unknown 33c66eb7fb MDEV-4120: UNIQUE indexes should not be considered for loose index scan ...

Currently the loose scan code in opt_range.cc considers all indexes as
possible for the access method. Due to inexact statistics it may happen
that a loose scan is selected over a unique index.
  
This is clearly wrong since a "loose scan" over a unique index will read
the same keys as a direct index scan, but the loose scan has more overhead.
  
This task adds a rule to skip unique indexes for loose scan.

2013-08-21 10:51:08 +03:00

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