Difference between revisions of "SET TCACHE"

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=SET TCACHE=
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''Deprecated in Recital 10''
 
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==Class==
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SQL Applications
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==Purpose==
 
==Purpose==
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==See Also==
 
==See Also==
ALTER INDEX, ALTER TABLE, CREATE INDEX, CREATE TRIGGER, DELETE, DROP INDEX, GRANT, INSERT, REVOKE, SELECT, UPDATE
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[[ALTER INDEX]], [[ALTER TABLE]], [[CLOSE]], [[CLOSE DATABASES]], [[CREATE INDEX]], [[CREATE TRIGGER]], [[SQL DELETE|DELETE]], [[DROP INDEX]], [[GRANT]], [[SQL INSERT|INSERT]], [[REVOKE]], [[SQL SELECT|SELECT]], [[SQL UPDATE|UPDATE]], [[USE]]
  
  
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The SET TCACHE command is used to enable or disable table caching and configure the number of tables that can be cached during SQL operations.  If SET TCACHE is ON, a table accessed by an SQL statement is left open until the session or connection is closed.  With SET TCACHE OFF, tables are opened and closed with every SQL statement.
 
The SET TCACHE command is used to enable or disable table caching and configure the number of tables that can be cached during SQL operations.  If SET TCACHE is ON, a table accessed by an SQL statement is left open until the session or connection is closed.  With SET TCACHE OFF, tables are opened and closed with every SQL statement.
  
With SET TCACHE ON, the default number of tables that can be cached corresponds to the number of available workareas (DB_MAXWKA environment variable / symbol).  This number can be reduced using the SET TCACHE TO <expN> command.  The <expN> specifies the maximum number of tables that can be cached.
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With SET TCACHE ON, the default number of tables that can be cached corresponds to the number of available workareas.  This number can be reduced using the SET TCACHE TO <expN> command.  The <expN> specifies the maximum number of tables that can be cached.
  
 
Enabling TCACHE can give significant performance benefits where multiple operations are being carried out on the same table or tables.  With TCACHE ON, individual tables can still be closed if required using the USE command in the relevant workarea or the CLOSE <alias> command.
 
Enabling TCACHE can give significant performance benefits where multiple operations are being carried out on the same table or tables.  With TCACHE ON, individual tables can still be closed if required using the USE command in the relevant workarea or the CLOSE <alias> command.
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==Example==
 
==Example==
<pre>
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<code lang="recital">
 
// Up to 4 tables will remain open after a completed SQL statement
 
// Up to 4 tables will remain open after a completed SQL statement
 
set tcache on
 
set tcache on
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? workarea()
 
? workarea()
 
?
 
?
close databases</pre>
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close databases</code>
  
  
 
==Products==
 
==Products==
Recital Database Server, Recital Mirage Server, Recital Terminal Developer
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Recital Server, Recital  
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[[Category:Documentation]]
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[[Category:Commands]]
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[[Category:Set_Commands|TCACHE]]
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[[Category:SQL]]
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[[Category:SQL Set Commands]]
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[[Category:Performance and Optimization]]
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[[Category:Performance and Optimization Set Commands]]
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[[Category:Deprecated]]

Latest revision as of 16:44, 15 December 2009

Deprecated in Recital 10

Purpose

Enable, disable and configure table caching during SQL operations


Syntax

SET TCACHE ON | OFF | TO <expN>


See Also

ALTER INDEX, ALTER TABLE, CLOSE, CLOSE DATABASES, CREATE INDEX, CREATE TRIGGER, DELETE, DROP INDEX, GRANT, INSERT, REVOKE, SELECT, UPDATE, USE


Description

The SET TCACHE command is used to enable or disable table caching and configure the number of tables that can be cached during SQL operations. If SET TCACHE is ON, a table accessed by an SQL statement is left open until the session or connection is closed. With SET TCACHE OFF, tables are opened and closed with every SQL statement.

With SET TCACHE ON, the default number of tables that can be cached corresponds to the number of available workareas. This number can be reduced using the SET TCACHE TO <expN> command. The <expN> specifies the maximum number of tables that can be cached.

Enabling TCACHE can give significant performance benefits where multiple operations are being carried out on the same table or tables. With TCACHE ON, individual tables can still be closed if required using the USE command in the relevant workarea or the CLOSE <alias> command.


Example

// Up to 4 tables will remain open after a completed SQL statement
set tcache on
set tcache to 4
set sql to recital
 
EXEC SQL
  OPEN DATABASE southwind;
 
EXEC SQL
  INSERT INTO shippers
  VALUES (4,"Recital Corporation","(978) 921-5594");
 
EXEC SQL
  UPDATE employees
  SET extension="256"
  WHERE employeeid=4;
 
EXEC SQL
  DELETE FROM suppliers
  WHERE supplierid=1;
 
 
EXEC SQL
  ALTER TABLE example
  ADD (email char(40));
 
EXEC SQL
SELECT * from products;
 
// Next free workarea is workarea 5
// as tables in workareas 1 to 4 remain open
? workarea()
?
close databases


Products

Recital Server, Recital