Cloudera Impala Translator (impala)
Also see common JDBC Translator Information
The Coudera Impala Translator, known by the type name impala, is for use with Cloudera Impala 1.2.1 or later.
Impala has limited support for data types. It is does not have native support for time/date/xml or LOBs. These limitations are reflected in the translator capabilities. A Teiid view can use these types, however the transformation would need to specify the necessary conversions. Note that in those situations, the evaluations will be done in the Teiid engine.
The DatabaseTimeZone translator property should not be used.
Impala only supports EQUI join, so using any other joins types on its source tables will result in inefficient queries.
To write criteria based on partitioned columns, modeled them on source table, but do not include them in selection columns.
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Impala Hive importer does not have concept of catalog or source schema, nor does it import keys, procedures, indexes, etc. |
Impala specific importer properties:
useDatabaseMetaData- Set to true to use the normal import logic with the option to import index information disabled. Defaults to false.
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If useDatabaseMetaData is false the typical JDBC DatabaseMetaData calls are not used so not all of the common JDBC importer properties are applicable to Impala. You may still use excludeTables regardless. |
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Some versions of Impala requires the use of a LIMIT when performing an ORDER BY. If no default is configured in Impala, then an exception can occur when a Teiid query with an ORDER BY but no LIMIT is issued. You should set an Impala wide default, or configure the connection pool to use a new connection sql string to issue a SET DEFAULT_ORDER_BY_LIMIT statement. See the Cloudera docs for more on limit options - such as controlling what happens when the limit is exceeded. |
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The Impala JDBC driver seems to have issues with PreparedStatements and statement parsing in general that may require disabling useBindVariables - see link:https://issues.jboss.org/browse/TEIID-4610 |