Valid types are smallint, integer, and bigint. The optional clause AS data_type specifies the data type of the sequence. The name (optionally schema-qualified) of the sequence to be created. Note that there is no guarantee that the existing relation is anything like the sequence that would have been created - it might not even be a sequence. IF NOT EXISTSĭo not throw an error if a relation with the same name already exists. In those cases, it usually wouldn't make sense to have the sequence WAL-logged and replicated but not its associated table.
Oracle data generator serial#
This option is mainly intended for sequences associated with unlogged tables via identity columns or serial columns. Unlike unlogged tables, unlogged sequences do not offer a significant performance advantage. Unlogged sequences are also not replicated to standby servers. They are not crash-safe: an unlogged sequence is automatically reset to its initial state after a crash or unclean shutdown. Changes to unlogged sequences are not written to the write-ahead log. If specified, the sequence is created as an unlogged sequence. Existing permanent sequences with the same name are not visible (in this session) while the temporary sequence exists, unless they are referenced with schema-qualified names.
If specified, the sequence object is created only for this session, and is automatically dropped on session exit. (Of course, this value might be obsolete by the time it's printed, if other sessions are actively doing nextval calls.) In particular, the last_value field of the sequence shows the last value allocated by any session. To examine the parameters and current state of a sequence. These functions are documented in Section 9.17.Īlthough you cannot update a sequence directly, you can use a query like: The sequence name must be distinct from the name of any other relation (table, sequence, index, view, materialized view, or foreign table) in the same schema.Īfter a sequence is created, you use the functions nextval, currval, and setval to operate on the sequence. Temporary sequences exist in a special schema, so a schema name cannot be given when creating a temporary sequence. Otherwise it is created in the current schema. If a schema name is given then the sequence is created in the specified schema.
Oracle data generator generator#
The generator will be owned by the user issuing the command. This involves creating and initializing a new special single-row table with the name name. CREATE SEQUENCE creates a new sequence number generator.
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