When an XQuery is run, the XQuery engine performs schema type validations in the XQuery file before running the XQuery. This may cause performance overheads for certain applications.

If you must optimize your XQuery for performance, you can use type annotations to specify schema information in the XQuery file. Type annotations enable you to hide the schema type definitions from the XQuery execution engine. The schema definitions are still visible to the Xquery Mapper, which enables you to edit your XQuery map in the usual fashion.

To use type annotations in your XQuery file, select Use Schema Type Annotations in the Create XQuery Map Main/Library Module dialog when creating a new XQuery file. See How to Create an XQuery Main/Library Module for more information on creating an XQuery file.

Type annotations, in an XQuery file, look similar to standard XQuery comments. While standard XQuery comments are delimited by the parentheses and colon, type annotations use parentheses and double colons. So, for example:

(: This is an XQuery comment :)
(:: This is a type annotation ::)

An XQuery file that uses type annotations has the following version annotation at the beginning of the file, immediately following the version declaration:

(:: OracleAnnotationVersion "1.0" ::)

The following example compares a few XQuery constructs with and without the type annotations.

• Schema import (without type annotation):

  import schema namespace ns1="http://www.oracle.com/pcbpel/po" at "../Schemas/PurchaseOrder.xsd";
  

  Schema import (with type annotation):

  declare namespace ns1="http://www.oracle.com/pcbpel/po";
  (:: import schema at "../Schemas/PurchaseOrder.xsd" ::)
  

• Variable declaration (without type annotation):

  declare variable $test_param as schema-element(ns1:PurchaseOrder) external;
  

  Variable declaration (with type annotation):

  declare variable $test_param as element() 
  (:: schema-element(ns1:PurchaseOrder) ::) external;