Don't try to a histogram if it is not read into the cache for statistical data.
It may happen so if optimizer_use_condition_selectivity is set to 3. This
setting orders the optimizer not use histograms to calculate selectivity.
When performing the range analysis for a conjunction the function
calculate_cond_selectivity_for_table should take in to account that
the analysis of some conjuncts may return SEL_ARG::IMPOSSIBLE.
One of them is quite serious: the function table_cond_selectivity used
the TABLE_REF structure for ref/eq_ref access methods as if they had been
filled. In fact these structure are filled after the best execution plan
has been chosen.
The other bugs happened due to:
- an erroneous attempt at get statistics on the result of materialization
of a view
- incorrect handling of ranges with no left/right limits when calculating
selectivity of range conditions on non-indexed columns
- lack of cleanup for some newly introduced fields
