- pg_repack -- Reorganize tables in PostgreSQL databases with minimal locks
- See Also
pg_repack -- Reorganize tables in PostgreSQL databases with minimal locks
pg_repack is a PostgreSQL extension which lets you remove bloat from tables and indexes, and optionally restore the physical order of clustered indexes. Unlike CLUSTER and VACUUM FULL it works online, without holding an exclusive lock on the processed tables during processing. pg_repack is efficient to boot, with performance comparable to using CLUSTER directly.
You can choose one of the following methods to reorganize:
- Online CLUSTER (ordered by cluster index)
- Ordered by specified columns
- Online VACUUM FULL (packing rows only)
- Rebuild or relocate only the indexes of a table
- Only superusers can use the utility.
- Target table must have a PRIMARY KEY, or at least a UNIQUE total index on a NOT NULL column.
- PostgreSQL versions
- PostgreSQL 8.3, 8.4, 9.0, 9.1, 9.2, 9.3, 9.4
- Performing a full-table repack requires free disk space about twice as large as the target table(s) and its indexes. For example, if the total size of the tables and indexes to be reorganized is 1GB, an additional 2GB of disk space is required.
Alternatively you can use the PGXN Client to download, compile and install the package; use:
$ pgxn install pg_repack
Check the pgxn install documentation for the options available.
pg_repack can be built with make on UNIX or Linux. The PGXS build framework is used automatically. Before building, you might need to install the PostgreSQL development packages (postgresql-devel, etc.) and add the directory containing pg_config to your $PATH. Then you can run:
$ cd pg_repack $ make $ sudo make install
You can also use Microsoft Visual C++ 2010 to build the program on Windows. There are project files in the msvc folder.
After installation, load the pg_repack extension in the database you want to process. On PostgreSQL 9.1 and following pg_repack is packaged as an extension, so you can execute:
$ psql -c "CREATE EXTENSION pg_repack" -d your_database
For previous PostgreSQL versions you should load the script $SHAREDIR/contrib/pg_repack.sql in the database to process; you can get $SHAREDIR using pg_config --sharedir, e.g.
$ psql -f "$(pg_config --sharedir)/contrib/pg_repack.sql" -d your_database
You can remove pg_repack from a PostgreSQL 9.1 and following database using DROP EXTENSION pg_repack. For previous Postgresql versions load the $SHAREDIR/contrib/uninstall_pg_repack.sql script or just drop the repack schema.
If you are upgrading from a previous version of pg_repack or pg_reorg, just drop the old version from the database as explained above and install the new version.
pg_repack [OPTION]... [DBNAME]
The following options can be specified in OPTIONS.
-a, --all repack all databases -t, --table=TABLE repack specific table only -c, --schema=SCHEMA repack tables in specific schema only -s, --tablespace=TBLSPC move repacked tables to a new tablespace -S, --moveidx move repacked indexes to TBLSPC too -o, --order-by=COLUMNS order by columns instead of cluster keys -n, --no-order do vacuum full instead of cluster -N, --dry-run print what would have been repacked and exit -j, --jobs=NUM Use this many parallel jobs for each table -i, --index=INDEX move only the specified index -x, --only-indexes move only indexes of the specified table -T, --wait-timeout=SECS timeout to cancel other backends on conflict -Z, --no-analyze don't analyze at end
- Connection options:
-d, --dbname=DBNAME database to connect -h, --host=HOSTNAME database server host or socket directory -p, --port=PORT database server port -U, --username=USERNAME user name to connect as -w, --no-password never prompt for password -W, --password force password prompt
- Generic options:
-e, --echo echo queries -E, --elevel=LEVEL set output message level --help show this help, then exit --version output version information, then exit
- -a, --all
- Attempt to repack all the databases of the cluster. Databases where the pg_repack extension is not installed will be skipped.
- -t TABLE, --table=TABLE
- Reorganize the specified table(s) only. Multiple tables may be reorganized by writing multiple -t switches. By default, all eligible tables in the target databases are reorganized.
- -c, --schema
- Repack the tables in the specified schema(s) only. Multiple schemas may be repacked by writing multiple -c switches. May be used in conjunction with --tablespace to move tables to a different tablespace.
- -o COLUMNS [,...], --order-by=COLUMNS [,...]
- Perform an online CLUSTER ordered by the specified columns.
- -n, --no-order
- Perform an online VACUUM FULL. Since version 1.2 this is the default for non-clustered tables.
- -N, --dry-run
- List what would be repacked and exit.
- -j, --jobs
- Create the specified number of extra connections to PostgreSQL, and use these extra connections to parallelize the rebuild of indexes on each table. Parallel index builds are only supported for full-table repacks, not with --index or --only-indexes options. If your PostgreSQL server has extra cores and disk I/O available, this can be a useful way to speed up pg_repack.
- -s TBLSPC, --tablespace=TBLSPC
- Move the repacked tables to the specified tablespace: essentially an online version of ALTER TABLE ... SET TABLESPACE. The tables' indexes are left in the original tablespace unless --moveidx is specified too.
- -S, --moveidx
- Also move the indexes of the repacked tables to the tablespace specified by the --tablespace option.
- -i, --index
- Repack the specified index(es) only. Multiple indexes may be repacked by writing multiple -i switches. May be used in conjunction with --tablespace to move the index to a different tablespace.
- -x, --only-indexes
- Repack only the indexes of the specified table(s), which must be specified with the --table option.
- -T SECS, --wait-timeout=SECS
- pg_repack needs to take an exclusive lock at the end of the reorganization. This setting controls how many seconds pg_repack will wait to acquire this lock. If the lock cannot be taken after this duration, pg_repack will forcibly cancel the conflicting queries. If you are using PostgreSQL version 8.4 or newer, pg_repack will fall back to using pg_terminate_backend() to disconnect any remaining backends after twice this timeout has passed. The default is 60 seconds.
- -Z, --no-analyze
- Disable ANALYZE after a full-table reorganization. If not specified, run ANALYZE after the reorganization.
Options to connect to servers. You cannot use --all and --dbname or --table together.
- -a, --all
- Reorganize all databases.
- -d DBNAME, --dbname=DBNAME
- Specifies the name of the database to be reorganized. If this is not specified and -a (or --all) is not used, the database name is read from the environment variable PGDATABASE. If that is not set, the user name specified for the connection is used.
- -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=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 the program to prompt for a password before connecting to a database.
This option is never essential, since the program will automatically prompt for a password if the server demands password authentication. However, pg_repack 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.
- -e, --echo
- Echo commands sent to server.
- -E LEVEL, --elevel=LEVEL
- Choose the output message level from DEBUG, INFO, NOTICE, WARNING, ERROR, LOG, FATAL, and PANIC. The default is INFO.
- Show usage of the program.
- Show the version number of the program.
- PGDATABASE, PGHOST, PGPORT, PGUSER
Default connection parameters
This utility, like most other PostgreSQL utilities, also uses the environment variables supported by libpq (see Environment Variables).
Perform an online CLUSTER of all the clustered tables in the database test, and perform an online VACUUM FULL of all the non-clustered tables:
$ pg_repack test
Perform an online VACUUM FULL on the tables foo and bar in the database test (an eventual cluster index is ignored):
$ pg_repack --no-order --table foo --table bar test
Move all indexes of table foo to tablespace tbs:
$ pg_repack -d test --table foo --only-indexes --tablespace tbs
Move the specified index to tablespace tbs:
$ pg_repack -d test --index idx --tablespace tbs
Error messages are reported when pg_repack fails. The following list shows the cause of errors.
You need to cleanup by hand after fatal errors. To cleanup, just remove pg_repack from the database and install it again: for PostgreSQL 9.1 and following execute DROP EXTENSION pg_repack CASCADE in the database where the error occurred, followed by CREATE EXTENSION pg_repack; for previous version load the script $SHAREDIR/contrib/uninstall_pg_repack.sql into the database where the error occured and then load $SHAREDIR/contrib/pg_repack.sql again.
- INFO: database "db" skipped: pg_repack VER is not installed in the database
pg_repack is not installed in the database when the --all option is specified.
Create the pg_repack extension in the database.
- ERROR: pg_repack VER is not installed in the database
pg_repack is not installed in the database specified by --dbname.
Create the pg_repack extension in the database.
- ERROR: program 'pg_repack V1' does not match database library 'pg_repack V2'
There is a mismatch between the pg_repack binary and the database library (.so or .dll).
The mismatch could be due to the wrong binary in the $PATH or the wrong database being addressed. Check the program directory and the database; if they are what expected you may need to repeat pg_repack installation.
- ERROR: extension 'pg_repack V1' required, found extension 'pg_repack V2'
The SQL extension found in the database does not match the version required by the pg_repack program.
You should drop the extension from the database and reload it as described in the installation section.
- ERROR: relation "table" must have a primary key or not-null unique keys
The target table doesn't have a PRIMARY KEY or any UNIQUE constraints defined.
Define a PRIMARY KEY or a UNIQUE constraint on the table.
- ERROR: query failed: ERROR: column "col" does not exist
The target table doesn't have columns specified by --order-by option.
Specify existing columns.
- WARNING: the table "tbl" already has a trigger called z_repack_trigger
The trigger was probably installed during a previous attempt to run pg_repack on the table which was interrupted and for some reason failed to clean up the temporary objects.
You can remove all the temporary objects by dropping and re-creating the extension: see the installation section for the details.
- WARNING: trigger "trg" conflicting on table "tbl"
The target table has a trigger whose name follows z_repack_trigger in alphabetical order.
The z_repack_trigger should be the last BEFORE trigger to fire. Please rename your trigger so that it sorts alphabetically before pg_repack's one; you can use:
ALTER TRIGGER zzz_my_trigger ON sometable RENAME TO yyy_my_trigger;
- ERROR: Another pg_repack command may be running on the table. Please try again
There is a chance of deadlock when two concurrent pg_repack commands are run on the same table. So, try to run the command after some time.
WARNING: Cannot create index "schema"."index_xxxxx", already exists DETAIL: An invalid index may have been left behind by a previous pg_repack on the table which was interrupted. Please use DROP INDEX "schema"."index_xxxxx" to remove this index and try again.
A temporary index apparently created by pg_repack has been left behind, and we do not want to risk dropping this index ourselves. If the index was in fact created by an old pg_repack job which didn't get cleaned up, you should just use DROP INDEX and try the repack command again.
pg_repack comes with the following restrictions.
pg_repack cannot reorganize temp tables.
pg_repack cannot reorganize tables using GiST indexes.
You will not be able to perform DDL commands of the target table(s) except VACUUM or ANALYZE while pg_repack is working. pg_repack will hold an ACCESS SHARE lock on the target table during a full-table repack, to enforce this restriction.
If you are using version 1.1.8 or earlier, you must not attempt to perform any DDL commands on the target table(s) while pg_repack is running. In many cases pg_repack would fail and rollback correctly, but there were some cases in these earlier versions which could result in data corruption.
Full Table Repacks
To perform a full-table repack, pg_repack will:
- create a log table to record changes made to the original table
- add a trigger onto the original table, logging INSERTs, UPDATEs and DELETEs into our log table
- create a new table containing all the rows in the old table
- build indexes on this new table
- apply all changes which have accrued in the log table to the new table
- swap the tables, including indexes and toast tables, using the system catalogs
- drop the original table
pg_repack will only hold an ACCESS EXCLUSIVE lock for a short period during initial setup (steps 1 and 2 above) and during the final swap-and-drop phase (steps 6 and 7). For the rest of its time, pg_repack only needs to hold an ACCESS SHARE lock on the original table, meaning INSERTs, UPDATEs, and DELETEs may proceed as usual.
Index Only Repacks
To perform an index-only repack, pg_repack will:
- create new indexes on the table using CONCURRENTLY matching the definitions of the old indexes
- swap out the old for the new indexes in the catalogs
- drop the old indexes
Creating indexes concurrently comes with a few caveats, please see the documentation for details.
- pg_repack 1.3.1
- Added support for PostgreSQL 9.4.
- pg_repack 1.3
- Added --schema to repack only the specified schema (issue #20).
- Added --dry-run to do a dry run (issue #21).
- Fixed advisory locking for >2B OID values (issue #30).
- Avoid possible deadlock when other sessions lock a to-be-repacked table (issue #32).
- Performance improvement for performing sql_pop DELETEs many-at-a-time.
- Attempt to avoid pg_repack taking forever when dealing with a constant heavy stream of changes to a table.
- pg_repack 1.2
- Support PostgreSQL 9.3.
- Added --tablespace and --moveidx options to perform online SET TABLESPACE.
- Added --index to repack the specified index only.
- Added --only-indexes to repack only the indexes of the specified table
- Added --jobs option for parallel operation.
- Don't require --no-order to perform a VACUUM FULL on non-clustered tables (pg_repack issue #6).
- Don't wait for locks held in other databases (pg_repack issue #11).
- Bugfix: correctly handle key indexes with options such as DESC, NULL FIRST/LAST, COLLATE (pg_repack issue #3).
- Fixed data corruption bug on delete (pg_repack issue #23).
- More helpful program output and error messages.
- pg_repack 1.1.8
- Added support for PostgreSQL 9.2.
- Added support for CREATE EXTENSION on PostgreSQL 9.1 and following.
- Give user feedback while waiting for transactions to finish (pg_reorg issue #5).
- Bugfix: Allow running on newly promoted streaming replication slaves (pg_reorg issue #1).
- Bugfix: Fix interaction between pg_repack and Slony 2.0/2.1 (pg_reorg issue #4)
- Bugfix: Properly escape column names (pg_reorg issue #6).
- Bugfix: Avoid recreating invalid indexes, or choosing them as key (pg_reorg issue #9).
- Bugfix: Never choose a partial index as primary key (pg_reorg issue #22).
- pg_reorg 1.1.7 (2011-08-07)
- Bugfix: VIEWs and FUNCTIONs could be corrupted that used a reorganized table which has a dropped column.
- Supports PostgreSQL 9.1 and 9.2dev. (but EXTENSION is not yet)