Database Bridge and JDBC/ESQL

The following tips are applicable to JDBC so they affect both Database Bridge and ESQL.

•	If you're working on Microsoft SQL Server with either the official driver (sqljdbc.jar) or JTDS, then add the JDBC option sendStringParametersAsUnicode=false to your connection URL. Example:

iscobol.jdbc.url=jdbc:sqlserver://localhost:1433\SQLEXPRESS;databasename=master;sendStringParametersAsUnicode=false

The follwing tips are applicable when working on databases with isCOBOL Database Bridge.

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Handling locks through the Application Server or through the File Server by setting iscobol.file.lock_manager * to "com.iscobol.as.locking.InternalLockManager" is faster than having locks handled by the database engine. The only side effect is that in this case the concurrency is managed only between clients connected to the same isCOBOL Server so this tip is not applicable if you’re working on the database with other tools in addition to the COBOL application.

•	When you generate subroutines for Oracle using edbiis, use the -Oho option in order to obtain better performance for START on alternate keys on huge tables.

•	When you generate subroutines for MySQL using edbiis, , use either -dmld or -dmlu in order to optimize the use of SQL cursors for read operations.

•	When you generate subroutines for PostgreSQL using edbiis, use either -dpld or -dplu in order to optimize the use of SQL cursors for read operations.

•	You can reduce the number of processed records by setting edbi-where-constraint.

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If the key you use for the START has a lot of segments, but you need to use only the first few of them, you can rely on the SIZE clause to limit the size of the key to the size of the useful segments only. This will reduce the number of SELECT queries generated by the Database Bridge to simulate the START. In order to activate this feature, the -sl option must be used for the subroutines generation.

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For multi-record files, where you have a table for each record definition, you can tell the START statement to use one specific table depending on the record type instead of using all the tables related to the multi-record file. To achieve it, set iscobol.easydb.start_on_specific_table (boolean) to true in the configuration and ensure that the record type field is properly set before the START statement.

•	ESQL (SQL logic) is preferable to the COBOL code generated by isCOBOL Database Bridge (COBOL logic) when you need to perform

o	huge update operations (one single complex query is usually faster than multiple small queries generated by multiple REWRITE statements)

o	complex searches (filters in the WHERE condition of SELECT are preferable to reading all records and performing checks with COBOL statements).

o	testing of few fields (specifying the fields you wish to test in SELECT is preferable to reading the whole record including the fields you’re not interested in)