On Wed, Mar 11, 2020 at 12:27:03PM +0900, Michael Paquier wrote: >> Also, I think the function comment could stand some more detailing. > > What kind of additional information would you like to add on top of > what the updated version attached does?
I have been working more on that, and attached is an updated version of the main feature based on 0001, attached as 0002. I have applied the following changes, fixing some actual bugs while on it: - Added back expectedSize, so as frontends can also fetch things other than WAL segments from the archives, including history files. pg_rewind needs only WAL segments, still other tools may want more. - Fixed an issue with ENOENT when doing stat() on a segment after running the restore command. Like the backend, there is an argument for looping here. - Switched the several failures to issue exit() for the several failure types possible instead of looping. If a file has an incorrect expected size or that stat() fails for a non-ENOENT, things are more likely going to repeat if the frontend tool loops, so exiting immediately is safer. I think that we need a better name for RestoreArchivedFile() in fe_archive.c. The backend uses RestoreArchivedFile(), and the previous versions of the patch switched to RestoreArchivedWALFile() which is incorrect if working on something else than a WAL segment. The version attached uses FrontendRestoreArchivedFile(), still we could do better. I'd like to commit the refactoring piece in 0001 tomorrow, then let's move on with the rest as of 0002. If more comments and docs are needed for archive.c, let's continue discussing that. -- Michael
From 43ac17434f5fba9effd77c1962d46589ba693874 Mon Sep 17 00:00:00 2001 From: Michael Paquier <mich...@paquier.xyz> Date: Thu, 12 Mar 2020 13:22:34 +0900 Subject: [PATCH 1/2] Move routine generating restore_command to src/common/ restore_command has only been used until now by the backend, but there is a pending patch for pg_rewind to make use of that in the frontend. Author: Alexey Kondratov Reviewed-by: Andrey Borodin, Andres Freund, Alvaro Herrera, Alexander Korotkov, Michael Paquier Discussion: https://postgr.es/m/a3acff50-5a0d-9a2c-b3b2-ee3616895...@postgrespro.ru --- src/include/common/archive.h | 27 +++++ src/backend/access/transam/xlogarchive.c | 66 ++----------- src/common/Makefile | 1 + src/common/archive.c | 119 +++++++++++++++++++++++ src/tools/msvc/Mkvcbuild.pm | 4 +- 5 files changed, 159 insertions(+), 58 deletions(-) create mode 100644 src/include/common/archive.h create mode 100644 src/common/archive.c diff --git a/src/include/common/archive.h b/src/include/common/archive.h new file mode 100644 index 0000000000..8af0b4566f --- /dev/null +++ b/src/include/common/archive.h @@ -0,0 +1,27 @@ +/*------------------------------------------------------------------------- + * + * archive.h + * Common WAL archive routines + * + * Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group + * Portions Copyright (c) 1994, Regents of the University of California + * + * src/include/common/archive.h + * + *------------------------------------------------------------------------- + */ +#ifndef ARCHIVE_H +#define ARCHIVE_H + +/* + * Routine to build a restore command to retrieve WAL segments from a WAL + * archive. This uses the arguments given by the caller to replace the + * corresponding alias fields as defined in the GUC parameter + * restore_command. + */ +extern char *BuildRestoreCommand(const char *restoreCommand, + const char *xlogpath, /* %p */ + const char *xlogfname, /* %f */ + const char *lastRestartPointFname); /* %r */ + +#endif /* ARCHIVE_H */ diff --git a/src/backend/access/transam/xlogarchive.c b/src/backend/access/transam/xlogarchive.c index 188b73e752..914ad340ea 100644 --- a/src/backend/access/transam/xlogarchive.c +++ b/src/backend/access/transam/xlogarchive.c @@ -21,6 +21,7 @@ #include "access/xlog.h" #include "access/xlog_internal.h" +#include "common/archive.h" #include "miscadmin.h" #include "postmaster/startup.h" #include "replication/walsender.h" @@ -53,11 +54,8 @@ RestoreArchivedFile(char *path, const char *xlogfname, bool cleanupEnabled) { char xlogpath[MAXPGPATH]; - char xlogRestoreCmd[MAXPGPATH]; + char *xlogRestoreCmd; char lastRestartPointFname[MAXPGPATH]; - char *dp; - char *endp; - const char *sp; int rc; struct stat stat_buf; XLogSegNo restartSegNo; @@ -149,58 +147,13 @@ RestoreArchivedFile(char *path, const char *xlogfname, else XLogFileName(lastRestartPointFname, 0, 0L, wal_segment_size); - /* - * construct the command to be executed - */ - dp = xlogRestoreCmd; - endp = xlogRestoreCmd + MAXPGPATH - 1; - *endp = '\0'; - - for (sp = recoveryRestoreCommand; *sp; sp++) - { - if (*sp == '%') - { - switch (sp[1]) - { - case 'p': - /* %p: relative path of target file */ - sp++; - StrNCpy(dp, xlogpath, endp - dp); - make_native_path(dp); - dp += strlen(dp); - break; - case 'f': - /* %f: filename of desired file */ - sp++; - StrNCpy(dp, xlogfname, endp - dp); - dp += strlen(dp); - break; - case 'r': - /* %r: filename of last restartpoint */ - sp++; - StrNCpy(dp, lastRestartPointFname, endp - dp); - dp += strlen(dp); - break; - case '%': - /* convert %% to a single % */ - sp++; - if (dp < endp) - *dp++ = *sp; - break; - default: - /* otherwise treat the % as not special */ - if (dp < endp) - *dp++ = *sp; - break; - } - } - else - { - if (dp < endp) - *dp++ = *sp; - } - } - *dp = '\0'; + /* Build the restore command to execute */ + xlogRestoreCmd = BuildRestoreCommand(recoveryRestoreCommand, + xlogpath, xlogfname, + lastRestartPointFname); + if (xlogRestoreCmd == NULL) + elog(ERROR, "could not build restore command \"%s\"", + recoveryRestoreCommand); ereport(DEBUG3, (errmsg_internal("executing restore command \"%s\"", @@ -217,6 +170,7 @@ RestoreArchivedFile(char *path, const char *xlogfname, rc = system(xlogRestoreCmd); PostRestoreCommand(); + pfree(xlogRestoreCmd); if (rc == 0) { diff --git a/src/common/Makefile b/src/common/Makefile index ce01df68b9..6939b9d087 100644 --- a/src/common/Makefile +++ b/src/common/Makefile @@ -46,6 +46,7 @@ LIBS += $(PTHREAD_LIBS) # If you add objects here, see also src/tools/msvc/Mkvcbuild.pm OBJS_COMMON = \ + archive.o \ base64.o \ config_info.o \ controldata_utils.o \ diff --git a/src/common/archive.c b/src/common/archive.c new file mode 100644 index 0000000000..783fc3d752 --- /dev/null +++ b/src/common/archive.c @@ -0,0 +1,119 @@ +/*------------------------------------------------------------------------- + * + * archive.c + * Common WAL archive routines + * + * Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group + * Portions Copyright (c) 1994, Regents of the University of California + * + * + * IDENTIFICATION + * src/common/archive.c + * + *------------------------------------------------------------------------- + */ + +#ifndef FRONTEND +#include "postgres.h" +#else +#include "postgres_fe.h" +#endif + +#include "common/archive.h" + +/* + * BuildRestoreCommand + * + * Builds a restore command to retrieve a file from WAL archives, replacing + * the supported aliases with values supplied by the caller as defined by + * the GUC parameter restore_command: xlogpath for %p, xlogfname for %f and + * lastRestartPointFname for %r. + * + * The result is a palloc'd string for the restore command built. The + * caller is responsible for freeing it. If any of the required arguments + * is NULL and that the corresponding alias is found in the command given + * by the caller, then NULL is returned. + */ +char * +BuildRestoreCommand(const char *restoreCommand, + const char *xlogpath, + const char *xlogfname, + const char *lastRestartPointFname) +{ + char *dp; + char *endp; + char *result; + const char *sp; + + result = palloc0(MAXPGPATH); + + /* + * Build the command to be executed. + */ + dp = result; + endp = result + MAXPGPATH - 1; + *endp = '\0'; + + for (sp = restoreCommand; *sp; sp++) + { + if (*sp == '%') + { + switch (sp[1]) + { + case 'p': + /* %p: relative path of target file */ + if (xlogpath == NULL) + { + pfree(result); + return NULL; + } + sp++; + StrNCpy(dp, xlogpath, endp - dp); + make_native_path(dp); + dp += strlen(dp); + break; + case 'f': + /* %f: filename of desired file */ + if (xlogfname == NULL) + { + pfree(result); + return NULL; + } + sp++; + StrNCpy(dp, xlogfname, endp - dp); + dp += strlen(dp); + break; + case 'r': + /* %r: filename of last restartpoint */ + if (lastRestartPointFname == NULL) + { + pfree(result); + return NULL; + } + sp++; + StrNCpy(dp, lastRestartPointFname, endp - dp); + dp += strlen(dp); + break; + case '%': + /* convert %% to a single % */ + sp++; + if (dp < endp) + *dp++ = *sp; + break; + default: + /* otherwise treat the % as not special */ + if (dp < endp) + *dp++ = *sp; + break; + } + } + else + { + if (dp < endp) + *dp++ = *sp; + } + } + *dp = '\0'; + + return result; +} diff --git a/src/tools/msvc/Mkvcbuild.pm b/src/tools/msvc/Mkvcbuild.pm index f89a8a4fdb..c648078e20 100644 --- a/src/tools/msvc/Mkvcbuild.pm +++ b/src/tools/msvc/Mkvcbuild.pm @@ -120,8 +120,8 @@ sub mkvcbuild } our @pgcommonallfiles = qw( - base64.c config_info.c controldata_utils.c d2s.c encnames.c exec.c - f2s.c file_perm.c hashfn.c ip.c jsonapi.c + archive.c base64.c config_info.c controldata_utils.c d2s.c encnames.c + exec.c f2s.c file_perm.c hashfn.c ip.c jsonapi.c keywords.c kwlookup.c link-canary.c md5.c pg_lzcompress.c pgfnames.c psprintf.c relpath.c rmtree.c saslprep.c scram-common.c string.c stringinfo.c unicode_norm.c username.c -- 2.25.1
From ccf64c26b425ef4d36bb409a9e6f2e70c64513e8 Mon Sep 17 00:00:00 2001 From: Michael Paquier <mich...@paquier.xyz> Date: Thu, 12 Mar 2020 13:03:23 +0900 Subject: [PATCH 2/2] Add -c/--restore-target-wal to pg_rewind pg_rewind needs to copy from the source server to the target a set of relation blocks changed from the previous checkpoint where WAL forked between both up to the end of WAL on the target. This may require WAL segments that are not present anymore on the target's pg_wal, causing pg_rewind to fail. It is possible to fix that by copying manually the WAL segments needed but this may lead to extra and useless work. Instead, this commit introduces a new option allowing pg_rewind to use a restore_command when running by grabbing it from the target configuration. This allows the rewind operation to be more reliable, and only the necessary segments are fetched from the archives in this case. In order to do that, a new routine is added to src/common/ to allow frontend tools to retrieve a WAL segment using an already-built restore command. This version is much more simple than the backend equivalent. Author: Alexey Kondratov Reviewed-by: Andrey Borodin, Andres Freund, Alvaro Herrera, Alexander Korotkov, Michael Paquier Discussion: https://postgr.es/m/a3acff50-5a0d-9a2c-b3b2-ee3616895...@postgrespro.ru --- src/include/common/fe_archive.h | 21 +++++ src/include/port.h | 3 +- src/common/Makefile | 1 + src/common/exec.c | 3 +- src/common/fe_archive.c | 129 ++++++++++++++++++++++++++++++ src/bin/pg_rewind/parsexlog.c | 33 +++++++- src/bin/pg_rewind/pg_rewind.c | 87 ++++++++++++++++++-- src/bin/pg_rewind/pg_rewind.h | 6 +- src/bin/pg_rewind/t/001_basic.pl | 3 +- src/bin/pg_rewind/t/RewindTest.pm | 64 ++++++++++++++- doc/src/sgml/ref/pg_rewind.sgml | 28 +++++-- src/tools/msvc/Mkvcbuild.pm | 4 +- 12 files changed, 355 insertions(+), 27 deletions(-) create mode 100644 src/include/common/fe_archive.h create mode 100644 src/common/fe_archive.c diff --git a/src/include/common/fe_archive.h b/src/include/common/fe_archive.h new file mode 100644 index 0000000000..13d19d11e7 --- /dev/null +++ b/src/include/common/fe_archive.h @@ -0,0 +1,21 @@ +/*------------------------------------------------------------------------- + * + * fe_archive.h + * Routines to access WAL archives from frontend + * + * Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group + * Portions Copyright (c) 1994, Regents of the University of California + * + * src/include/common/fe_archive.h + * + *------------------------------------------------------------------------- + */ +#ifndef FE_ARCHIVE_H +#define FE_ARCHIVE_H + +extern int FrontendRestoreArchivedFile(const char *path, + const char *xlogfname, + off_t expectedSize, + const char *restoreCommand); + +#endif /* FE_ARCHIVE_H */ diff --git a/src/include/port.h b/src/include/port.h index 29f3e39e5b..20a5de1b7a 100644 --- a/src/include/port.h +++ b/src/include/port.h @@ -102,10 +102,11 @@ extern void pgfnames_cleanup(char **filenames); /* Portable locale initialization (in exec.c) */ extern void set_pglocale_pgservice(const char *argv0, const char *app); -/* Portable way to find binaries (in exec.c) */ +/* Portable way to find and execute binaries (in exec.c) */ extern int find_my_exec(const char *argv0, char *retpath); extern int find_other_exec(const char *argv0, const char *target, const char *versionstr, char *retpath); +extern char *pipe_read_line(char *cmd, char *line, int maxsize); /* Doesn't belong here, but this is used with find_other_exec(), so... */ #define PG_BACKEND_VERSIONSTR "postgres (PostgreSQL) " PG_VERSION "\n" diff --git a/src/common/Makefile b/src/common/Makefile index 6939b9d087..a97c723fbd 100644 --- a/src/common/Makefile +++ b/src/common/Makefile @@ -88,6 +88,7 @@ endif # (Mkvcbuild.pm has a copy of this list, too) OBJS_FRONTEND = \ $(OBJS_COMMON) \ + fe_archive.o \ fe_memutils.o \ file_utils.o \ logging.o \ diff --git a/src/common/exec.c b/src/common/exec.c index 88400daa47..f39b0a294b 100644 --- a/src/common/exec.c +++ b/src/common/exec.c @@ -51,7 +51,6 @@ static int validate_exec(const char *path); static int resolve_symlinks(char *path); -static char *pipe_read_line(char *cmd, char *line, int maxsize); #ifdef WIN32 static BOOL GetTokenUser(HANDLE hToken, PTOKEN_USER *ppTokenUser); @@ -356,7 +355,7 @@ find_other_exec(const char *argv0, const char *target, /* * Execute a command in a pipe and read the first line from it. */ -static char * +char * pipe_read_line(char *cmd, char *line, int maxsize) { FILE *pgver; diff --git a/src/common/fe_archive.c b/src/common/fe_archive.c new file mode 100644 index 0000000000..1716e754ee --- /dev/null +++ b/src/common/fe_archive.c @@ -0,0 +1,129 @@ +/*------------------------------------------------------------------------- + * + * fe_archive.c + * Routines to access WAL archives from frontend + * + * Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group + * Portions Copyright (c) 1994, Regents of the University of California + * + * + * IDENTIFICATION + * src/common/fe_archive.c + * + *------------------------------------------------------------------------- + */ + +#ifndef FRONTEND +#error "This file is not expected to be compiled for backend code" +#endif + +#include "postgres_fe.h" + +#include <unistd.h> +#include <sys/stat.h> + +#include "access/xlog_internal.h" +#include "common/archive.h" +#include "common/fe_archive.h" +#include "common/logging.h" + + +/* + * FrontendRestoreArchivedFile + * + * Attempt to retrieve the specified file from off-line archival storage. + * If successful, return a file descriptor of the restored file, else + * return -1. + * + * For fixed-size files, the caller may pass the expected size as an + * additional crosscheck on successful recovery. If the file size is not + * known, set expectedSize = 0. + */ +int +FrontendRestoreArchivedFile(const char *path, const char *xlogfname, + off_t expectedSize, const char *restoreCommand) +{ + char xlogpath[MAXPGPATH]; + char *xlogRestoreCmd; + int rc; + struct stat stat_buf; + + snprintf(xlogpath, MAXPGPATH, "%s/" XLOGDIR "/%s", path, xlogfname); + + xlogRestoreCmd = BuildRestoreCommand(restoreCommand, xlogpath, + xlogfname, NULL); + if (xlogRestoreCmd == NULL) + { + pg_log_fatal("could not use restore_command with %%r alias"); + exit(1); + } + + /* + * Execute restore_command, which should copy the missing file from + * archival storage. + */ + rc = system(xlogRestoreCmd); + pfree(xlogRestoreCmd); + + if (rc == 0) + { + /* + * Command apparently succeeded, but let's make sure the file is + * really there now and has the correct size. + */ + if (stat(xlogpath, &stat_buf) == 0) + { + if (expectedSize > 0 && stat_buf.st_size != expectedSize) + { + pg_log_fatal("unexpected file size for \"%s\": %lu instead of %lu", + xlogfname, (unsigned long) stat_buf.st_size, + (unsigned long) expectedSize); + exit(1); + } + else + { + int xlogfd = open(xlogpath, O_RDONLY | PG_BINARY, 0); + + if (xlogfd < 0) + { + pg_log_fatal("could not open file \"%s\" restored from archive: %m", + xlogpath); + exit(1); + } + else + return xlogfd; + } + } + else + { + if (errno != ENOENT) + { + pg_log_fatal("could not stat file \"%s\": %m", + xlogpath); + exit(1); + } + return -1; + } + } + + /* + * If the failure was due to a signal, then it would be misleading to + * return with a failure at restoring the file. So just bail out and + * exit. Hard shell errors such as "command not found" are treated as + * fatal too. + */ + if (wait_result_is_any_signal(rc, true)) + { + pg_log_fatal("restore_command failed due to the signal: %s", + wait_result_to_str(rc)); + exit(1); + } + + /* + * The file is not available, so just let the caller decide what to do + * next. + */ + pg_log_error("could not restore file \"%s\" from archive", + xlogfname); + return -1; +} diff --git a/src/bin/pg_rewind/parsexlog.c b/src/bin/pg_rewind/parsexlog.c index eb61cb8803..7c8bc1dfe2 100644 --- a/src/bin/pg_rewind/parsexlog.c +++ b/src/bin/pg_rewind/parsexlog.c @@ -19,6 +19,7 @@ #include "catalog/pg_control.h" #include "catalog/storage_xlog.h" #include "commands/dbcommands_xlog.h" +#include "common/fe_archive.h" #include "filemap.h" #include "pg_rewind.h" @@ -41,6 +42,7 @@ static char xlogfpath[MAXPGPATH]; typedef struct XLogPageReadPrivate { + const char *restoreCommand; int tliIndex; } XLogPageReadPrivate; @@ -55,7 +57,7 @@ static int SimpleXLogPageRead(XLogReaderState *xlogreader, */ void extractPageMap(const char *datadir, XLogRecPtr startpoint, int tliIndex, - XLogRecPtr endpoint) + XLogRecPtr endpoint, const char *restore_command) { XLogRecord *record; XLogReaderState *xlogreader; @@ -63,6 +65,7 @@ extractPageMap(const char *datadir, XLogRecPtr startpoint, int tliIndex, XLogPageReadPrivate private; private.tliIndex = tliIndex; + private.restoreCommand = restore_command; xlogreader = XLogReaderAllocate(WalSegSz, datadir, &SimpleXLogPageRead, &private); if (xlogreader == NULL) @@ -146,7 +149,7 @@ readOneRecord(const char *datadir, XLogRecPtr ptr, int tliIndex) void findLastCheckpoint(const char *datadir, XLogRecPtr forkptr, int tliIndex, XLogRecPtr *lastchkptrec, TimeLineID *lastchkpttli, - XLogRecPtr *lastchkptredo) + XLogRecPtr *lastchkptredo, const char *restoreCommand) { /* Walk backwards, starting from the given record */ XLogRecord *record; @@ -170,6 +173,7 @@ findLastCheckpoint(const char *datadir, XLogRecPtr forkptr, int tliIndex, } private.tliIndex = tliIndex; + private.restoreCommand = restoreCommand; xlogreader = XLogReaderAllocate(WalSegSz, datadir, &SimpleXLogPageRead, &private); if (xlogreader == NULL) @@ -281,8 +285,29 @@ SimpleXLogPageRead(XLogReaderState *xlogreader, XLogRecPtr targetPagePtr, if (xlogreadfd < 0) { - pg_log_error("could not open file \"%s\": %m", xlogfpath); - return -1; + /* + * If we have no restore_command to execute, then exit. + */ + if (private->restoreCommand == NULL) + { + pg_log_error("could not open file \"%s\": %m", xlogfpath); + return -1; + } + + /* + * Since we have restore_command, then try to retrieve missing WAL + * file from the archive. + */ + xlogreadfd = FrontendRestoreArchivedFile(xlogreader->segcxt.ws_dir, + xlogfname, + WalSegSz, + private->restoreCommand); + + if (xlogreadfd < 0) + return -1; + else + pg_log_debug("using file \"%s\" restored from archive", + xlogfpath); } } diff --git a/src/bin/pg_rewind/pg_rewind.c b/src/bin/pg_rewind/pg_rewind.c index bf2d2983e7..44eb15b269 100644 --- a/src/bin/pg_rewind/pg_rewind.c +++ b/src/bin/pg_rewind/pg_rewind.c @@ -22,6 +22,7 @@ #include "common/file_perm.h" #include "common/file_utils.h" #include "common/restricted_token.h" +#include "common/string.h" #include "fe_utils/recovery_gen.h" #include "fetch.h" #include "file_ops.h" @@ -38,6 +39,7 @@ static void createBackupLabel(XLogRecPtr startpoint, TimeLineID starttli, static void digestControlFile(ControlFileData *ControlFile, char *source, size_t size); static void syncTargetDirectory(void); +static void getRestoreCommand(const char *argv0); static void sanityChecks(void); static void findCommonAncestorTimeline(XLogRecPtr *recptr, int *tliIndex); static void ensureCleanShutdown(const char *argv0); @@ -53,11 +55,13 @@ int WalSegSz; char *datadir_target = NULL; char *datadir_source = NULL; char *connstr_source = NULL; +char *restore_command = NULL; static bool debug = false; bool showprogress = false; bool dry_run = false; bool do_sync = true; +bool restore_wal = false; /* Target history */ TimeLineHistoryEntry *targetHistory; @@ -74,6 +78,8 @@ usage(const char *progname) printf(_("%s resynchronizes a PostgreSQL cluster with another copy of the cluster.\n\n"), progname); printf(_("Usage:\n %s [OPTION]...\n\n"), progname); printf(_("Options:\n")); + printf(_(" -c, --restore-target-wal use restore_command in target config\n" + " to retrieve WAL files from archive\n")); printf(_(" -D, --target-pgdata=DIRECTORY existing data directory to modify\n")); printf(_(" --source-pgdata=DIRECTORY source data directory to synchronize with\n")); printf(_(" --source-server=CONNSTR source server to synchronize with\n")); @@ -103,6 +109,7 @@ main(int argc, char **argv) {"source-server", required_argument, NULL, 2}, {"no-ensure-shutdown", no_argument, NULL, 4}, {"version", no_argument, NULL, 'V'}, + {"restore-target-wal", no_argument, NULL, 'c'}, {"dry-run", no_argument, NULL, 'n'}, {"no-sync", no_argument, NULL, 'N'}, {"progress", no_argument, NULL, 'P'}, @@ -144,7 +151,7 @@ main(int argc, char **argv) } } - while ((c = getopt_long(argc, argv, "D:nNPR", long_options, &option_index)) != -1) + while ((c = getopt_long(argc, argv, "cD:nNPR", long_options, &option_index)) != -1) { switch (c) { @@ -152,6 +159,10 @@ main(int argc, char **argv) fprintf(stderr, _("Try \"%s --help\" for more information.\n"), progname); exit(1); + case 'c': + restore_wal = true; + break; + case 'P': showprogress = true; break; @@ -255,6 +266,8 @@ main(int argc, char **argv) umask(pg_mode_mask); + getRestoreCommand(argv[0]); + atexit(disconnect_atexit); /* Connect to remote server */ @@ -350,9 +363,8 @@ main(int argc, char **argv) exit(0); } - findLastCheckpoint(datadir_target, divergerec, - lastcommontliIndex, - &chkptrec, &chkpttli, &chkptredo); + findLastCheckpoint(datadir_target, divergerec, lastcommontliIndex, + &chkptrec, &chkpttli, &chkptredo, restore_command); pg_log_info("rewinding from last common checkpoint at %X/%X on timeline %u", (uint32) (chkptrec >> 32), (uint32) chkptrec, chkpttli); @@ -378,7 +390,7 @@ main(int argc, char **argv) if (showprogress) pg_log_info("reading WAL in target"); extractPageMap(datadir_target, chkptrec, lastcommontliIndex, - ControlFile_target.checkPoint); + ControlFile_target.checkPoint, restore_command); filemap_finalize(); if (showprogress) @@ -804,6 +816,71 @@ syncTargetDirectory(void) fsync_pgdata(datadir_target, PG_VERSION_NUM); } +/* + * Get value of GUC parameter restore_command from the target cluster. + * + * This uses a logic based on "postgres -C" to get the value from + * from the cluster. + */ +static void +getRestoreCommand(const char *argv0) +{ + int rc; + char postgres_exec_path[MAXPGPATH], + postgres_cmd[MAXPGPATH], + cmd_output[MAXPGPATH]; + + if (!restore_wal) + return; + + /* find postgres executable */ + rc = find_other_exec(argv0, "postgres", + PG_BACKEND_VERSIONSTR, + postgres_exec_path); + + if (rc < 0) + { + char full_path[MAXPGPATH]; + + if (find_my_exec(argv0, full_path) < 0) + strlcpy(full_path, progname, sizeof(full_path)); + + if (rc == -1) + pg_log_error("The program \"postgres\" is needed by %s but was not found in the\n" + "same directory as \"%s\".\n" + "Check your installation.", + progname, full_path); + else + pg_log_error("The program \"postgres\" was found by \"%s\"\n" + "but was not the same version as %s.\n" + "Check your installation.", + full_path, progname); + exit(1); + } + + /* + * Build a command able to retrieve the value of GUC parameter + * restore_command, if set. + */ + snprintf(postgres_cmd, sizeof(postgres_cmd), + "\"%s\" -D \"%s\" -C restore_command", + postgres_exec_path, datadir_target); + + if (!pipe_read_line(postgres_cmd, cmd_output, sizeof(cmd_output))) + exit(1); + + (void) pg_strip_crlf(cmd_output); + + if (strcmp(cmd_output, "") == 0) + pg_fatal("restore_command is not set on the target cluster"); + + restore_command = pg_strdup(cmd_output); + + pg_log_debug("using for rewind restore_command = \'%s\'", + restore_command); +} + + /* * Ensure clean shutdown of target instance by launching single-user mode * postgres to do crash recovery. diff --git a/src/bin/pg_rewind/pg_rewind.h b/src/bin/pg_rewind/pg_rewind.h index e4e8d23c32..b122ae43e5 100644 --- a/src/bin/pg_rewind/pg_rewind.h +++ b/src/bin/pg_rewind/pg_rewind.h @@ -42,11 +42,13 @@ extern uint64 fetch_done; /* in parsexlog.c */ extern void extractPageMap(const char *datadir, XLogRecPtr startpoint, - int tliIndex, XLogRecPtr endpoint); + int tliIndex, XLogRecPtr endpoint, + const char *restoreCommand); extern void findLastCheckpoint(const char *datadir, XLogRecPtr searchptr, int tliIndex, XLogRecPtr *lastchkptrec, TimeLineID *lastchkpttli, - XLogRecPtr *lastchkptredo); + XLogRecPtr *lastchkptredo, + const char *restoreCommand); extern XLogRecPtr readOneRecord(const char *datadir, XLogRecPtr ptr, int tliIndex); diff --git a/src/bin/pg_rewind/t/001_basic.pl b/src/bin/pg_rewind/t/001_basic.pl index 95d8ccfced..d97e437741 100644 --- a/src/bin/pg_rewind/t/001_basic.pl +++ b/src/bin/pg_rewind/t/001_basic.pl @@ -1,7 +1,7 @@ use strict; use warnings; use TestLib; -use Test::More tests => 15; +use Test::More tests => 20; use FindBin; use lib $FindBin::RealBin; @@ -171,5 +171,6 @@ in master, before promotion # Run the test in both modes run_test('local'); run_test('remote'); +run_test('archive'); exit(0); diff --git a/src/bin/pg_rewind/t/RewindTest.pm b/src/bin/pg_rewind/t/RewindTest.pm index 82fa220ac8..349d2fa0b2 100644 --- a/src/bin/pg_rewind/t/RewindTest.pm +++ b/src/bin/pg_rewind/t/RewindTest.pm @@ -38,6 +38,7 @@ use File::Copy; use File::Path qw(rmtree); use IPC::Run qw(run); use PostgresNode; +use RecursiveCopy; use TestLib; use Test::More; @@ -227,10 +228,23 @@ sub run_pg_rewind # Append the rewind-specific role to the connection string. $standby_connstr = "$standby_connstr user=rewind_user"; - # Stop the master and be ready to perform the rewind. The cluster - # needs recovery to finish once, and pg_rewind makes sure that it - # happens automatically. - $node_master->stop('immediate'); + if ($test_mode eq 'archive') + { + # We test pg_rewind with restore_command by simply moving all WAL files + # to another location. It leads to failed ensureCleanShutdown + # execution. Since it is difficult to emulate a situation, when + # keeping the last WAL segment is enough for startup recovery, but + # not enough for successful pg_rewind run, we run these modes with + # --no-ensure-shutdown. So stop the master gracefully. + $node_master->stop; + } + else + { + # Stop the master and be ready to perform the rewind. The cluster + # needs recovery to finish once, and pg_rewind makes sure that it + # happens automatically. + $node_master->stop('immediate'); + } # At this point, the rewind processing is ready to run. # We now have a very simple scenario with a few diverged WAL record. @@ -284,6 +298,48 @@ sub run_pg_rewind $node_standby->safe_psql('postgres', "ALTER ROLE rewind_user WITH REPLICATION;"); } + elsif ($test_mode eq "archive") + { + + # Do rewind using a local pgdata as source and specified + # directory with target WAL archive. The old master has + # to be stopped at this point. + + # Remove the existing archive directory and move all WAL + # segments from the old master to the archives. These + # will be used by pg_rewind. + rmtree($node_master->archive_dir); + RecursiveCopy::copypath($node_master->data_dir . "/pg_wal", + $node_master->archive_dir); + + # Fast way to remove entire directory content + rmtree($node_master->data_dir . "/pg_wal"); + mkdir($node_master->data_dir . "/pg_wal"); + + # Make sure that directories have the right umask as this is + # required by a follow-up check on permissions, and better + # safe than sorry. + chmod(0700, $node_master->archive_dir); + chmod(0700, $node_master->data_dir . "/pg_wal"); + + # Add appropriate restore_command to the target cluster + $node_master->enable_restoring($node_master, 0); + + # Stop the new master and be ready to perform the rewind. + $node_standby->stop; + + command_ok( + [ + 'pg_rewind', + "--debug", + "--source-pgdata=$standby_pgdata", + "--target-pgdata=$master_pgdata", + "--no-sync", + "--no-ensure-shutdown", + "--restore-target-wal" + ], + 'pg_rewind archive'); + } else { diff --git a/doc/src/sgml/ref/pg_rewind.sgml b/doc/src/sgml/ref/pg_rewind.sgml index f64d659522..07c49e4719 100644 --- a/doc/src/sgml/ref/pg_rewind.sgml +++ b/doc/src/sgml/ref/pg_rewind.sgml @@ -66,11 +66,11 @@ PostgreSQL documentation can be found either on the target timeline, the source timeline, or their common ancestor. In the typical failover scenario where the target cluster was shut down soon after the divergence, this is not a problem, but if the - target cluster ran for a long time after the divergence, the old WAL - files might no longer be present. In that case, they can be manually - copied from the WAL archive to the <filename>pg_wal</filename> directory, or - fetched on startup by configuring <xref linkend="guc-primary-conninfo"/> or - <xref linkend="guc-restore-command"/>. The use of + target cluster ran for a long time after the divergence, its old WAL + files might no longer be present. In this case, you can manually copy them + from the WAL archive to the <filename>pg_wal</filename> directory, or run + <application>pg_rewind</application> with the <literal>-c</literal> option to + automatically retrieve them from the WAL archive. The use of <application>pg_rewind</application> is not limited to failover, e.g. a standby server can be promoted, run some write transactions, and then rewinded to become a standby again. @@ -232,6 +232,19 @@ PostgreSQL documentation </listitem> </varlistentry> + <varlistentry> + <term><option>-c</option></term> + <term><option>--restore-target-wal</option></term> + <listitem> + <para> + Use <varname>restore_command</varname> defined in the target cluster + configuration to retrieve WAL files from the WAL archive if these + files are no longer available in the <filename>pg_wal</filename> + directory. + </para> + </listitem> + </varlistentry> + <varlistentry> <term><option>--debug</option></term> <listitem> @@ -318,7 +331,10 @@ GRANT EXECUTE ON function pg_catalog.pg_read_binary_file(text, bigint, bigint, b history forked off from the target cluster. For each WAL record, record each data block that was touched. This yields a list of all the data blocks that were changed in the target cluster, after the - source cluster forked off. + source cluster forked off. If some of the WAL files are no longer + available, try re-running <application>pg_rewind</application> with + the <option>-c</option> option to search for the missing files in + the WAL archive. </para> </step> <step> diff --git a/src/tools/msvc/Mkvcbuild.pm b/src/tools/msvc/Mkvcbuild.pm index c648078e20..92df33a7e9 100644 --- a/src/tools/msvc/Mkvcbuild.pm +++ b/src/tools/msvc/Mkvcbuild.pm @@ -138,8 +138,8 @@ sub mkvcbuild } our @pgcommonfrontendfiles = ( - @pgcommonallfiles, qw(fe_memutils.c file_utils.c - logging.c restricted_token.c)); + @pgcommonallfiles, qw(fe_archive.c fe_memutils.c + file_utils.c logging.c restricted_token.c)); our @pgcommonbkndfiles = @pgcommonallfiles; -- 2.25.1
signature.asc
Description: PGP signature
