Enables and disables literal parameterization at the session level.
The range of values for opttimeoutlimit has been changed to 0 – 4000, with 0 indicating no optimization limit.
When enabled, set index_union limits the scan of a table with an or clause.
Index unions (also known as an or strategy) are used for queries that contain or clauses. For example:
select * from titleauthor where au_id = "409-56-7008" or title_id = "PC8888"
If you have enabled index_union,
this example uses an index on au_id to
find the row IDs (RIDs) of all titleauthor tuples
with au_id = "409-56-7008", and
uses an index on title_id to find
the RIDs of all titleauthor tuples with title_id = "PC8888".
Adaptive Server then performs a union on all RIDs to eliminate duplicates. The
resulting RIDs are joined with a RidJoin to access the
data tuples.
If index_union is disabled, Adaptive Server does not use an index union strategy in a query to limit the table scan. Instead, it uses other access paths on the table (in the example above, it would use a table scan for table titleauthor), and applies the or clause as a filter in the scan operator.
