fn, ThisTimeLineID, logsegno);
_tarWriteHeader(fn, NULL, &statbuf);
/* Send the actual WAL file contents, block-by-block */
@ -254,8 +252,7 @@ perform_base_backup(basebackup_options *opt, DIR *tblspcdir)
char buf[TAR_SEND_SIZE];
XLogRecPtr ptr;
ptr.xlogid = logid;
ptr.xrecoff = logseg * XLogSegSize + TAR_SEND_SIZE * i;
XLogSegNoOffsetToRecPtr(logsegno, TAR_SEND_SIZE * i, ptr);
/*
* Some old compilers, e.g. gcc 2.95.3/x86, think that passing
@ -277,11 +274,10 @@ perform_base_backup(basebackup_options *opt, DIR *tblspcdir)
/* Advance to the next WAL file */
NextLogSeg(logid, logseg);
logsegno++;
/* Have we reached our stop position yet? */
if (logid > endlogid ||
(logid == endlogid && logseg > endlogseg))
if (logsegno > endlogsegno)
break;
}