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Asif: Gets a best match index which is available. An index with match level equal to 0 is the
best index to use as it implies that the query from clause iterators belonging to the region
exactly match the index from clause iterators ( the difference in the relative positions of the
iterators do not matter). A match level less than 0 means that number of iteratots in the index
resultset is more than that present in the query from clause and hence index resultset will
need a cutdown. A match level greater than 0 means that there definitely is atleast one
iterator in the query from clause which is more than the index from clause iterators & hence
definitely expansion of index results will be needed. Pls note that a match level greater than
0 does not imply that index from clause does not have an extra iterator in it , too. Hence a
match level greater than 0 will definitely mean expansion of index results but may also require
a cut down of results . The order of preference is match level 0 , less than 0 and lastly
greater than 0