Volatile Tables in WebSphere Commerce V7.0 for DB2

Technote (FAQ)


Question

What are the declared Volatile tables for WebSphere Commerce V7.0 for DB2?

Answer

The reason a table is declared Volatile in DB2:
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A volatile table is defined as a table whose contents can vary from empty to very large at run time. The volatility or extreme changeability of this type of table makes reliance on the statistics collected by RUNSTATS inaccurate. Statistics are gathered at, and only reflect, a point in time. To generate an access plan that uses a volatile table can result in an incorrect or poorly performing plan. For example, if statistics are gathered when the volatile table is empty, the optimizer tends to favor accessing the volatile table using a table scan rather than an index scan.

To prevent this, you should consider declaring the table as volatile using the ALTER TABLE statement. By declaring the table volatile, the optimizer will consider using index scan rather than table scan. The access plans that use declared volatile tables will not depend on the existing statistics for that table.
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In WebSphere Commerce V7.0 these 9 tables are declared as Volatile:

ORDADJDSC
ORDIADJUST
SUBORDADJ
TMPBOLIST
TMPCMPLIST
TMPFFCLIST
TMPRADTL
TMPRCTLIST
STAGLOG

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Document information


More support for:

WebSphere Commerce Enterprise
Database

Software version:

7.0

Operating system(s):

AIX, IBM i, Linux, Solaris, Windows, i5/OS

Reference #:

1627018

Modified date:

2013-03-11

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