User Guide

SAP AG November 2002
If the Optimizer estimates that the percentage of all pages of an index that need to be read in
order to get results is greater than the figure defined in OPTIM_BUILD_RESLT, this index will
not be used.
OPTIM_FETCH_RESLT
The special database parameter [Page 80] OPTIM_FETCH_RESLT determines how the
Optimizer is used.
If the Optimizer estimates that the percentage of all pages of an index that need to be read is
greater than the figure defined in OPTIM_BUILD_RESLT and no results need to be built up,
this index will not be used.
OPTIM_KEY_INV_RATE
The special database parameter [Page 80] OPTIM_KEY_INV_RATE determines which
optimizing algorithm should be used. This depends on whether it would be better to use the
index or the primary key.
• Relationship 1: The number of index pages that need to be read in relation to the size of
the index
• Relationship 2: The number of pages that need to be read using the primary key (primary
data pages) in relation to the number of all primary data pages
If relationship 1 is OPTIM_KEY_INV_RATE percent smaller than relationship 2, the index will
be used. If not, the data will be accessed directly using the primary key.
OPTIM_MAX_MERGE
The special database parameter [Page 80] OPTIM_MAX_MERGE denotes how the
optimizing algorithm for merging index lists changes.
If the number of pages of an index that need to be merged exceeds the value specified in
OPTIM_MAX_MERGE, this index will not be used for an index merging strategy.
OPTIM_ORDERBY_IDX
The special database parameter [Page 80] OPTIM_ORDERBY_IDX denotes how the
optimization algorithm changes if you are using ORDER BY clauses.
If the OPTIM_ORDERBY_IDX values are quite high, the system will tend to use inversions to
process SQL statements with ORDER BY clauses. If this is the case, the results do not need
to be built up so the first results can be delivered quickly.
This parameter does not affect the join SELECT statements.
User Manual: SAP DB 87