NAME

       pg_amcheck - checks for corruption in one or more PostgreSQL databases

SYNOPSIS

       pg_amcheck [option...] [dbname]

DESCRIPTION

       pg_amcheck supports running amcheck's corruption checking functions against one or more databases, with
       options to select which schemas, tables and indexes to check, which kinds of checking to perform, and
       whether to perform the checks in parallel, and if so, the number of parallel connections to establish and
       use.

       Only table relations and btree indexes are currently supported. Other relation types are silently
       skipped.

       If dbname is specified, it should be the name of a single database to check, and no other database
       selection options should be present. Otherwise, if any database selection options are present, all
       matching databases will be checked. If no such options are present, the default database will be checked.
       Database selection options include --all, --database and --exclude-database. They also include
       --relation, --exclude-relation, --table, --exclude-table, --index, and --exclude-index, but only when
       such options are used with a three-part pattern (e.g.  mydb*.myschema*.myrel*). Finally, they include
       --schema and --exclude-schema when such options are used with a two-part pattern (e.g.  mydb*.myschema*).

       dbname can also be a connection string.

OPTIONS

       The following command-line options control what is checked:

       -a
       --all
           Check all databases, except for any excluded via --exclude-database.

       -d pattern
       --database=pattern
           Check databases matching the specified pattern, except for any excluded by --exclude-database. This
           option can be specified more than once.

       -D pattern
       --exclude-database=pattern
           Exclude databases matching the given pattern. This option can be specified more than once.

       -i pattern
       --index=pattern
           Check indexes matching the specified pattern, unless they are otherwise excluded. This option can be
           specified more than once.

           This is similar to the --relation option, except that it applies only to indexes, not tables.

       -I pattern
       --exclude-index=pattern
           Exclude indexes matching the specified pattern. This option can be specified more than once.

           This is similar to the --exclude-relation option, except that it applies only to indexes, not tables.

       -r pattern
       --relation=pattern
           Check relations matching the specified pattern, unless they are otherwise excluded. This option can
           be specified more than once.

           Patterns may be unqualified, e.g.  myrel*, or they may be schema-qualified, e.g.  myschema*.myrel* or
           database-qualified and schema-qualified, e.g.  mydb*.myschema*.myrel*. A database-qualified pattern
           will add matching databases to the list of databases to be checked.

       -R pattern
       --exclude-relation=pattern
           Exclude relations matching the specified pattern. This option can be specified more than once.

           As with --relation, the pattern may be unqualified, schema-qualified, or database- and
           schema-qualified.

       -s pattern
       --schema=pattern
           Check tables and indexes in schemas matching the specified pattern, unless they are otherwise
           excluded. This option can be specified more than once.

           To select only tables in schemas matching a particular pattern, consider using something like
           --table=SCHEMAPAT.* --no-dependent-indexes. To select only indexes, consider using something like
           --index=SCHEMAPAT.*.

           A schema pattern may be database-qualified. For example, you may write --schema=mydb*.myschema* to
           select schemas matching myschema* in databases matching mydb*.

       -S pattern
       --exclude-schema=pattern
           Exclude tables and indexes in schemas matching the specified pattern. This option can be specified
           more than once.

           As with --schema, the pattern may be database-qualified.

       -t pattern
       --table=pattern
           Check tables matching the specified pattern, unless they are otherwise excluded. This option can be
           specified more than once.

           This is similar to the --relation option, except that it applies only to tables, not indexes.

       -T pattern
       --exclude-table=pattern
           Exclude tables matching the specified pattern. This option can be specified more than once.

           This is similar to the --exclude-relation option, except that it applies only to tables, not indexes.

       --no-dependent-indexes
           By default, if a table is checked, any btree indexes of that table will also be checked, even if they
           are not explicitly selected by an option such as --index or --relation. This option suppresses that
           behavior.

       --no-dependent-toast
           By default, if a table is checked, its toast table, if any, will also be checked, even if it is not
           explicitly selected by an option such as --table or --relation. This option suppresses that behavior.

       --no-strict-names
           By default, if an argument to --database, --table, --index, or --relation matches no objects, it is a
           fatal error. This option downgrades that error to a warning.

       The following command-line options control checking of tables:

       --exclude-toast-pointers
           By default, whenever a toast pointer is encountered in a table, a lookup is performed to ensure that
           it references apparently-valid entries in the toast table. These checks can be quite slow, and this
           option can be used to skip them.

       --on-error-stop
           After reporting all corruptions on the first page of a table where corruption is found, stop
           processing that table relation and move on to the next table or index.

           Note that index checking always stops after the first corrupt page. This option only has meaning
           relative to table relations.

       --skip=option
           If all-frozen is given, table corruption checks will skip over pages in all tables that are marked as
           all frozen.

           If all-visible is given, table corruption checks will skip over pages in all tables that are marked
           as all visible.

           By default, no pages are skipped. This can be specified as none, but since this is the default, it
           need not be mentioned.

       --startblock=block
           Start checking at the specified block number. An error will occur if the table relation being checked
           has fewer than this number of blocks. This option does not apply to indexes, and is probably only
           useful when checking a single table relation. See --endblock for further caveats.

       --endblock=block
           End checking at the specified block number. An error will occur if the table relation being checked
           has fewer than this number of blocks. This option does not apply to indexes, and is probably only
           useful when checking a single table relation. If both a regular table and a toast table are checked,
           this option will apply to both, but higher-numbered toast blocks may still be accessed while
           validating toast pointers, unless that is suppressed using --exclude-toast-pointers.

       The following command-line options control checking of B-tree indexes:

       --heapallindexed
           For each index checked, verify the presence of all heap tuples as index tuples in the index using
           amcheck's heapallindexed option.

       --parent-check
           For each btree index checked, use amcheck's bt_index_parent_check function, which performs additional
           checks of parent/child relationships during index checking.

           The default is to use amcheck's bt_index_check function, but note that use of the --rootdescend
           option implicitly selects bt_index_parent_check.

       --rootdescend
           For each index checked, re-find tuples on the leaf level by performing a new search from the root
           page for each tuple using amcheck's rootdescend option.

           Use of this option implicitly also selects the --parent-check option.

           This form of verification was originally written to help in the development of btree index features.
           It may be of limited use or even of no use in helping detect the kinds of corruption that occur in
           practice. It may also cause corruption checking to take considerably longer and consume considerably
           more resources on the server.

           Warning

           The extra checks performed against B-tree indexes when the --parent-check option or the --rootdescend
           option is specified require relatively strong relation-level locks. These checks are the only checks
           that will block concurrent data modification from INSERT, UPDATE, and DELETE commands.

       The following command-line options control the connection to the server:

       -h hostname
       --host=hostname
           Specifies the host name of the machine on which the server is running. If the value begins with a
           slash, it is used as the directory for the Unix domain socket.

       -p port
       --port=port
           Specifies the TCP port or local Unix domain socket file extension on which the server is listening
           for connections.

       -U
       --username=username
           User name to connect as.

       -w
       --no-password
           Never issue a password prompt. If the server requires password authentication and a password is not
           available by other means such as a .pgpass file, the connection attempt will fail. This option can be
           useful in batch jobs and scripts where no user is present to enter a password.

       -W
       --password
           Force pg_amcheck to prompt for a password before connecting to a database.

           This option is never essential, since pg_amcheck will automatically prompt for a password if the
           server demands password authentication. However, pg_amcheck will waste a connection attempt finding
           out that the server wants a password. In some cases it is worth typing -W to avoid the extra
           connection attempt.

       --maintenance-db=dbname
           Specifies a database or connection string to be used to discover the list of databases to be checked.
           If neither --all nor any option including a database pattern is used, no such connection is required
           and this option does nothing. Otherwise, any connection string parameters other than the database
           name which are included in the value for this option will also be used when connecting to the
           databases being checked. If this option is omitted, the default is postgres or, if that fails,
           template1.

       Other options are also available:

       -e
       --echo
           Echo to stdout all SQL sent to the server.

       -j num
       --jobs=num
           Use num concurrent connections to the server, or one per object to be checked, whichever is less.

           The default is to use a single connection.

       -P
       --progress
           Show progress information. Progress information includes the number of relations for which checking
           has been completed, and the total size of those relations. It also includes the total number of
           relations that will eventually be checked, and the estimated size of those relations.

       -v
       --verbose
           Print more messages. In particular, this will print a message for each relation being checked, and
           will increase the level of detail shown for server errors.

       -V
       --version
           Print the pg_amcheck version and exit.

       --install-missing
       --install-missing=schema
           Install any missing extensions that are required to check the database(s). If not yet installed, each
           extension's objects will be installed into the given schema, or if not specified into schema
           pg_catalog.

           At present, the only required extension is amcheck.

       -?
       --help
           Show help about pg_amcheck command line arguments, and exit.

NOTES

       pg_amcheck is designed to work with PostgreSQL 14.0 and later.

SEE ALSO

       amcheck

PostgreSQL 14.18                                      2025                                         PG_AMCHECK(1)