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
).
Db2 12 introduces this subsystem parameter. It takes
effect in function level 100. However, during coexistence with Db2 11, no storage is allocated for fast index traversal of group buffer pool dependent indexes.
| Acceptable values: |
The range for n is 10–200000. |
|---|---|
| Default: |
|
| 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.