Enabling and Configuring PowerExchange Data Maps Caching

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Multiple-Jobs Mode

In multiple-jobs mode, PowerExchange maintains copies of previously read data maps in

job-level

memory. Additionally, when you start a PowerExchange Listener, PowerExchange dynamically allocates 4096 bytes of ECSA memory in which PowerExchange maintains the name of the data maps KSDS file and the time stamp of its last update. PowerExchange uses this information to determine whether the data maps cache is stale and needs to be cleared.

On subsequent reads of data maps, PowerExchange retrieves the data maps from

job-level

memory, which eliminates the overhead of enqueues, opens, points, reads, and closes of the data maps KSDS file.

When a data map changes or is deleted, PowerExchange completes the following processing:

In ECSA memory, PowerExchange changes the time stamp of the last update to the data maps KSDS file.

When another task tries to access any data map, PowerExchange determines if the cache is stale by comparing the time stamp in ECSA memory against the time stamp of the data maps cache. If the cache is stale, PowerExchange clears it and PowerExchange reads the required data map from disk and adds it to the cache.

To configure PowerExchange to run data maps caching in multiple-jobs mode, define the following DBMOVER configuration statement:

DMXCACHE_MULTIPLEJOBS=Y

Additionally, if you want PowerExchange to free the ECSA memory after the PowerExchange Listener closes, define the following DBMOVER configuration statement:

DMXCACHE_DELETEECSA=Y

However, because shared memory allocation is a complex task and 4096 bytes of memory is a small amount, you can accept the default value, which is N, to permanently retain the ECSA memory.

For information about the DMXCACHE_MULTIPLEJOBS statement, see DMXCACHE_MULTIPLEJOBS Statement. For information about the DMXCACHE_DELETEECSA statement, see DMXCACHE_DELETEECSA Statement.

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Table of Contents

Enabling and Configuring PowerExchange Data Maps Caching

Enabling and Configuring PowerExchange Data Maps Caching

Multiple-Jobs Mode

Multiple-Jobs Mode