diff options
author | Thomas G. Lockhart <lockhart@fourpalms.org> | 1999-08-08 15:21:50 +0000 |
---|---|---|
committer | Thomas G. Lockhart <lockhart@fourpalms.org> | 1999-08-08 15:21:50 +0000 |
commit | a76ad509fef621719abb95fedb526e9a0092a312 (patch) | |
tree | 1a5295dbdce9296f23f252898aea402f411e7d23 /src/man/create_sequence.l | |
parent | d0a1919852b8c98f43f2795c23690024707fc1e5 (diff) |
Remove old man pages. All info is in new man pages or other docs.
Diffstat (limited to 'src/man/create_sequence.l')
-rw-r--r-- | src/man/create_sequence.l | 156 |
1 files changed, 0 insertions, 156 deletions
diff --git a/src/man/create_sequence.l b/src/man/create_sequence.l deleted file mode 100644 index 588e70f3944..00000000000 --- a/src/man/create_sequence.l +++ /dev/null @@ -1,156 +0,0 @@ -.\" This is -*-nroff-*- -.\" XXX standard disclaimer belongs here.... -.\" $Header: /cvsroot/pgsql/src/man/Attic/create_sequence.l,v 1.6 1998/08/30 21:03:19 scrappy Exp $ -.TH "CREATE SEQUENCE" SQL 07/13/98 PostgreSQL PostgreSQL -.SH NAME -create sequence - create a new sequence number generator -.SH SYNOPSIS -.nf -\fBcreate sequence\fR seqname - [\fBincrement\fP incby_value] - [\fBminvalue\fP min_value] - [\fBmaxvalue\fP max_value] - [\fBstart\fP start_value] - [\fBcache\fP cache_value] - [\fBcycle\fP] -.fi -.SH DESCRIPTION -.BR "Create sequence" -will enter a new sequence number generator into the current data base. -Actually, a new single-record -.BR table -with name -.IR seqname -will be created and initialized. -The generator will be -\*(lqowned\*(rq by the user issuing the command. -.PP -The -.BR increment -clause is optional. A positive value will make an ascending sequence, -negative - descending. Default value is 1. -.PP -The optional integer -.BR minvalue -determines the minimum value the sequence can generate. Defaults are -1/-2147483647 for ascending/descending sequences. -.PP -The optional integer -.BR maxvalue -determines the maximum value the sequence can generate. Defaults are -2147483647/-1 for ascending/descending sequences. -.PP -The optional -.BR start -value sets the first value to be generated. Default is -.BR minvalue -for ascending sequences and -.BR maxvalue -for descending ones. -.PP -The -.BR cache -option enables sequence numbers to be preallocated and -stored in memory for faster access. The minimum value is 1 -(one value will be allocated at a time, i.e., no cache) -and that is the default. See below for details. -.PP -The optional -.BR cycle -keyword may be used to enable the sequence to continue after the -.BR maxvalue/minvalue -has been reached by ascending/descending sequence. -If the limit is reached, the next number generated will be -whatever the -.BR minvalue/maxvalue -is. -.PP -After a sequence object has been created, you may use the function -.BR nextval -with the sequence name as argument to generate a new number from the -specified sequence. -.PP -The function -.BR currval -('sequence_name') -may be used to re-fetch the number returned by the last call to -.BR nextval -for the specified sequence in the current session. -.BR NOTE: -currval will return an error if nextval has never been called for the -given sequence in the current backend session. Also beware that it -does not give the last number ever allocated, only the last one allocated -by this backend. -.PP -The function -.BR setval -('sequence_name', value) -may be used to set the current value of the specified sequence. -The next call to -.BR nextval -will return the given value + the sequence increment. -.PP -Use a query like -.nf -SELECT * FROM <sequence_name>; -.fi -to get the parameters of a sequence. Aside from fetching the original -parameters, you can use -.nf -SELECT last_value FROM <sequence_name>; -.fi -to obtain the last value allocated by any backend. -.PP -Low-level locking is used to ensure that multiple backends can safely use -a sequence object concurrently. -.PP -.BR NOTE: -Unexpected results may be obtained if a cache setting greater than one -is used for a sequence object that will be used concurrently by multiple -backends. Each backend will allocate "cache" successive sequence values -during one access to the sequence object and increase the sequence -object's last_value accordingly. Then, the next cache-1 uses of nextval -within that backend simply return the preallocated values without touching -the shared object. So, numbers allocated but not used in the current session -will be lost. Furthermore, although multiple backends are guaranteed to -allocate distinct sequence values, the values may be generated out of -sequence when all the backends are considered. (For example, with a cache -setting of 10, backend A might reserve values 1..10 and return nextval=1, then -backend B might reserve values 11..20 and return nextval=11 before backend -A has generated nextval=2.) Thus, with a cache setting of one it is safe -to assume that nextval values are generated sequentially; with a cache -setting greater than one you should only assume that the nextval values -are all distinct, not that they are generated purely sequentially. -Also, last_value will reflect the latest value reserved by any backend, -whether or not it has yet been returned by nextval. -.PP -.SH EXAMPLES -.nf --- --- Create sequence seq caching 2 numbers, starting with 10 --- -create sequence seq cache 2 start 10; -.fi -.nf --- --- Select next number from sequence --- -select nextval ('seq'); -.fi -.nf --- --- Use sequence in insert --- -insert into table _table_ values (nextval ('seq'),...); -.nf --- --- Set the sequence value after a copy in --- -create function table_id_max() returns int4 - as 'select max(id) from _table_' - language 'sql'; -copy _table_ from 'input_file'; -select setval('seq', table_id_max()); -.fi -.SH "SEE ALSO" -drop_sequence(l). |