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13.12. Cassandra Translator
Warning
The Cassandra Translator is a technology preview only. Technology Preview features are not supported with Red Hat production service level agreements (SLAs), may not be functionally complete, and are not recommended to be used for production. These features provide early access to upcoming product features, enabling customers to test functionality and provide feedback during the development process.
The Cassandra Translator, known by the type name cassandra, exposes querying functionality to Cassandra Data Sources. The translator translates Teiid push down commands into Cassandra CQL.
The Cassandra Translator currently has no import or execution properties.
The Cassandra Translator supports only SELECT statements with a restrictive set of capabilities including: count(*), comparison predicates, IN predicates, and LIMIT. Consider a custom extension or create an enhancement request should your usage require additional capabilities.
The Teiid-specific Cassandra Resource Adapter should be used with this translator.
Cassandra source procedures may be created using the teiid_rel:native-query extension. The procedure will invoke the native-query similar to a direct procedure call with the benefits that the query is predetermined and that result column types are known, rather than requiring the use of ARRAYTABLE or similar functionality.
Warning
The direct query procedure feature is turned off by default because of the security risk this exposes to execute any command against the source. To enable this feature, override the execution property called SupportsDirectQueryProcedure to true.
By default the name of the procedure that executes the queries directly is called native. Override the execution property DirectQueryProcedureName to change it to another name.
The Cassandra translator provides a procedure to execute any ad-hoc CQL query directly against the source without Teiid parsing or resolving. Since the metadata of this procedure's results are not known to Teiid, they are returned as an object array. ARRAYTABLE can be used construct tabular output for consumption by client applications.
SELECT X.*
FROM cassandra_source.native('SELECT firstname, lastname FROM users WHERE birth_year = $1 AND country = $2 ALLOW FILTERING', 1981, 'US') n,
ARRAYTABLE(n.tuple COLUMNS firstname string, lastname string) AS X
SELECT X.*
FROM cassandra_source.native('SELECT firstname, lastname FROM users WHERE birth_year = $1 AND country = $2 ALLOW FILTERING', 1981, 'US') n,
ARRAYTABLE(n.tuple COLUMNS firstname string, lastname string) AS X
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