<refnamediv>

<refname>pg_checksums</refname>

<refpurpose>verify data checksums in a <productname>PostgreSQL</productname> database cluster</refpurpose>

<refpurpose>enable, disable or check data checksums in a <productname>PostgreSQL</productname> database cluster</refpurpose>

</refnamediv>

<refsynopsisdiv>

<refsect1 id="r1-app-pg_checksums-1">

<title>Description</title>

<para>

<application>pg_checksums</application> verifies data checksums in a

<productname>PostgreSQL</productname> cluster. The server must be shut

down cleanly before running <application>pg_checksums</application>.

The exit status is zero if there are no checksum errors, otherwise nonzero.

<application>pg_checksums</application> checks, enables or disables data

checksums in a <productname>PostgreSQL</productname> cluster. The server

must be shut down cleanly before running

<application>pg_checksums</application>. The exit status is zero if there

are no checksum errors when checking them, and nonzero if at least one

checksum failure is detected. If enabling or disabling checksums, the

exit status is nonzero if the operation failed.

</para>

<para>

While checking or enabling checksums needs to scan or write every file in

the cluster, disabling checksums will only update the file

<filename>pg_control</filename>.

</para>

</refsect1>

</listitem>

</varlistentry>

<varlistentry>

<term><option>-c</option></term>

<term><option>--check</option></term>

<listitem>

<para>

Checks checksums. This is the default mode if nothing else is

specified.

</para>

</listitem>

</varlistentry>

<varlistentry>

<term><option>-d</option></term>

<term><option>--disable</option></term>

<listitem>

<para>

Disables checksums.

</para>

</listitem>

</varlistentry>

<varlistentry>

<term><option>-e</option></term>

<term><option>--enable</option></term>

<listitem>

<para>

Enables checksums.

</para>

</listitem>

</varlistentry>

<varlistentry>

<term><option>-v</option></term>

<term><option>--verbose</option></term>

</varlistentry>

</variablelist>

</refsect1>

<refsect1>

<title>Notes</title>

<para>

When disabling or enabling checksums in a replication setup of multiple

clusters, it is recommended to stop all the clusters before doing

the switch to all the clusters consistently. When using a replication

setup with tools which perform direct copies of relation file blocks

(for example <xref linkend="app-pgrewind"/>), enabling or disabling

checksums can lead to page corruptions in the shape of incorrect

checksums if the operation is not done consistently across all nodes.

Destroying all the standbys in the setup first, enabling or disabling

checksums on the primary and finally recreating the standbys from

scratch is also safe.

</para>

<para>

If <application>pg_checksums</application> is aborted or killed in

its operation while enabling or disabling checksums, the cluster

will have the same state with respect of checksums as before the

operation and <application>pg_checksums</application> needs to be

restarted.

</para>

<para>

When enabling checksums in a cluster, the operation can potentially

take a long time if the data directory is large. During this operation,

the cluster or other programs that write to the data directory must not

be started or else data loss may occur.

</para>

</refsect1>

</refentry>

staticint64files=0;

staticchar*only_relfilenode=NULL;

staticboolverbose= false;

{

PG_MODE_CHECK,

PG_MODE_DISABLE,

}PgChecksumMode;

#definePG_TEMP_FILES_DIR "pgsql_tmp"

#definePG_TEMP_FILE_PREFIX "pgsql_tmp"

staticPgChecksumModemode=PG_MODE_CHECK;

staticconstchar*progname;

usage(void)

{

printf(_("%s verifies data checksums in a PostgreSQL database cluster.\n\n"),progname);

printf(_("%senables, disables orverifies data checksums in a PostgreSQL database cluster.\n\n"),progname);

printf(_("Usage:\n"));

printf(_(" %s [OPTION]... [DATADIR]\n"),progname);

printf(_("\nOptions:\n"));

printf(_(" [-D, --pgdata=]DATADIR data directory\n"));

printf(_(" -c, --check check data checksums (default)\n"));

printf(_(" -d, --disable disable data checksums\n"));

printf(_(" -e, --enable enable data checksums\n"));

printf(_(" -v, --verbose output verbose messages\n"));

printf(_(" -r RELFILENODE check only relation with specified relfilenode\n"));

printf(_(" -V, --version output version information, then exit\n"));

PageHeaderheader= (PageHeader)buf.data;

intf;

BlockNumberblockno;

intflags;

Assert(mode==PG_MODE_ENABLE||

mode==PG_MODE_CHECK);

flags= (mode==PG_MODE_ENABLE) ?O_RDWR :O_RDONLY;

f=open(fn,PG_BINARY |flags,0);

f=open(fn,O_RDONLY |PG_BINARY,0);

if (f<0)

{

fprintf(stderr,_("%s: could not open file \"%s\": %s\n"),

continue;

csum=pg_checksum_page(buf.data,blockno+segmentno*RELSEG_SIZE);

if (csum!=header->pd_checksum)

if (mode==PG_MODE_CHECK)

{

if (ControlFile->data_checksum_version==PG_DATA_CHECKSUM_VERSION)

fprintf(stderr,_("%s: checksum verification failed in file \"%s\", block %u: calculated checksum %X but block contains %X\n"),

progname,fn,blockno,csum,header->pd_checksum);

badblocks++;

if (csum!=header->pd_checksum)

{

if (ControlFile->data_checksum_version==PG_DATA_CHECKSUM_VERSION)

fprintf(stderr,_("%s: checksum verification failed in file \"%s\", block %u: calculated checksum %X but block contains %X\n"),

progname,fn,blockno,csum,header->pd_checksum);

badblocks++;

}

}

elseif (mode==PG_MODE_ENABLE)

{

header->pd_checksum=csum;

if (lseek(f,-BLCKSZ,SEEK_CUR)<0)

{

fprintf(stderr,_("%s: seek failed for block %d in file \"%s\": %s\n"),progname,blockno,fn,strerror(errno));

exit(1);

}

if (write(f,buf.data,BLCKSZ)!=BLCKSZ)

{

fprintf(stderr,_("%s: could not update checksum of block %d in file \"%s\": %s\n"),

progname,blockno,fn,strerror(errno));

exit(1);

}

}

}

if (verbose)

fprintf(stderr,

_("%s: checksums verified in file \"%s\"\n"),progname,fn);

{

if (mode==PG_MODE_CHECK)

fprintf(stderr,

_("%s: checksums verified in file \"%s\"\n"),progname,fn);

if (mode==PG_MODE_ENABLE)

fprintf(stderr,

_("%s: checksums enabled in file \"%s\"\n"),progname,fn);

}

close(f);

}

main(intargc,char*argv[])

{

staticstructoptionlong_options[]= {

{"check",no_argument,NULL,'c'},

{"pgdata",required_argument,NULL,'D'},

{"disable",no_argument,NULL,'d'},

{"enable",no_argument,NULL,'e'},

{"verbose",no_argument,NULL,'v'},

{NULL,0,NULL,0}

};

}

}

while ((c=getopt_long(argc,argv,"D:r:v",long_options,&option_index))!=-1)

while ((c=getopt_long(argc,argv,"cD:der:v",long_options,&option_index))!=-1)

{

switch (c)

{

case'c':

mode=PG_MODE_CHECK;

break;

case'd':

mode=PG_MODE_DISABLE;

break;

case'e':

mode=PG_MODE_ENABLE;

break;

case'v':

verbose= true;

break;

exit(1);

}

if (mode!=PG_MODE_CHECK&&only_relfilenode)

{

fprintf(stderr,_("%s: relfilenode option only possible with --check\n"),progname);

fprintf(stderr,_("Try \"%s --help\" for more information.\n"),

progname);

exit(1);

}

ControlFile=get_controlfile(DataDir,progname,&crc_ok);

if (!crc_ok)

if (ControlFile->state!=DB_SHUTDOWNED&&

ControlFile->state!=DB_SHUTDOWNED_IN_RECOVERY)

{

fprintf(stderr,_("%s: cluster must be shut down to verify checksums\n"),progname);

fprintf(stderr,_("%s: cluster must be shut down\n"),progname);

exit(1);

}

if (ControlFile->data_checksum_version==0)

if (ControlFile->data_checksum_version==0&&

mode==PG_MODE_CHECK)

{

fprintf(stderr,_("%s: data checksums are not enabled in cluster\n"),progname);

exit(1);

}

if (ControlFile->data_checksum_version==0&&

mode==PG_MODE_DISABLE)

{

fprintf(stderr,_("%s: data checksums are already disabled in cluster.\n"),progname);

exit(1);

}

if (ControlFile->data_checksum_version>0&&

mode==PG_MODE_ENABLE)

{

fprintf(stderr,_("%s: data checksums are already enabled in cluster.\n"),progname);

exit(1);

}

if (mode==PG_MODE_CHECK||mode==PG_MODE_ENABLE)

{

scan_directory(DataDir,"global");

scan_directory(DataDir,"base");

scan_directory(DataDir,"pg_tblspc");

printf(_("Checksum operation completed\n"));

printf(_("Files scanned: %s\n"),psprintf(INT64_FORMAT,files));

printf(_("Blocks scanned: %s\n"),psprintf(INT64_FORMAT,blocks));

if (mode==PG_MODE_CHECK)

{

printf(_("Bad checksums: %s\n"),psprintf(INT64_FORMAT,badblocks));

printf(_("Data checksum version: %d\n"),ControlFile->data_checksum_version);

if (badblocks>0)

exit(1);

}

}

if (mode==PG_MODE_ENABLE||mode==PG_MODE_DISABLE)

{

(mode==PG_MODE_ENABLE) ?PG_DATA_CHECKSUM_VERSION :0;

scan_directory(DataDir,"global");

scan_directory(DataDir,"base");

scan_directory(DataDir,"pg_tblspc");

printf(_("Syncing data directory\n"));

fsync_pgdata(DataDir,progname,PG_VERSION_NUM);

printf(_("Checksum scan completed\n"));

printf(_("Data checksum version: %d\n"),ControlFile->data_checksum_version);

printf(_("Files scanned: %s\n"),psprintf(INT64_FORMAT,files));

printf(_("Blocks scanned: %s\n"),psprintf(INT64_FORMAT,blocks));

printf(_("Bad checksums: %s\n"),psprintf(INT64_FORMAT,badblocks));

printf(_("Updating control file\n"));

update_controlfile(DataDir,progname,ControlFile, true);

if (badblocks>0)

return1;

if (verbose)

printf(_("Data checksum version: %d\n"),ControlFile->data_checksum_version);

if (mode==PG_MODE_ENABLE)

printf(_("Checksums enabled in cluster\n"));

printf(_("Checksums disabled in cluster\n"));

}

return0;

}