Elevate Software Blog - DBISAM 4.45 Released

DBISAM 4.45 Released

Posted by Tim Young on Mon, Apr 30 2018

DBISAM 4.45 is now available for download. If you're an existing customer, then you should be receiving an email shortly with download instructions.

The breaking changes and new features for both the DBISAM VCL and ODBC products are below.

4.45 Breaking Changes for VCL Products

The following are breaking changes in 4.45:

The TDBISAMEngine LargeFileSupport property has been removed and large file support is now always on. This functionality has its roots in the old Windows 9x series of operating systems and is no longer relevant.

If you are using local DBISAM sessions to directly access shared databases on a file server, you need to make sure that all client applications that are accessing the data are either updated to 4.45 or have their pre-4.45 TDBISAMEngine LargeFileSupport property set to True. Failure to do so can cause the local DBISAM sessions to not see each other's locks, which can lead to database table corruption.

The TDBISAMSession PrivateDir property has been changed from being a published property to a public property, so you may see a missing property error when loading forms or data modules in the IDE that contain the TDBISAMSession component after updating to 4.45. This property is typically only useful at run-time, and setting it at design-time could cause run-time errors if its value did not work properly with the target operating system's configuration.

To make sure that you don't experience any "missing property" exceptions at run-time in your application, please open any forms or data modules in your application that contain an existing TDBISAMSession component at design-time, ignore any "missing property" errors, and then re-save the owner form(s) or data module(s) that contain the TDBISAMSession component(s).

The TDBISAMEngine TableReadLockRetryCount, TableReadLockWaitTime, TableTransLockRetryCount, TableTransLockWaitTime, TableWriteLockRetryCount, and TableWriteLockWaitTime properties have been replaced with the equivalent TableReadLockTimeout, TableTransLockTimeout, and TableWriteLockTimeout properties.

To make sure that you don't experience any "missing property" exceptions at run-time in your application, please open any forms or data modules in your application that contain an existing TDBISAMEngine component at design-time, ignore any "missing property" errors, and then re-save the owner form(s) or data module(s) that contain the TDBISAMEngine component.

4.45 New Features for VCL Products

The following are the new features in 4.45:

The SQL join performance has been improved by up to 30-40%, depending upon how join-intensive the SQL being executed is. For example, SQL SELECT statements that contain INNER JOINs but no WHERE clauses are very join-intensive, and will benefit the most from this performance improvement.

The internal bitmap set handling for filters and SQL has been changed so that DBISAM uses sparse bitmaps instead of linear bitmaps, resulting in faster performance and less memory consumption. Part of the join performance improvements mentioned previously are due to the use of the new sparse bitmaps.

The sockets functionality in the DBISAM engine has been replaced with a new implementation, which should result in better overall performance and stability for remote sessions and the database server.

There is a new NOWHEREJOINS clause available for the SQL SELECT, UPDATE, and DELETE statements. This clause allows you to prevent DBISAM from treating any inner joins in the WHERE clause (SQL-89-style joins) as optimized joins, instead allowing the expressions to be treated as un-optimized expressions that will be evaluated after any joins are executed.

There are new TDBISAMEngine StoreActive, TDBISAMSession StoreActive, TDBISAMDatabase StoreConnected, TDBISAMTable StoreActive, and TDBISAMQuery StoreActive properties for specifying whether the component's related Active and Connected properties are stored in the owner form or data module.

4.45 Breaking Changes for ODBC Products

The following are breaking changes in 4.45:

The large file support driver configuration option has been removed and large file support is now always on. This functionality has its roots in the old Windows 9x series of operating systems and is no longer relevant.

If you are using local DBISAM ODBC Driver connections to directly access shared databases on a file server, you need to make sure that all client applications that are accessing the data are either updated to use the 4.45 DBISAM ODBC Driver or turn on the pre-4.45 large file support driver configuration option turned on by using the ODBC Driver Configuration Utility that is included with the DBISAM ODBC Driver installation. Failure to do so can cause the local DBISAM sessions to not see each other's locks, which can lead to database table corruption.

The DBISAM ODBC Driver Table Read Lock Retry Count, Table Read Lock Wait Time, Table Transaction Lock Retry Count, Table Transaction Lock Wait Time, Table Write Lock Retry Count, and Table Write Lock Wait Time driver configuration options have been replaced with Table Read Lock Timeout, Table Transaction Lock Timeout, and Table Write Lock Timeout configuration options. These options can be modified using the ODBC Driver Configuration Utility that is included with the DBISAM ODBC Driver installation.

4.45 New Features for ODBC Products

The following are the new features in 4.45:

The SQL join performance has been improved by up to 30-40%, depending upon how join-intensive the SQL being executed is. For example, SQL SELECT statements that contain INNER JOINs but no WHERE clauses are very join-intensive, and will benefit the most from this performance improvement.

The internal bitmap set handling for filters and SQL has been changed so that DBISAM uses sparse bitmaps instead of linear bitmaps, resulting in faster performance and less memory consumption. Part of the join performance improvements mentioned previously are due to the use of the new sparse bitmaps.

The sockets functionality in the DBISAM engine has been replaced with a new implementation, which should result in better overall performance and stability for remote sessions and the database server.

There is a new NOWHEREJOINS clause available for the SQL SELECT, UPDATE, and DELETE statements. This clause allows you to prevent DBISAM from treating any inner joins in the WHERE clause (SQL-89-style joins) as optimized joins, instead allowing the expressions to be treated as un-optimized expressions that will be evaluated after any joins are executed.

Tags: DBISAM, New Releases

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