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 XCassandra Translator
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.
Properties
The Cassandra Translator currently has no import or execution properties.
Usage
The Cassandra Translator supports INSERT/UPDATE/DELETE/SELECT statements with a restrictive set of capabilities including: count(*), comparison predicates, IN predicates, and LIMIT. Only indexed columns are searchable. Consider a custom extension or create an enhancement request should your usage require additional capabilities.
Cassandra updates always return an update count of 1 per update regardless of the number of rows affected.
Cassandra inserts are functionally upserts, that is if a given row exists it will be updated rather than causing an exception.
JCA Resource Adapter
The Teiid specific Cassandra Resource Adapter should be used with this translator. See Cassandra Data Sources for connecting to a Cassandra cluster.
Native Queries
Cassandra source procedures may be created using the teiid_rel:native-query extension - see Parameterizable Native Queries. 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.
Direct Query Procedure
This 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.
Example CQL Direct Query