'\" t .\" Title: ALTER SEQUENCE .\" Author: The PostgreSQL Global Development Group .\" Generator: DocBook XSL Stylesheets v1.75.2 .\" Date: 2016 .\" Manual: PostgreSQL 9.5.2 Documentation .\" Source: PostgreSQL 9.5.2 .\" Language: English .\" .TH "ALTER SEQUENCE" "5sql" "2016" "PostgreSQL 9.5.2" "PostgreSQL 9.5.2 Documentation" .\" ----------------------------------------------------------------- .\" * set default formatting .\" ----------------------------------------------------------------- .\" disable hyphenation .nh .\" disable justification (adjust text to left margin only) .ad l .\" ----------------------------------------------------------------- .\" * MAIN CONTENT STARTS HERE * .\" ----------------------------------------------------------------- .SH "NAME" ALTER_SEQUENCE \- change the definition of a sequence generator .SH "SYNOPSIS" .sp .nf ALTER SEQUENCE [ IF EXISTS ] \fIname\fR [ INCREMENT [ BY ] \fIincrement\fR ] [ MINVALUE \fIminvalue\fR | NO MINVALUE ] [ MAXVALUE \fImaxvalue\fR | NO MAXVALUE ] [ START [ WITH ] \fIstart\fR ] [ RESTART [ [ WITH ] \fIrestart\fR ] ] [ CACHE \fIcache\fR ] [ [ NO ] CYCLE ] [ OWNED BY { \fItable_name\fR\&.\fIcolumn_name\fR | NONE } ] ALTER SEQUENCE [ IF EXISTS ] \fIname\fR OWNER TO { \fInew_owner\fR | CURRENT_USER | SESSION_USER } ALTER SEQUENCE [ IF EXISTS ] \fIname\fR RENAME TO \fInew_name\fR ALTER SEQUENCE [ IF EXISTS ] \fIname\fR SET SCHEMA \fInew_schema\fR .fi .SH "DESCRIPTION" .PP \fBALTER SEQUENCE\fR changes the parameters of an existing sequence generator\&. Any parameters not specifically set in the \fBALTER SEQUENCE\fR command retain their prior settings\&. .PP You must own the sequence to use \fBALTER SEQUENCE\fR\&. To change a sequence\(aqs schema, you must also have CREATE privilege on the new schema\&. To alter the owner, you must also be a direct or indirect member of the new owning role, and that role must have CREATE privilege on the sequence\(aqs schema\&. (These restrictions enforce that altering the owner doesn\(aqt do anything you couldn\(aqt do by dropping and recreating the sequence\&. However, a superuser can alter ownership of any sequence anyway\&.) .SH "PARAMETERS" .PP .PP \fIname\fR .RS 4 The name (optionally schema\-qualified) of a sequence to be altered\&. .RE .PP IF EXISTS .RS 4 Do not throw an error if the sequence does not exist\&. A notice is issued in this case\&. .RE .PP \fIincrement\fR .RS 4 The clause INCREMENT BY \fIincrement\fR is optional\&. A positive value will make an ascending sequence, a negative one a descending sequence\&. If unspecified, the old increment value will be maintained\&. .RE .PP \fIminvalue\fR .br NO MINVALUE .RS 4 The optional clause MINVALUE \fIminvalue\fR determines the minimum value a sequence can generate\&. If NO MINVALUE is specified, the defaults of 1 and \-263\-1 for ascending and descending sequences, respectively, will be used\&. If neither option is specified, the current minimum value will be maintained\&. .RE .PP \fImaxvalue\fR .br NO MAXVALUE .RS 4 The optional clause MAXVALUE \fImaxvalue\fR determines the maximum value for the sequence\&. If NO MAXVALUE is specified, the defaults are 263\-1 and \-1 for ascending and descending sequences, respectively, will be used\&. If neither option is specified, the current maximum value will be maintained\&. .RE .PP \fIstart\fR .RS 4 The optional clause START WITH \fIstart\fR changes the recorded start value of the sequence\&. This has no effect on the \fIcurrent\fR sequence value; it simply sets the value that future \fBALTER SEQUENCE RESTART\fR commands will use\&. .RE .PP \fIrestart\fR .RS 4 The optional clause RESTART [ WITH \fIrestart\fR ] changes the current value of the sequence\&. This is equivalent to calling the \fBsetval\fR function with is_called = false: the specified value will be returned by the \fInext\fR call of \fBnextval\fR\&. Writing RESTART with no \fIrestart\fR value is equivalent to supplying the start value that was recorded by \fBCREATE SEQUENCE\fR or last set by \fBALTER SEQUENCE START WITH\fR\&. .RE .PP \fIcache\fR .RS 4 The clause CACHE \fIcache\fR enables sequence numbers to be preallocated and stored in memory for faster access\&. The minimum value is 1 (only one value can be generated at a time, i\&.e\&., no cache)\&. If unspecified, the old cache value will be maintained\&. .RE .PP CYCLE .RS 4 The optional CYCLE key word can be used to enable the sequence to wrap around when the \fImaxvalue\fR or \fIminvalue\fR has been reached by an ascending or descending sequence respectively\&. If the limit is reached, the next number generated will be the \fIminvalue\fR or \fImaxvalue\fR, respectively\&. .RE .PP NO CYCLE .RS 4 If the optional NO CYCLE key word is specified, any calls to \fBnextval\fR after the sequence has reached its maximum value will return an error\&. If neither CYCLE or NO CYCLE are specified, the old cycle behavior will be maintained\&. .RE .PP OWNED BY \fItable_name\fR\&.\fIcolumn_name\fR .br OWNED BY NONE .RS 4 The OWNED BY option causes the sequence to be associated with a specific table column, such that if that column (or its whole table) is dropped, the sequence will be automatically dropped as well\&. If specified, this association replaces any previously specified association for the sequence\&. The specified table must have the same owner and be in the same schema as the sequence\&. Specifying OWNED BY NONE removes any existing association, making the sequence \(lqfree\-standing\(rq\&. .RE .PP \fInew_owner\fR .RS 4 The user name of the new owner of the sequence\&. .RE .PP \fInew_name\fR .RS 4 The new name for the sequence\&. .RE .PP \fInew_schema\fR .RS 4 The new schema for the sequence\&. .RE .SH "NOTES" .PP To avoid blocking of concurrent transactions that obtain numbers from the same sequence, \fBALTER SEQUENCE\fR\(aqs effects on the sequence generation parameters are never rolled back; those changes take effect immediately and are not reversible\&. However, the OWNED BY, OWNER TO, RENAME TO, and SET SCHEMA clauses cause ordinary catalog updates that can be rolled back\&. .PP \fBALTER SEQUENCE\fR will not immediately affect \fBnextval\fR results in backends, other than the current one, that have preallocated (cached) sequence values\&. They will use up all cached values prior to noticing the changed sequence generation parameters\&. The current backend will be affected immediately\&. .PP \fBALTER SEQUENCE\fR does not affect the \fBcurrval\fR status for the sequence\&. (Before PostgreSQL 8\&.3, it sometimes did\&.) .PP For historical reasons, \fBALTER TABLE\fR can be used with sequences too; but the only variants of \fBALTER TABLE\fR that are allowed with sequences are equivalent to the forms shown above\&. .SH "EXAMPLES" .PP Restart a sequence called serial, at 105: .sp .if n \{\ .RS 4 .\} .nf ALTER SEQUENCE serial RESTART WITH 105; .fi .if n \{\ .RE .\} .SH "COMPATIBILITY" .PP \fBALTER SEQUENCE\fR conforms to the SQL standard, except for the START WITH, OWNED BY, OWNER TO, RENAME TO, and SET SCHEMA clauses, which are PostgreSQL extensions\&. .SH "SEE ALSO" CREATE SEQUENCE (\fBCREATE_SEQUENCE\fR(5)), DROP SEQUENCE (\fBDROP_SEQUENCE\fR(5))