postgresql在流複製模式（stream）時，slave側log出現以下錯誤：
record with zero length at XXX
FATAL:terminating walreceiver process due to administrator command
錯誤
| xlog.c | ||||||
| 4069 | ||||||
| else if (record->xl_len == 0) | ||||||
| { | ||||||
| ereport(emode_for_corrupt_record(emode, *RecPtr), | ||||||
| (errmsg("record with zero length at %X/%X", | ||||||
| RecPtr->xlogid, RecPtr->xrecoff))); | ||||||
| goto next_record_is_invalid; | ||||||
| } | ||||||
| next_record_is_invalid: | ||||||
| failedSources |= readSource; | ||||||
| if (readFile >= 0) | ||||||
| { | ||||||
| close(readFile); | ||||||
| readFile = -1; | ||||||
| } | ||||||
| /* | ||||||
| * If archive recovery was requested, but we were still doing crash | ||||||
| * recovery, switch to archive recovery and retry using the offline | ||||||
| * archive. We have now replayed all the valid WAL in pg_xlog, so | ||||||
| * we are presumably now consistent. | ||||||
| * | ||||||
| * We require that there's at least some valid WAL present in | ||||||
| * pg_xlog, however (!fetch_ckpt). We could recover using the WAL | ||||||
| * from the archive, even if pg_xlog is completely empty, but we'd | ||||||
| * have no idea how far we'd have to replay to reach consistency. | ||||||
| * So err on the safe side and give up. | ||||||
| */ | ||||||
| if (!InArchiveRecovery && ArchiveRecoveryRequested && !fetching_ckpt) | ||||||
| { | ||||||
| ereport(DEBUG1, | ||||||
| (errmsg_internal("reached end of WAL in pg_xlog, entering archive recovery"))); | ||||||
| InArchiveRecovery = true; | ||||||
| if (StandbyModeRequested) | ||||||
| StandbyMode = true; | ||||||
| /* initialize minRecoveryPoint to this record */ | ||||||
| LWLockAcquire(ControlFileLock, LW_EXCLUSIVE); | ||||||
| ControlFile->state = DB_IN_ARCHIVE_RECOVERY; | ||||||
| if (XLByteLT(ControlFile->minRecoveryPoint, EndRecPtr)) | ||||||
| ControlFile->minRecoveryPoint = EndRecPtr; | ||||||
| /* update local copy */ | ||||||
| minRecoveryPoint = ControlFile->minRecoveryPoint; | ||||||
| UpdateControlFile(); | ||||||
| LWLockRelease(ControlFileLock); | ||||||
| CheckRecoveryConsistency(); | ||||||
| goto retry; | ||||||
| } | ||||||
| retry: | ||||||
| /* See if we need to retrieve more data */ | ||||||
| if (readFile < 0 || | ||||||
| (readSource == XLOG_FROM_STREAM && !XLByteLT(*RecPtr, receivedUpto))) | ||||||
| { | ||||||
| if (StandbyMode) | ||||||
| { | ||||||
| /* | ||||||
| * In standby mode, wait for the requested record to become | ||||||
| * available, either via restore_command succeeding to restore the | ||||||
| * segment, or via walreceiver having streamed the record. | ||||||
| */ | ||||||
| for (;;) | ||||||
| { | ||||||
| if (WalRcvInProgress()) | ||||||
| { | ||||||
| bool | ||||||
| /* | ||||||
| * If we find an invalid record in the WAL streamed from | ||||||
| * master, something is seriously wrong. There's little | ||||||
| * chance that the problem will just go away, but PANIC is | ||||||
| * not good for availability either, especially in hot | ||||||
| * standby mode. Disconnect, and retry from | ||||||
| * archive/pg_xlog again. The WAL in the archive should be | ||||||
| * identical to what was streamed, so it's unlikely that | ||||||
| * it helps, but one can hope... | ||||||
| */ | ||||||
| if (failedSources & XLOG_FROM_STREAM) | ||||||
| { | ||||||
| ShutdownWalRcv(); | ||||||
| continue; | ||||||
| } | ||||||
| /* | ||||||
| * Walreceiver is active, so see if new data has arrived. | ||||||
| * | ||||||
| * We only advance XLogReceiptTime when we obtain fresh | ||||||
| * WAL from walreceiver and observe that we had already | ||||||
| * processed everything before the most recent "chunk" | ||||||
| * that it flushed to disk. In steady state where we are | ||||||
| * keeping up with the incoming data, XLogReceiptTime will | ||||||
| * be updated on each cycle. When we are behind, | ||||||
| * XLogReceiptTime will not advance, so the grace time | ||||||
| * alloted to conflicting queries will decrease. | ||||||
| */ | ||||||
| if (XLByteLT(*RecPtr, receivedUpto)) | ||||||
| havedata = true; | ||||||
| else | ||||||
| { | ||||||
| XLogRecPtr | ||||||
| receivedUpto = GetWalRcvWriteRecPtr(&latestChunkStart); | ||||||
| if (XLByteLT(*RecPtr, receivedUpto)) | ||||||
| { | ||||||
| } | ||||||
| else | ||||||
| } | ||||||
| if (havedata) | ||||||
| { | ||||||
| /* | ||||||
| * Great, streamed far enough. Open the file if it's | ||||||
| * not open already. Use XLOG_FROM_STREAM so that | ||||||
| * source info is set correctly and XLogReceiptTime | ||||||
| * isn't changed. | ||||||
| */ | ||||||
| if (readFile < 0) | ||||||
| { | ||||||
| } | ||||||
| else | ||||||
| { | ||||||
| } | ||||||
| break; | ||||||
| } | ||||||
| /* | ||||||
| * Data not here yet, so check for trigger then sleep for | ||||||
| * five seconds like in the WAL file polling case below. | ||||||
| */ | ||||||
| if (CheckForStandbyTrigger()) | ||||||
| goto retry; | ||||||
| /* | ||||||
| * Wait for more WAL to arrive, or timeout to be reached | ||||||
| */ | ||||||
| WaitLatch(&XLogCtl->recoveryWakeupLatch, | ||||||
| ResetLatch(&XLogCtl->recoveryWakeupLatch); | ||||||
| } | ||||||
| else | ||||||
| { | ||||||
| int | ||||||
| pg_time_t | now; | |||||
| /* | ||||||
| * Until walreceiver manages to reconnect, poll the | ||||||
| * archive. | ||||||
| */ | ||||||
| if (readFile >= 0) | ||||||
| { | ||||||
| close(readFile); | ||||||
| readFile = -1; | ||||||
| } | ||||||
| /* Reset curFileTLI if random fetch. */ | ||||||
| if (randAccess) | ||||||
| curFileTLI = 0; | ||||||
| /* | ||||||
| * Try to restore the file from archive, or read an | ||||||
| * existing file from pg_xlog. | ||||||
| */ | ||||||
| sources = XLOG_FROM_ARCHIVE | XLOG_FROM_PG_XLOG; | ||||||
| if (!(sources & ~failedSources)) | ||||||
| { | ||||||
| /* | ||||||
| * We've exhausted all options for retrieving the | ||||||
| * file. Retry. | ||||||
| */ | ||||||
| failedSources = 0; | ||||||
| /* | ||||||
| * Before we sleep, re-scan for possible new timelines | ||||||
| * if we were requested to recover to the latest | ||||||
| * timeline. | ||||||
| */ | ||||||
| if (recoveryTargetIsLatest) | ||||||
| { | ||||||
| } | ||||||
| /* | ||||||
| * If it hasn't been long since last attempt, sleep to | ||||||
| * avoid busy-waiting. | ||||||
| */ | ||||||
| now = (pg_time_t) time(NULL); | ||||||
| if ((now - last_fail_time) < 5) | ||||||
| { | ||||||
| } | ||||||
| last_fail_time = now; | ||||||
| /* | ||||||
| * If primary_conninfo is set, launch walreceiver to | ||||||
| * try to stream the missing WAL, before retrying to | ||||||
| * restore from archive/pg_xlog. | ||||||
| * | ||||||
| * If fetching_ckpt is TRUE, RecPtr points to the | ||||||
| * initial checkpoint location. In that case, we use | ||||||
| * RedoStartLSN as the streaming start position | ||||||
| * instead of RecPtr, so that when we later jump | ||||||
| * backwards to start redo at RedoStartLSN, we will | ||||||
| * have the logs streamed already. | ||||||
| */ | ||||||
| if (PrimaryConnInfo) | ||||||
| { | ||||||
| } | ||||||
| } | ||||||
| /* Don't try to read from a source that just failed */ | ||||||
| sources &= ~failedSources; | ||||||
| readFile = XLogFileReadAnyTLI(readId, readSeg, DEBUG2, | ||||||
| switched_segment = true; | ||||||
| if (readFile >= 0) | ||||||
| break; | ||||||
| /* | ||||||
| * Nope, not found in archive and/or pg_xlog. | ||||||
| */ | ||||||
| failedSources |= sources; | ||||||
| /* | ||||||
| * Check to see if the trigger file exists. Note that we | ||||||
| * do this only after failure, so when you create the | ||||||
| * trigger file, we still finish replaying as much as we | ||||||
| * can from archive and pg_xlog before failover. | ||||||
| */ | ||||||
| if (CheckForStandbyTrigger()) | ||||||
| goto triggered; | ||||||
| } | ||||||
| /* | ||||||
| * This possibly-long loop needs to handle interrupts of | ||||||
| * startup process. | ||||||
| */ | ||||||
| HandleStartupProcInterrupts(); | ||||||
| } | ||||||
| } | ||||||
| else | ||||||
| { | ||||||
| /* In archive or crash recovery. */ | ||||||
| if (readFile < 0) | ||||||
| { | ||||||
| int | ||||||
| /* Reset curFileTLI if random fetch. */ | ||||||
| if (randAccess) | ||||||
| curFileTLI = 0; | ||||||
| sources = XLOG_FROM_PG_XLOG; | ||||||
| if (InArchiveRecovery) | ||||||
| sources |= XLOG_FROM_ARCHIVE; | ||||||
| readFile = XLogFileReadAnyTLI(readId, readSeg, emode, | ||||||
| switched_segment = true; | ||||||
| if (readFile < 0) | ||||||
| return false; | ||||||
| } | ||||||
| } | ||||||
| } | ||||||
| /* | ||||||
| * At this point, we have the right segment open and if we're streaming we | ||||||
| * know the requested record is in it. | ||||||
| */ | ||||||
| Assert(readFile != -1); | ||||||
| /* | ||||||
| * If the current segment is being streamed from master, calculate how | ||||||
| * much of the current page we have received already. We know the | ||||||
| * requested record has been received, but this is for the benefit of | ||||||
| * future calls, to allow quick exit at the top of this function. | ||||||
| */ | ||||||
| if (readSource == XLOG_FROM_STREAM) | ||||||
| { | ||||||
| if (RecPtr->xlogid != receivedUpto.xlogid || | ||||||
| (RecPtr->xrecoff / XLOG_BLCKSZ) != (receivedUpto.xrecoff / XLOG_BLCKSZ)) | ||||||
| { | ||||||
| readLen = XLOG_BLCKSZ; | ||||||
| } | ||||||
| else | ||||||
| readLen = receivedUpto.xrecoff % XLogSegSize - targetPageOff; | ||||||
| } | ||||||
| else | ||||||
| readLen = XLOG_BLCKSZ; | ||||||
| if (switched_segment && targetPageOff != 0) | ||||||
| { | ||||||
| /* | ||||||
| * Whenever switching to a new WAL segment, we read the first page of | ||||||
| * the file and validate its header, even if that's not where the | ||||||
| * target record is. This is so that we can check the additional | ||||||
| * identification info that is present in the first page's "long" | ||||||
| * header. | ||||||
| */ | ||||||
| readOff = 0; | ||||||
| if (read(readFile, readBuf, XLOG_BLCKSZ) != XLOG_BLCKSZ) | ||||||
| { | ||||||
| ereport(emode_for_corrupt_record(emode, *RecPtr), | ||||||
| (errcode_for_file_access(), | ||||||
| errmsg("could not read from log file %u, segment %u, offset %u: %m", | ||||||
| goto next_record_is_invalid; | ||||||
| } | ||||||
| if (!ValidXLOGHeader((XLogPageHeader) readBuf, emode, true)) | ||||||
| goto next_record_is_invalid; | ||||||
| } | ||||||
| /* Read the requested page */ | ||||||
| readOff = targetPageOff; | ||||||
| if (lseek(readFile, (off_t) readOff, SEEK_SET) < 0) | ||||||
| { | ||||||
| ereport(emode_for_corrupt_record(emode, *RecPtr), | ||||||
| (errcode_for_file_access(), | ||||||
| errmsg("could not seek in log file %u, segment %u to offset %u: %m", | ||||||
| readId, readSeg, readOff))); | ||||||
| goto next_record_is_invalid; | ||||||
| } | ||||||
| if (read(readFile, readBuf, XLOG_BLCKSZ) != XLOG_BLCKSZ) | ||||||
| { | ||||||
| ereport(emode_for_corrupt_record(emode, *RecPtr), | ||||||
| (errcode_for_file_access(), | ||||||
| errmsg("could not read from log file %u, segment %u, offset %u: %m", | ||||||
| readId, readSeg, readOff))); | ||||||
| goto next_record_is_invalid; | ||||||
| } | ||||||
| if (!ValidXLOGHeader((XLogPageHeader) readBuf, emode, false)) | ||||||
| goto next_record_is_invalid; | ||||||
| Assert(targetId == readId); | ||||||
| Assert(targetSeg == readSeg); | ||||||
| Assert(targetPageOff == readOff); | ||||||
| Assert(targetRecOff < readLen); | ||||||
| return true; | ||||||
| next_record_is_invalid: | ||||||
| failedSources |= readSource; | ||||||
| if (readFile >= 0) | ||||||
| close(readFile); | ||||||
| readFile = -1; | ||||||
| readLen = 0; | ||||||
| readSource = 0; | ||||||
| /* In standby-mode, keep trying */ | ||||||
| if (StandbyMode) | ||||||
| goto retry; | ||||||
| else | ||||||
| return false; | ||||||
| triggered: | ||||||
| if (readFile >= 0) | ||||||
| close(readFile); | ||||||
| readFile = -1; | ||||||
| readLen = 0; | ||||||
| readSource = 0; | ||||||
| return false; | ||||||
| } | ||||||
