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To read part one in this series on O ...

Quest Recursive SQL Transformation technology is an innovative AI technology that simulates human SQL transformation technique. It incorporates a set of transformation rules to transform SQL statements on a section-by-section basis. This replaces the trial and error method used by human to rewrite the syntax of a SQL statement. Each t ...

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I have been asked many times that why there are some dummy SQL transformations/rewrites that look meaningless, but it works in certain situations.  Let me give you some examples that may help to explain what theory on behind of Quest SQL Optimizer.

In Quest SQL Optimizer, transformation rules relating to index usage are designed to guide the database SQL optimizer as to how it should use the indexes for a specific SQL statement.  Although those rules may familiar to most of SQL developers, but it is still worth to illustrate some commonly used rules for SQL beg ...

In old version of Oracle database, it is easy to control the join path by reordering the tables in table list after the FROM clause, but it is getting difficult to control the join path in today’s cost based SQL optimizer, I am going to introduce method that is applicable in most databases such as Oracle, Sybase, DB2 and SQL Server in the following:

To control a join path, we cannot tell the database SQL optimizer which path is the best one to select. Instead, we add something to the syntax of the SQL statement that causes an increase to the cost of the current join path selected by database SQL optimizer. Let’s take a look at the following example of two table join scenarios.