Sybase 12.4.2 User Manual

Page 451

CHAPTER 12 Managing System Resources

431

Table 12-3: Default block sizes

Data compression

Adaptive Server IQ compresses all data when storing it on disk. Data
compression both reduces disk space requirements and contributes to
performance. The amount of compression is determined automatically, based
on the IQ page size.

Saving memory

If your machine does not have enough memory, to save memory you can try
the following adjustments.

Decrease buffer cache settings

You may be able to save memory by decreasing buffer cache sizes. Keep in
mind that if you decrease the buffer caches too much, you could make your
data loads or queries inefficient or incomplete due to insufficient buffers.

Decrease memory used for loads

You can set the

LOAD_MEMORY_MB

option to limit the amount of heap

memory used for loads and other similar operations. See “Memory for loads,
synchronizations, and deletions” on page 421.

Adjust blocking factor for loads

Use

BLOCK FACTOR

to reduce I/O when loading from a flat file. The

BLOCK

FACTOR

option of the

LOAD

command specifies the blocking factor, or number

of records per block, that were used when the input file was created. The
default

BLOCK FACTOR

is 10,000.

The syntax for this load option is as follows:

BLOCK FACTOR =

integer

Page Size (KB)

Block Size (bytes)

4096

128

8192

256

16384

512

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