INDEX MEMORY CONTROL field (INDEX_MEMORY_CONTROL subsystem parameter)

The INDEX_MEMORY_CONTROL subsystem parameter specifies the amount of memory that Db2 allocates for fast traversing of indexes (sometimes called fast traverse blocks or FTB).

Acceptable values:
INDEX MEMORY CONTROL field
AUTO, DISABLE, or n
FOR SELECTED INDEXES ONLY field
NO or YES
INDEX_MEMORY CONTROL subsystem parameter
AUTO, DISABLE, n, (SELECTED,AUTO), or (SELECTED,n)

The range for n is 10–200000.
Default:
INDEX MEMORY CONTROL field
AUTO
FOR SELECTED INDEXES ONLY field
NO
INDEX_MEMORY CONTROL subsystem parameter
AUTO
Data sharing scope: It is recommended that all members use the same setting
Online changeable: Yes
Update: Option 15 on panel DSNTIPB
DSNZPxxx: DSN6SPRM.INDEX_MEMORY_CONTROL
AUTO

Db2 sets the upper limit to 20 percent of the currently allocated buffer pool storage, or 10 MB, whichever is larger.

DISABLE

Db2 returns any existing storage that is allocated for fast index traversal and allocates no more storage for fast index traversal.

This setting is accepted only when FOR SELECTED INDEXES ONLY is NO on panel DSNTIP71.

10–200000
Specifies the storage limit for fast index traversal, in megabytes.
(SELECTED,AUTO)
Specifies that fast index traversal is enabled only for specific indexes, and Db2 calculates the storage size limit. When this setting is specified, Db2 considers fast index traversal only for indexes recorded with ACTION='A' in the SYSIBM.SYSINDEXCONTROL catalog table.

This setting is used when INDEX MEMORY CONTOL is AUTO and FOR SELECTED INDEXES ONLY is YES on panel DSNTIP71.

(SELECTED,n)
Specifies that fast index traversal is enabled only for selected indexes, and n specifies the storage size limit. When this setting is specified, Db2 considers fast index traversal only for indexes recorded with ACTION='A' in the SYSIBM.SYSINDEXCONTROL catalog table.

This setting is used when the INDEX MEMORY CONTROL field is n in the range 10–200000, and the FOR SELECTED INDEXES ONLY field is YES on panel DSNTIP71.