2 .\" Title: CREATE TABLE
3 .\" Author: The PostgreSQL Global Development Group
4 .\" Generator: DocBook XSL Stylesheets vsnapshot <http://docbook.sf.net/>
6 .\" Manual: PostgreSQL 18.0 Documentation
7 .\" Source: PostgreSQL 18.0
10 .TH "CREATE TABLE" "7" "2025" "PostgreSQL 18.0" "PostgreSQL 18.0 Documentation"
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15 .\" http://bugs.debian.org/507673
16 .\" http://lists.gnu.org/archive/html/groff/2009-02/msg00013.html
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31 CREATE_TABLE \- define a new table
35 CREATE [ [ GLOBAL | LOCAL ] { TEMPORARY | TEMP } | UNLOGGED ] TABLE [ IF NOT EXISTS ] \fItable_name\fR ( [
36 { \fIcolumn_name\fR \fIdata_type\fR [ STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN | DEFAULT } ] [ COMPRESSION \fIcompression_method\fR ] [ COLLATE \fIcollation\fR ] [ \fIcolumn_constraint\fR [ \&.\&.\&. ] ]
37 | \fItable_constraint\fR
38 | LIKE \fIsource_table\fR [ \fIlike_option\fR \&.\&.\&. ] }
41 [ INHERITS ( \fIparent_table\fR [, \&.\&.\&. ] ) ]
42 [ PARTITION BY { RANGE | LIST | HASH } ( { \fIcolumn_name\fR | ( \fIexpression\fR ) } [ COLLATE \fIcollation\fR ] [ \fIopclass\fR ] [, \&.\&.\&. ] ) ]
43 [ USING \fImethod\fR ]
44 [ WITH ( \fIstorage_parameter\fR [= \fIvalue\fR] [, \&.\&.\&. ] ) | WITHOUT OIDS ]
45 [ ON COMMIT { PRESERVE ROWS | DELETE ROWS | DROP } ]
46 [ TABLESPACE \fItablespace_name\fR ]
48 CREATE [ [ GLOBAL | LOCAL ] { TEMPORARY | TEMP } | UNLOGGED ] TABLE [ IF NOT EXISTS ] \fItable_name\fR
49 OF \fItype_name\fR [ (
50 { \fIcolumn_name\fR [ WITH OPTIONS ] [ \fIcolumn_constraint\fR [ \&.\&.\&. ] ]
51 | \fItable_constraint\fR }
54 [ PARTITION BY { RANGE | LIST | HASH } ( { \fIcolumn_name\fR | ( \fIexpression\fR ) } [ COLLATE \fIcollation\fR ] [ \fIopclass\fR ] [, \&.\&.\&. ] ) ]
55 [ USING \fImethod\fR ]
56 [ WITH ( \fIstorage_parameter\fR [= \fIvalue\fR] [, \&.\&.\&. ] ) | WITHOUT OIDS ]
57 [ ON COMMIT { PRESERVE ROWS | DELETE ROWS | DROP } ]
58 [ TABLESPACE \fItablespace_name\fR ]
60 CREATE [ [ GLOBAL | LOCAL ] { TEMPORARY | TEMP } | UNLOGGED ] TABLE [ IF NOT EXISTS ] \fItable_name\fR
61 PARTITION OF \fIparent_table\fR [ (
62 { \fIcolumn_name\fR [ WITH OPTIONS ] [ \fIcolumn_constraint\fR [ \&.\&.\&. ] ]
63 | \fItable_constraint\fR }
65 ) ] { FOR VALUES \fIpartition_bound_spec\fR | DEFAULT }
66 [ PARTITION BY { RANGE | LIST | HASH } ( { \fIcolumn_name\fR | ( \fIexpression\fR ) } [ COLLATE \fIcollation\fR ] [ \fIopclass\fR ] [, \&.\&.\&. ] ) ]
67 [ USING \fImethod\fR ]
68 [ WITH ( \fIstorage_parameter\fR [= \fIvalue\fR] [, \&.\&.\&. ] ) | WITHOUT OIDS ]
69 [ ON COMMIT { PRESERVE ROWS | DELETE ROWS | DROP } ]
70 [ TABLESPACE \fItablespace_name\fR ]
72 where \fIcolumn_constraint\fR is:
74 [ CONSTRAINT \fIconstraint_name\fR ]
75 { NOT NULL [ NO INHERIT ] |
77 CHECK ( \fIexpression\fR ) [ NO INHERIT ] |
78 DEFAULT \fIdefault_expr\fR |
79 GENERATED ALWAYS AS ( \fIgeneration_expr\fR ) [ STORED | VIRTUAL ] |
80 GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( \fIsequence_options\fR ) ] |
81 UNIQUE [ NULLS [ NOT ] DISTINCT ] \fIindex_parameters\fR |
82 PRIMARY KEY \fIindex_parameters\fR |
83 REFERENCES \fIreftable\fR [ ( \fIrefcolumn\fR ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
84 [ ON DELETE \fIreferential_action\fR ] [ ON UPDATE \fIreferential_action\fR ] }
85 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ] [ ENFORCED | NOT ENFORCED ]
87 and \fItable_constraint\fR is:
89 [ CONSTRAINT \fIconstraint_name\fR ]
90 { CHECK ( \fIexpression\fR ) [ NO INHERIT ] |
91 NOT NULL \fIcolumn_name\fR [ NO INHERIT ] |
92 UNIQUE [ NULLS [ NOT ] DISTINCT ] ( \fIcolumn_name\fR [, \&.\&.\&. ] [, \fIcolumn_name\fR WITHOUT OVERLAPS ] ) \fIindex_parameters\fR |
93 PRIMARY KEY ( \fIcolumn_name\fR [, \&.\&.\&. ] [, \fIcolumn_name\fR WITHOUT OVERLAPS ] ) \fIindex_parameters\fR |
94 EXCLUDE [ USING \fIindex_method\fR ] ( \fIexclude_element\fR WITH \fIoperator\fR [, \&.\&.\&. ] ) \fIindex_parameters\fR [ WHERE ( \fIpredicate\fR ) ] |
95 FOREIGN KEY ( \fIcolumn_name\fR [, \&.\&.\&. ] [, PERIOD \fIcolumn_name\fR ] ) REFERENCES \fIreftable\fR [ ( \fIrefcolumn\fR [, \&.\&.\&. ] [, PERIOD \fIrefcolumn\fR ] ) ]
96 [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ] [ ON DELETE \fIreferential_action\fR ] [ ON UPDATE \fIreferential_action\fR ] }
97 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ] [ ENFORCED | NOT ENFORCED ]
99 and \fIlike_option\fR is:
101 { INCLUDING | EXCLUDING } { COMMENTS | COMPRESSION | CONSTRAINTS | DEFAULTS | GENERATED | IDENTITY | INDEXES | STATISTICS | STORAGE | ALL }
103 and \fIpartition_bound_spec\fR is:
105 IN ( \fIpartition_bound_expr\fR [, \&.\&.\&.] ) |
106 FROM ( { \fIpartition_bound_expr\fR | MINVALUE | MAXVALUE } [, \&.\&.\&.] )
107 TO ( { \fIpartition_bound_expr\fR | MINVALUE | MAXVALUE } [, \&.\&.\&.] ) |
108 WITH ( MODULUS \fInumeric_literal\fR, REMAINDER \fInumeric_literal\fR )
110 \fIindex_parameters\fR in UNIQUE, PRIMARY KEY, and EXCLUDE constraints are:
112 [ INCLUDE ( \fIcolumn_name\fR [, \&.\&.\&. ] ) ]
113 [ WITH ( \fIstorage_parameter\fR [= \fIvalue\fR] [, \&.\&.\&. ] ) ]
114 [ USING INDEX TABLESPACE \fItablespace_name\fR ]
116 \fIexclude_element\fR in an EXCLUDE constraint is:
118 { \fIcolumn_name\fR | ( \fIexpression\fR ) } [ COLLATE \fIcollation\fR ] [ \fIopclass\fR [ ( \fIopclass_parameter\fR = \fIvalue\fR [, \&.\&.\&. ] ) ] ] [ ASC | DESC ] [ NULLS { FIRST | LAST } ]
120 \fIreferential_action\fR in a FOREIGN KEY/REFERENCES constraint is:
122 { NO ACTION | RESTRICT | CASCADE | SET NULL [ ( \fIcolumn_name\fR [, \&.\&.\&. ] ) ] | SET DEFAULT [ ( \fIcolumn_name\fR [, \&.\&.\&. ] ) ] }
127 will create a new, initially empty table in the current database\&. The table will be owned by the user issuing the command\&.
129 If a schema name is given (for example,
130 CREATE TABLE myschema\&.mytable \&.\&.\&.) then the table is created in the specified schema\&. Otherwise it is created in the current schema\&. Temporary tables exist in a special schema, so a schema name cannot be given when creating a temporary table\&. The name of the table must be distinct from the name of any other relation (table, sequence, index, view, materialized view, or foreign table) in the same schema\&.
133 also automatically creates a data type that represents the composite type corresponding to one row of the table\&. Therefore, tables cannot have the same name as any existing data type in the same schema\&.
135 The optional constraint clauses specify constraints (tests) that new or updated rows must satisfy for an insert or update operation to succeed\&. A constraint is an SQL object that helps define the set of valid values in the table in various ways\&.
137 There are two ways to define constraints: table constraints and column constraints\&. A column constraint is defined as part of a column definition\&. A table constraint definition is not tied to a particular column, and it can encompass more than one column\&. Every column constraint can also be written as a table constraint; a column constraint is only a notational convenience for use when the constraint only affects one column\&.
139 To be able to create a table, you must have
141 privilege on all column types or the type in the
143 clause, respectively\&.
148 If specified, the table is created as a temporary table\&. Temporary tables are automatically dropped at the end of a session, or optionally at the end of the current transaction (see
150 below)\&. The default search_path includes the temporary schema first and so identically named existing permanent tables are not chosen for new plans while the temporary table exists, unless they are referenced with schema\-qualified names\&. Any indexes created on a temporary table are automatically temporary as well\&.
154 cannot access and therefore cannot vacuum or analyze temporary tables\&. For this reason, appropriate vacuum and analyze operations should be performed via session SQL commands\&. For example, if a temporary table is going to be used in complex queries, it is wise to run
156 on the temporary table after it is populated\&.
162 can be written before
165 TEMP\&. This presently makes no difference in
167 and is deprecated; see
174 If specified, the table is created as an unlogged table\&. Data written to unlogged tables is not written to the write\-ahead log (see
175 Chapter\ \&28), which makes them considerably faster than ordinary tables\&. However, they are not crash\-safe: an unlogged table is automatically truncated after a crash or unclean shutdown\&. The contents of an unlogged table are also not replicated to standby servers\&. Any indexes created on an unlogged table are automatically unlogged as well\&.
177 If this is specified, any sequences created together with the unlogged table (for identity or serial columns) are also created as unlogged\&.
179 This form is not supported for partitioned tables\&.
184 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 relation is anything like the one that would have been created\&.
189 The name (optionally schema\-qualified) of the table to be created\&.
195 typed table, which takes its structure from the specified stand\-alone composite type (that is, one created using
196 CREATE TYPE (\fBCREATE_TYPE\fR(7))) though it still produces a new composite type as well\&. The table will have a dependency on the referenced type, meaning that cascaded alter and drop actions on that type will propagate to the table\&.
198 A typed table always has the same column names and data types as the type it is derived from, so you cannot specify additional columns\&. But the
200 command can add defaults and constraints to the table, as well as specify storage parameters\&.
205 The name of a column to be created in the new table\&.
210 The data type of the column\&. This can include array specifiers\&. For more information on the data types supported by
215 COLLATE \fIcollation\fR
219 clause assigns a collation to the column (which must be of a collatable data type)\&. If not specified, the column data type\*(Aqs default collation is used\&.
222 STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN | DEFAULT }
224 This form sets the storage mode for the column\&. This controls whether this column is held inline or in a secondary
226 table, and whether the data should be compressed or not\&.
228 must be used for fixed\-length values such as
230 and is inline, uncompressed\&.
232 is for inline, compressible data\&.
234 is for external, uncompressed data, and
236 is for external, compressed data\&. Writing
238 sets the storage mode to the default mode for the column\*(Aqs data type\&.
240 is the default for most data types that support non\-PLAIN
243 will make substring operations on very large
247 values run faster, at the penalty of increased storage space\&. See
249 for more information\&.
252 COMPRESSION \fIcompression_method\fR
256 clause sets the compression method for the column\&. Compression is supported only for variable\-width data types, and is used only when the column\*(Aqs storage mode is
260 ALTER TABLE (\fBALTER_TABLE\fR(7))
261 for information on column storage modes\&.) Setting this property for a partitioned table has no direct effect, because such tables have no storage of their own, but the configured value will be inherited by newly\-created partitions\&. The supported compression methods are
267 was used when building
268 PostgreSQL\&.) In addition,
269 \fIcompression_method\fR
272 to explicitly specify the default behavior, which is to consult the
273 default_toast_compression
274 setting at the time of data insertion to determine the method to use\&.
277 INHERITS ( \fIparent_table\fR [, \&.\&.\&. ] )
281 clause specifies a list of tables from which the new table automatically inherits all columns\&. Parent tables can be plain tables or foreign tables\&.
285 creates a persistent relationship between the new child table and its parent table(s)\&. Schema modifications to the parent(s) normally propagate to children as well, and by default the data of the child table is included in scans of the parent(s)\&.
287 If the same column name exists in more than one parent table, an error is reported unless the data types of the columns match in each of the parent tables\&. If there is no conflict, then the duplicate columns are merged to form a single column in the new table\&. If the column name list of the new table contains a column name that is also inherited, the data type must likewise match the inherited column(s), and the column definitions are merged into one\&. If the new table explicitly specifies a default value for the column, this default overrides any defaults from inherited declarations of the column\&. Otherwise, any parents that specify default values for the column must all specify the same default, or an error will be reported\&.
290 constraints are merged in essentially the same way as columns: if multiple parent tables and/or the new table definition contain identically\-named
292 constraints, these constraints must all have the same check expression, or an error will be reported\&. Constraints having the same name and expression will be merged into one copy\&. A constraint marked
294 in a parent will not be considered\&. Notice that an unnamed
296 constraint in the new table will never be merged, since a unique name will always be chosen for it\&.
300 settings are also copied from parent tables\&.
302 If a column in the parent table is an identity column, that property is not inherited\&. A column in the child table can be declared identity column if desired\&.
305 PARTITION BY { RANGE | LIST | HASH } ( { \fIcolumn_name\fR | ( \fIexpression\fR ) } [ \fIopclass\fR ] [, \&.\&.\&.] )
309 clause specifies a strategy of partitioning the table\&. The table thus created is called a
311 table\&. The parenthesized list of columns or expressions forms the
313 for the table\&. When using range or hash partitioning, the partition key can include multiple columns or expressions (up to 32, but this limit can be altered when building
314 PostgreSQL), but for list partitioning, the partition key must consist of a single column or expression\&.
316 Range and list partitioning require a btree operator class, while hash partitioning requires a hash operator class\&. If no operator class is specified explicitly, the default operator class of the appropriate type will be used; if no default operator class exists, an error will be raised\&. When hash partitioning is used, the operator class used must implement support function 2 (see
320 A partitioned table is divided into sub\-tables (called partitions), which are created using separate
322 commands\&. The partitioned table is itself empty\&. A data row inserted into the table is routed to a partition based on the value of columns or expressions in the partition key\&. If no existing partition matches the values in the new row, an error will be reported\&.
326 for more discussion on table partitioning\&.
329 PARTITION OF \fIparent_table\fR { FOR VALUES \fIpartition_bound_spec\fR | DEFAULT }
331 Creates the table as a
333 of the specified parent table\&. The table can be created either as a partition for specific values using
335 or as a default partition using
336 DEFAULT\&. Any indexes, constraints and user\-defined row\-level triggers that exist in the parent table are cloned on the new partition\&.
339 \fIpartition_bound_spec\fR
340 must correspond to the partitioning method and partition key of the parent table, and must not overlap with any existing partition of that parent\&. The form with
342 is used for list partitioning, the form with
346 is used for range partitioning, and the form with
348 is used for hash partitioning\&.
350 \fIpartition_bound_expr\fR
351 is any variable\-free expression (subqueries, window functions, aggregate functions, and set\-returning functions are not allowed)\&. Its data type must match the data type of the corresponding partition key column\&. The expression is evaluated once at table creation time, so it can even contain volatile expressions such as
352 \fBCURRENT_TIMESTAMP\fR\&.
354 When creating a list partition,
356 can be specified to signify that the partition allows the partition key column to be null\&. However, there cannot be more than one such list partition for a given parent table\&.
358 cannot be specified for range partitions\&.
360 When creating a range partition, the lower bound specified with
362 is an inclusive bound, whereas the upper bound specified with
364 is an exclusive bound\&. That is, the values specified in the
366 list are valid values of the corresponding partition key columns for this partition, whereas those in the
368 list are not\&. Note that this statement must be understood according to the rules of row\-wise comparison (Section\ \&9.25.5)\&. For example, given
369 PARTITION BY RANGE (x,y), a partition bound
370 FROM (1, 2) TO (3, 4)
386 may be used when creating a range partition to indicate that there is no lower or upper bound on the column\*(Aqs value\&. For example, a partition defined using
387 FROM (MINVALUE) TO (10)
388 allows any values less than 10, and a partition defined using
389 FROM (10) TO (MAXVALUE)
390 allows any values greater than or equal to 10\&.
392 When creating a range partition involving more than one column, it can also make sense to use
394 as part of the lower bound, and
396 as part of the upper bound\&. For example, a partition defined using
397 FROM (0, MAXVALUE) TO (10, MAXVALUE)
398 allows any rows where the first partition key column is greater than 0 and less than or equal to 10\&. Similarly, a partition defined using
399 FROM (\*(Aqa\*(Aq, MINVALUE) TO (\*(Aqb\*(Aq, MINVALUE)
400 allows any rows where the first partition key column starts with "a"\&.
406 is used for one column of a partitioning bound, the same value must be used for all subsequent columns\&. For example,
408 is not a valid bound; you should write
409 (10, MINVALUE, MINVALUE)\&.
411 Also note that some element types, such as
412 timestamp, have a notion of "infinity", which is just another value that can be stored\&. This is different from
415 MAXVALUE, which are not real values that can be stored, but rather they are ways of saying that the value is unbounded\&.
417 can be thought of as being greater than any other value, including "infinity" and
419 as being less than any other value, including "minus infinity"\&. Thus the range
420 FROM (\*(Aqinfinity\*(Aq) TO (MAXVALUE)
421 is not an empty range; it allows precisely one value to be stored \(em "infinity"\&.
425 is specified, the table will be created as the default partition of the parent table\&. This option is not available for hash\-partitioned tables\&. A partition key value not fitting into any other partition of the given parent will be routed to the default partition\&.
427 When a table has an existing
429 partition and a new partition is added to it, the default partition must be scanned to verify that it does not contain any rows which properly belong in the new partition\&. If the default partition contains a large number of rows, this may be slow\&. The scan will be skipped if the default partition is a foreign table or if it has a constraint which proves that it cannot contain rows which should be placed in the new partition\&.
431 When creating a hash partition, a modulus and remainder must be specified\&. The modulus must be a positive integer, and the remainder must be a non\-negative integer less than the modulus\&. Typically, when initially setting up a hash\-partitioned table, you should choose a modulus equal to the number of partitions and assign every table the same modulus and a different remainder (see examples, below)\&. However, it is not required that every partition have the same modulus, only that every modulus which occurs among the partitions of a hash\-partitioned table is a factor of the next larger modulus\&. This allows the number of partitions to be increased incrementally without needing to move all the data at once\&. For example, suppose you have a hash\-partitioned table with 8 partitions, each of which has modulus 8, but find it necessary to increase the number of partitions to 16\&. You can detach one of the modulus\-8 partitions, create two new modulus\-16 partitions covering the same portion of the key space (one with a remainder equal to the remainder of the detached partition, and the other with a remainder equal to that value plus 8), and repopulate them with data\&. You can then repeat this \-\- perhaps at a later time \-\- for each modulus\-8 partition until none remain\&. While this may still involve a large amount of data movement at each step, it is still better than having to create a whole new table and move all the data at once\&.
433 A partition must have the same column names and types as the partitioned table to which it belongs\&. Modifications to the column names or types of a partitioned table will automatically propagate to all partitions\&.
435 constraints will be inherited automatically by every partition, but an individual partition may specify additional
437 constraints; additional constraints with the same name and condition as in the parent will be merged with the parent constraint\&. Defaults may be specified separately for each partition\&. But note that a partition\*(Aqs default value is not applied when inserting a tuple through a partitioned table\&.
439 Rows inserted into a partitioned table will be automatically routed to the correct partition\&. If no suitable partition exists, an error will occur\&.
443 which normally affect a table and all of its inheritance children will cascade to all partitions, but may also be performed on an individual partition\&.
445 Note that creating a partition using
449 lock on the parent partitioned table\&. Likewise, dropping a partition with
453 lock on the parent table\&. It is possible to use
454 \fBALTER TABLE ATTACH/DETACH PARTITION\fR
455 to perform these operations with a weaker lock, thus reducing interference with concurrent operations on the partitioned table\&.
458 LIKE \fIsource_table\fR [ \fIlike_option\fR \&.\&.\&. ]
462 clause specifies a table from which the new table automatically copies all column names, their data types, and their not\-null constraints\&.
465 INHERITS, the new table and original table are completely decoupled after creation is complete\&. Changes to the original table will not be applied to the new table, and it is not possible to include data of the new table in scans of the original table\&.
468 INHERITS, columns and constraints copied by
470 are not merged with similarly named columns and constraints\&. If the same name is specified explicitly or in another
472 clause, an error is signaled\&.
476 clauses specify which additional properties of the original table to copy\&. Specifying
478 copies the property, specifying
480 omits the property\&.
482 is the default\&. If multiple specifications are made for the same kind of object, the last one is used\&. The available options are:
486 Comments for the copied columns, constraints, and indexes will be copied\&. The default behavior is to exclude comments, resulting in the copied columns and constraints in the new table having no comments\&.
489 INCLUDING COMPRESSION
491 Compression method of the columns will be copied\&. The default behavior is to exclude compression methods, resulting in columns having the default compression method\&.
494 INCLUDING CONSTRAINTS
497 constraints will be copied\&. No distinction is made between column constraints and table constraints\&. Not\-null constraints are always copied to the new table\&.
502 Default expressions for the copied column definitions will be copied\&. Otherwise, default expressions are not copied, resulting in the copied columns in the new table having null defaults\&. Note that copying defaults that call database\-modification functions, such as
503 \fBnextval\fR, may create a functional linkage between the original and new tables\&.
508 Any generation expressions as well as the stored/virtual choice of copied column definitions will be copied\&. By default, new columns will be regular base columns\&.
513 Any identity specifications of copied column definitions will be copied\&. A new sequence is created for each identity column of the new table, separate from the sequences associated with the old table\&.
522 constraints on the original table will be created on the new table\&. Names for the new indexes and constraints are chosen according to the default rules, regardless of how the originals were named\&. (This behavior avoids possible duplicate\-name failures for the new indexes\&.)
527 Extended statistics are copied to the new table\&.
533 settings for the copied column definitions will be copied\&. The default behavior is to exclude
535 settings, resulting in the copied columns in the new table having type\-specific default settings\&. For more on
544 is an abbreviated form selecting all the available individual options\&. (It could be useful to write individual
548 to select all but some specific options\&.)
553 clause can also be used to copy column definitions from views, foreign tables, or composite types\&. Inapplicable options (e\&.g\&.,
555 from a view) are ignored\&.
558 CONSTRAINT \fIconstraint_name\fR
560 An optional name for a column or table constraint\&. If the constraint is violated, the constraint name is present in error messages, so constraint names like
562 can be used to communicate helpful constraint information to client applications\&. (Double\-quotes are needed to specify constraint names that contain spaces\&.) If a constraint name is not specified, the system generates a name\&.
565 NOT NULL [ NO INHERIT ]
567 The column is not allowed to contain null values\&.
569 A constraint marked with
571 will not propagate to child tables\&.
576 The column is allowed to contain null values\&. This is the default\&.
578 This clause is only provided for compatibility with non\-standard SQL databases\&. Its use is discouraged in new applications\&.
581 CHECK ( \fIexpression\fR ) [ NO INHERIT ]
585 clause specifies an expression producing a Boolean result which new or updated rows must satisfy for an insert or update operation to succeed\&. Expressions evaluating to TRUE or UNKNOWN succeed\&. Should any row of an insert or update operation produce a FALSE result, an error exception is raised and the insert or update does not alter the database\&. A check constraint specified as a column constraint should reference that column\*(Aqs value only, while an expression appearing in a table constraint can reference multiple columns\&.
589 expressions cannot contain subqueries nor refer to variables other than columns of the current row (see
590 Section\ \&5.5.1)\&. The system column
592 may be referenced, but not any other system column\&.
594 A constraint marked with
596 will not propagate to child tables\&.
598 When a table has multiple
600 constraints, they will be tested for each row in alphabetical order by name, after checking
602 constraints\&. (PostgreSQL
603 versions before 9\&.5 did not honor any particular firing order for
608 DEFAULT \fIdefault_expr\fR
612 clause assigns a default data value for the column whose column definition it appears within\&. The value is any variable\-free expression (in particular, cross\-references to other columns in the current table are not allowed)\&. Subqueries are not allowed either\&. The data type of the default expression must match the data type of the column\&.
614 The default expression will be used in any insert operation that does not specify a value for the column\&. If there is no default for a column, then the default is null\&.
617 GENERATED ALWAYS AS ( \fIgeneration_expr\fR ) [ STORED | VIRTUAL ]
619 This clause creates the column as a
620 generated column\&. The column cannot be written to, and when read the result of the specified expression will be returned\&.
624 is specified, the column will be computed when it is read, and it will not occupy any storage\&. When
626 is specified, the column will be computed on write and will be stored on disk\&.
630 The generation expression can refer to other columns in the table, but not other generated columns\&. Any functions and operators used must be immutable\&. References to other tables are not allowed\&.
632 A virtual generated column cannot have a user\-defined type, and the generation expression of a virtual generated column must not reference user\-defined functions or types, that is, it can only use built\-in functions or types\&. This applies also indirectly, such as for functions or types that underlie operators or casts\&. (This restriction does not exist for stored generated columns\&.)
635 GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( \fIsequence_options\fR ) ]
637 This clause creates the column as an
638 identity column\&. It will have an implicit sequence attached to it and in newly\-inserted rows the column will automatically have values from the sequence assigned to it\&. Such a column is implicitly
645 determine how explicitly user\-specified values are handled in
655 is selected, a user\-specified value is only accepted if the
658 OVERRIDING SYSTEM VALUE\&. If
660 is selected, then the user\-specified value takes precedence\&. See
662 for details\&. (In the
664 command, user\-specified values are always used regardless of this setting\&.)
670 is selected, any update of the column to any value other than
672 will be rejected\&. If
674 is selected, the column can be updated normally\&. (There is no
681 \fIsequence_options\fR
682 clause can be used to override the parameters of the sequence\&. The available options include those shown for
683 CREATE SEQUENCE (\fBCREATE_SEQUENCE\fR(7)), plus
684 SEQUENCE NAME \fIname\fR,
686 UNLOGGED, which allow selection of the name and persistence level of the sequence\&. Without
687 SEQUENCE NAME, the system chooses an unused name for the sequence\&. Without
690 UNLOGGED, the sequence will have the same persistence level as the table\&.
693 UNIQUE [ NULLS [ NOT ] DISTINCT ] (column constraint)
695 UNIQUE [ NULLS [ NOT ] DISTINCT ] ( \fIcolumn_name\fR [, \&.\&.\&. ] [, \fIcolumn_name\fR WITHOUT OVERLAPS ] ) [ INCLUDE ( \fIcolumn_name\fR [, \&.\&.\&.]) ] (table constraint)
699 constraint specifies that a group of one or more columns of a table can contain only unique values\&. The behavior of a unique table constraint is the same as that of a unique column constraint, with the additional capability to span multiple columns\&. The constraint therefore enforces that any two rows must differ in at least one of these columns\&.
703 option is specified for the last column, then that column is checked for overlaps instead of equality\&. In that case, the other columns of the constraint will allow duplicates so long as the duplicates don\*(Aqt overlap in the
705 column\&. (This is sometimes called a temporal key, if the column is a range of dates or timestamps, but
707 allows ranges over any base type\&.) In effect, such a constraint is enforced with an
709 constraint rather than a
711 constraint\&. So for example
712 UNIQUE (id, valid_at WITHOUT OVERLAPS)
714 EXCLUDE USING GIST (id WITH =, valid_at WITH &&)\&. The
716 column must have a range or multirange type\&. Empty ranges/multiranges are not permitted\&. The non\-WITHOUT OVERLAPS
717 columns of the constraint can be any type that can be compared for equality in a GiST index\&. By default, only range types are supported, but you can use other types by adding the
719 extension (which is the expected way to use this feature)\&.
721 For the purpose of a unique constraint, null values are not considered equal, unless
725 Each unique constraint should name a set of columns that is different from the set of columns named by any other unique or primary key constraint defined for the table\&. (Otherwise, redundant unique constraints will be discarded\&.)
727 When establishing a unique constraint for a multi\-level partition hierarchy, all the columns in the partition key of the target partitioned table, as well as those of all its descendant partitioned tables, must be included in the constraint definition\&.
729 Adding a unique constraint will automatically create a unique btree index on the column or group of columns used in the constraint\&. But if the constraint includes a
731 clause, it will use a GiST index\&. The created index has the same name as the unique constraint\&.
735 clause adds to that index one or more columns that are simply
736 \(lqpayload\(rq: uniqueness is not enforced on them, and the index cannot be searched on the basis of those columns\&. However they can be retrieved by an index\-only scan\&. Note that although the constraint is not enforced on included columns, it still depends on them\&. Consequently, some operations on such columns (e\&.g\&.,
737 DROP COLUMN) can cause cascaded constraint and index deletion\&.
740 PRIMARY KEY (column constraint)
742 PRIMARY KEY ( \fIcolumn_name\fR [, \&.\&.\&. ] [, \fIcolumn_name\fR WITHOUT OVERLAPS ] ) [ INCLUDE ( \fIcolumn_name\fR [, \&.\&.\&.]) ] (table constraint)
746 constraint specifies that a column or columns of a table can contain only unique (non\-duplicate), nonnull values\&. Only one primary key can be specified for a table, whether as a column constraint or a table constraint\&.
748 The primary key constraint should name a set of columns that is different from the set of columns named by any unique constraint defined for the same table\&. (Otherwise, the unique constraint is redundant and will be discarded\&.)
751 enforces the same data constraints as a combination of
754 NOT NULL\&. However, identifying a set of columns as the primary key also provides metadata about the design of the schema, since a primary key implies that other tables can rely on this set of columns as a unique identifier for rows\&.
756 When placed on a partitioned table,
758 constraints share the restrictions previously described for
764 constraint will automatically create a unique btree index on the column or group of columns used in the constraint, or GiST if
770 clause adds to that index one or more columns that are simply
771 \(lqpayload\(rq: uniqueness is not enforced on them, and the index cannot be searched on the basis of those columns\&. However they can be retrieved by an index\-only scan\&. Note that although the constraint is not enforced on included columns, it still depends on them\&. Consequently, some operations on such columns (e\&.g\&.,
772 DROP COLUMN) can cause cascaded constraint and index deletion\&.
775 EXCLUDE [ USING \fIindex_method\fR ] ( \fIexclude_element\fR WITH \fIoperator\fR [, \&.\&.\&. ] ) \fIindex_parameters\fR [ WHERE ( \fIpredicate\fR ) ]
779 clause defines an exclusion constraint, which guarantees that if any two rows are compared on the specified column(s) or expression(s) using the specified operator(s), not all of these comparisons will return
780 TRUE\&. If all of the specified operators test for equality, this is equivalent to a
782 constraint, although an ordinary unique constraint will be faster\&. However, exclusion constraints can specify constraints that are more general than simple equality\&. For example, you can specify a constraint that no two rows in the table contain overlapping circles (see
783 Section\ \&8.8) by using the
785 operator\&. The operator(s) are required to be commutative\&.
787 Exclusion constraints are implemented using an index that has the same name as the constraint, so each specified operator must be associated with an appropriate operator class (see
788 Section\ \&11.10) for the index access method
789 \fIindex_method\fR\&. Each
790 \fIexclude_element\fR
791 defines a column of the index, so it can optionally specify a collation, an operator class, operator class parameters, and/or ordering options; these are described fully under
792 CREATE INDEX (\fBCREATE_INDEX\fR(7))\&.
794 The access method must support
797 Chapter\ \&63); at present this means
799 cannot be used\&. Although it\*(Aqs allowed, there is little point in using B\-tree or hash indexes with an exclusion constraint, because this does nothing that an ordinary unique constraint doesn\*(Aqt do better\&. So in practice the access method will always be
806 allows you to specify an exclusion constraint on a subset of the table; internally this creates a partial index\&. Note that parentheses are required around the predicate\&.
808 When establishing an exclusion constraint for a multi\-level partition hierarchy, all the columns in the partition key of the target partitioned table, as well as those of all its descendant partitioned tables, must be included in the constraint definition\&. Additionally, those columns must be compared using the equality operator\&. These restrictions ensure that potentially\-conflicting rows will exist in the same partition\&. The constraint may also refer to other columns which are not a part of any partition key, which can be compared using any appropriate operator\&.
811 REFERENCES \fIreftable\fR [ ( \fIrefcolumn\fR ) ] [ MATCH \fImatchtype\fR ] [ ON DELETE \fIreferential_action\fR ] [ ON UPDATE \fIreferential_action\fR ] (column constraint)
813 FOREIGN KEY ( \fIcolumn_name\fR [, \&.\&.\&. ] [, PERIOD \fIcolumn_name\fR ] ) REFERENCES \fIreftable\fR [ ( \fIrefcolumn\fR [, \&.\&.\&. ] [, PERIOD \fIrefcolumn\fR ] ) ] [ MATCH \fImatchtype\fR ] [ ON DELETE \fIreferential_action\fR ] [ ON UPDATE \fIreferential_action\fR ] (table constraint)
815 These clauses specify a foreign key constraint, which requires that a group of one or more columns of the new table must only contain values that match values in the referenced column(s) of some row of the referenced table\&. If the
817 list is omitted, the primary key of the
819 is used\&. Otherwise, the
821 list must refer to the columns of a non\-deferrable unique or primary key constraint or be the columns of a non\-partial unique index\&.
823 If the last column is marked with
824 PERIOD, it is treated in a special way\&. While the non\-PERIOD
825 columns are compared for equality (and there must be at least one of them), the
827 column is not\&. Instead, the constraint is considered satisfied if the referenced table has matching records (based on the non\-PERIOD
828 parts of the key) whose combined
830 values completely cover the referencing record\*(Aqs\&. In other words, the reference must have a referent for its entire duration\&. This column must be a range or multirange type\&. In addition, the referenced table must have a primary key or unique constraint declared with
831 WITHOUT OVERLAPS\&. Finally, if the foreign key has a PERIOD
833 specification the corresponding
834 \fIrefcolumn\fR, if present, must also be marked
837 clause is omitted, and thus the reftable\*(Aqs primary key constraint chosen, the primary key must have its final column marked
840 For each pair of referencing and referenced column, if they are of a collatable data type, then the collations must either be both deterministic or else both the same\&. This ensures that both columns have a consistent notion of equality\&.
844 permission on the referenced table (either the whole table, or the specific referenced columns)\&. The addition of a foreign key constraint requires a
846 lock on the referenced table\&. Note that foreign key constraints cannot be defined between temporary tables and permanent tables\&.
848 A value inserted into the referencing column(s) is matched against the values of the referenced table and referenced columns using the given match type\&. There are three match types:
852 (which is the default)\&.
854 will not allow one column of a multicolumn foreign key to be null unless all foreign key columns are null; if they are all null, the row is not required to have a match in the referenced table\&.
856 allows any of the foreign key columns to be null; if any of them are null, the row is not required to have a match in the referenced table\&.
858 is not yet implemented\&. (Of course,
860 constraints can be applied to the referencing column(s) to prevent these cases from arising\&.)
862 In addition, when the data in the referenced columns is changed, certain actions are performed on the data in this table\*(Aqs columns\&. The
864 clause specifies the action to perform when a referenced row in the referenced table is being deleted\&. Likewise, the
866 clause specifies the action to perform when a referenced column in the referenced table is being updated to a new value\&. If the row is updated, but the referenced column is not actually changed, no action is done\&. Referential actions are executed as part of the data changing command, even if the constraint is deferred\&. There are the following possible actions for each clause:
870 Produce an error if the deletion or update would create a foreign key constraint violation\&. If the constraint is deferred, this error will be produced at constraint check time if there still exist any referencing rows\&. This is the default action\&.
875 Produce an error if a row to be deleted or updated matches a row in the referencing table\&. This prevents the action even if the state after the action would not violate the foreign key constraint\&. In particular, it prevents updates of referenced rows to values that are distinct but compare as equal\&. (But it does not prevent
877 updates that update a column to the same value\&.)
879 In a temporal foreign key, this option is not supported\&.
884 Delete any rows referencing the deleted row, or update the values of the referencing column(s) to the new values of the referenced columns, respectively\&.
886 In a temporal foreign key, this option is not supported\&.
889 SET NULL [ ( \fIcolumn_name\fR [, \&.\&.\&. ] ) ]
891 Set all of the referencing columns, or a specified subset of the referencing columns, to null\&. A subset of columns can only be specified for
895 In a temporal foreign key, this option is not supported\&.
898 SET DEFAULT [ ( \fIcolumn_name\fR [, \&.\&.\&. ] ) ]
900 Set all of the referencing columns, or a specified subset of the referencing columns, to their default values\&. A subset of columns can only be specified for
902 actions\&. (There must be a row in the referenced table matching the default values, if they are not null, or the operation will fail\&.)
904 In a temporal foreign key, this option is not supported\&.
907 If the referenced column(s) are changed frequently, it might be wise to add an index to the referencing column(s) so that referential actions associated with the foreign key constraint can be performed more efficiently\&.
914 This controls whether the constraint can be deferred\&. A constraint that is not deferrable will be checked immediately after every command\&. Checking of constraints that are deferrable can be postponed until the end of the transaction (using the
915 \fBSET CONSTRAINTS\fR
918 is the default\&. Currently, only
923 (foreign key) constraints accept this clause\&.
927 constraints are not deferrable\&. Note that deferrable constraints cannot be used as conflict arbitrators in an
929 statement that includes an
930 ON CONFLICT DO UPDATE
938 If a constraint is deferrable, this clause specifies the default time to check the constraint\&. If the constraint is
939 INITIALLY IMMEDIATE, it is checked after each statement\&. This is the default\&. If the constraint is
940 INITIALLY DEFERRED, it is checked only at the end of the transaction\&. The constraint check time can be altered with the
941 \fBSET CONSTRAINTS\fR
949 When the constraint is
950 ENFORCED, then the database system will ensure that the constraint is satisfied, by checking the constraint at appropriate times (after each statement or at the end of the transaction, as appropriate)\&. That is the default\&. If the constraint is
951 NOT ENFORCED, the database system will not check the constraint\&. It is then up to the application code to ensure that the constraints are satisfied\&. The database system might still assume that the data actually satisfies the constraint for optimization decisions where this does not affect the correctness of the result\&.
954 constraints can be useful as documentation if the actual checking of the constraint at run time is too expensive\&.
956 This is currently only supported for foreign key and
963 This optional clause specifies the table access method to use to store the contents for the new table; the method needs be an access method of type
966 for more information\&. If this option is not specified, the default table access method is chosen for the new table\&. See
967 default_table_access_method
968 for more information\&.
970 When creating a partition, the table access method is the access method of its partitioned table, if set\&.
973 WITH ( \fIstorage_parameter\fR [= \fIvalue\fR] [, \&.\&.\&. ] )
975 This clause specifies optional storage parameters for a table or index; see
977 below for more information\&. For backward\-compatibility the
979 clause for a table can also include
981 to specify that rows of the new table should not contain OIDs (object identifiers),
983 is not supported anymore\&.
988 This is backward\-compatible syntax for declaring a table
989 WITHOUT OIDS, creating a table
991 is not supported anymore\&.
996 The behavior of temporary tables at the end of a transaction block can be controlled using
997 ON COMMIT\&. The three options are:
1001 No special action is taken at the ends of transactions\&. This is the default behavior\&.
1006 All rows in the temporary table will be deleted at the end of each transaction block\&. Essentially, an automatic
1008 is done at each commit\&. When used on a partitioned table, this is not cascaded to its partitions\&.
1013 The temporary table will be dropped at the end of the current transaction block\&. When used on a partitioned table, this action drops its partitions and when used on tables with inheritance children, it drops the dependent children\&.
1017 TABLESPACE \fItablespace_name\fR
1020 \fItablespace_name\fR
1021 is the name of the tablespace in which the new table is to be created\&. If not specified,
1025 if the table is temporary\&. For partitioned tables, since no storage is required for the table itself, the tablespace specified overrides
1027 as the default tablespace to use for any newly created partitions when no other tablespace is explicitly specified\&.
1030 USING INDEX TABLESPACE \fItablespace_name\fR
1032 This clause allows selection of the tablespace in which the index associated with a
1036 constraint will be created\&. If not specified,
1040 if the table is temporary\&.
1042 .SS "Storage Parameters"
1048 for tables, and for indexes associated with a
1052 constraint\&. Storage parameters for indexes are documented in
1053 CREATE INDEX (\fBCREATE_INDEX\fR(7))\&. The storage parameters currently available for tables are listed below\&. For many of these parameters, as shown, there is an additional parameter with the same name prefixed with
1054 toast\&., which controls the behavior of the table\*(Aqs secondary
1058 for more information about TOAST)\&. If a table parameter value is set and the equivalent
1060 parameter is not, the TOAST table will use the table\*(Aqs parameter value\&. Specifying these parameters for partitioned tables is not supported, but you may specify them for individual leaf partitions\&.
1062 \fIfillfactor\fR (integer)
1064 The fillfactor for a table is a percentage between 10 and 100\&. 100 (complete packing) is the default\&. When a smaller fillfactor is specified,
1066 operations pack table pages only to the indicated percentage; the remaining space on each page is reserved for updating rows on that page\&. This gives
1068 a chance to place the updated copy of a row on the same page as the original, which is more efficient than placing it on a different page, and makes
1069 heap\-only tuple updates
1070 more likely\&. For a table whose entries are never updated, complete packing is the best choice, but in heavily updated tables smaller fillfactors are appropriate\&. This parameter cannot be set for TOAST tables\&.
1073 toast_tuple_target (integer)
1075 The toast_tuple_target specifies the minimum tuple length required before we try to compress and/or move long column values into TOAST tables, and is also the target length we try to reduce the length below once toasting begins\&. This affects columns marked as External (for move), Main (for compression), or Extended (for both) and applies only to new tuples\&. There is no effect on existing rows\&. By default this parameter is set to allow at least 4 tuples per block, which with the default block size will be 2040 bytes\&. Valid values are between 128 bytes and the (block size \- header), by default 8160 bytes\&. Changing this value may not be useful for very short or very long rows\&. Note that the default setting is often close to optimal, and it is possible that setting this parameter could have negative effects in some cases\&. This parameter cannot be set for TOAST tables\&.
1078 parallel_workers (integer)
1080 This sets the number of workers that should be used to assist a parallel scan of this table\&. If not set, the system will determine a value based on the relation size\&. The actual number of workers chosen by the planner or by utility statements that use parallel scans may be less, for example due to the setting of
1081 max_worker_processes\&.
1084 autovacuum_enabled, toast\&.autovacuum_enabled (boolean)
1086 Enables or disables the autovacuum daemon for a particular table\&. If true, the autovacuum daemon will perform automatic
1090 operations on this table following the rules discussed in
1091 Section\ \&24.1.6\&. If false, this table will not be autovacuumed, except to prevent transaction ID wraparound\&. See
1093 for more about wraparound prevention\&. Note that the autovacuum daemon does not run at all (except to prevent transaction ID wraparound) if the
1095 parameter is false; setting individual tables\*(Aq storage parameters does not override that\&. Therefore there is seldom much point in explicitly setting this storage parameter to
1100 vacuum_index_cleanup, toast\&.vacuum_index_cleanup (enum)
1102 Forces or disables index cleanup when
1104 is run on this table\&. The default value is
1106 OFF, index cleanup is disabled, with
1108 it is enabled, and with
1110 a decision is made dynamically, each time
1112 runs\&. The dynamic behavior allows
1114 to avoid needlessly scanning indexes to remove very few dead tuples\&. Forcibly disabling all index cleanup can speed up
1116 very significantly, but may also lead to severely bloated indexes if table modifications are frequent\&. The
1119 \fBVACUUM\fR, if specified, overrides the value of this option\&.
1122 vacuum_truncate, toast\&.vacuum_truncate (boolean)
1124 Per\-table value for
1129 \fBVACUUM\fR, if specified, overrides the value of this option\&.
1132 autovacuum_vacuum_threshold, toast\&.autovacuum_vacuum_threshold (integer)
1134 Per\-table value for
1135 autovacuum_vacuum_threshold
1139 autovacuum_vacuum_max_threshold, toast\&.autovacuum_vacuum_max_threshold (integer)
1141 Per\-table value for
1142 autovacuum_vacuum_max_threshold
1146 autovacuum_vacuum_scale_factor, toast\&.autovacuum_vacuum_scale_factor (floating point)
1148 Per\-table value for
1149 autovacuum_vacuum_scale_factor
1153 autovacuum_vacuum_insert_threshold, toast\&.autovacuum_vacuum_insert_threshold (integer)
1155 Per\-table value for
1156 autovacuum_vacuum_insert_threshold
1157 parameter\&. The special value of \-1 may be used to disable insert vacuums on the table\&.
1160 autovacuum_vacuum_insert_scale_factor, toast\&.autovacuum_vacuum_insert_scale_factor (floating point)
1162 Per\-table value for
1163 autovacuum_vacuum_insert_scale_factor
1167 autovacuum_analyze_threshold (integer)
1169 Per\-table value for
1170 autovacuum_analyze_threshold
1174 autovacuum_analyze_scale_factor (floating point)
1176 Per\-table value for
1177 autovacuum_analyze_scale_factor
1181 autovacuum_vacuum_cost_delay, toast\&.autovacuum_vacuum_cost_delay (floating point)
1183 Per\-table value for
1184 autovacuum_vacuum_cost_delay
1188 autovacuum_vacuum_cost_limit, toast\&.autovacuum_vacuum_cost_limit (integer)
1190 Per\-table value for
1191 autovacuum_vacuum_cost_limit
1195 autovacuum_freeze_min_age, toast\&.autovacuum_freeze_min_age (integer)
1197 Per\-table value for
1198 vacuum_freeze_min_age
1199 parameter\&. Note that autovacuum will ignore per\-table
1200 autovacuum_freeze_min_age
1201 parameters that are larger than half the system\-wide
1202 autovacuum_freeze_max_age
1206 autovacuum_freeze_max_age, toast\&.autovacuum_freeze_max_age (integer)
1208 Per\-table value for
1209 autovacuum_freeze_max_age
1210 parameter\&. Note that autovacuum will ignore per\-table
1211 autovacuum_freeze_max_age
1212 parameters that are larger than the system\-wide setting (it can only be set smaller)\&.
1215 autovacuum_freeze_table_age, toast\&.autovacuum_freeze_table_age (integer)
1217 Per\-table value for
1218 vacuum_freeze_table_age
1222 autovacuum_multixact_freeze_min_age, toast\&.autovacuum_multixact_freeze_min_age (integer)
1224 Per\-table value for
1225 vacuum_multixact_freeze_min_age
1226 parameter\&. Note that autovacuum will ignore per\-table
1227 autovacuum_multixact_freeze_min_age
1228 parameters that are larger than half the system\-wide
1229 autovacuum_multixact_freeze_max_age
1233 autovacuum_multixact_freeze_max_age, toast\&.autovacuum_multixact_freeze_max_age (integer)
1235 Per\-table value for
1236 autovacuum_multixact_freeze_max_age
1237 parameter\&. Note that autovacuum will ignore per\-table
1238 autovacuum_multixact_freeze_max_age
1239 parameters that are larger than the system\-wide setting (it can only be set smaller)\&.
1242 autovacuum_multixact_freeze_table_age, toast\&.autovacuum_multixact_freeze_table_age (integer)
1244 Per\-table value for
1245 vacuum_multixact_freeze_table_age
1249 log_autovacuum_min_duration, toast\&.log_autovacuum_min_duration (integer)
1251 Per\-table value for
1252 log_autovacuum_min_duration
1256 vacuum_max_eager_freeze_failure_rate, toast\&.vacuum_max_eager_freeze_failure_rate (floating point)
1258 Per\-table value for
1259 vacuum_max_eager_freeze_failure_rate
1263 user_catalog_table (boolean)
1265 Declare the table as an additional catalog table for purposes of logical replication\&. See
1267 for details\&. This parameter cannot be set for TOAST tables\&.
1272 automatically creates an index for each unique constraint and primary key constraint to enforce uniqueness\&. Thus, it is not necessary to create an index explicitly for primary key columns\&. (See
1273 CREATE INDEX (\fBCREATE_INDEX\fR(7))
1274 for more information\&.)
1276 Unique constraints and primary keys are not inherited in the current implementation\&. This makes the combination of inheritance and unique constraints rather dysfunctional\&.
1278 A table cannot have more than 1600 columns\&. (In practice, the effective limit is usually lower because of tuple\-length constraints\&.)
1290 CREATE TABLE films (
1291 code char(5) CONSTRAINT firstkey PRIMARY KEY,
1292 title varchar(40) NOT NULL,
1293 did integer NOT NULL,
1296 len interval hour to minute
1299 CREATE TABLE distributors (
1300 did integer PRIMARY KEY GENERATED BY DEFAULT AS IDENTITY,
1301 name varchar(40) NOT NULL CHECK (name <> \*(Aq\*(Aq)
1308 Create a table with a 2\-dimensional array:
1314 CREATE TABLE array_int (
1322 Define a unique table constraint for the table
1323 films\&. Unique table constraints can be defined on one or more columns of the table:
1329 CREATE TABLE films (
1335 len interval hour to minute,
1336 CONSTRAINT production UNIQUE(date_prod)
1343 Define a check column constraint:
1349 CREATE TABLE distributors (
1350 did integer CHECK (did > 100),
1358 Define a check table constraint:
1364 CREATE TABLE distributors (
1367 CONSTRAINT con1 CHECK (did > 100 AND name <> \*(Aq\*(Aq)
1374 Define a primary key table constraint for the table
1381 CREATE TABLE films (
1387 len interval hour to minute,
1388 CONSTRAINT code_title PRIMARY KEY(code,title)
1395 Define a primary key constraint for table
1396 distributors\&. The following two examples are equivalent, the first using the table constraint syntax, the second the column constraint syntax:
1402 CREATE TABLE distributors (
1408 CREATE TABLE distributors (
1409 did integer PRIMARY KEY,
1417 Assign a literal constant default value for the column
1418 name, arrange for the default value of column
1420 to be generated by selecting the next value of a sequence object, and make the default value of
1422 be the time at which the row is inserted:
1428 CREATE TABLE distributors (
1429 name varchar(40) DEFAULT \*(AqLuso Films\*(Aq,
1430 did integer DEFAULT nextval(\*(Aqdistributors_serial\*(Aq),
1431 modtime timestamp DEFAULT current_timestamp
1440 column constraints on the table
1441 distributors, one of which is explicitly given a name:
1447 CREATE TABLE distributors (
1448 did integer CONSTRAINT no_null NOT NULL,
1449 name varchar(40) NOT NULL
1456 Define a unique constraint for the
1464 CREATE TABLE distributors (
1466 name varchar(40) UNIQUE
1473 The same, specified as a table constraint:
1479 CREATE TABLE distributors (
1489 Create the same table, specifying 70% fill factor for both the table and its unique index:
1495 CREATE TABLE distributors (
1498 UNIQUE(name) WITH (fillfactor=70)
1500 WITH (fillfactor=70);
1508 with an exclusion constraint that prevents any two circles from overlapping:
1514 CREATE TABLE circles (
1516 EXCLUDE USING gist (c WITH &&)
1532 CREATE TABLE cinemas (
1536 ) TABLESPACE diskvol1;
1542 Create a composite type and a typed table:
1548 CREATE TYPE employee_type AS (name text, salary numeric);
1550 CREATE TABLE employees OF employee_type (
1552 salary WITH OPTIONS DEFAULT 1000
1559 Create a range partitioned table:
1565 CREATE TABLE measurement (
1566 logdate date not null,
1569 ) PARTITION BY RANGE (logdate);
1575 Create a range partitioned table with multiple columns in the partition key:
1581 CREATE TABLE measurement_year_month (
1582 logdate date not null,
1585 ) PARTITION BY RANGE (EXTRACT(YEAR FROM logdate), EXTRACT(MONTH FROM logdate));
1591 Create a list partitioned table:
1597 CREATE TABLE cities (
1598 city_id bigserial not null,
1601 ) PARTITION BY LIST (left(lower(name), 1));
1607 Create a hash partitioned table:
1613 CREATE TABLE orders (
1614 order_id bigint not null,
1615 cust_id bigint not null,
1617 ) PARTITION BY HASH (order_id);
1623 Create partition of a range partitioned table:
1629 CREATE TABLE measurement_y2016m07
1630 PARTITION OF measurement (
1632 ) FOR VALUES FROM (\*(Aq2016\-07\-01\*(Aq) TO (\*(Aq2016\-08\-01\*(Aq);
1638 Create a few partitions of a range partitioned table with multiple columns in the partition key:
1644 CREATE TABLE measurement_ym_older
1645 PARTITION OF measurement_year_month
1646 FOR VALUES FROM (MINVALUE, MINVALUE) TO (2016, 11);
1648 CREATE TABLE measurement_ym_y2016m11
1649 PARTITION OF measurement_year_month
1650 FOR VALUES FROM (2016, 11) TO (2016, 12);
1652 CREATE TABLE measurement_ym_y2016m12
1653 PARTITION OF measurement_year_month
1654 FOR VALUES FROM (2016, 12) TO (2017, 01);
1656 CREATE TABLE measurement_ym_y2017m01
1657 PARTITION OF measurement_year_month
1658 FOR VALUES FROM (2017, 01) TO (2017, 02);
1664 Create partition of a list partitioned table:
1670 CREATE TABLE cities_ab
1671 PARTITION OF cities (
1672 CONSTRAINT city_id_nonzero CHECK (city_id != 0)
1673 ) FOR VALUES IN (\*(Aqa\*(Aq, \*(Aqb\*(Aq);
1679 Create partition of a list partitioned table that is itself further partitioned and then add a partition to it:
1685 CREATE TABLE cities_ab
1686 PARTITION OF cities (
1687 CONSTRAINT city_id_nonzero CHECK (city_id != 0)
1688 ) FOR VALUES IN (\*(Aqa\*(Aq, \*(Aqb\*(Aq) PARTITION BY RANGE (population);
1690 CREATE TABLE cities_ab_10000_to_100000
1691 PARTITION OF cities_ab FOR VALUES FROM (10000) TO (100000);
1697 Create partitions of a hash partitioned table:
1703 CREATE TABLE orders_p1 PARTITION OF orders
1704 FOR VALUES WITH (MODULUS 4, REMAINDER 0);
1705 CREATE TABLE orders_p2 PARTITION OF orders
1706 FOR VALUES WITH (MODULUS 4, REMAINDER 1);
1707 CREATE TABLE orders_p3 PARTITION OF orders
1708 FOR VALUES WITH (MODULUS 4, REMAINDER 2);
1709 CREATE TABLE orders_p4 PARTITION OF orders
1710 FOR VALUES WITH (MODULUS 4, REMAINDER 3);
1716 Create a default partition:
1722 CREATE TABLE cities_partdef
1723 PARTITION OF cities DEFAULT;
1732 command conforms to the
1734 standard, with exceptions listed below\&.
1735 .SS "Temporary Tables"
1737 Although the syntax of
1738 CREATE TEMPORARY TABLE
1739 resembles that of the SQL standard, the effect is not the same\&. In the standard, temporary tables are defined just once and automatically exist (starting with empty contents) in every session that needs them\&.
1741 instead requires each session to issue its own
1742 CREATE TEMPORARY TABLE
1743 command for each temporary table to be used\&. This allows different sessions to use the same temporary table name for different purposes, whereas the standard\*(Aqs approach constrains all instances of a given temporary table name to have the same table structure\&.
1745 The standard\*(Aqs definition of the behavior of temporary tables is widely ignored\&.
1746 PostgreSQL\*(Aqs behavior on this point is similar to that of several other SQL databases\&.
1748 The SQL standard also distinguishes between global and local temporary tables, where a local temporary table has a separate set of contents for each SQL module within each session, though its definition is still shared across sessions\&. Since
1750 does not support SQL modules, this distinction is not relevant in
1753 For compatibility\*(Aqs sake,
1759 keywords in a temporary table declaration, but they currently have no effect\&. Use of these keywords is discouraged, since future versions of
1761 might adopt a more standard\-compliant interpretation of their meaning\&.
1765 clause for temporary tables also resembles the SQL standard, but has some differences\&. If the
1767 clause is omitted, SQL specifies that the default behavior is
1768 ON COMMIT DELETE ROWS\&. However, the default behavior in
1771 ON COMMIT PRESERVE ROWS\&. The
1773 option does not exist in SQL\&.
1774 .SS "Non\-Deferred Uniqueness Constraints"
1780 constraint is not deferrable,
1782 checks for uniqueness immediately whenever a row is inserted or modified\&. The SQL standard says that uniqueness should be enforced only at the end of the statement; this makes a difference when, for example, a single command updates multiple key values\&. To obtain standard\-compliant behavior, declare the constraint as
1784 but not deferred (i\&.e\&.,
1785 INITIALLY IMMEDIATE)\&. Be aware that this can be significantly slower than immediate uniqueness checking\&.
1786 .SS "Column Check Constraints"
1788 The SQL standard says that
1790 column constraints can only refer to the column they apply to; only
1792 table constraints can refer to multiple columns\&.
1794 does not enforce this restriction; it treats column and table check constraints alike\&.
1795 .SS "EXCLUDE Constraint"
1799 constraint type is a
1802 .SS "Foreign Key Constraints"
1804 The ability to specify column lists in the foreign key actions
1814 extension that a foreign key constraint may reference columns of a unique index instead of columns of a primary key or unique constraint\&.
1815 .SS "NULL \(lqConstraint\(rq"
1820 (actually a non\-constraint) is a
1822 extension to the SQL standard that is included for compatibility with some other database systems (and for symmetry with the
1824 constraint)\&. Since it is the default for any column, its presence is simply noise\&.
1825 .SS "Constraint Naming"
1827 The SQL standard says that table and domain constraints must have names that are unique across the schema containing the table or domain\&.
1829 is laxer: it only requires constraint names to be unique across the constraints attached to a particular table or domain\&. However, this extra freedom does not exist for index\-based constraints (UNIQUE,
1832 constraints), because the associated index is named the same as the constraint, and index names must be unique across all relations within the same schema\&.
1835 Multiple inheritance via the
1839 language extension\&. SQL:1999 and later define single inheritance using a different syntax and different semantics\&. SQL:1999\-style inheritance is not yet supported by
1841 .SS "Zero\-Column Tables"
1844 allows a table of no columns to be created (for example,
1845 CREATE TABLE foo();)\&. This is an extension from the SQL standard, which does not allow zero\-column tables\&. Zero\-column tables are not in themselves very useful, but disallowing them creates odd special cases for
1846 \fBALTER TABLE DROP COLUMN\fR, so it seems cleaner to ignore this spec restriction\&.
1847 .SS "Multiple Identity Columns"
1850 allows a table to have more than one identity column\&. The standard specifies that a table can have at most one identity column\&. This is relaxed mainly to give more flexibility for doing schema changes or migrations\&. Note that the
1852 command supports only one override clause that applies to the entire statement, so having multiple identity columns with different behaviors is not well supported\&.
1853 .SS "Generated Columns"
1859 are not standard but are also used by other SQL implementations\&. The SQL standard does not specify the storage of generated columns\&.
1864 clause exists in the SQL standard, many of the options that
1866 accepts for it are not in the standard, and some of the standard\*(Aqs options are not implemented by
1874 extension; storage parameters are not in the standard\&.
1879 concept of tablespaces is not part of the standard\&. Hence, the clauses
1882 USING INDEX TABLESPACE
1886 Typed tables implement a subset of the SQL standard\&. According to the standard, a typed table has columns corresponding to the underlying composite type as well as one other column that is the
1887 \(lqself\-referencing column\(rq\&.
1889 does not support self\-referencing columns explicitly\&.
1890 .SS "PARTITION BY Clause"
1897 .SS "PARTITION OF Clause"
1905 ALTER TABLE (\fBALTER_TABLE\fR(7)), DROP TABLE (\fBDROP_TABLE\fR(7)), CREATE TABLE AS (\fBCREATE_TABLE_AS\fR(7)), CREATE TABLESPACE (\fBCREATE_TABLESPACE\fR(7)), CREATE TYPE (\fBCREATE_TYPE\fR(7))
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