Remove ChangeDataSource from all IndexPredicates
The index rewriter will always combine IndexPredicates for known
fields into a single IndexedChangeQuery. The only way that the query
system could choose a ChangeDataSource that is also an IndexPredicate
is if that field is not supported in the live index version. But for
all such predicates, they have been in the index for a very long time.
The ChangeDataSource pieces were therefore just dead code. Remove them
and set all costs to 1, which is standard for index predicates; this
also means we can delete the ChangeCosts class entirely.
Change-Id: Ib3eb4cadb77fbfd32e7036c9b1ccbc3706ce68e6
10 files changed
