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Persistence Layer

The persistence layer stores model data to the persistent backend. This definition is part of the MDM configuration and is shared by all defined models, that is, shared tables are created in the specified database.

VLDB persistence

VLDB persistence (also known as the logical transaction persistence) is a database persistence that does not rely on database transactions and supports large change sets through an application transaction handling. All data changes are realized as INSERT commands, with obsolete records being deleted over time (expunger job, also known as Logical Transaction Collector).

Major features supported by the persistence are listed in Available features by persistence type.

<persistenceLayers>
    <persistenceLayer class="com.ataccama.nme.persistence.vldb.VldbPersistenceFactory">
        <dataSource>MDC_DB</dataSource>
        <prefix>A_</prefix>
        <binding>true</binding>
        <commandTemplatesFile>vldb-commands.xml</commandTemplatesFile>
    </persistenceLayer>
</persistenceLayers>
The following optional settings affect the MDM engine performance. Use with caution.
Parameter Default Description

binding

true

Setting the parameter to false forces the MDM engine to prepare database queries without SQL bind variables.

commandTemplatesFile

Oracle DB hints

Path to a file with hinted database queries used by VLDB persistence. See Runtime Parameters for Oracle hint explanations and Database Hints for template file samples.

Database persistence

Standard database persistence relying on database transactions. Usable for medium-sized implementations and large-size implementations where only a reasonable amount of data is changed in each load.

Major features supported by the persistence are listed in Available features by persistence type.

<persistenceLayers>
    <persistenceLayer class="com.ataccama.nme.persistence.database.DbPersistenceFactory">
        <dataSource>MDC_DB</dataSource>
        <prefix>A_</prefix>
    </persistenceLayer>
</persistenceLayers>

Available features by persistence type

Choosing a proper type of persistence layer depends on the expected behavior of the MDM solution. The following is a list of supported features.

Group Feature DB persistence VLDB persistence Notes

Load

Delta load

Yes

Yes

/

Load

Multiload

Yes

Yes

Ability to load data from multiple systems in one batch.

Load

Streaming

Yes

Yes

/

Services

Read-only services

Yes

Yes

/

Services

Read-write services

Yes

Yes

/

Export

Batch export

Yes

Yes

/

Export

Event handler

Yes

Yes

/

Parallelism

Batch load

Yes

Yes

Run multiple independent batch load operations.

Parallelism

Streaming

Yes

Yes

Consume data from multiple independent stream input interfaces at once.

Parallelism

Online (RO)

Yes

Yes

/

Parallelism

Online (RW)

Yes

Yes

Support multiple RW services calls concurrently, typically processDelta.

Parallelism

Export

Yes

Yes

Run multiple independent batch export operations.

Parallelism

Batch load and online (RW)

Yes

Yes

Run a batch load opearation with concurrent online RW services (for example, processDelta).

Parallelism

Batch load and export

Yes

Yes

Run any batch load concurrently with any batch export.

Parallelism

Transaction

DB

LT

Database transactions vs. NME logical (application) transaction.

Parallelism

Default transaction isolation level

Read committed

Repeatable read

The setting always depends on the database setup (specifically, the transaction isolation level).

Parallelism

Reprocess only conflicting rows

No

Yes

Restarting only conflicting records of a transaction vs. the entire transaction reload.

Parallelism

Parallel change detection

No

Yes

Run parallel change detection for multiple entities during a load operation.

Parallelism

Parallel master data consolidation

No

Yes

Ability to run parts of the NME iWF in parallel (for example, cleansing of two independent entities).

Parallelism

Elastic committing

No

Yes

Ability to dynamically adjust the number of parallel threads performing the Commit phase.

Parallelism

Parallel data reading in export

No

Yes

Data preparation (reading from MDM storage) can read multiple entities at once in export.

Matching

Matching step

Yeses

Yeses

/

MDA

MDA data storage

Yes

Yes

VLDB is supported as MDA storage starting from 12.3.0.

MDA

Record drafts

Yes

Yes

/

MDA

Attribute overrides

Yes

Yes

/

Optimization

Customization of SQL commands via templates

No

Yes

Adjustment of internal SQL statements for accessing MDM storage.

Optimization

Support SQL hints for small or large data sets

No

Yes

Support different SQL statements (DB hints) for different sizes of data sets.

Optimization

Support for very small transactions

Yes

Yes

Support for very small transactions (for example, web services) using nme.db.tinyDataThreshold and nme.vldb.tinyDataThreshold properties respectively.

Optimization

Exported columns selection

No

Yes

Retrieve only selected columns from the database, as defined in the export operation.

Typical usage

VLDB persistence

This is a good choice with default settings for most projects.

Database persistence

Use this persistence in cases with smaller to medium data volumes, with high demanding online service integration or SOA environments.

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