1REINDEX(7)               PostgreSQL 10.7 Documentation              REINDEX(7)
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NAME

6       REINDEX - rebuild indexes
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SYNOPSIS

9       REINDEX [ ( VERBOSE ) ] { INDEX | TABLE | SCHEMA | DATABASE | SYSTEM } name
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DESCRIPTION

12       REINDEX rebuilds an index using the data stored in the index's table,
13       replacing the old copy of the index. There are several scenarios in
14       which to use REINDEX:
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16       ·   An index has become corrupted, and no longer contains valid data.
17           Although in theory this should never happen, in practice indexes
18           can become corrupted due to software bugs or hardware failures.
19           REINDEX provides a recovery method.
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21       ·   An index has become “bloated”, that is it contains many empty or
22           nearly-empty pages. This can occur with B-tree indexes in
23           PostgreSQL under certain uncommon access patterns.  REINDEX
24           provides a way to reduce the space consumption of the index by
25           writing a new version of the index without the dead pages. See
26           Section 24.2 for more information.
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28       ·   You have altered a storage parameter (such as fillfactor) for an
29           index, and wish to ensure that the change has taken full effect.
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31       ·   An index build with the CONCURRENTLY option failed, leaving an
32           “invalid” index. Such indexes are useless but it can be convenient
33           to use REINDEX to rebuild them. Note that REINDEX will not perform
34           a concurrent build. To build the index without interfering with
35           production you should drop the index and reissue the CREATE INDEX
36           CONCURRENTLY command.
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PARAMETERS

39       INDEX
40           Recreate the specified index.
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42       TABLE
43           Recreate all indexes of the specified table. If the table has a
44           secondary “TOAST” table, that is reindexed as well.
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46       SCHEMA
47           Recreate all indexes of the specified schema. If a table of this
48           schema has a secondary “TOAST” table, that is reindexed as well.
49           Indexes on shared system catalogs are also processed. This form of
50           REINDEX cannot be executed inside a transaction block.
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52       DATABASE
53           Recreate all indexes within the current database. Indexes on shared
54           system catalogs are also processed. This form of REINDEX cannot be
55           executed inside a transaction block.
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57       SYSTEM
58           Recreate all indexes on system catalogs within the current
59           database. Indexes on shared system catalogs are included. Indexes
60           on user tables are not processed. This form of REINDEX cannot be
61           executed inside a transaction block.
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63       name
64           The name of the specific index, table, or database to be reindexed.
65           Index and table names can be schema-qualified. Presently, REINDEX
66           DATABASE and REINDEX SYSTEM can only reindex the current database,
67           so their parameter must match the current database's name.
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69       VERBOSE
70           Prints a progress report as each index is reindexed.
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NOTES

73       If you suspect corruption of an index on a user table, you can simply
74       rebuild that index, or all indexes on the table, using REINDEX INDEX or
75       REINDEX TABLE.
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77       Things are more difficult if you need to recover from corruption of an
78       index on a system table. In this case it's important for the system to
79       not have used any of the suspect indexes itself. (Indeed, in this sort
80       of scenario you might find that server processes are crashing
81       immediately at start-up, due to reliance on the corrupted indexes.) To
82       recover safely, the server must be started with the -P option, which
83       prevents it from using indexes for system catalog lookups.
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85       One way to do this is to shut down the server and start a single-user
86       PostgreSQL server with the -P option included on its command line.
87       Then, REINDEX DATABASE, REINDEX SYSTEM, REINDEX TABLE, or REINDEX INDEX
88       can be issued, depending on how much you want to reconstruct. If in
89       doubt, use REINDEX SYSTEM to select reconstruction of all system
90       indexes in the database. Then quit the single-user server session and
91       restart the regular server. See the postgres(1) reference page for more
92       information about how to interact with the single-user server
93       interface.
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95       Alternatively, a regular server session can be started with -P included
96       in its command line options. The method for doing this varies across
97       clients, but in all libpq-based clients, it is possible to set the
98       PGOPTIONS environment variable to -P before starting the client. Note
99       that while this method does not require locking out other clients, it
100       might still be wise to prevent other users from connecting to the
101       damaged database until repairs have been completed.
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103       REINDEX is similar to a drop and recreate of the index in that the
104       index contents are rebuilt from scratch. However, the locking
105       considerations are rather different.  REINDEX locks out writes but not
106       reads of the index's parent table. It also takes an exclusive lock on
107       the specific index being processed, which will block reads that attempt
108       to use that index. In contrast, DROP INDEX momentarily takes an
109       exclusive lock on the parent table, blocking both writes and reads. The
110       subsequent CREATE INDEX locks out writes but not reads; since the index
111       is not there, no read will attempt to use it, meaning that there will
112       be no blocking but reads might be forced into expensive sequential
113       scans.
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115       Reindexing a single index or table requires being the owner of that
116       index or table. Reindexing a database requires being the owner of the
117       database (note that the owner can therefore rebuild indexes of tables
118       owned by other users). Of course, superusers can always reindex
119       anything.
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EXAMPLES

122       Rebuild a single index:
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124           REINDEX INDEX my_index;
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126       Rebuild all the indexes on the table my_table:
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128           REINDEX TABLE my_table;
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130       Rebuild all indexes in a particular database, without trusting the
131       system indexes to be valid already:
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133           $ export PGOPTIONS="-P"
134           $ psql broken_db
135           ...
136           broken_db=> REINDEX DATABASE broken_db;
137           broken_db=> \q
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COMPATIBILITY

140       There is no REINDEX command in the SQL standard.
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144PostgreSQL 10.7                      2019                           REINDEX(7)
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