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Code Issues Releases Activity

do not read wal file in backward

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This commit is contained in:
Yura Sokolov
2022-12-10 20:35:47 +03:00
parent 822fbbfe50
commit 81f1ed2293
1 changed files with 48 additions and 35 deletions
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src/parsexlog.c
+32 -19
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@@ -107,7 +107,7 @@ typedef struct XLogReaderData
bool xlogexists;
char page_buf[XLOG_BLCKSZ];
uint32 prev_page_off;
int64_t prev_page_ptr;
bool need_switch;
@@ -533,7 +533,8 @@ read_recovery_info(const char *archivedir, TimeLineID tli, uint32 wal_seg_size,
XLogRecPtr start_lsn, XLogRecPtr stop_lsn,
time_t *recovery_time)
{
XLogRecPtr startpoint = stop_lsn;
XLogRecPtr startpoint = stop_lsn - (stop_lsn % wal_seg_size) + SizeOfXLogLongPHD;
XLogRecPtr endpoint = stop_lsn;
XLogReaderState *xlogreader;
XLogReaderData reader_data;
bool res;
@@ -552,22 +553,28 @@ read_recovery_info(const char *archivedir, TimeLineID tli, uint32 wal_seg_size,
/* Read records from stop_lsn down to start_lsn */
do
{
XLogRecPtr curpoint = startpoint;
XLogRecord *record;
TimestampTz last_time = 0;
char *errormsg;
if (curpoint < start_lsn)
curpoint = start_lsn;
#if PG_VERSION_NUM >= 130000
if (XLogRecPtrIsInvalid(startpoint))
startpoint = SizeOfXLogShortPHD;
XLogBeginRead(xlogreader, startpoint);
if (XLogRecPtrIsInvalid(curpoint))
curpoint = SizeOfXLogShortPHD;
XLogBeginRead(xlogreader, curpoint);
#endif
record = WalReadRecord(xlogreader, startpoint, &errormsg);
do {
record = WalReadRecord(xlogreader, curpoint, &errormsg);
if (record == NULL)
{
XLogRecPtr errptr;
errptr = startpoint ? startpoint : xlogreader->EndRecPtr;
//errptr = startpoint ? startpoint : xlogreader->EndRecPtr;
errptr = curpoint;
if (errormsg)
elog(ERROR, "Could not read WAL record at %X/%X: %s",
@@ -578,8 +585,7 @@ read_recovery_info(const char *archivedir, TimeLineID tli, uint32 wal_seg_size,
(uint32) (errptr >> 32), (uint32) (errptr));
}
/* Read previous record */
startpoint = record->xl_prev;
curpoint = xlogreader->EndRecPtr;
if (getRecordTimestamp(xlogreader, &last_time))
{
@@ -587,9 +593,15 @@ read_recovery_info(const char *archivedir, TimeLineID tli, uint32 wal_seg_size,
/* Found timestamp in WAL record 'record' */
res = true;
goto cleanup;
}
} while (startpoint >= start_lsn);
} while (curpoint <= endpoint);
if (res)
goto cleanup;
/* goto previous segment */
startpoint -= wal_seg_size;
} while (startpoint + wal_seg_size > start_lsn);
/* Didn't find timestamp from WAL records between start_lsn and stop_lsn */
res = false;
@@ -1079,11 +1091,11 @@ SimpleXLogPageRead(XLogReaderState *xlogreader, XLogRecPtr targetPagePtr,
*/
Assert(reader_data->xlogexists);
Assert(reader_data->prev_page_ptr <= (int64_t)targetPagePtr);
/*
* Do not read same page read earlier from the file, read it from the buffer
*/
if (reader_data->prev_page_off != 0 &&
reader_data->prev_page_off == targetPageOff)
if (reader_data->prev_page_ptr == targetPagePtr)
{
memcpy(readBuf, reader_data->page_buf, XLOG_BLCKSZ);
#if PG_VERSION_NUM < 130000
@@ -1131,7 +1143,7 @@ SimpleXLogPageRead(XLogReaderState *xlogreader, XLogRecPtr targetPagePtr,
#endif
memcpy(reader_data->page_buf, readBuf, XLOG_BLCKSZ);
reader_data->prev_page_off = targetPageOff;
reader_data->prev_page_ptr = targetPagePtr;
#if PG_VERSION_NUM < 130000
*pageTLI = reader_data->tli;
#endif
@@ -1156,6 +1168,7 @@ InitXLogPageRead(XLogReaderData *reader_data, const char *archivedir,
MemSet(reader_data, 0, sizeof(XLogReaderData));
reader_data->tli = tli;
reader_data->xlogfile = -1;
reader_data->prev_page_ptr = -1;
if (allocate_reader)
{
@@ -1361,7 +1374,7 @@ XLogThreadWorker(void *arg)
XLogReaderState *xlogreader;
XLogSegNo nextSegNo = 0;
XLogRecPtr found;
uint32 prev_page_off = 0;
int64_t prev_page_ptr = -1;
bool need_read = true;
xlogreader = WalReaderAllocate(wal_seg_size, reader_data);
@@ -1532,8 +1545,8 @@ XLogThreadWorker(void *arg)
* Check if other thread got the target segment. Check it not very
* often, only every WAL page.
*/
if (wal_consistent_read && prev_page_off != 0 &&
prev_page_off != reader_data->prev_page_off)
if (wal_consistent_read &&
prev_page_ptr != reader_data->prev_page_ptr)
{
XLogSegNo segno;
@@ -1544,7 +1557,7 @@ XLogThreadWorker(void *arg)
if (segno != 0 && segno < reader_data->xlogsegno)
break;
}
prev_page_off = reader_data->prev_page_off;
prev_page_ptr = reader_data->prev_page_ptr;
/* continue reading at next record */
thread_arg->startpoint = InvalidXLogRecPtr;
@@ -1726,7 +1739,7 @@ CleanupXLogPageRead(XLogReaderState *xlogreader)
reader_data->gz_xlogfile = NULL;
}
#endif
reader_data->prev_page_off = 0;
reader_data->prev_page_ptr = -1;
reader_data->xlogexists = false;
}