SETVAL
Syntax
SETVAL(sequence_name, next_value, [is_used, [round]])
Contents
Description
Set the next value to be returned for a SEQUENCE.
This function is compatible with PostgreSQL syntax, extended
with the round argument.
If the is_used argument is not given or is 1 or true, then the next used value will
one after the given value. If is_used is 0 or false then the next generated value
will be the given value.
If round is used then it will set the round value (or the internal cycle count, starting at zero) for the sequence.
If round is not used, it's assumed to be 0.
next_value must be an integer literal.
For SEQUENCE tables defined with CYCLE (see CREATE SEQUENCE) one should use both next_value and round to define the next value. In this case the
current sequence value is defined to be round, next_value.
The result returned by SETVAL() is next_value or NULL if the given next_value and round is smaller than the current value.
SETVAL() will not set the SEQUENCE value to a something that is less than
its current value. This is needed to ensure that SETVAL()
is replication safe. If you want to set the SEQUENCE to a smaller number
use ALTER SEQUENCE.
If CYCLE is used, first round and then next_value are compared
to see if the value is bigger than the current value.
Internally, in the MariaDB server, SETVAL() is used to inform
replicas that a SEQUENCE has changed value. The replica may get
SETVAL() statements out of order, but this is ok as only the
biggest one will have an effect.
SETVAL requires the INSERT privilege.
Examples
SELECT setval(foo, 42); -- Next nextval will return 43 SELECT setval(foo, 42, true); -- Same as above SELECT setval(foo, 42, false); -- Next nextval will return 42
SETVAL setting higher and lower values on a sequence with an increment of 10:
SELECT NEXTVAL(s); +------------+ | NEXTVAL(s) | +------------+ | 50 | +------------+ SELECT SETVAL(s, 100); +----------------+ | SETVAL(s, 100) | +----------------+ | 100 | +----------------+ SELECT NEXTVAL(s); +------------+ | NEXTVAL(s) | +------------+ | 110 | +------------+ SELECT SETVAL(s, 50); +---------------+ | SETVAL(s, 50) | +---------------+ | NULL | +---------------+ SELECT NEXTVAL(s); +------------+ | NEXTVAL(s) | +------------+ | 120 | +------------+
Example demonstrating round:
CREATE OR REPLACE SEQUENCE s1 START WITH 1 MINVALUE 1 MAXVALUE 99 INCREMENT BY 1 CACHE 20 CYCLE; SELECT SETVAL(s1, 99, 1, 0); +----------------------+ | SETVAL(s1, 99, 1, 0) | +----------------------+ | 99 | +----------------------+ SELECT NEXTVAL(s1); +-------------+ | NEXTVAL(s1) | +-------------+ | 1 | +-------------+
The following statement returns NULL, as the given next_value and round is smaller than the current value.
SELECT SETVAL(s1, 99, 1, 0); +----------------------+ | SETVAL(s1, 99, 1, 0) | +----------------------+ | NULL | +----------------------+ SELECT NEXTVAL(s1); +-------------+ | NEXTVAL(s1) | +-------------+ | 2 | +-------------+
Increasing the round from zero to 1 will allow next_value to be returned.
SELECT SETVAL(s1, 99, 1, 1); +----------------------+ | SETVAL(s1, 99, 1, 1) | +----------------------+ | 99 | +----------------------+ SELECT NEXTVAL(s1); +-------------+ | NEXTVAL(s1) | +-------------+ | 1 | +-------------+
