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Chapter 19. Building a Query using the Ickle Query Language

19.1. Building a Query using the Ickle Query Language

Using Ickle, a light and small subset of JP-QL with full-text extensions, it is possible to create relational and full-text queries in both Library and Remote Client-Server mode. Ickle is a string-based querying language, and has the following characteristics:

  • Queres Java classes and supports Protocol Buffers.
  • Queries can target a single entity type.
  • Queries can filter on properties of embedded objects, including collections.
  • Supports projections, aggregations, sorting, named parameters.
  • Supports indexed and non-indexed execution.
  • Supports complex boolean expressions.
  • Supports full-text queries.
  • Does not support computations in expressions, such as user.age > sqrt(user.shoeSize+3).
  • Does not support joins.
  • Does not support subqueries.
  • Is supported across various JBoss Data Grid APIs. Whenever a Query is produced by the QueryBuilder is accepted, including continuous queries or in event filters for listeners.

To use the API, first obtain a QueryFactory to the cache and then call the .create() method, passing in the string to use in the query. For instance:

QueryFactory qf = Search.getQueryFactory(remoteCache);
Query q = qf.create("from sample_bank_account.Transaction where amount > 20");

When using Ickle all fields used with full-text operators must be both Indexed and Analysed.

Note

Ickle is a Technology Preview feature in JBoss Data Grid 7.1.

19.2. Deviations from the Lucene Query Parser Syntax

While Ickle is a subset of JP-QL it does have the following deviations in its query syntax:

  • Whitespace is not significant.
  • There is no support for wildcards in field names.
  • A field name or path must always be specified, as there is no default field.
  • && and || are accepted instead of AND or OR in both full-text and JPA predicates.
  • ! may be used instead of NOT.
  • A missing boolean operator is interpreted as OR.
  • String terms must be enclosed with either single or double quotes.
  • Fuzziness and boosting are not accepted in arbitrary order; fuzziness always comes first.
  • != is accepted instead of <>.
  • Boosting cannot be applied to >,>=,<, operators. Ranges may be used to achieve the same result.

19.3. Fuzzy Queries

To execute a fuzzy query add ~ along with an integer, representing the distance from the term used, after the term. For instance

Query fuzzyQuery = qf.create("from sample_bank_account.Transaction where description : 'cofee'~2");

19.4. Range Queries

To execute a range query define the given boundaries within a pair of braces, as seen in the following example:

Query rangeQuery = qf.create("from sample_bank_account.Transaction where amount : [20 to 50]");

19.5. Phrase Queries

A group of words may be searched by surrounding them in quotation marks, as seen in the following example:

Query q = qf.create("from sample_bank_account.Transaction where description : 'bus fare'");

19.6. Proximity Queries

To execute a proximity query, finding two terms within a specific distance, add a ~ along with the distance after the phrase. For instance, the following example will find the words canceling and fee provided they are not more than 3 words apart:

Query proximityQuery = qf.create("from sample_bank_account.Transaction where description : 'canceling fee'~3 ");

19.7. Wildcard Queries

Both single-character and multi-character wildcard searches may be performed:

  • A single-character wildcard search may be used with the ? character.
  • A multi-character wildcard search may be used with the * character.

To search for text or test the following single-character wildcard search would be used:

Query wildcardQuery = qf.create("from sample_bank_account.Transaction where description : 'te?t'");

To search for test, tests, or tester the following multi-character wildcard search would be useD:

Query wildcardQuery = qf.create("from sample_bank_account.Transaction where description : 'test*'");

19.8. Regular Expression Queries

Regular expression queries may be performed by specifing a pattern between /. Ickle uses Lucene’s regular expression syntax, so to search for the words moat or boat the following could be used:

Query regExpQuery = qf.create("from sample_library.Book  where title : /[mb]oat/");

19.9. Boosting Queries

Terms may be boosted by adding a ^ after the term to increase their relevance in a given query, the higher the boost factor the more relevant the term will be. For instance to search for titles containing beer and wine with a higher relevance on beer, by a factor of 3, the following could be used:

Query boostedQuery = qf.create("from sample_library.Book where title : beer^3 OR wine");