From 1571a39ecfcc97607d3202d112b7a401ee758385 Mon Sep 17 00:00:00 2001 From: Ashutosh Sharma Date: Fri, 23 Sep 2022 06:40:32 +0000 Subject: [PATCH] Enhance pg_waldump to show latest LSN and the corrresponding WAL file. When -l/--lastLSN is passed as an argument along with datadir, pg_waldump returns the last LSN aka EndRecPtr along with the WAL file name that the last LSN belongs to. Usage: ashu@ubuntu:~/pgsql$ pg_waldump -l -D data-dir Latest LSN: 0/148A45F8 Latest WAL filename: 000000010000000000000014 --- src/bin/pg_waldump/pg_waldump.c | 64 ++++++++++++++++++++++++++++++++- 1 file changed, 63 insertions(+), 1 deletion(-) diff --git a/src/bin/pg_waldump/pg_waldump.c b/src/bin/pg_waldump/pg_waldump.c index 9993378ca5..cb784362da 100644 --- a/src/bin/pg_waldump/pg_waldump.c +++ b/src/bin/pg_waldump/pg_waldump.c @@ -22,6 +22,8 @@ #include "access/xlogreader.h" #include "access/xlogrecord.h" #include "access/xlogstats.h" +#include "catalog/pg_control.h" +#include "common/controldata_utils.h" #include "common/fe_memutils.h" #include "common/logging.h" #include "getopt_long.h" @@ -57,6 +59,7 @@ typedef struct XLogDumpConfig bool follow; bool stats; bool stats_per_record; + bool output_lastLSN; /* filter options */ bool filter_by_rmgr[RM_MAX_ID + 1]; @@ -662,10 +665,12 @@ usage(void) printf(_("\nOptions:\n")); printf(_(" -b, --bkp-details output detailed information about backup blocks\n")); printf(_(" -B, --block=N with --relation, only show records that modify block N\n")); + printf(_(" -D, --datadir=DATADIR location of data directory\n")); printf(_(" -e, --end=RECPTR stop reading at WAL location RECPTR\n")); printf(_(" -f, --follow keep retrying after reaching end of WAL\n")); printf(_(" -F, --fork=FORK only show records that modify blocks in fork FORK;\n" " valid names are main, fsm, vm, init\n")); + printf(_(" -l, --lastLSN output latest LSN in the wal directory, then exit\n")); printf(_(" -n, --limit=N number of records to display\n")); printf(_(" -p, --path=PATH directory in which to find WAL segment files or a\n" " directory with a ./pg_wal that contains such files\n" @@ -699,16 +704,19 @@ main(int argc, char **argv) XLogRecord *record; XLogRecPtr first_record; char *waldir = NULL; + char *datadir = NULL; char *errormsg; static struct option long_options[] = { {"bkp-details", no_argument, NULL, 'b'}, {"block", required_argument, NULL, 'B'}, + {"datadir", required_argument, NULL, 'D'}, {"end", required_argument, NULL, 'e'}, {"follow", no_argument, NULL, 'f'}, {"fork", required_argument, NULL, 'F'}, {"fullpage", no_argument, NULL, 'w'}, {"help", no_argument, NULL, '?'}, + {"lastLSN", no_argument, NULL, 'l'}, {"limit", required_argument, NULL, 'n'}, {"path", required_argument, NULL, 'p'}, {"quiet", no_argument, NULL, 'q'}, @@ -761,6 +769,7 @@ main(int argc, char **argv) config.stop_after_records = -1; config.already_displayed_records = 0; config.follow = false; + config.output_lastLSN = false; /* filter_by_rmgr array was zeroed by memset above */ config.filter_by_rmgr_enabled = false; config.filter_by_xid = InvalidTransactionId; @@ -782,7 +791,7 @@ main(int argc, char **argv) goto bad_argument; } - while ((option = getopt_long(argc, argv, "bB:e:fF:n:p:qr:R:s:t:wx:z", + while ((option = getopt_long(argc, argv, "bB:D:e:fF:ln:p:qr:R:s:t:wx:z", long_options, &optindex)) != -1) { switch (option) @@ -800,6 +809,10 @@ main(int argc, char **argv) config.filter_by_relation_block_enabled = true; config.filter_by_extended = true; break; + case 'D': + datadir = pg_strdup(optarg); + setenv("PGDATA", datadir, 1); + break; case 'e': if (sscanf(optarg, "%X/%X", &xlogid, &xrecoff) != 2) { @@ -821,6 +834,9 @@ main(int argc, char **argv) } config.filter_by_extended = true; break; + case 'l': + config.output_lastLSN = true; + break; case 'n': if (sscanf(optarg, "%d", &config.stop_after_records) != 1) { @@ -947,6 +963,12 @@ main(int argc, char **argv) } } + if (config.output_lastLSN && !datadir) + { + pg_log_error("option -l/--lastLSN requires option -D/--datadir to be specified"); + goto bad_argument; + } + if (config.filter_by_relation_block_enabled && !config.filter_by_relation_enabled) { @@ -972,6 +994,28 @@ main(int argc, char **argv) } } + if (config.output_lastLSN) + { + ControlFileData *ControlFile; + bool crc_ok; + + /* read the control file */ + ControlFile = get_controlfile(datadir, &crc_ok); + + if (!crc_ok) + { + pg_fatal("Calculated CRC checksum does not match value stored in file."); + exit(EXIT_FAILURE); + } + + private.timeline = ControlFile->checkPointCopy.ThisTimeLineID; + private.startptr = ControlFile->checkPointCopy.redo; + private.endptr = InvalidXLogRecPtr; + waldir = identify_target_directory(waldir, NULL); + config.quiet = true; + goto start_reading_wal; + } + /* parse files as start/end boundaries, extract path if not specified */ if (optind < argc) { @@ -1064,6 +1108,7 @@ main(int argc, char **argv) /* done with argument parsing, do the actual work */ /* we have everything we need, start reading */ +start_reading_wal: xlogreader_state = XLogReaderAllocate(WalSegSz, waldir, XL_ROUTINE(.page_read = WALDumpReadPage, @@ -1109,6 +1154,23 @@ main(int argc, char **argv) record = XLogReadRecord(xlogreader_state, &errormsg); if (!record) { + if (config.output_lastLSN) + { + XLogSegNo xlogsegno; + char xlogfilename[MAXFNAMELEN]; + + XLByteToPrevSeg(xlogreader_state->EndRecPtr, xlogsegno, WalSegSz); + XLogFileName(xlogfilename, private.timeline, xlogsegno, + WalSegSz); + + printf("Latest LSN: %X/%X\n" + "Latest WAL filename: %s\n", + LSN_FORMAT_ARGS(xlogreader_state->EndRecPtr), + xlogfilename); + + exit(EXIT_SUCCESS); + } + if (!config.follow || private.endptr_reached) break; else -- 2.17.1