PartitionDistribution

When the High-speed Apply Engine distributes work between agents based on the physical partitions of a table, it must determine the partition that is affected by each record in the input. The PartitionDistribution parameter specifies how the High-speed Apply Engine determines the partition or group of partitions that are affected by an input record. This parameter is valid only for logical log input generated by BMC AMI Log Master for Db2.

Related topic

LogicalLog-parameters

Attributes

This parameter has the following attributes:

Attribute

Value

Section

[LogicalLog]

Abbreviation

None

Required?

No

Valid values

UseHeader or Calculate

Default value

If the value of the SQLType parameter is Migrate, the default value of PartitionDistribution is Calculate

If the value of the SQLType parameter is Redo or Undo, the default value of PartitionDistribution is UseHeader

Usage

High-speed Apply Engine can determine the affected partition in the following ways:

  • Specify UseHeader to direct High-speed Apply Engine to determine the partition by using the partition number provided in the header of each logical log record in the input. This value can improve the performance of the initial run and any restarted runs of an apply request.
  • Specify Calculate to direct High-speed Apply Engine to determine the partition by reading the values of partitioning key columns in the input record, building a key value, and comparing that value to the high limit key.

Consider the following points as you use the PartitionDistribution parameter:

  • High-speed Apply Engine ignores this parameter when any of the following conditions is true:
    • The value of the PartitionClustering parameter is Yes
    • The value of the DistributionType parameter is UR
  • When you specify logical partitions for a table with [ObjectPartition] parameters, the High-speed Apply Engine determines the partition by reading the values of partitioning key columns (Calculate) for all input statements that affect that table.
  • The value of this parameter applies to the entire logical log input file.
  • Do not set this parameter to UseHeader if your input contains data definition language (DDL) objects that change the partitioning limit keys of the target table.
  • If the partitioning limit keys of the target table are different than those of the source table from which the input was generated, but you execute the input because the differences are compatible, the partition distribution statistics in messages such as BMCAPT0048 reflect the distribution of work based on the partitions of the target table.

 

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