Sybase ADAPTIVE SERVER IQ 12.4.0 Release Manual page 31

Adaptive Server IQ 12.4.0
Description
JOIN_PREFERENCE Option
Function
Allowed Values
Default
Release Bulletin for Digital UNIX
This option specifies an upper bound (in MB) on the amount of heap memory
subsequent loads can use. The default setting, 0 (zero), means that there is no
upper bound, and Adaptive Server IQ can use as much heap memory as
necessary to perform the load. A non-zero value means that the user has set an
upper bound. This option is typically used for LOAD statements, but affects all
operations where loads occur, including SYNCHRONIZE and DELETE
operations.
Setting a non-zero value for this option is typically done to avoid
overallocating the physical memory on the machine and exhausting virtual
memory during a load operation. Given a user-specified upper limit, the load
process will attempt to ensure that the load can succeed even if it means
incurring degradation in load performance. However, every load requires some
minimal amount of heap memory. If the user-specified limit is lower than this
amount, the user will receive the following error:
The load user approximately <x> MB, but only <y> MB was specified
where <x> is a rough approximation of the minimum amount of heap memory
needed and <y> is the upper limit set by the user. If this error occurs, then the
user must increase or turn off the Load_Memory_MB option and try again.
We are removing the following options and replacing them with the new
LOAD_MEMORY_MB option:
• INSERT_NUMBER_PRODUCERS
• INSERT_NUMBER_MT_BUFFERS
• INSERT_NUMBER_RAW_IO_BUFFERS
• INSERT_NUMBER_ROWS_PER_BUFFER
• INSERT_NUMBER_ROWS_PER_RAW_IO_BUFFER
This version includes two new option values, 6 and –6 to prefer or avoid using
a join index.
Controls the choice of algorithms when processing joins.
-6 to 6
0
Description
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