--- /dev/null
+pg_standby README 2006/12/08 Simon Riggs
+
+o What is pg_standby?
+
+ pg_standby is a production-ready program that can be used to
+ create a Warm Standby server. Other configuration is required
+ as well, all of which is described in the main server manual.
+
+ The program is designed to be a wait-for restore_command,
+ required to turn a normal archive recovery into a Warm Standby.
+ Within the restore_command of the recovery.conf you could
+ configure pg_standby in the following way:
+
+ restore_command = 'pg_standby archiveDir %f %p'
+
+ which would be sufficient to define that files will be restored
+ from archiveDir.
+
+o features of pg_standby
+
+ - pg_standby is written in C. So it is very portable
+ and easy to install.
+
+ - supports copy or link from a directory (only)
+
+ - source easy to modify, with specifically designated
+ sections to modify for your own needs, allowing
+ interfaces to be written for additional Backup Archive Restore
+ (BAR) systems
+
+ - portable: tested on Linux and Windows
+
+o How to install pg_standby
+
+ $make
+ $make install
+
+o How to use pg_standby?
+
+ pg_standby should be used within the restore_command of the
+ recovery.conf file. See the main PostgreSQL manual for details.
+
+ The basic usage should be like this:
+
+ restore_command = 'pg_standby archiveDir %f %p'
+
+ with the pg_standby command usage as
+
+ pg_standby [OPTION]... [ARCHIVELOCATION] [NEXTWALFILE] [XLOGFILEPATH]
+
+ When used within the restore_command the %f and %p macros
+ will provide the actual file and path required for the restore/recovery.
+
+o options
+
+ pg_standby has number of options.
+
+ -c
+ use copy/cp command to restore WAL files from archive
+
+ -d
+ debug/logging option.
+
+ -k numfiles
+ Cleanup files in the archive so that we maintain no more
+ than this many files in the archive.
+
+ You should be wary against setting this number too low,
+ since this may mean you cannot restart the standby. This
+ is because the last restartpoint marked in the WAL files
+ may be many files in the past and can vary considerably.
+ This should be set to a value exceeding the number of WAL
+ files that can be recovered in 2*checkpoint_timeout seconds,
+ according to the value in the warm standby postgresql.conf.
+ It is wholly unrelated to the setting of checkpoint_segments
+ on either primary or standby.
+
+ If in doubt, use a large value or do not set a value at all.
+
+ -l
+ use ln command to restore WAL files from archive
+ WAL files will remain in archive
+
+ Link is more efficient, but the default is copy to
+ allow you to maintain the WAL archive for recovery
+ purposes as well as high-availability.
+
+ This option uses the Windows Vista command mklink
+ to provide a file-to-file symbolic link. -l will
+ not work on versions of Windows prior to Vista.
+ Use the -c option instead.
+ see http://en.wikipedia.org/wiki/NTFS_symbolic_link
+
+ -r maxretries
+ the maximum number of times to retry the restore command if it
+ fails. After each failure, we wait for sleeptime * num_retries
+ so that the wait time increases progressively, so by default
+ we will wait 5 secs, 10 secs then 15 secs before reporting
+ the failure back to the database server. This will be
+ interpreted as and end of recovery and the Standby will come
+ up fully as a result.
+ Default=3
+
+ -s sleeptime
+ the number of seconds to sleep between testing to see
+ if the file to be restored is available in the archive yet.
+ The default setting is not necessarily recommended,
+ consult the main database server manual for discussion.
+ Default=5
+
+ -t triggerfile
+ the presence of the triggerfile will cause recovery to end
+ whether or not the next file is available
+ It is recommended that you use a structured filename to
+ avoid confusion as to which server is being triggered
+ when multiple servers exist on same system.
+ e.g. /tmp/pgsql.trigger.5432
+
+ -w maxwaittime
+ the maximum number of seconds to wait for the next file,
+ after which recovery will end and the Standby will come up.
+ The default setting is not necessarily recommended,
+ consult the main database server manual for discussion.
+ Default=0
+
+ Note: --help is not supported since pg_standby is not intended
+ for interactive use, except during dev/test
+
+o examples
+
+ Linux
+
+ archive_command = 'cp %p ../archive/%f'
+
+ restore_command = 'pg_standby -l -d -k 255 -r 2 -s 2 -w 0 -t /tmp/pgsql.trigger.5442 $PWD/../archive %f %p 2>> standby.log'
+
+ which will
+ - use a ln command to restore WAL files from archive
+ - produce logfile output in standby.log
+ - keep the last 255 full WAL files, plus the current one
+ - sleep for 2 seconds between checks for next WAL file is full
+ - never timeout if file not found
+ - stop waiting when a trigger file called /tmp.pgsql.trigger.5442 appears
+
+ Windows
+
+ archive_command = 'copy %p ..\\archive\\%f'
+ Note that backslashes need to be doubled in the archive_command, but
+ *not* in the restore_command, in 8.2, 8.1, 8.0 on Windows.
+
+ restore_command = 'pg_standby -c -d -s 5 -w 0 -t C:\pgsql.trigger.5442
+..\archive %f %p 2>> standby.log'
+
+ which will
+ - use a copy command to restore WAL files from archive
+ - produce logfile output in standby.log
+ - sleep for 5 seconds between checks for next WAL file is full
+ - never timeout if file not found
+ - stop waiting when a trigger file called C:\pgsql.trigger.5442 appears
+
+o reported test success
+
+ SUSE Linux 10.2
+ Windows XP Pro
--- /dev/null
+/*
+ * pg_standby.c
+ *
+ * Production-ready example of how to create a Warm Standby
+ * database server using continuous archiving as a
+ * replication mechanism
+ *
+ * We separate the parameters for archive and nextWALfile
+ * so that we can check the archive exists, even if the
+ * WAL file doesn't (yet).
+ *
+ * This program will be executed once in full for each file
+ * requested by the warm standby server.
+ *
+ * It is designed to cater to a variety of needs, as well
+ * providing a customizable section.
+ *
+ * Original author: Simon Riggs simon@2ndquadrant.com
+ * Current maintainer: Simon Riggs
+ */
+#include "postgres_fe.h"
+#include "pg_config_manual.h"
+
+#include <ctype.h>
+#include <dirent.h>
+#include <sys/stat.h>
+#include <signal.h>
+
+#ifdef WIN32
+#include "win32.h"
+int getopt(int argc, char * const argv[], const char *optstring);
+#else
+#include <sys/time.h>
+#include <unistd.h>
+
+#ifdef HAVE_GETOPT_H
+#include <getopt.h>
+#endif
+
+#endif /* ! WIN32 */
+
+extern char *optarg;
+extern int optind;
+
+/* Options and defaults */
+int sleeptime = 5; /* amount of time to sleep between file checks */
+int waittime = -1; /* how long we have been waiting, -1 no wait yet */
+int maxwaittime = 0; /* how long are we prepared to wait for? */
+int keepfiles = 0; /* number of WAL files to keep, 0 keep all */
+int maxretries = 3; /* number of retries on restore command */
+bool debug = false; /* are we debugging? */
+bool triggered = false;
+bool signaled = false;
+
+char *archiveLocation; /* where to find the archive? */
+char *triggerPath; /* where to find the trigger file? */
+char *xlogFilePath; /* where we are going to restore to */
+char *nextWALFileName; /* the file we need to get from archive */
+char *priorWALFileName; /* the file we need to get from archive */
+char WALFilePath[MAXPGPATH];/* the file path including archive */
+char restoreCommand[MAXPGPATH]; /* run this to restore */
+char inclusiveCleanupFileName[MAXPGPATH]; /* the file we need to get from archive */
+
+#define RESTORE_COMMAND_COPY 0
+#define RESTORE_COMMAND_LINK 1
+int restoreCommandType;
+
+#define XLOG_DATA 0
+#define XLOG_HISTORY 1
+#define XLOG_BACKUP_LABEL 2
+int nextWALFileType;
+
+#define SET_RESTORE_COMMAND(cmd, arg1, arg2) \
+ snprintf(restoreCommand, MAXPGPATH, cmd " %s %s", arg1, arg2)
+
+struct stat stat_buf;
+
+/* =====================================================================
+ *
+ * Customizable section
+ *
+ * =====================================================================
+ *
+ * Currently, this section assumes that the Archive is a locally
+ * accessible directory. If you want to make other assumptions,
+ * such as using a vendor-specific archive and access API, these
+ * routines are the ones you'll need to change. You're
+ * enouraged to submit any changes to pgsql-patches@postgresql.org
+ * or personally to the current maintainer. Those changes may be
+ * folded in to later versions of this program.
+ */
+
+#define XLOG_DATA_FNAME_LEN 24
+/* Reworked from access/xlog_internal.h */
+#define XLogFileName(fname, tli, log, seg) \
+ snprintf(fname, XLOG_DATA_FNAME_LEN + 1, "%08X%08X%08X", tli, log, seg)
+
+/*
+ * Initialize allows customized commands into the warm standby program.
+ *
+ * As an example, and probably the common case, we use either
+ * cp/ln commands on *nix, or copy/move command on Windows.
+ *
+ */
+static void
+CustomizableInitialize(void)
+{
+#ifdef WIN32
+ snprintf(WALFilePath, MAXPGPATH, "%s\\%s", archiveLocation, nextWALFileName);
+ switch (restoreCommandType)
+ {
+ case RESTORE_COMMAND_LINK:
+ SET_RESTORE_COMMAND("mklink",WALFilePath, xlogFilePath);
+ case RESTORE_COMMAND_COPY:
+ default:
+ SET_RESTORE_COMMAND("copy",WALFilePath, xlogFilePath);
+ break;
+ }
+#else
+ snprintf(WALFilePath, MAXPGPATH, "%s/%s", archiveLocation, nextWALFileName);
+ switch (restoreCommandType)
+ {
+ case RESTORE_COMMAND_LINK:
+#if HAVE_WORKING_LINK
+ SET_RESTORE_COMMAND("ln -s -f",WALFilePath, xlogFilePath);
+ break;
+#endif
+ case RESTORE_COMMAND_COPY:
+ default:
+ SET_RESTORE_COMMAND("cp",WALFilePath, xlogFilePath);
+ break;
+ }
+#endif
+
+ /*
+ * This code assumes that archiveLocation is a directory
+ * You may wish to add code to check for tape libraries, etc..
+ * So, since it is a directory, we use stat to test if its accessible
+ */
+ if (stat(archiveLocation, &stat_buf) != 0)
+ {
+ fprintf(stderr, "pg_standby: archiveLocation \"%s\" does not exist\n", archiveLocation);
+ fflush(stderr);
+ exit(2);
+ }
+}
+
+/*
+ * CustomizableNextWALFileReady()
+ *
+ * Is the requested file ready yet?
+ */
+static bool
+CustomizableNextWALFileReady()
+{
+ if (stat(WALFilePath, &stat_buf) == 0)
+ {
+ /*
+ * If its a backup file, return immediately
+ * If its a regular file return only if its the right size already
+ */
+ if (strlen(nextWALFileName) > 24 &&
+ strspn(nextWALFileName, "0123456789ABCDEF") == 24 &&
+ strcmp(nextWALFileName + strlen(nextWALFileName) - strlen(".backup"),
+ ".backup") == 0)
+ {
+ nextWALFileType = XLOG_BACKUP_LABEL;
+ return true;
+ }
+ else
+ if (stat_buf.st_size == XLOG_SEG_SIZE)
+ {
+#ifdef WIN32
+ /*
+ * Windows reports that the file has the right number of bytes
+ * even though the file is still being copied and cannot be
+ * opened by pg_standby yet. So we wait for sleeptime secs
+ * before attempting to restore. If that is not enough, we
+ * will rely on the retry/holdoff mechanism.
+ */
+ pg_usleep(sleeptime * 1000000L);
+#endif
+ nextWALFileType = XLOG_DATA;
+ return true;
+ }
+
+ /*
+ * If still too small, wait until it is the correct size
+ */
+ if (stat_buf.st_size > XLOG_SEG_SIZE)
+ {
+ if (debug)
+ {
+ fprintf(stderr, "file size greater than expected\n");
+ fflush(stderr);
+ }
+ exit(3);
+ }
+ }
+
+ return false;
+}
+
+#define MaxSegmentsPerLogFile ( 0xFFFFFFFF / XLOG_SEG_SIZE )
+
+static void
+CustomizableCleanupPriorWALFiles(void)
+{
+ uint32 tli,
+ log,
+ seg;
+ int signed_log = 0;
+
+ if (keepfiles > 0)
+ {
+ sscanf(nextWALFileName, "%08X%08X%08X", &tli, &log, &seg);
+ signed_log = log - (keepfiles / MaxSegmentsPerLogFile);
+ if (keepfiles <= seg)
+ seg -= keepfiles;
+ else
+ {
+ seg = MaxSegmentsPerLogFile - (keepfiles % MaxSegmentsPerLogFile);
+ signed_log--;
+ }
+ log = (uint32) signed_log;
+ }
+
+ /*
+ * Work out name of prior file from current filename
+ */
+ if (keepfiles > 0 && signed_log >= 0 && nextWALFileType == XLOG_DATA)
+ {
+ int rc;
+ DIR *xldir;
+ struct dirent *xlde;
+
+ XLogFileName(inclusiveCleanupFileName, tli, log, seg);
+
+ /*
+ * Assume its OK to keep failing. The failure situation may change over
+ * time, so we'd rather keep going on the main processing than fail
+ * because we couldnt clean up yet.
+ */
+ if ((xldir = opendir(archiveLocation)) != NULL)
+ {
+ while ((xlde = readdir(xldir)) != NULL)
+ {
+ /*
+ * We ignore the timeline part of the XLOG segment identifiers in
+ * deciding whether a segment is still needed. This ensures that we
+ * won't prematurely remove a segment from a parent timeline. We could
+ * probably be a little more proactive about removing segments of
+ * non-parent timelines, but that would be a whole lot more
+ * complicated.
+ *
+ * We use the alphanumeric sorting property of the filenames to decide
+ * which ones are earlier than the inclusiveCleanupFileName file.
+ */
+ if (strlen(xlde->d_name) == XLOG_DATA_FNAME_LEN &&
+ strspn(xlde->d_name, "0123456789ABCDEF") == XLOG_DATA_FNAME_LEN &&
+ strcmp(xlde->d_name + 8, inclusiveCleanupFileName + 8) <= 0)
+ {
+#ifdef WIN32
+ snprintf(WALFilePath, MAXPGPATH, "%s\\%s", archiveLocation, xlde->d_name);
+#else
+ snprintf(WALFilePath, MAXPGPATH, "%s/%s", archiveLocation, xlde->d_name);
+#endif
+ rc = unlink(WALFilePath);
+
+ if (debug)
+ fprintf(stderr, "\npg_standby: removed \"%s\"\n", WALFilePath);
+ }
+ }
+ }
+ else
+ fprintf(stderr, "pg_standby: archiveLocation \"%s\" open error\n", archiveLocation);
+
+ closedir(xldir);
+ }
+ fflush(stderr);
+}
+
+/* =====================================================================
+ * End of Customizable section
+ * =====================================================================
+ */
+
+/*
+ * CheckForExternalTrigger()
+ *
+ * Is there a trigger file?
+ */
+static bool
+CheckForExternalTrigger(void)
+{
+ int rc;
+
+ /*
+ * Look for a trigger file, if that option has been selected
+ *
+ * We use stat() here because triggerPath is always a file
+ * rather than potentially being in an archive
+ */
+ if (triggerPath && stat(triggerPath, &stat_buf) == 0)
+ {
+ fprintf(stderr, "trigger file found\n");
+ fflush(stderr);
+
+ /*
+ * If trigger file found, we *must* delete it. Here's why:
+ * When recovery completes, we will be asked again
+ * for the same file from the archive using pg_standby
+ * so must remove trigger file so we can reload file again
+ * and come up correctly.
+ */
+ rc = unlink(triggerPath);
+ if (rc != 0)
+ {
+ fprintf(stderr, "\n ERROR: unable to remove \"%s\", rc=%d", triggerPath, rc);
+ fflush(stderr);
+ exit(rc);
+ }
+ return true;
+ }
+
+ return false;
+}
+
+/*
+ * RestoreWALFileForRecovery()
+ *
+ * Perform the action required to restore the file from archive
+ */
+static bool
+RestoreWALFileForRecovery(void)
+{
+ int rc = 0;
+ int numretries = 0;
+
+ if (debug)
+ {
+ fprintf(stderr, "\nrunning restore :");
+ fflush(stderr);
+ }
+
+ while (numretries < maxretries)
+ {
+ rc = system(restoreCommand);
+ if (rc == 0)
+ {
+ if (debug)
+ {
+ fprintf(stderr, " success\n");
+ fflush(stderr);
+ }
+ return true;
+ }
+ pg_usleep(numretries++ * sleeptime * 1000000L);
+ }
+
+ /*
+ * Allow caller to add additional info
+ */
+ if (debug)
+ fprintf(stderr, "not restored : ");
+ return false;
+}
+
+static void
+usage()
+{
+ fprintf(stderr, "\npg_standby allows Warm Standby servers to be configured\n");
+ fprintf(stderr, "Usage:\n");
+ fprintf(stderr, " pg_standby [OPTION]... [ARCHIVELOCATION] [NEXTWALFILE] [XLOGFILEPATH]\n");
+ fprintf(stderr, " note space between [ARCHIVELOCATION] and [NEXTWALFILE]\n");
+ fprintf(stderr, "with main intended use via restore_command in the recovery.conf\n");
+ fprintf(stderr, " restore_command = 'pg_standby [OPTION]... [ARCHIVELOCATION] %%f %%p'\n");
+ fprintf(stderr, "e.g. restore_command = 'pg_standby -l -u /mnt/server/archiverdir %%f %%p'\n");
+ fprintf(stderr, "\nOptions:\n");
+ fprintf(stderr, " -c copies file from archive (default)\n");
+ fprintf(stderr, " -d generate lots of debugging output (testing only)\n");
+ fprintf(stderr, " -k [NUMFILESTOKEEP] keeps history of # files in archives; unlinks/removes files beyond that\n");
+ fprintf(stderr, " -l links into archive (leaves file in archive)\n");
+ fprintf(stderr, " -t [TRIGGERFILE] defines a trigger file to initiate failover (no default)\n");
+ fprintf(stderr, " -r [MAXRETRIES] maximum number of times to retry, with progressive wait (default=3)\n");
+ fprintf(stderr, " -s [SLEEPTIME] number of seconds to wait between file checks (default=5)\n");
+ fprintf(stderr, " -w [MAXWAITTIME] max number of seconds to wait for a file (0 disables)(default=0)\n");
+ fflush(stderr);
+}
+
+static void
+sighandler(int sig)
+{
+ triggered = true;
+ signaled = true;
+}
+
+/*------------ MAIN ----------------------------------------*/
+int
+main(int argc, char **argv)
+{
+ int c;
+
+ (void) signal(SIGINT, sighandler);
+ (void) signal(SIGQUIT, sighandler);
+
+ while ((c = getopt(argc, argv, "cdk:lr:s:t:w:")) != -1)
+ {
+ switch (c)
+ {
+ case 'c': /* Use copy */
+ restoreCommandType = RESTORE_COMMAND_COPY;
+ break;
+ case 'd': /* Debug mode */
+ debug = true;
+ break;
+ case 'k': /* keepfiles */
+ keepfiles = atoi(optarg);
+ if (keepfiles <= 0)
+ {
+ fprintf(stderr, "usage: pg_standby -k keepfiles must be > 0\n");
+ usage();
+ exit(2);
+ }
+ break;
+ case 'l': /* Use link */
+ restoreCommandType = RESTORE_COMMAND_LINK;
+ break;
+ case 'r': /* Retries */
+ maxretries = atoi(optarg);
+ if (maxretries < 0)
+ {
+ fprintf(stderr, "usage: pg_standby -r maxretries must be > 0\n");
+ usage();
+ exit(2);
+ }
+ break;
+ case 's': /* Sleep time */
+ sleeptime = atoi(optarg);
+ if (sleeptime <= 0 || sleeptime > 60)
+ {
+ fprintf(stderr, "usage: pg_standby -s sleeptime incorrectly set\n");
+ usage();
+ exit(2);
+ }
+ break;
+ case 't': /* Trigger file */
+ triggerPath = optarg;
+ if (CheckForExternalTrigger())
+ exit(1); /* Normal exit, with non-zero */
+ break;
+ case 'w': /* Max wait time */
+ maxwaittime = atoi(optarg);
+ if (maxwaittime < 0)
+ {
+ fprintf(stderr, "usage: pg_standby -w maxwaittime incorrectly set\n");
+ usage();
+ exit(2);
+ }
+ break;
+ default:
+ usage();
+ exit(2);
+ break;
+ }
+ }
+
+ /*
+ * Parameter checking - after checking to see if trigger file present
+ */
+ if (argc == 1)
+ {
+ usage();
+ exit(2);
+ }
+
+ /*
+ * We will go to the archiveLocation to get nextWALFileName.
+ * nextWALFileName may not exist yet, which would not be an error,
+ * so we separate the archiveLocation and nextWALFileName so we can check
+ * separately whether archiveLocation exists, if not that is an error
+ */
+ if (optind < argc)
+ {
+ archiveLocation = argv[optind];
+ optind++;
+ }
+ else
+ {
+ fprintf(stderr, "pg_standby: must specify archiveLocation\n");
+ usage();
+ exit(2);
+ }
+
+ if (optind < argc)
+ {
+ nextWALFileName = argv[optind];
+ optind++;
+ }
+ else
+ {
+ fprintf(stderr, "pg_standby: use %%f to specify nextWALFileName\n");
+ usage();
+ exit(2);
+ }
+
+ if (optind < argc)
+ {
+ xlogFilePath = argv[optind];
+ optind++;
+ }
+ else
+ {
+ fprintf(stderr, "pg_standby: use %%p to specify xlogFilePath\n");
+ usage();
+ exit(2);
+ }
+
+ CustomizableInitialize();
+
+ if (debug)
+ {
+ fprintf(stderr, "\nTrigger file : %s", triggerPath ? triggerPath : "<not set>");
+ fprintf(stderr, "\nWaiting for WAL file : %s", WALFilePath);
+ fprintf(stderr, "\nWAL file path : %s", nextWALFileName);
+ fprintf(stderr, "\nRestoring to... : %s", xlogFilePath);
+ fprintf(stderr, "\nSleep interval : %d second%s",
+ sleeptime, (sleeptime > 1 ? "s" : " "));
+ fprintf(stderr, "\nMax wait interval : %d %s",
+ maxwaittime, (maxwaittime > 0 ? "seconds" : "forever"));
+ fprintf(stderr, "\nCommand for restore : %s", restoreCommand);
+ if (keepfiles > 0)
+ fprintf(stderr, "\nNum archived files kept : last %d files", keepfiles);
+ else
+ fprintf(stderr, "\nNum archived files kept : all files");
+ fflush(stderr);
+ }
+
+ /*
+ * Check for initial history file: always the first file to be requested
+ * It's OK if the file isn't there - all other files need to wait
+ */
+ if (strlen(nextWALFileName) > 8 &&
+ strspn(nextWALFileName, "0123456789ABCDEF") == 8 &&
+ strcmp(nextWALFileName + strlen(nextWALFileName) - strlen(".history"),
+ ".history") == 0)
+ {
+ nextWALFileType = XLOG_HISTORY;
+ if (RestoreWALFileForRecovery())
+ exit(0);
+ else
+ {
+ if (debug)
+ {
+ fprintf(stderr, "history file not found\n");
+ fflush(stderr);
+ }
+ exit(1);
+ }
+ }
+
+ /*
+ * Main wait loop
+ */
+ while (!CustomizableNextWALFileReady() && !triggered)
+ {
+ if (sleeptime <= 60)
+ pg_usleep(sleeptime * 1000000L);
+
+ if (signaled)
+ {
+ if (debug)
+ {
+ fprintf(stderr, "\nsignaled to exit\n");
+ fflush(stderr);
+ }
+ }
+ else
+ {
+
+ if (debug)
+ {
+ fprintf(stderr, "\nWAL file not present yet.");
+ if (triggerPath)
+ fprintf(stderr, " Checking for trigger file...");
+ fflush(stderr);
+ }
+
+ waittime += sleeptime;
+
+ if (!triggered && (CheckForExternalTrigger() || (waittime >= maxwaittime && maxwaittime > 0)))
+ {
+ triggered = true;
+ if (debug && waittime >= maxwaittime && maxwaittime > 0)
+ fprintf(stderr, "\nTimed out after %d seconds\n",waittime);
+ }
+ }
+ }
+
+ /*
+ * Action on exit
+ */
+ if (triggered)
+ exit(1); /* Normal exit, with non-zero */
+ else
+ {
+ /*
+ * Once we have restored this file successfully we
+ * can remove some prior WAL files.
+ * If this restore fails we musn't remove any
+ * file because some of them will be requested again
+ * immediately after the failed restore, or when
+ * we restart recovery.
+ */
+ if (RestoreWALFileForRecovery())
+ CustomizableCleanupPriorWALFiles();
+ exit(0);
+ }
+}