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MDEV-6480: Remove conditions for which range optimizer returned SEL_ARG::IMPOSSIBLE

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Let range optimizer remove parts of OR-clauses for which range analysis
produced SEL_TREE(IMPOSSIBLE).
There is no need to remove parts of AND-clauses: either they are inside
of OR (and the whole AND-clause will be removed), or the AND-clause is
at the top level, in which case the whole WHERE (or ON) is always FALSE
and this is a degenerate case which receives special treatment.

The removal process takes care not to produce 1-way ORs (in that case
we substitute the OR for its remaining member).
This commit is contained in:
Sergei Petrunia
2014-08-27 18:47:33 +04:00
parent 9534fd83ce
commit be00e279c6
9 changed files with 241 additions and 38 deletions
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6
sql/opt_range.h
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@ -994,7 +994,7 @@ class SQL_SELECT :public Sql_alloc {
{
key_map tmp;
tmp.set_all();
return test_quick_select(thd, tmp, 0, limit, force_quick_range, FALSE) < 0;
return test_quick_select(thd, tmp, 0, limit, force_quick_range, FALSE, FALSE) < 0;
}
/*
RETURN
@ -1011,7 +1011,7 @@ class SQL_SELECT :public Sql_alloc {
}
int test_quick_select(THD *thd, key_map keys, table_map prev_tables,
ha_rows limit, bool force_quick_range,
bool ordered_output);
bool ordered_output, bool remove_false_parts_of_where);
};
@ -1036,7 +1036,7 @@ SQL_SELECT *make_select(TABLE *head, table_map const_tables,
table_map read_tables, COND *conds,
bool allow_null_cond, int *error);
bool calculate_cond_selectivity_for_table(THD *thd, TABLE *table, Item *cond);
bool calculate_cond_selectivity_for_table(THD *thd, TABLE *table, Item **cond);
#ifdef WITH_PARTITION_STORAGE_ENGINE
bool prune_partitions(THD *thd, TABLE *table, Item *pprune_cond);