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Sync pg_dump and pg_dumpall output
Before exiting any files are fsync'ed. A --no-sync option is also provided for a faster exit if desired. Michael Paquier. Reviewed by Albe Laurenz Discussion: https://postgr.es/m/CAB7nPqS1uZ=Ov+UruW6jr3vB-S_DLVMPc0dQpV-fTDjmm0ZQMg@mail.gmail.com
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12 files changed

+103
-8
lines changed

12 files changed

+103
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‎doc/src/sgml/ref/pg_dump.sgml

Lines changed: 14 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -859,6 +859,20 @@ PostgreSQL documentation
859859
</listitem>
860860
</varlistentry>
861861

862+
<varlistentry>
863+
<term><option>--no-sync</option></term>
864+
<listitem>
865+
<para>
866+
By default, <command>pg_dump</command> will wait for all files
867+
to be written safely to disk. This option causes
868+
<command>pg_dump</command> to return without waiting, which is
869+
faster, but means that a subsequent operating system crash can leave
870+
the dump corrupt. Generally, this option is useful for testing
871+
but should not be used when dumping data from production installation.
872+
</para>
873+
</listitem>
874+
</varlistentry>
875+
862876
<varlistentry>
863877
<term><option>--quote-all-identifiers</></term>
864878
<listitem>

‎doc/src/sgml/ref/pg_dumpall.sgml

Lines changed: 14 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -354,6 +354,20 @@ PostgreSQL documentation
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</listitem>
355355
</varlistentry>
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357+
<varlistentry>
358+
<term><option>--no-sync</option></term>
359+
<listitem>
360+
<para>
361+
By default, <command>pg_dumpall</command> will wait for all files
362+
to be written safely to disk. This option causes
363+
<command>pg_dumpall</command> to return without waiting, which is
364+
faster, but means that a subsequent operating system crash can leave
365+
the dump corrupt. Generally, this option is useful for testing
366+
but should not be used when dumping data from production installation.
367+
</para>
368+
</listitem>
369+
</varlistentry>
370+
357371
<varlistentry>
358372
<term><option>--no-tablespaces</option></term>
359373
<listitem>

‎src/bin/pg_dump/pg_backup.h

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -276,7 +276,7 @@ extern Archive *OpenArchive(const char *FileSpec, const ArchiveFormat fmt);
276276

277277
/* Create a new archive */
278278
extern Archive *CreateArchive(const char *FileSpec, const ArchiveFormat fmt,
279-
const int compression, ArchiveMode mode,
279+
const int compression, bool dosync, ArchiveMode mode,
280280
SetupWorkerPtr setupDumpWorker);
281281

282282
/* The --list option */

‎src/bin/pg_dump/pg_backup_archiver.c

Lines changed: 10 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -54,7 +54,8 @@ static const char *modulename = gettext_noop("archiver");
5454

5555

5656
static ArchiveHandle *_allocAH(const char *FileSpec, const ArchiveFormat fmt,
57-
const int compression, ArchiveMode mode, SetupWorkerPtr setupWorkerPtr);
57+
const int compression, bool dosync, ArchiveMode mode,
58+
SetupWorkerPtr setupWorkerPtr);
5859
static void _getObjectDescription(PQExpBuffer buf, TocEntry *te,
5960
ArchiveHandle *AH);
6061
static void _printTocEntry(ArchiveHandle *AH, TocEntry *te, bool isData, bool acl_pass);
@@ -202,10 +203,12 @@ setupRestoreWorker(Archive *AHX)
202203
/* Public */
203204
Archive *
204205
CreateArchive(const char *FileSpec, const ArchiveFormat fmt,
205-
const int compression, ArchiveMode mode, SetupWorkerPtr setupDumpWorker)
206+
const int compression, bool dosync, ArchiveMode mode,
207+
SetupWorkerPtr setupDumpWorker)
206208

207209
{
208-
ArchiveHandle *AH = _allocAH(FileSpec, fmt, compression, mode, setupDumpWorker);
210+
ArchiveHandle *AH = _allocAH(FileSpec, fmt, compression, dosync,
211+
mode, setupDumpWorker);
209212

210213
return (Archive *) AH;
211214
}
@@ -215,7 +218,7 @@ CreateArchive(const char *FileSpec, const ArchiveFormat fmt,
215218
Archive *
216219
OpenArchive(const char *FileSpec, const ArchiveFormat fmt)
217220
{
218-
ArchiveHandle *AH = _allocAH(FileSpec, fmt, 0, archModeRead, setupRestoreWorker);
221+
ArchiveHandle *AH = _allocAH(FileSpec, fmt, 0, true, archModeRead, setupRestoreWorker);
219222

220223
return (Archive *) AH;
221224
}
@@ -2269,7 +2272,8 @@ _discoverArchiveFormat(ArchiveHandle *AH)
22692272
*/
22702273
static ArchiveHandle *
22712274
_allocAH(const char *FileSpec, const ArchiveFormat fmt,
2272-
const int compression, ArchiveMode mode, SetupWorkerPtr setupWorkerPtr)
2275+
const int compression, bool dosync, ArchiveMode mode,
2276+
SetupWorkerPtr setupWorkerPtr)
22732277
{
22742278
ArchiveHandle *AH;
22752279

@@ -2323,6 +2327,7 @@ _allocAH(const char *FileSpec, const ArchiveFormat fmt,
23232327

23242328
AH->mode = mode;
23252329
AH->compression = compression;
2330+
AH->dosync = dosync;
23262331

23272332
memset(&(AH->sqlparse), 0, sizeof(AH->sqlparse));
23282333

‎src/bin/pg_dump/pg_backup_archiver.h

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Original file line numberDiff line numberDiff line change
@@ -312,6 +312,7 @@ struct _archiveHandle
312312
* values for compression: -1
313313
* Z_DEFAULT_COMPRESSION 0 COMPRESSION_NONE
314314
* 1-9 levels for gzip compression */
315+
bool dosync; /* data requested to be synced on sight */
315316
ArchiveMode mode; /* File mode - r or w */
316317
void *formatData; /* Header data specific to file format */
317318

‎src/bin/pg_dump/pg_backup_custom.c

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Original file line numberDiff line numberDiff line change
@@ -28,6 +28,7 @@
2828
#include "compress_io.h"
2929
#include "parallel.h"
3030
#include "pg_backup_utils.h"
31+
#include "common/file_utils.h"
3132

3233
/*--------
3334
* Routines in the format interface
@@ -721,6 +722,10 @@ _CloseArchive(ArchiveHandle *AH)
721722
if (fclose(AH->FH) != 0)
722723
exit_horribly(modulename, "could not close archive file: %s\n", strerror(errno));
723724

725+
/* Sync the output file if one is defined */
726+
if (AH->dosync && AH->mode == archModeWrite && AH->fSpec)
727+
(void) fsync_fname(AH->fSpec, false, progname);
728+
724729
AH->FH = NULL;
725730
}
726731

‎src/bin/pg_dump/pg_backup_directory.c

Lines changed: 8 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -37,6 +37,7 @@
3737
#include "compress_io.h"
3838
#include "parallel.h"
3939
#include "pg_backup_utils.h"
40+
#include "common/file_utils.h"
4041

4142
#include <dirent.h>
4243
#include <sys/stat.h>
@@ -593,6 +594,13 @@ _CloseArchive(ArchiveHandle *AH)
593594
WriteDataChunks(AH, ctx->pstate);
594595

595596
ParallelBackupEnd(AH, ctx->pstate);
597+
598+
/*
599+
* In directory mode, there is no need to sync all the entries
600+
* individually. Just recurse once through all the files generated.
601+
*/
602+
if (AH->dosync)
603+
fsync_dir_recurse(ctx->directory, progname);
596604
}
597605
AH->FH = NULL;
598606
}

‎src/bin/pg_dump/pg_backup_tar.c

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@@ -33,6 +33,7 @@
3333
#include "pg_backup_tar.h"
3434
#include "pg_backup_utils.h"
3535
#include "pgtar.h"
36+
#include "common/file_utils.h"
3637
#include "fe_utils/string_utils.h"
3738

3839
#include <sys/stat.h>
@@ -901,6 +902,10 @@ _CloseArchive(ArchiveHandle *AH)
901902
if (fputc(0, ctx->tarFH) == EOF)
902903
WRITE_ERROR_EXIT;
903904
}
905+
906+
/* Sync the output file if one is defined */
907+
if (AH->dosync && AH->fSpec)
908+
(void) fsync_fname(AH->fSpec, false, progname);
904909
}
905910

906911
AH->FH = NULL;

‎src/bin/pg_dump/pg_dump.c

Lines changed: 10 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -89,6 +89,8 @@ typedef enum OidOptions
8989
/* global decls */
9090
bool g_verbose; /* User wants verbose narration of our
9191
* activities. */
92+
static bool dosync = true; /* Issue fsync() to make dump durable
93+
* on disk. */
9294

9395
/* subquery used to convert user ID (eg, datdba) to user name */
9496
static const char *username_subquery;
@@ -353,6 +355,7 @@ main(int argc, char **argv)
353355
{"no-security-labels", no_argument, &dopt.no_security_labels, 1},
354356
{"no-synchronized-snapshots", no_argument, &dopt.no_synchronized_snapshots, 1},
355357
{"no-unlogged-table-data", no_argument, &dopt.no_unlogged_table_data, 1},
358+
{"no-sync", no_argument, NULL, 7},
356359

357360
{NULL, 0, NULL, 0}
358361
};
@@ -533,6 +536,10 @@ main(int argc, char **argv)
533536
dumpsnapshot = pg_strdup(optarg);
534537
break;
535538

539+
case 7: /* no-sync */
540+
dosync = false;
541+
break;
542+
536543
default:
537544
fprintf(stderr, _("Try \"%s --help\" for more information.\n"), progname);
538545
exit_nicely(1);
@@ -632,8 +639,8 @@ main(int argc, char **argv)
632639
exit_horribly(NULL, "parallel backup only supported by the directory format\n");
633640

634641
/* Open the output file */
635-
fout = CreateArchive(filename, archiveFormat, compressLevel, archiveMode,
636-
setupDumpWorker);
642+
fout = CreateArchive(filename, archiveFormat, compressLevel, dosync,
643+
archiveMode, setupDumpWorker);
637644

638645
/* Make dump options accessible right away */
639646
SetArchiveOptions(fout, &dopt, NULL);
@@ -914,6 +921,7 @@ help(const char *progname)
914921
printf(_(" -V, --version output version information, then exit\n"));
915922
printf(_(" -Z, --compress=0-9 compression level for compressed formats\n"));
916923
printf(_(" --lock-wait-timeout=TIMEOUT fail after waiting TIMEOUT for a table lock\n"));
924+
printf(_(" --no-sync do not wait for changes to be written safely to disk\n"));
917925
printf(_(" -?, --help show this help, then exit\n"));
918926

919927
printf(_("\nOptions controlling the output content:\n"));

‎src/bin/pg_dump/pg_dumpall.c

Lines changed: 15 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -22,6 +22,7 @@
2222

2323
#include "dumputils.h"
2424
#include "pg_backup.h"
25+
#include "common/file_utils.h"
2526
#include "fe_utils/string_utils.h"
2627

2728
/* version string we expect back from pg_dump */
@@ -63,6 +64,7 @@ static PQExpBuffer pgdumpopts;
6364
static char *connstr = "";
6465
static bool skip_acls = false;
6566
static bool verbose = false;
67+
static bool dosync = true;
6668

6769
static int binary_upgrade = 0;
6870
static int column_inserts = 0;
@@ -127,6 +129,7 @@ main(int argc, char *argv[])
127129
{"role", required_argument, NULL, 3},
128130
{"use-set-session-authorization", no_argument, &use_setsessauth, 1},
129131
{"no-security-labels", no_argument, &no_security_labels, 1},
132+
{"no-sync", no_argument, NULL, 4},
130133
{"no-unlogged-table-data", no_argument, &no_unlogged_table_data, 1},
131134
{"no-role-passwords", no_argument, &no_role_passwords, 1},
132135

@@ -297,6 +300,11 @@ main(int argc, char *argv[])
297300
appendShellString(pgdumpopts, use_role);
298301
break;
299302

303+
case 4:
304+
dosync = false;
305+
appendPQExpBufferStr(pgdumpopts, " --no-sync");
306+
break;
307+
300308
default:
301309
fprintf(stderr, _("Try \"%s --help\" for more information.\n"), progname);
302310
exit_nicely(1);
@@ -549,8 +557,14 @@ main(int argc, char *argv[])
549557
fprintf(OPF, "--\n-- PostgreSQL database cluster dump complete\n--\n\n");
550558

551559
if (filename)
560+
{
552561
fclose(OPF);
553562

563+
/* sync the resulting file, errors are not fatal */
564+
if (dosync)
565+
(void) fsync_fname(filename, false, progname);
566+
}
567+
554568
exit_nicely(0);
555569
}
556570

@@ -586,6 +600,7 @@ help(void)
586600
printf(_(" --if-exists use IF EXISTS when dropping objects\n"));
587601
printf(_(" --inserts dump data as INSERT commands, rather than COPY\n"));
588602
printf(_(" --no-security-labels do not dump security label assignments\n"));
603+
printf(_(" --no-sync do not wait for changes to be written safely to disk\n"));
589604
printf(_(" --no-tablespaces do not dump tablespace assignments\n"));
590605
printf(_(" --no-unlogged-table-data do not dump unlogged table data\n"));
591606
printf(_(" --no-role-passwords do not dump passwords for roles\n"));

‎src/common/file_utils.c

Lines changed: 19 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -115,6 +115,25 @@ fsync_pgdata(const char *pg_data,
115115
walkdir(pg_tblspc, fsync_fname, true, progname);
116116
}
117117

118+
/*
119+
* Issue fsync recursively on the given directory and all its contents.
120+
*
121+
* This is a convenient wrapper on top of walkdir().
122+
*/
123+
void
124+
fsync_dir_recurse(const char *dir, const char *progname)
125+
{
126+
/*
127+
* If possible, hint to the kernel that we're soon going to fsync the data
128+
* directory and its contents.
129+
*/
130+
#ifdef PG_FLUSH_DATA_WORKS
131+
walkdir(dir, pre_sync_fname, false, progname);
132+
#endif
133+
134+
walkdir(dir, fsync_fname, false, progname);
135+
}
136+
118137
/*
119138
* walkdir: recursively walk a directory, applying the action to each
120139
* regular file and directory (including the named directory itself).

‎src/include/common/file_utils.h

Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -19,6 +19,7 @@ extern int fsync_fname(const char *fname, bool isdir,
1919
const char *progname);
2020
extern void fsync_pgdata(const char *pg_data, const char *progname,
2121
int serverVersion);
22+
extern void fsync_dir_recurse(const char *dir, const char *progname);
2223
extern int durable_rename(const char *oldfile, const char *newfile,
2324
const char *progname);
2425
extern int fsync_parent_path(const char *fname, const char *progname);

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