16.10 - DictionaryCacheSize - Teradata Database

Teradata Database Utilities

Product

Teradata Database

Release Number

16.10

Published

June 2017

Language

English (United States)

Last Update

2018-04-26

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Purpose

Defines the size in kilobytes of the dictionary cache for each PE on the system.

Field Group

Performance

Valid Range

64 KB through 32768 KB

If the value of DictionaryCacheSegmentSize is 0, the value of DictionaryCacheSize should not exceed 16384 KB.

Default

8192 KB on SLES 11 systems

Changes Take Effect

After the next Teradata Database restart.

Usage Notes

The value of DictionaryCacheSize should be a multiple of the value of DictionaryCacheSegmentSize.

DictionaryCacheSize Performance Implications

The default value allows more caching of table header information and reduces the number of I/Os required. It is especially effective for workloads that access many tables (more than 200) and for those that generate many dictionary seeks.

Increase the size of the dictionary cache to allow the parser to cache additional data dictionary and table header information.

For tactical and Online Complex Processing (OLCP) type workloads, maintaining a consistently short, few-second response time is important. These workloads may benefit from a larger dictionary cache, particularly when their query plans have not been cached in the request cache. A larger dictionary cache will allow more dictionary detail, needed for parsing and optimizing, to remain in memory for a longer period of time. For query workloads with a response time of more than one minute, there may be no measurable difference when this field is set to a higher value.