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diff --git a/doc/src/sgml/man7/CREATE_INDEX.7 b/doc/src/sgml/man7/CREATE_INDEX.7 new file mode 100644 index 0000000..d0c2c02 --- /dev/null +++ b/doc/src/sgml/man7/CREATE_INDEX.7 @@ -0,0 +1,714 @@ +'\" t +.\" Title: CREATE INDEX +.\" Author: The PostgreSQL Global Development Group +.\" Generator: DocBook XSL Stylesheets v1.79.1 <http://docbook.sf.net/> +.\" Date: 2021 +.\" Manual: PostgreSQL 13.4 Documentation +.\" Source: PostgreSQL 13.4 +.\" Language: English +.\" +.TH "CREATE INDEX" "7" "2021" "PostgreSQL 13.4" "PostgreSQL 13.4 Documentation" +.\" ----------------------------------------------------------------- +.\" * Define some portability stuff +.\" ----------------------------------------------------------------- +.\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +.\" http://bugs.debian.org/507673 +.\" http://lists.gnu.org/archive/html/groff/2009-02/msg00013.html +.\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +.ie \n(.g .ds Aq \(aq +.el .ds Aq ' +.\" ----------------------------------------------------------------- +.\" * set default formatting +.\" ----------------------------------------------------------------- +.\" disable hyphenation +.nh +.\" disable justification (adjust text to left margin only) +.ad l +.\" ----------------------------------------------------------------- +.\" * MAIN CONTENT STARTS HERE * +.\" ----------------------------------------------------------------- +.SH "NAME" +CREATE_INDEX \- define a new index +.SH "SYNOPSIS" +.sp +.nf +CREATE [ UNIQUE ] INDEX [ CONCURRENTLY ] [ [ IF NOT EXISTS ] \fIname\fR ] ON [ ONLY ] \fItable_name\fR [ USING \fImethod\fR ] + ( { \fIcolumn_name\fR | ( \fIexpression\fR ) } [ COLLATE \fIcollation\fR ] [ \fIopclass\fR [ ( \fIopclass_parameter\fR = \fIvalue\fR [, \&.\&.\&. ] ) ] ] [ ASC | DESC ] [ NULLS { FIRST | LAST } ] [, \&.\&.\&.] ) + [ INCLUDE ( \fIcolumn_name\fR [, \&.\&.\&.] ) ] + [ WITH ( \fIstorage_parameter\fR [= \fIvalue\fR] [, \&.\&.\&. ] ) ] + [ TABLESPACE \fItablespace_name\fR ] + [ WHERE \fIpredicate\fR ] +.fi +.SH "DESCRIPTION" +.PP +\fBCREATE INDEX\fR +constructs an index on the specified column(s) of the specified relation, which can be a table or a materialized view\&. Indexes are primarily used to enhance database performance (though inappropriate use can result in slower performance)\&. +.PP +The key field(s) for the index are specified as column names, or alternatively as expressions written in parentheses\&. Multiple fields can be specified if the index method supports multicolumn indexes\&. +.PP +An index field can be an expression computed from the values of one or more columns of the table row\&. This feature can be used to obtain fast access to data based on some transformation of the basic data\&. For example, an index computed on +upper(col) +would allow the clause +WHERE upper(col) = \*(AqJIM\*(Aq +to use an index\&. +.PP +PostgreSQL +provides the index methods B\-tree, hash, GiST, SP\-GiST, GIN, and BRIN\&. Users can also define their own index methods, but that is fairly complicated\&. +.PP +When the +WHERE +clause is present, a +partial index +is created\&. A partial index is an index that contains entries for only a portion of a table, usually a portion that is more useful for indexing than the rest of the table\&. For example, if you have a table that contains both billed and unbilled orders where the unbilled orders take up a small fraction of the total table and yet that is an often used section, you can improve performance by creating an index on just that portion\&. Another possible application is to use +WHERE +with +UNIQUE +to enforce uniqueness over a subset of a table\&. See +Section\ \&11.8 +for more discussion\&. +.PP +The expression used in the +WHERE +clause can refer only to columns of the underlying table, but it can use all columns, not just the ones being indexed\&. Presently, subqueries and aggregate expressions are also forbidden in +WHERE\&. The same restrictions apply to index fields that are expressions\&. +.PP +All functions and operators used in an index definition must be +\(lqimmutable\(rq, that is, their results must depend only on their arguments and never on any outside influence (such as the contents of another table or the current time)\&. This restriction ensures that the behavior of the index is well\-defined\&. To use a user\-defined function in an index expression or +WHERE +clause, remember to mark the function immutable when you create it\&. +.SH "PARAMETERS" +.PP +UNIQUE +.RS 4 +Causes the system to check for duplicate values in the table when the index is created (if data already exist) and each time data is added\&. Attempts to insert or update data which would result in duplicate entries will generate an error\&. +.sp +Additional restrictions apply when unique indexes are applied to partitioned tables; see +CREATE TABLE (\fBCREATE_TABLE\fR(7))\&. +.RE +.PP +CONCURRENTLY +.RS 4 +When this option is used, +PostgreSQL +will build the index without taking any locks that prevent concurrent inserts, updates, or deletes on the table; whereas a standard index build locks out writes (but not reads) on the table until it\*(Aqs done\&. There are several caveats to be aware of when using this option \(em see +Building Indexes Concurrently +below\&. +.sp +For temporary tables, +\fBCREATE INDEX\fR +is always non\-concurrent, as no other session can access them, and non\-concurrent index creation is cheaper\&. +.RE +.PP +IF NOT EXISTS +.RS 4 +Do not throw an error if a relation with the same name already exists\&. A notice is issued in this case\&. Note that there is no guarantee that the existing index is anything like the one that would have been created\&. Index name is required when +IF NOT EXISTS +is specified\&. +.RE +.PP +INCLUDE +.RS 4 +The optional +INCLUDE +clause specifies a list of columns which will be included in the index as +non\-key +columns\&. A non\-key column cannot be used in an index scan search qualification, and it is disregarded for purposes of any uniqueness or exclusion constraint enforced by the index\&. However, an index\-only scan can return the contents of non\-key columns without having to visit the index\*(Aqs table, since they are available directly from the index entry\&. Thus, addition of non\-key columns allows index\-only scans to be used for queries that otherwise could not use them\&. +.sp +It\*(Aqs wise to be conservative about adding non\-key columns to an index, especially wide columns\&. If an index tuple exceeds the maximum size allowed for the index type, data insertion will fail\&. In any case, non\-key columns duplicate data from the index\*(Aqs table and bloat the size of the index, thus potentially slowing searches\&. Furthermore, B\-tree deduplication is never used with indexes that have a non\-key column\&. +.sp +Columns listed in the +INCLUDE +clause don\*(Aqt need appropriate operator classes; the clause can include columns whose data types don\*(Aqt have operator classes defined for a given access method\&. +.sp +Expressions are not supported as included columns since they cannot be used in index\-only scans\&. +.sp +Currently, the B\-tree and the GiST index access methods support this feature\&. In B\-tree and the GiST indexes, the values of columns listed in the +INCLUDE +clause are included in leaf tuples which correspond to heap tuples, but are not included in upper\-level index entries used for tree navigation\&. +.RE +.PP +\fIname\fR +.RS 4 +The name of the index to be created\&. No schema name can be included here; the index is always created in the same schema as its parent table\&. If the name is omitted, +PostgreSQL +chooses a suitable name based on the parent table\*(Aqs name and the indexed column name(s)\&. +.RE +.PP +ONLY +.RS 4 +Indicates not to recurse creating indexes on partitions, if the table is partitioned\&. The default is to recurse\&. +.RE +.PP +\fItable_name\fR +.RS 4 +The name (possibly schema\-qualified) of the table to be indexed\&. +.RE +.PP +\fImethod\fR +.RS 4 +The name of the index method to be used\&. Choices are +btree, +hash, +gist, +spgist, +gin, and +brin\&. The default method is +btree\&. +.RE +.PP +\fIcolumn_name\fR +.RS 4 +The name of a column of the table\&. +.RE +.PP +\fIexpression\fR +.RS 4 +An expression based on one or more columns of the table\&. The expression usually must be written with surrounding parentheses, as shown in the syntax\&. However, the parentheses can be omitted if the expression has the form of a function call\&. +.RE +.PP +\fIcollation\fR +.RS 4 +The name of the collation to use for the index\&. By default, the index uses the collation declared for the column to be indexed or the result collation of the expression to be indexed\&. Indexes with non\-default collations can be useful for queries that involve expressions using non\-default collations\&. +.RE +.PP +\fIopclass\fR +.RS 4 +The name of an operator class\&. See below for details\&. +.RE +.PP +\fIopclass_parameter\fR +.RS 4 +The name of an operator class parameter\&. See below for details\&. +.RE +.PP +ASC +.RS 4 +Specifies ascending sort order (which is the default)\&. +.RE +.PP +DESC +.RS 4 +Specifies descending sort order\&. +.RE +.PP +NULLS FIRST +.RS 4 +Specifies that nulls sort before non\-nulls\&. This is the default when +DESC +is specified\&. +.RE +.PP +NULLS LAST +.RS 4 +Specifies that nulls sort after non\-nulls\&. This is the default when +DESC +is not specified\&. +.RE +.PP +\fIstorage_parameter\fR +.RS 4 +The name of an index\-method\-specific storage parameter\&. See +Index Storage Parameters +below for details\&. +.RE +.PP +\fItablespace_name\fR +.RS 4 +The tablespace in which to create the index\&. If not specified, +default_tablespace +is consulted, or +temp_tablespaces +for indexes on temporary tables\&. +.RE +.PP +\fIpredicate\fR +.RS 4 +The constraint expression for a partial index\&. +.RE +.SS "Index Storage Parameters" +.PP +The optional +WITH +clause specifies +storage parameters +for the index\&. Each index method has its own set of allowed storage parameters\&. The B\-tree, hash, GiST and SP\-GiST index methods all accept this parameter: +.PP +fillfactor (integer) +.RS 4 +The fillfactor for an index is a percentage that determines how full the index method will try to pack index pages\&. For B\-trees, leaf pages are filled to this percentage during initial index build, and also when extending the index at the right (adding new largest key values)\&. If pages subsequently become completely full, they will be split, leading to gradual degradation in the index\*(Aqs efficiency\&. B\-trees use a default fillfactor of 90, but any integer value from 10 to 100 can be selected\&. If the table is static then fillfactor 100 is best to minimize the index\*(Aqs physical size, but for heavily updated tables a smaller fillfactor is better to minimize the need for page splits\&. The other index methods use fillfactor in different but roughly analogous ways; the default fillfactor varies between methods\&. +.RE +.PP +B\-tree indexes additionally accept this parameter: +.PP +deduplicate_items (boolean) +.RS 4 +Controls usage of the B\-tree deduplication technique described in +Section\ \&63.4.2\&. Set to +ON +or +OFF +to enable or disable the optimization\&. (Alternative spellings of +ON +and +OFF +are allowed as described in +Section\ \&19.1\&.) The default is +ON\&. +.if n \{\ +.sp +.\} +.RS 4 +.it 1 an-trap +.nr an-no-space-flag 1 +.nr an-break-flag 1 +.br +.ps +1 +\fBNote\fR +.ps -1 +.br +Turning +deduplicate_items +off via +\fBALTER INDEX\fR +prevents future insertions from triggering deduplication, but does not in itself make existing posting list tuples use the standard tuple representation\&. +.sp .5v +.RE +.RE +.PP +GiST indexes additionally accept this parameter: +.PP +buffering (enum) +.RS 4 +Determines whether the buffering build technique described in +Section\ \&64.4.1 +is used to build the index\&. With +OFF +it is disabled, with +ON +it is enabled, and with +AUTO +it is initially disabled, but turned on on\-the\-fly once the index size reaches +effective_cache_size\&. The default is +AUTO\&. +.RE +.PP +GIN indexes accept different parameters: +.PP +fastupdate (boolean) +.RS 4 +This setting controls usage of the fast update technique described in +Section\ \&66.4.1\&. It is a Boolean parameter: +ON +enables fast update, +OFF +disables it\&. The default is +ON\&. +.if n \{\ +.sp +.\} +.RS 4 +.it 1 an-trap +.nr an-no-space-flag 1 +.nr an-break-flag 1 +.br +.ps +1 +\fBNote\fR +.ps -1 +.br +Turning +fastupdate +off via +\fBALTER INDEX\fR +prevents future insertions from going into the list of pending index entries, but does not in itself flush previous entries\&. You might want to +\fBVACUUM\fR +the table or call +\fBgin_clean_pending_list\fR +function afterward to ensure the pending list is emptied\&. +.sp .5v +.RE +.RE +.PP +gin_pending_list_limit (integer) +.RS 4 +Custom +gin_pending_list_limit +parameter\&. This value is specified in kilobytes\&. +.RE +.PP +BRIN +indexes accept different parameters: +.PP +pages_per_range (integer) +.RS 4 +Defines the number of table blocks that make up one block range for each entry of a +BRIN +index (see +Section\ \&67.1 +for more details)\&. The default is +128\&. +.RE +.PP +autosummarize (boolean) +.RS 4 +Defines whether a summarization run is invoked for the previous page range whenever an insertion is detected on the next one\&. +.RE +.SS "Building Indexes Concurrently" +.PP +Creating an index can interfere with regular operation of a database\&. Normally +PostgreSQL +locks the table to be indexed against writes and performs the entire index build with a single scan of the table\&. Other transactions can still read the table, but if they try to insert, update, or delete rows in the table they will block until the index build is finished\&. This could have a severe effect if the system is a live production database\&. Very large tables can take many hours to be indexed, and even for smaller tables, an index build can lock out writers for periods that are unacceptably long for a production system\&. +.PP +PostgreSQL +supports building indexes without locking out writes\&. This method is invoked by specifying the +CONCURRENTLY +option of +\fBCREATE INDEX\fR\&. When this option is used, +PostgreSQL +must perform two scans of the table, and in addition it must wait for all existing transactions that could potentially modify or use the index to terminate\&. Thus this method requires more total work than a standard index build and takes significantly longer to complete\&. However, since it allows normal operations to continue while the index is built, this method is useful for adding new indexes in a production environment\&. Of course, the extra CPU and I/O load imposed by the index creation might slow other operations\&. +.PP +In a concurrent index build, the index is actually entered into the system catalogs in one transaction, then two table scans occur in two more transactions\&. Before each table scan, the index build must wait for existing transactions that have modified the table to terminate\&. After the second scan, the index build must wait for any transactions that have a snapshot (see +Chapter\ \&13) predating the second scan to terminate, including transactions used by any phase of concurrent index builds on other tables\&. Then finally the index can be marked ready for use, and the +\fBCREATE INDEX\fR +command terminates\&. Even then, however, the index may not be immediately usable for queries: in the worst case, it cannot be used as long as transactions exist that predate the start of the index build\&. +.PP +If a problem arises while scanning the table, such as a deadlock or a uniqueness violation in a unique index, the +\fBCREATE INDEX\fR +command will fail but leave behind an +\(lqinvalid\(rq +index\&. This index will be ignored for querying purposes because it might be incomplete; however it will still consume update overhead\&. The +psql +\fB\ed\fR +command will report such an index as +INVALID: +.sp +.if n \{\ +.RS 4 +.\} +.nf +postgres=# \ed tab + Table "public\&.tab" + Column | Type | Collation | Nullable | Default +\-\-\-\-\-\-\-\-+\-\-\-\-\-\-\-\-\-+\-\-\-\-\-\-\-\-\-\-\-+\-\-\-\-\-\-\-\-\-\-+\-\-\-\-\-\-\-\-\- + col | integer | | | +Indexes: + "idx" btree (col) INVALID +.fi +.if n \{\ +.RE +.\} +.sp +The recommended recovery method in such cases is to drop the index and try again to perform +\fBCREATE INDEX CONCURRENTLY\fR\&. (Another possibility is to rebuild the index with +\fBREINDEX INDEX CONCURRENTLY\fR)\&. +.PP +Another caveat when building a unique index concurrently is that the uniqueness constraint is already being enforced against other transactions when the second table scan begins\&. This means that constraint violations could be reported in other queries prior to the index becoming available for use, or even in cases where the index build eventually fails\&. Also, if a failure does occur in the second scan, the +\(lqinvalid\(rq +index continues to enforce its uniqueness constraint afterwards\&. +.PP +Concurrent builds of expression indexes and partial indexes are supported\&. Errors occurring in the evaluation of these expressions could cause behavior similar to that described above for unique constraint violations\&. +.PP +Regular index builds permit other regular index builds on the same table to occur simultaneously, but only one concurrent index build can occur on a table at a time\&. In either case, schema modification of the table is not allowed while the index is being built\&. Another difference is that a regular +\fBCREATE INDEX\fR +command can be performed within a transaction block, but +\fBCREATE INDEX CONCURRENTLY\fR +cannot\&. +.PP +Concurrent builds for indexes on partitioned tables are currently not supported\&. However, you may concurrently build the index on each partition individually and then finally create the partitioned index non\-concurrently in order to reduce the time where writes to the partitioned table will be locked out\&. In this case, building the partitioned index is a metadata only operation\&. +.SH "NOTES" +.PP +See +Chapter\ \&11 +for information about when indexes can be used, when they are not used, and in which particular situations they can be useful\&. +.PP +Currently, only the B\-tree, GiST, GIN, and BRIN index methods support multicolumn indexes\&. Up to 32 fields can be specified by default\&. (This limit can be altered when building +PostgreSQL\&.) Only B\-tree currently supports unique indexes\&. +.PP +An +operator class +with optional parameters can be specified for each column of an index\&. The operator class identifies the operators to be used by the index for that column\&. For example, a B\-tree index on four\-byte integers would use the +int4_ops +class; this operator class includes comparison functions for four\-byte integers\&. In practice the default operator class for the column\*(Aqs data type is usually sufficient\&. The main point of having operator classes is that for some data types, there could be more than one meaningful ordering\&. For example, we might want to sort a complex\-number data type either by absolute value or by real part\&. We could do this by defining two operator classes for the data type and then selecting the proper class when creating an index\&. More information about operator classes is in +Section\ \&11.10 +and in +Section\ \&37.16\&. +.PP +When +CREATE INDEX +is invoked on a partitioned table, the default behavior is to recurse to all partitions to ensure they all have matching indexes\&. Each partition is first checked to determine whether an equivalent index already exists, and if so, that index will become attached as a partition index to the index being created, which will become its parent index\&. If no matching index exists, a new index will be created and automatically attached; the name of the new index in each partition will be determined as if no index name had been specified in the command\&. If the +ONLY +option is specified, no recursion is done, and the index is marked invalid\&. (\fBALTER INDEX \&.\&.\&. ATTACH PARTITION\fR +marks the index valid, once all partitions acquire matching indexes\&.) Note, however, that any partition that is created in the future using +\fBCREATE TABLE \&.\&.\&. PARTITION OF\fR +will automatically have a matching index, regardless of whether +ONLY +is specified\&. +.PP +For index methods that support ordered scans (currently, only B\-tree), the optional clauses +ASC, +DESC, +NULLS FIRST, and/or +NULLS LAST +can be specified to modify the sort ordering of the index\&. Since an ordered index can be scanned either forward or backward, it is not normally useful to create a single\-column +DESC +index \(em that sort ordering is already available with a regular index\&. The value of these options is that multicolumn indexes can be created that match the sort ordering requested by a mixed\-ordering query, such as +SELECT \&.\&.\&. ORDER BY x ASC, y DESC\&. The +NULLS +options are useful if you need to support +\(lqnulls sort low\(rq +behavior, rather than the default +\(lqnulls sort high\(rq, in queries that depend on indexes to avoid sorting steps\&. +.PP +The system regularly collects statistics on all of a table\*(Aqs columns\&. Newly\-created non\-expression indexes can immediately use these statistics to determine an index\*(Aqs usefulness\&. For new expression indexes, it is necessary to run +\fBANALYZE\fR +or wait for the +autovacuum daemon +to analyze the table to generate statistics for these indexes\&. +.PP +For most index methods, the speed of creating an index is dependent on the setting of +maintenance_work_mem\&. Larger values will reduce the time needed for index creation, so long as you don\*(Aqt make it larger than the amount of memory really available, which would drive the machine into swapping\&. +.PP +PostgreSQL +can build indexes while leveraging multiple CPUs in order to process the table rows faster\&. This feature is known as +parallel index build\&. For index methods that support building indexes in parallel (currently, only B\-tree), +\fImaintenance_work_mem\fR +specifies the maximum amount of memory that can be used by each index build operation as a whole, regardless of how many worker processes were started\&. Generally, a cost model automatically determines how many worker processes should be requested, if any\&. +.PP +Parallel index builds may benefit from increasing +\fImaintenance_work_mem\fR +where an equivalent serial index build will see little or no benefit\&. Note that +\fImaintenance_work_mem\fR +may influence the number of worker processes requested, since parallel workers must have at least a +32MB +share of the total +\fImaintenance_work_mem\fR +budget\&. There must also be a remaining +32MB +share for the leader process\&. Increasing +max_parallel_maintenance_workers +may allow more workers to be used, which will reduce the time needed for index creation, so long as the index build is not already I/O bound\&. Of course, there should also be sufficient CPU capacity that would otherwise lie idle\&. +.PP +Setting a value for +parallel_workers +via +ALTER TABLE (\fBALTER_TABLE\fR(7)) +directly controls how many parallel worker processes will be requested by a +\fBCREATE INDEX\fR +against the table\&. This bypasses the cost model completely, and prevents +\fImaintenance_work_mem\fR +from affecting how many parallel workers are requested\&. Setting +parallel_workers +to 0 via +\fBALTER TABLE\fR +will disable parallel index builds on the table in all cases\&. +.if n \{\ +.sp +.\} +.RS 4 +.it 1 an-trap +.nr an-no-space-flag 1 +.nr an-break-flag 1 +.br +.ps +1 +\fBTip\fR +.ps -1 +.br +.PP +You might want to reset +parallel_workers +after setting it as part of tuning an index build\&. This avoids inadvertent changes to query plans, since +parallel_workers +affects +\fIall\fR +parallel table scans\&. +.sp .5v +.RE +.PP +While +\fBCREATE INDEX\fR +with the +CONCURRENTLY +option supports parallel builds without special restrictions, only the first table scan is actually performed in parallel\&. +.PP +Use +DROP INDEX (\fBDROP_INDEX\fR(7)) +to remove an index\&. +.PP +Like any long\-running transaction, +\fBCREATE INDEX\fR +on a table can affect which tuples can be removed by concurrent +\fBVACUUM\fR +on any other table\&. +.PP +Prior releases of +PostgreSQL +also had an R\-tree index method\&. This method has been removed because it had no significant advantages over the GiST method\&. If +USING rtree +is specified, +\fBCREATE INDEX\fR +will interpret it as +USING gist, to simplify conversion of old databases to GiST\&. +.SH "EXAMPLES" +.PP +To create a unique B\-tree index on the column +title +in the table +films: +.sp +.if n \{\ +.RS 4 +.\} +.nf +CREATE UNIQUE INDEX title_idx ON films (title); +.fi +.if n \{\ +.RE +.\} +.PP +To create a unique B\-tree index on the column +title +with included columns +director +and +rating +in the table +films: +.sp +.if n \{\ +.RS 4 +.\} +.nf +CREATE UNIQUE INDEX title_idx ON films (title) INCLUDE (director, rating); +.fi +.if n \{\ +.RE +.\} +.PP +To create a B\-Tree index with deduplication disabled: +.sp +.if n \{\ +.RS 4 +.\} +.nf +CREATE INDEX title_idx ON films (title) WITH (deduplicate_items = off); +.fi +.if n \{\ +.RE +.\} +.PP +To create an index on the expression +lower(title), allowing efficient case\-insensitive searches: +.sp +.if n \{\ +.RS 4 +.\} +.nf +CREATE INDEX ON films ((lower(title))); +.fi +.if n \{\ +.RE +.\} +.sp +(In this example we have chosen to omit the index name, so the system will choose a name, typically +films_lower_idx\&.) +.PP +To create an index with non\-default collation: +.sp +.if n \{\ +.RS 4 +.\} +.nf +CREATE INDEX title_idx_german ON films (title COLLATE "de_DE"); +.fi +.if n \{\ +.RE +.\} +.PP +To create an index with non\-default sort ordering of nulls: +.sp +.if n \{\ +.RS 4 +.\} +.nf +CREATE INDEX title_idx_nulls_low ON films (title NULLS FIRST); +.fi +.if n \{\ +.RE +.\} +.PP +To create an index with non\-default fill factor: +.sp +.if n \{\ +.RS 4 +.\} +.nf +CREATE UNIQUE INDEX title_idx ON films (title) WITH (fillfactor = 70); +.fi +.if n \{\ +.RE +.\} +.PP +To create a +GIN +index with fast updates disabled: +.sp +.if n \{\ +.RS 4 +.\} +.nf +CREATE INDEX gin_idx ON documents_table USING GIN (locations) WITH (fastupdate = off); +.fi +.if n \{\ +.RE +.\} +.PP +To create an index on the column +code +in the table +films +and have the index reside in the tablespace +indexspace: +.sp +.if n \{\ +.RS 4 +.\} +.nf +CREATE INDEX code_idx ON films (code) TABLESPACE indexspace; +.fi +.if n \{\ +.RE +.\} +.PP +To create a GiST index on a point attribute so that we can efficiently use box operators on the result of the conversion function: +.sp +.if n \{\ +.RS 4 +.\} +.nf +CREATE INDEX pointloc + ON points USING gist (box(location,location)); +SELECT * FROM points + WHERE box(location,location) && \*(Aq(0,0),(1,1)\*(Aq::box; +.fi +.if n \{\ +.RE +.\} +.PP +To create an index without locking out writes to the table: +.sp +.if n \{\ +.RS 4 +.\} +.nf +CREATE INDEX CONCURRENTLY sales_quantity_index ON sales_table (quantity); +.fi +.if n \{\ +.RE +.\} +.SH "COMPATIBILITY" +.PP +\fBCREATE INDEX\fR +is a +PostgreSQL +language extension\&. There are no provisions for indexes in the SQL standard\&. +.SH "SEE ALSO" +ALTER INDEX (\fBALTER_INDEX\fR(7)), DROP INDEX (\fBDROP_INDEX\fR(7)), \fBREINDEX\fR(7) |