REINDEX(7) PostgreSQL 10.1 Documentation REINDEX(7)NAMEREINDEX - rebuild indexes
SYNOPSISREINDEX [ ( VERBOSE ) ] { INDEX | TABLE | SCHEMA | DATABASE | SYSTEM } name
DESCRIPTIONREINDEX rebuilds an index using the data stored in the index's table,
replacing the old copy of the index. There are several scenarios in
which to use REINDEX:
· An index has become corrupted, and no longer contains valid data.
Although in theory this should never happen, in practice indexes
can become corrupted due to software bugs or hardware failures.
REINDEX provides a recovery method.
· An index has become “bloated”, that is it contains many empty or
nearly-empty pages. This can occur with B-tree indexes in
PostgreSQL under certain uncommon access patterns. REINDEX
provides a way to reduce the space consumption of the index by
writing a new version of the index without the dead pages. See
Section 24.2 for more information.
· You have altered a storage parameter (such as fillfactor) for an
index, and wish to ensure that the change has taken full effect.
· An index build with the CONCURRENTLY option failed, leaving an
“invalid” index. Such indexes are useless but it can be convenient
to use REINDEX to rebuild them. Note that REINDEX will not perform
a concurrent build. To build the index without interfering with
production you should drop the index and reissue the CREATE INDEX
CONCURRENTLY command.
PARAMETERS
INDEX
Recreate the specified index.
TABLE
Recreate all indexes of the specified table. If the table has a
secondary “TOAST” table, that is reindexed as well.
SCHEMA
Recreate all indexes of the specified schema. If a table of this
schema has a secondary “TOAST” table, that is reindexed as well.
Indexes on shared system catalogs are also processed. This form of
REINDEX cannot be executed inside a transaction block.
DATABASE
Recreate all indexes within the current database. Indexes on shared
system catalogs are also processed. This form of REINDEX cannot be
executed inside a transaction block.
SYSTEM
Recreate all indexes on system catalogs within the current
database. Indexes on shared system catalogs are included. Indexes
on user tables are not processed. This form of REINDEX cannot be
executed inside a transaction block.
name
The name of the specific index, table, or database to be reindexed.
Index and table names can be schema-qualified. Presently, REINDEX
DATABASE and REINDEX SYSTEM can only reindex the current database,
so their parameter must match the current database's name.
VERBOSE
Prints a progress report as each index is reindexed.
NOTES
If you suspect corruption of an index on a user table, you can simply
rebuild that index, or all indexes on the table, using REINDEX INDEX or
REINDEX TABLE.
Things are more difficult if you need to recover from corruption of an
index on a system table. In this case it's important for the system to
not have used any of the suspect indexes itself. (Indeed, in this sort
of scenario you might find that server processes are crashing
immediately at start-up, due to reliance on the corrupted indexes.) To
recover safely, the server must be started with the -P option, which
prevents it from using indexes for system catalog lookups.
One way to do this is to shut down the server and start a single-user
PostgreSQL server with the -P option included on its command line.
Then, REINDEX DATABASE, REINDEX SYSTEM, REINDEX TABLE, or REINDEX INDEX
can be issued, depending on how much you want to reconstruct. If in
doubt, use REINDEX SYSTEM to select reconstruction of all system
indexes in the database. Then quit the single-user server session and
restart the regular server. See the postgres(1) reference page for more
information about how to interact with the single-user server
interface.
Alternatively, a regular server session can be started with -P included
in its command line options. The method for doing this varies across
clients, but in all libpq-based clients, it is possible to set the
PGOPTIONS environment variable to -P before starting the client. Note
that while this method does not require locking out other clients, it
might still be wise to prevent other users from connecting to the
damaged database until repairs have been completed.
REINDEX is similar to a drop and recreate of the index in that the
index contents are rebuilt from scratch. However, the locking
considerations are rather different. REINDEX locks out writes but not
reads of the index's parent table. It also takes an exclusive lock on
the specific index being processed, which will block reads that attempt
to use that index. In contrast, DROP INDEX momentarily takes an
exclusive lock on the parent table, blocking both writes and reads. The
subsequent CREATE INDEX locks out writes but not reads; since the index
is not there, no read will attempt to use it, meaning that there will
be no blocking but reads might be forced into expensive sequential
scans.
Reindexing a single index or table requires being the owner of that
index or table. Reindexing a database requires being the owner of the
database (note that the owner can therefore rebuild indexes of tables
owned by other users). Of course, superusers can always reindex
anything.
EXAMPLES
Rebuild a single index:
REINDEX INDEX my_index;
Rebuild all the indexes on the table my_table:
REINDEX TABLE my_table;
Rebuild all indexes in a particular database, without trusting the
system indexes to be valid already:
$ export PGOPTIONS="-P"
$ psql broken_db
...
broken_db=> REINDEX DATABASE broken_db;
broken_db=> \q
COMPATIBILITY
There is no REINDEX command in the SQL standard.
PostgreSQL 10.1 2017 REINDEX(7)
