How the DataBlade module works

Standard SQL searches that include LIKE or MATCHES clauses use the B-tree access method to scan data. When you perform searches with the etx_contains() operator, alternatively, that part of the query is relayed to the Excalibur text search engine. You can think of the Excalibur text search engine as a specialized part of HCL OneDB™ that is executed when you specify an etx_contains() operation in a SELECT statement.

The text search engine produces a group of rows that satisfy the conditions you specify in the etx_contains() operator and returns them to the database server. If the query contains criteria other than those specified by the etx_contains() operator, HCL OneDB further qualifies the set of rows. Finally, HCL OneDB returns a list of rows that satisfy all the conditions of the WHERE clause. The following figure illustrates this process.

Diagram shows a SELECT query that uses the etx_contains() operator as well as the SQL LIKE keyword to return a value that satisfies both of the conditions of the WHERE clause. — Figure 1: Text search process illustrated

Even though, for illustrative purposes, the preceding figure shows the Excalibur text search engine as a separate process, it is important to remember that it is dynamically linked to, and considered part of, HCL OneDB.

The following sections describe the components of the and explain how it works in more detail.