Neoview Database Administrator's Guide (R2.2)

When you rerun the task, if job recovery was enabled, the system uses the built-in recovery
feature. For information on recovery, see “Recovery” (page 116).
Transaction Size Limit
When you configure the transaction size you can improve performance by setting the size to
2500 or higher. If you are not running multiple load tasks concurrently you can set the transaction
size close to the limit, described later in this chapter. For INSERT tasks, HP recommends that
you do not exceed a transaction size of 10000. This can cause issues with the size of transactions
on the target system.
If you are running multiple load tasks concurrently, performance can be adversely impacted by
setting the transaction close to the limit. This can cause unnecessary page swapping by the Linux
operating system when the task is running. The maximum size is based on the number of partitions
in the target table, the size of the rows in the target table, and the number of input files, pipes,
or queues.
Following is a formula for calculating the approximate amount of memory required for a given
transaction size:
memory allocation =((2 * number of input files) + (3 * number of
partitions)) * transaction size * internal record size
internal record size
is the number of bytes allocated per column of the target table based on the
following:
size of columnCHAR
size of columnVARCHAR
2/4/8 depending on precisionNUMERIC
2SMALLINT
4INTEGER
8LARGEINT
depends on precisionDECIMAL
8FLOAT
4REAL
8DOUBLE
PRECISION
10DATE
8TIME
19 or 20 (with timestamp precision)TIMESTAMP
When starting the task, the Linux gelserver ensures that the configured transaction size does not
result in more than 2.8 GB of memory is allocated. If that limit is exceeded this error message is
reported:
Program memory requirement exceeds 2.8 GB, try again by decreasing the transaction size.
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