Translators

The Teiid Connector Architecture (TCA) provides Teiid with a robust mechanism for integrating with external systems. The TCA defines a common client interface between Teiid and an external system that includes metadata as to what SQL constructs are supported for pushdown and the ability to import metadata from the external system.

A Translator is the heart of the TCA and acts as the bridge logic between Teiid and an external system, which is most commonly accessed through a JCA resource adapter. Refer to the Teiid Developers Guide for details on developing custom Translators and JCA resource adapters for use with Teiid.

Tip
 The TCA is not the same as the JCA, the JavaEE Connector Architecture, although the TCA is designed for use with JCA resource adapters.

A Translator is typically paired with a particular JCA resource adapter. In instances where pooling, environment dependent configuration management, advanced security handling, etc. are not needed, then a JCA resource adapter is not needed. The configuration of JCA ConnectionFactories for needed resource adapters is not part of this guide, please see the Teiid Administrator Guide and the kit examples for configuring resource adapters for use in WildFly.

Translators can have a number of configurable properties. These are broken down into execution properties, which determine aspects of how data is retrieved, and import settings, which determine what metadata is read for import.

The execution properties for a translator typically have reasonable defaults. For specific translator types, e.g. the Derby translator, base execution properties are already tuned to match the source. In most cases the user will not need to adjust their values.

Table 1. Base Execution Properties - shared by all translators
Name Description Default

Immutable

Set to true to indicate that the source never changes.

false

RequiresCriteria

Set to true to indicate that source SELECT/UPDATE/DELETE queries require a where clause.

false

SupportsOrderBy

Set to true to indicate that the ORDER BY clause is supported.

false

SupportsOuterJoins

Set to true to indicate that OUTER JOINs are supported.

false

SupportsFullOuterJoins

If outer joins are supported, true indicates that FULL OUTER JOINs are supported.

false

SupportsInnerJoins

Set to true to indicate that INNER JOINs are supported.

false

SupportedJoinCriteria

If joins are supported, defines what criteria may be used as the join criteria. May be one of (ANY, THETA, EQUI, or KEY).

ANY

MaxInCriteriaSize

If in criteria are supported, defines what the maximum number of in entries are per predicate. -1 indicates no limit.

-1

MaxDependentInPredicates

If in criteria are supported, defines what the maximum number of predicates that can be used for a dependent join. Values less than 1 indicate to use only one in predicate per dependent value pushed (which matches the pre-7.4 behavior).

-1

DirectQueryProcedureName

if the direct query procedure is supported on the translator, this property indicates the name of the procedure.

native

SupportsDirectQueryProcedure

Set to true to indicate the translator supports the direct execution of commands

false

ThreadBound

Set to true to indicate the translator’s Executions should be processed by only a single thread

false

CopyLobs

If true, then returned lobs (clob, blob, sql/xml) will be copied by the engine in a memory safe manner. Use this option if the source does not support memory safe lobs or you want to disconnect lobs from the source connection.

false

TransactionSupport

The highest level of transaction support. Used by the engine as a hint to determine if a transaction is needed for autoCommitTxn=DETECT mode. Can be one of XA, NONE, or LOCAL. If XA or LOCAL then access under a transaction will be serialized.

XA
Note
 Only a subset of the supports metadata can be set through execution properties. If more control is needed, please consult the Developer’s Guide.

There are no base importer settings.

Override Execution Properties

For all translators, you may override Execution Properties in the vdb.xml file.

Example Overriding of Translator Property

<model name="ora">
     <source name="ora" translator-name="oracle-override" connection-jndi-name="java:/oracle"/>
</model>

<translator name="oracle-override" type="oracle">
     <property name="RequiresCriteria" value="true"/>
</translator>

The above XML fragment is overriding the oracle translator and altering the behavior of RequiresCriteria property to true. Note that the modified translator is only available in the scope of this VDB. As many properties as desired may be overriden together.

See also VDB Definition.

Parameterizable Native Queries

In some situations the teiid_rel:native-query property and native procedures accept parameterizable strings that can positionally reference IN parameters. A parameter reference has the form $integer, i.e. $1 Note that 1 based indexing is used and that only IN parameters may be referenced. Dollar-sign integer is therefore reserved, but may be escaped with another $, i.e. $$1. The value will be bound as a prepared value or a literal is a source specific manner. The native query must return a result set that matches the expectation of the calling procedure.

For example the native-query select c from g where c1 = $1 and c2 = '$$1' results in a JDBC source query of select c from g where c1 = ? and c2 = '$1', where ? will be replaced with the actual value bound to parameter 1.

General Import Properties

Several import properties are shared by all translators.

When specifying an importer property, it must be prefixed with "importer.". Example: importer.tableTypes

Name Description Default

autoCorrectColumnNames

Replace any usage of . in a column name with _ as the period character is not supported by Teiid in column names.

true

renameDuplicateColumns

If true rename duplicate columns caused by either mixed case collisions or autoCorrectColumnNames replacing . with _. A suffix _n where n is an integer will be added to make the name unique.

false

renameDuplicateTables

If true rename duplicate tables caused by mixed case collisions. A suffix _n where n is an integer will be added to make the name unique.

false

renameAllDuplicates

If true rename all duplicate tables, columns, procedures, and parameters caused by mixed case collisions. A suffix _n where n is an integer will be added to make the name unique. Supersedes the individual rename duplicate options.

false

nameFormat

Set to a Java string format to modify table and procedure names on import. The only argument will be the original name Teiid name. For example use prod_%s to prefix all names with prod_.

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