B.4.6.2 TEMPORARY Table Problems

Temporary tables created with CREATE TEMPORARY TABLE have the following limitations:

TEMPORARY tables are supported only by the InnoDB, MEMORY, MyISAM, and MERGE storage engines.
Temporary tables are not supported for NDB Cluster.
The SHOW TABLES statement does not list TEMPORARY tables.
To rename TEMPORARY tables, RENAME TABLE does not work. Use ALTER TABLE instead:
1. ALTER TABLE old_name RENAME new_name;
You cannot refer to a TEMPORARY table more than once in the same query. For example, the following does not work:
1. SELECT * FROM temp_table JOIN temp_table AS t2;
The statement produces this error:
```
ERROR 1137: Can't reopen table: 'temp_table'
```
You can work around this issue if your query permits use of a common table expression (CTE) rather than a TEMPORARY table. For example, this fails with the Can't reopen table error:
1. CREATE TEMPORARY TABLE t SELECT 1 AS col_a, 2 AS col_b;
2. SELECT * FROM t AS t1 JOIN t AS t2;
To avoid the error, use a WITH clause that defines a CTE, rather than the TEMPORARY table:
1. WITH cte AS (SELECT 1 AS col_a, 2 AS col_b)
2. SELECT * FROM cte AS t1 JOIN cte AS t2;
The Can't reopen table error also occurs if you refer to a temporary table multiple times in a stored function under different aliases, even if the references occur in different statements within the function. It may occur for temporary tables created outside stored functions and referred to across multiple calling and callee functions.
If a TEMPORARY is created with the same name as an existing non-TEMPORARY table, the non-TEMPORARY table is hidden until the TEMPORARY table is dropped, even if the tables use different storage engines.
There are known issues in using temporary tables with replication. See Section 17.4.1.30, “Replication and Temporary Tables”, for more information.

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Document created the 26/06/2006, last modified the 26/10/2018
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