New in Indexing Service 3.0 is the extensible Dialect 2 of the Indexing Service query language. Its short form contains as a subset — with a few incompatibilities — the syntax of the original Indexing Service query language, now called Dialect 1. Except for the few incompatibilities, Dialect 2 processes queries written in both its long form and its short form (Dialect 1 subset). Most applications and scripts will specify Indexing Service query language queries in Dialect 2. For compatibility with earlier releases, applications and scripts can submit a query written in Dialect 1 and specify that Indexing Service process it as a Dialect 1 query. An alternative to the Indexing Service query language is the SQL query language.

This section describes several features of the Indexing Service query language. It consists of the following topics.

• Query Submittal for Indexing Service Query Language
• Query Syntax of Indexing Service Query Language
• Content Queries
• CONTAINS Operator
• Boolean and Proximity Operators
• Property-Value Queries
• Relational Queries
• Pattern-Matching Queries
• Term Weighting
• Vector-Space Queries
• Incompatibilities of Dialect 2 with Dialect 1

For a reference to the Indexing Service query language, see Query-Language Dialects.