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Update Strategy Transformation on the Blaze Engine

You can use the Update Strategy transformation on the Hadoop distributions that support Hive ACID.

Some processing rules for the Blaze engine differ from the processing rules for the Data Integration Service.

General Restrictions

If the Update Strategy transformation receives multiple update rows for the same primary key value, the transformation selects one random row to update the target.

If multiple Update Strategy transformations write to different instances of the same target, the target data might be unpredictable.

The Blaze engine executes operations in the following order: deletes, updates, inserts. It does not process rows in the same order as the Update Strategy transformation receives them.

Hive targets always perform Update as Update operations. Hive targets do not support Update Else Insert or Update as Insert.

Mapping Validation and Compile Validation

Mapping validation fails in the following situations:

The Update Strategy transformation is connected to more than one target.

The Update Strategy transformation is not located immediately before the target.

The Update Strategy target is not a Hive target.

The Update Strategy transformation target is an external ACID table.

The target does not contain a primary key.

The Hive target property to truncate the target table at run time is enabled.

The Hive target property to create or replace the target table at run time is enabled.

The mapping fails in the following situation:

The target is not ORC bucketed.

The Hive target is modified to have fewer rows than the actual table.

Compile validation errors occur and the mapping execution stops in the following situations:

The Hive version is earlier than 0.14.

The target table is not enabled for transactions.

Using Hive Target Tables

To use a Hive target table with an Update Strategy transformation, you must create the Hive target table with the following clause in the Hive Data Definition Language:

TBLPROPERTIES ("transactional"="true")

To use an Update Strategy transformation with a Hive target, verify that the following properties are configured in the hive-site.xml configuration set associated with the Hadoop connection:

hive.support.concurrency         true
hive.enforce.bucketing           true
hive.exec.dynamic.partition.mode nonstrict
hive.txn.manager         org.apache.hadoop.hive.ql.lockmgr.DbTxnManager
hive.compactor.initiator.on      true
hive.compactor.worker.threads    1

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Table of Contents

User Guide

User Guide

Update Strategy Transformation on the Blaze Engine

Update Strategy Transformation on the Blaze Engine

General Restrictions

Mapping Validation and Compile Validation

Using Hive Target Tables