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.\" This is -*-nroff-*- |
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.\" XXX standard disclaimer belongs here.... |
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.\" $Header: /cvsroot/pgsql/src/man/Attic/create_sequence.l,v 1.1 1997/04/02 04:19:58 vadim Exp $ |
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.TH "CREATE SEQUENCE" SQL 04/01/97 PostgreSQL PostgreSQL |
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.SH NAME |
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create sequence \(em create a new sequence number generator |
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.SH SYNOPSIS |
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.nf |
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\fBcreate sequence\fR seqname |
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[\fBincrement\fP incby_value] |
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[\fBminvalue\fP min_value] |
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[\fBmaxvalue\fP max_value] |
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[\fBstart\fP start_value] |
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[\fBcache\fP cache_value] |
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[\fBcycle\fP] |
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.fi |
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.SH DESCRIPTION |
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.BR "Create sequence" |
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will enter a new sequence number generator into the current data base. |
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Actually, new single block |
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.BR table |
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with name |
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.IR seqname |
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will be created and initialized. |
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The generator will be |
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\*(lqowned\*(rq by the user issuing the command. |
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.PP |
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The |
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.BR "increment" |
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is optional clause. Positive value will make ascending sequence, |
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negative - descending. Default value is 1. |
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.PP |
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The optional integer |
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.BR minvalue |
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determines the minimum value a sequence can be. Defaults are |
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1/-2147483647 for ascending/descending sequences. |
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.PP |
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Use optional integer |
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.BR maxvalue |
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to determine the maximum value for sequence. Defaults are |
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2147483647/-1 for ascending/descending sequences. |
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.PP |
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The optinal |
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.BR "start" |
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value enables sequence to begin anywhere. Default is |
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.BR minvalue |
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for ascending sequences and |
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.BR maxvalue |
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for descending ones. |
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.PP |
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The |
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.BR cache |
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option enables sequence numbers to be preallocated and |
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stored in memory for faster access. The minimum value is 1 |
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(i.e. - no cache) and it is default. |
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.BR NOTE: |
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each backend uses own cache to store allocated numbers. |
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Cached but not used in current session numbers will be lost. |
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.PP |
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The optional |
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.BR cycle |
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keyword may be used to enable sequence to continue when the |
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.BR maxvalue/minvalue |
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has been reached by ascending/descending sequence. |
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If the limit is reached, the next number generated will be |
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whatever the |
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.BR minvalue/maxvalue |
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is. |
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.PP |
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After sequence created, You may use function |
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.BR nextval |
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with sequence name as argument to get new number from sequence |
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specified. |
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To determine the current sequence number use function |
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.BR currval |
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('sequence_name'). |
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.BR NOTE: |
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after sequence creation You are to call |
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.BR nextval |
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before first call to |
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.BR currval. |
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.PP |
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.nf |
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Use query like |
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|
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select * from <sequence_name>; |
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|
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to get parameters of a sequence. |
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.fi |
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.PP |
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Low-level locking is used to enable multiple simultaneous calls |
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to a generator. |
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.PP |
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.SH EXAMPLES |
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.nf |
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-- |
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-- Create sequence seq caching 2 numbers, starting with 10 |
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-- |
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create sequence seq cache 2 start 10; |
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.fi |
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.nf |
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-- |
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-- Select next number from sequence |
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-- |
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select nextval ('seq'); |
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.fi |
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.nf |
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-- |
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-- Use sequence in insert |
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-- |
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insert into table _table_ values (nextval ('seq'),...); |
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.fi |
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.SH "SEE ALSO" |
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drop sequence(l). |
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@ -0,0 +1,15 @@ |
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.\" This is -*-nroff-*- |
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.\" XXX standard disclaimer belongs here.... |
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.\" $Header: /cvsroot/pgsql/src/man/Attic/drop_sequence.l,v 1.1 1997/04/02 04:20:00 vadim Exp $ |
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.TH "DROP TABLE" SQL 04/01/97 PostgreSQL PostgreSQL |
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.SH NAME |
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drop sequence \(em destroy existing sequence |
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.SH SYNOPSIS |
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.nf |
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\fBdrop sequence\fR sequence_name_1 { \fB,\fR sequence_name_N } |
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.fi |
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.SH DESCRIPTION |
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.BR "Drop Sequence" |
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removes sequence number generators from the data base. |
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With current implementation of sequences as special tables it |
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works just like \fBdrop table\fR(l). |
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