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Viewing changes to drizzled/optimizer/range.cc
- Committer: Prafulla Tekawade
- Date: 2010-07-13 16:07:35 UTC
- mto: (1662.1.4 rollup)
- mto: This revision was merged to the branch mainline in revision 1664.
- Revision ID: prafulla_t@users.sourceforge.net-20100713160735-2fsdtrm3azayuyu1
This bug is simillar to mysql bug 36133
http://bugs.mysql.com/bug.php?id=36133
Taking changes from that fix.
- The problem was that the range optimizer evaluated constant expressions,
and among them it would try to evaluate IN-subquery predicates slated for
handling with materialization strategy. However, these predicates require
that parent_join->setup_subquery_materialization() is invoked before one
attempts to evaluate them.
- Fixed by making the range optimizer not to evaluate expressions that have
item->is_expensive() == TRUE (these are materialization subqueries and
stored function calls). This should also resolve the problem that EXPLAIN
may be too long.
This change cuts off some opportunities for range optimizer, but this is
the price we're willing to pay for separation of query optimization and
execution.
http://bugs.mysql.com/bug.php?id=36133
Taking changes from that fix.
- The problem was that the range optimizer evaluated constant expressions,
and among them it would try to evaluate IN-subquery predicates slated for
handling with materialization strategy. However, these predicates require
that parent_join->setup_subquery_materialization() is invoked before one
attempts to evaluate them.
- Fixed by making the range optimizer not to evaluate expressions that have
item->is_expensive() == TRUE (these are materialization subqueries and
stored function calls). This should also resolve the problem that EXPLAIN
may be too long.
This change cuts off some opportunities for range optimizer, but this is
the price we're willing to pay for separation of query optimization and
execution.
- files modified:
- drizzled/item.h
added
removed
drizzled/optimizer/range.cc
