SAP ABAP Data Element DB2BACLPF (Number of list prefetch requests)
Hierarchy
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SAP_BASIS (Software Component) SAP Basis Component
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BC-DB-DB2 (Application Component) DB2 for z/OS
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STU2 (Package) CCMS for DB2 for OS/390
SAP_BASIS (Software Component) SAP Basis Component⤷
BC-DB-DB2 (Application Component) DB2 for z/OS⤷
STU2 (Package) CCMS for DB2 for OS/390
Basic Data
| Data Element | DB2BACLPF |
| Short Description | Number of list prefetch requests |
Data Type
| Category of Dictionary Type | D | Domain |
| Type of Object Referenced | No Information | |
| Domain / Name of Reference Type | DB2INT4U | |
| Data Type | INT4 | 4-byte integer, integer number with sign |
| Length | 10 | |
| Decimal Places | 0 | |
| Output Length | 10 | |
| Value Table |
Further Characteristics
| Search Help: Name | ||
| Search Help: Parameters | ||
| Parameter ID | ||
| Default Component name | ||
| Change document | ||
| No Input History | ||
| Basic direction is set to LTR | ||
| No BIDI Filtering |
Field Label
| Length | Field Label | |
| Short | 10 | List Pref |
| Medium | 15 | List Prefetch |
| Long | 22 | List prefetch requests |
| Heading | 0 |
Documentation
Definition
List prefetch allows DB2 to access data pages efficiently even when the needed data pages are not contiguous.
List prefetch can be used with single index access and is always used with multiple index access. It is always used to access data from the inner table during a hybrid join. Data pages are read in quantities equal to the sequential prefetch quantity which depends on buffer pool size and is usually 32 pages.
During bind time DB2 does not use list prefetch if the estimated number of RIDS to be processed would use more than 50% of the RID Pool. During execution time, list prefetch processing terminates if DB2 detects that more than 25% of the rows in the table need to be accessed.
History
| Last changed by/on | SAP | 20070813 |
| SAP Release Created in |
