000-349 · Question #4
Referring to the Exhibit, which map rule function takes the most time to run?
The correct answer is D. LOOKUP. Among common map rule functions, LOOKUP takes the longest to execute because it requires accessing external data sources, introducing I/O latency not present in purely in-memory operations.
Question
Referring to the Exhibit, which map rule function takes the most time to run?
Options
- ABUILD_CARD
- BMAP_NAME
- CTYPE_NAME
- DLOOKUP
How the community answered
(32 responses)- A9% (3)
- B3% (1)
- C3% (1)
- D84% (27)
Why each option
Among common map rule functions, LOOKUP takes the longest to execute because it requires accessing external data sources, introducing I/O latency not present in purely in-memory operations.
BUILD_CARD constructs output card structures in memory using already-parsed data, which is a fast in-memory operation with no external I/O.
MAP_NAME simply retrieves the name string of the currently executing map from metadata, requiring negligible processing time.
TYPE_NAME retrieves the name of a data type from the in-memory type tree metadata, which requires minimal CPU cycles.
LOOKUP functions retrieve data from external resources such as database tables or flat files, requiring disk or network I/O that is orders of magnitude slower than in-memory computations. Each LOOKUP call may involve index searches, query execution, and result retrieval, all of which add significant latency compared to built-in structural functions. This external dependency makes LOOKUP the most time-consuming map rule function in typical execution profiles, as visible in map execution exhibits.
Concept tested: Map rule function performance cost - LOOKUP external I/O overhead
Source: https://www.ibm.com/docs/en/wtx/8.4.1?topic=functions-built-in-map-rule-functions
Topics
Community Discussion
No community discussion yet for this question.