Varun Gupta 38b3e52c3c MDEV-16695: Estimate for rows of derived tables is very high when we are using index_merge union ...

For index merge union[or sort union], the estimates are not taken into account while calculating the selectivity of
a condition. So instead of showing the estimates of the index merge union[or sort union], it shows estimates equal to
all the records of the table.
The fix for the issue is to include the selectivity of index merge
union[or sort union] while calculating the selectivity of a condition.

2018-11-01 13:20:26 +05:30

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