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Fixed bug #52636.

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Applied the fix for bug #47217 from the mysql-6.0 codebase.
The patch adds not null predicates generated for the left parts
of the equality predicates used for ref accesses. This is done
for such predicates both in where conditions and on conditions.
For the where conditions the not null predicates were generated
but in 5.0/5.1 they actually never were used due to some lame
merge from 4.1 to 5.0. The fix for bug #47217 made these 
predicates to be used in the condition pushed to the tables.
Yet only this patch generates not null predicates for equality
predicated from on conditions of outer joins.
This patch introduces a performance regression that can be
observed on a test case from null_key.test. The regression
will disappear after the fix for bug #57024 from mariadb-5.1
is pulled into mariadb-5.3.
The patch contains many changes in the outputs of the EXPLAIN 
commands since generated not null predicates are considered as
parts of the conditions pushed to join tables and may add
'Usingwhere' in some rows of EXPLAINs where there used
to be no such comments.
This commit is contained in:
Igor Babaev
2010-09-28 12:39:33 -07:00
parent db37f2db82
commit 21b1b5f040
40 changed files with 404 additions and 238 deletions
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32
sql/sql_select.cc
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@ -6443,6 +6443,8 @@ inline void add_cond_and_fix(Item **e1, Item *e2)
{
if (*e1)
{
if (!e2)
return;
Item *res;
if ((res= new Item_cond_and(*e1, e2)))
{
@ -6513,9 +6515,8 @@ static void add_not_null_conds(JOIN *join)
for (uint i=join->const_tables ; i < join->tables ; i++)
{
JOIN_TAB *tab=join->join_tab+i;
if ((tab->type == JT_REF || tab->type == JT_EQ_REF ||
tab->type == JT_REF_OR_NULL) &&
!tab->table->maybe_null)
if (tab->type == JT_REF || tab->type == JT_EQ_REF ||
tab->type == JT_REF_OR_NULL)
{
for (uint keypart= 0; keypart < tab->ref.key_parts; keypart++)
{
@ -6547,9 +6548,14 @@ static void add_not_null_conds(JOIN *join)
DBUG_EXECUTE("where",print_where(notnull,
referred_tab->table->alias,
QT_ORDINARY););
COND *new_cond= referred_tab->select_cond;
add_cond_and_fix(&new_cond, notnull);
referred_tab->set_select_cond(new_cond, __LINE__);
if (!tab->first_inner)
{
COND *new_cond= referred_tab->select_cond;
add_cond_and_fix(&new_cond, notnull);
referred_tab->set_select_cond(new_cond, __LINE__);
}
else
add_cond_and_fix(tab->first_inner->on_expr_ref, notnull);
}
}
}
@ -6729,6 +6735,10 @@ make_join_select(JOIN *join,SQL_SELECT *select,COND *cond)
make_cond_for_table(cond,
join->const_table_map,
(table_map) 0, TRUE);
/* Add conditions added by add_not_null_conds(). */
for (uint i= 0 ; i < join->const_tables ; i++)
add_cond_and_fix(&const_cond, join->join_tab[i].select_cond);
DBUG_EXECUTE("where",print_where(const_cond,"constants", QT_ORDINARY););
for (JOIN_TAB *tab= join->join_tab+join->const_tables;
tab < join->join_tab+join->tables ; tab++)
@ -6827,6 +6837,9 @@ make_join_select(JOIN *join,SQL_SELECT *select,COND *cond)
tmp= NULL;
if (cond)
tmp= make_cond_for_table(cond, used_tables, current_map, FALSE);
/* Add conditions added by add_not_null_conds(). */
if (tab->select_cond)
add_cond_and_fix(&tmp, tab->select_cond);
if (cond && !tmp && tab->quick)
{ // Outer join
if (tab->type != JT_ALL)
@ -13898,13 +13911,6 @@ join_read_always_key(JOIN_TAB *tab)
}
}
/* Perform "Late NULLs Filtering" (see internals manual for explanations) */
for (uint i= 0 ; i < tab->ref.key_parts ; i++)
{
if ((tab->ref.null_rejecting & 1 << i) && tab->ref.items[i]->is_null())
return -1;
}
if (cp_buffer_from_ref(tab->join->thd, table, &tab->ref))
return -1;
if ((error= table->file->ha_index_read_map(table->record[0],