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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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30
src/backend/replication/walreceiver.c
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@@ -69,11 +69,12 @@ walrcv_disconnect_type walrcv_disconnect = NULL;
/*
* These variables are used similarly to openLogFile/Id/Seg/Off,
* but for walreceiver to write the XLOG.
* but for walreceiver to write the XLOG. recvFileTLI is the TimeLineID
* corresponding the filename of recvFile, used for error messages.
*/
static int recvFile = -1;
static uint32 recvId = 0;
static uint32 recvSeg = 0;
static TimeLineID recvFileTLI = -1;
static XLogSegNo recvSegNo = 0;
static uint32 recvOff = 0;
/*
@@ -481,7 +482,7 @@ XLogWalRcvWrite(char *buf, Size nbytes, XLogRecPtr recptr)
{
int segbytes;
if (recvFile < 0 || !XLByteInSeg(recptr, recvId, recvSeg))
if (recvFile < 0 || !XLByteInSeg(recptr, recvSegNo))
{
bool use_existent;
@@ -501,15 +502,16 @@ XLogWalRcvWrite(char *buf, Size nbytes, XLogRecPtr recptr)
if (close(recvFile) != 0)
ereport(PANIC,
(errcode_for_file_access(),
errmsg("could not close log file %u, segment %u: %m",
recvId, recvSeg)));
errmsg("could not close log segment %s: %m",
XLogFileNameP(recvFileTLI, recvSegNo))));
}
recvFile = -1;
/* Create/use new log file */
XLByteToSeg(recptr, recvId, recvSeg);
XLByteToSeg(recptr, recvSegNo);
use_existent = true;
recvFile = XLogFileInit(recvId, recvSeg, &use_existent, true);
recvFile = XLogFileInit(recvSegNo, &use_existent, true);
recvFileTLI = ThisTimeLineID;
recvOff = 0;
}
@@ -527,9 +529,9 @@ XLogWalRcvWrite(char *buf, Size nbytes, XLogRecPtr recptr)
if (lseek(recvFile, (off_t) startoff, SEEK_SET) < 0)
ereport(PANIC,
(errcode_for_file_access(),
errmsg("could not seek in log file %u, "
"segment %u to offset %u: %m",
recvId, recvSeg, startoff)));
errmsg("could not seek in log segment %s, to offset %u: %m",
XLogFileNameP(recvFileTLI, recvSegNo),
startoff)));
recvOff = startoff;
}
@@ -544,9 +546,9 @@ XLogWalRcvWrite(char *buf, Size nbytes, XLogRecPtr recptr)
errno = ENOSPC;
ereport(PANIC,
(errcode_for_file_access(),
errmsg("could not write to log file %u, segment %u "
errmsg("could not write to log segment %s "
"at offset %u, length %lu: %m",
recvId, recvSeg,
XLogFileNameP(recvFileTLI, recvSegNo),
recvOff, (unsigned long) segbytes)));
}
@@ -575,7 +577,7 @@ XLogWalRcvFlush(bool dying)
/* use volatile pointer to prevent code rearrangement */
volatile WalRcvData *walrcv = WalRcv;
issue_xlog_fsync(recvFile, recvId, recvSeg);
issue_xlog_fsync(recvFile, recvSegNo);
LogstreamResult.Flush = LogstreamResult.Write;