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fix comments
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@montywi @vuvova
montywi authored and vuvova committed Oct 5, 2015
1 parent 8ed5fde commit ae2cdc1
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Showing 2 changed files with 48 additions and 39 deletions.
2 changes: 1 addition & 1 deletion sql/sql_base.cc
View file
Expand Up @@ -8041,7 +8041,7 @@ void make_leaves_list(THD *thd, List<TABLE_LIST> &list, TABLE_LIST *tables,
from_clause Top-level list of table references in the FROM clause
tables Table list (select_lex->table_list)
leaves List of join table leaves list (select_lex->leaf_tables)
refresh It is onle refresh for subquery
refresh It is only refresh for subquery
select_insert It is SELECT ... INSERT command
full_table_list a parameter to pass to the make_leaves_list function
Expand Down
85 changes: 47 additions & 38 deletions sql/sql_select.cc
View file
Expand Up @@ -756,12 +756,11 @@ JOIN::prepare(Item ***rref_pointer_array,
}

table_count= select_lex->leaf_tables.elements;

TABLE_LIST *tbl;
List_iterator_fast<TABLE_LIST> li(select_lex->leaf_tables);
while ((tbl= li++))
{
//table_count++; /* Count the number of tables in the join. */
/*
If the query uses implicit grouping where the select list contains both
aggregate functions and non-aggregate fields, any non-aggregated field
Expand Down Expand Up @@ -805,8 +804,9 @@ JOIN::prepare(Item ***rref_pointer_array,
thd->lex->allow_sum_func|= (nesting_map)1 << select_lex_arg->nest_level;
select_lex->having_fix_field= 1;
/*
Wrap alone field in HAVING clause in case it will be outer field of subquery
which need persistent pointer on it, but having could be changed by optimizer
Wrap alone field in HAVING clause in case it will be outer field
of subquery which need persistent pointer on it, but having
could be changed by optimizer
*/
if (having->type() == Item::REF_ITEM &&
((Item_ref *)having)->ref_type() == Item_ref::REF)
Expand Down Expand Up @@ -1099,8 +1099,8 @@ JOIN::optimize_inner()
before 'optimize' from upper query 'optimize' to allow semijoin
conversion happened (which done in the same way.
*/
if(select_lex->first_cond_optimization &&
conds && conds->walk(&Item::exists2in_processor, 0, (uchar *)thd))
if (select_lex->first_cond_optimization &&
conds && conds->walk(&Item::exists2in_processor, 0, (uchar *)thd))
DBUG_RETURN(1);
/*
TODO: make view to decide if it is possible to write to WHERE directly or make Semi-Joins able to process ON condition if it is possible
Expand Down Expand Up @@ -2536,9 +2536,10 @@ void JOIN::exec_inner()
}

/*
Evaluate all constant expressions with subqueries in the ORDER/GROUP clauses
to make sure that all subqueries return a single row. The evaluation itself
will trigger an error if that is not the case.
Evaluate all constant expressions with subqueries in the
ORDER/GROUP clauses to make sure that all subqueries return a
single row. The evaluation itself will trigger an error if that is
not the case.
*/
if (exec_const_order_group_cond.elements &&
!(select_options & SELECT_DESCRIBE))
Expand Down Expand Up @@ -2763,7 +2764,6 @@ void JOIN::exec_inner()
(curr_join->tmp_all_fields1.elements-
curr_join->tmp_fields_list1.elements);


if (exec_tmp_table2)
curr_tmp_table= exec_tmp_table2;
else
Expand Down Expand Up @@ -2878,7 +2878,6 @@ void JOIN::exec_inner()
if (curr_tmp_table->distinct)
curr_join->select_distinct=0; /* Each row is unique */


curr_join->join_free(); /* Free quick selects */

if (curr_join->select_distinct && ! curr_join->group_list)
Expand Down Expand Up @@ -11880,7 +11879,6 @@ void JOIN::cleanup(bool full)
}
}
cleaned= true;

}
else
{
Expand Down Expand Up @@ -16071,11 +16069,15 @@ void setup_tmp_table_column_bitmaps(TABLE *table, uchar *bitmaps)
@param param a description used as input to create the table
@param fields list of items that will be used to define
column types of the table (also see NOTES)
@param group TODO document
@param group Create an unique key over all group by fields.
This is used to retrive the row during
end_write_group() and update them.
@param distinct should table rows be distinct
@param save_sum_fields see NOTES
@param select_options
@param rows_limit
@param select_options Optiions for how the select is run.
See sql_priv.h for a list of options.
@param rows_limit Maximum number of rows to insert into the
temporary table
@param table_alias possible name of the temporary table that can
be used for name resolving; can be "".
*/
Expand Down Expand Up @@ -16375,9 +16377,9 @@ create_tmp_table(THD *thd, TMP_TABLE_PARAM *param, List<Item> &fields,
/*
If item->marker == 4 then we force create_tmp_field
to create a 64-bit longs for BIT fields because HEAP
tables can't index BIT fields directly. We do the same
for distinct, as we want the distinct index to be
usable in this case too.
tables can't index BIT fields directly. We do the
same for distinct, as we want the distinct index
to be usable in this case too.
*/
item->marker == 4 || param->bit_fields_as_long,
force_copy_fields,
Expand All @@ -16397,16 +16399,19 @@ create_tmp_table(THD *thd, TMP_TABLE_PARAM *param, List<Item> &fields,
created temporary table is not to be used for subquery
materialization.

The reason is that for subqueries that require materialization as part
of their plan, we create the 'external' temporary table needed for IN
execution, after the 'internal' temporary table needed for grouping.
Since both the external and the internal temporary tables are created
for the same list of SELECT fields of the subquery, setting
'result_field' for each invocation of create_tmp_table overrides the
previous value of 'result_field'.

The condition below prevents the creation of the external temp table
to override the 'result_field' that was set for the internal temp table.
The reason is that for subqueries that require
materialization as part of their plan, we create the
'external' temporary table needed for IN execution, after
the 'internal' temporary table needed for grouping. Since
both the external and the internal temporary tables are
created for the same list of SELECT fields of the subquery,
setting 'result_field' for each invocation of
create_tmp_table overrides the previous value of
'result_field'.

The condition below prevents the creation of the external
temp table to override the 'result_field' that was set for
the internal temp table.
*/
if (!agg_item->result_field || !param->materialized_subquery)
agg_item->result_field= new_field;
Expand Down Expand Up @@ -17710,6 +17715,7 @@ Next_select_func setup_end_select_func(JOIN *join)
@retval
-1 if error should be sent
*/

static int
do_select(JOIN *join,List<Item> *fields,TABLE *table,Procedure *procedure)
{
Expand Down Expand Up @@ -17877,12 +17883,14 @@ int rr_sequential_and_unpack(READ_RECORD *info)


/*
Fill the join buffer with partial records, retrieve all full matches for them
Fill the join buffer with partial records, retrieve all full matches for
them

SYNOPSIS
sub_select_cache()
join pointer to the structure providing all context info for the query
join_tab the first next table of the execution plan to be retrieved
join pointer to the structure providing all context info for the
query
join_tab the first next table of the execution plan to be retrieved
end_records true when we need to perform final steps of the retrieval

DESCRIPTION
Expand Down Expand Up @@ -21059,8 +21067,9 @@ create_sort_index(THD *thd, JOIN *join, ORDER *order,
if (join->pre_sort_join_tab)
{
/*
we've already been in this function, and stashed away the original access
method in join->pre_sort_join_tab, restore it now.
we've already been in this function, and stashed away the
original access method in join->pre_sort_join_tab, restore it
now.
*/

/* First, restore state of the handler */
Expand Down Expand Up @@ -22795,11 +22804,11 @@ change_to_use_tmp_fields(THD *thd, Item **ref_pointer_array,
if (!suv || !new_field)
DBUG_RETURN(true); // Fatal error
/*
We are replacing the argument of Item_func_set_user_var
after its value has been read. The argument's null_value
should be set by now, so we must set it explicitly for the
replacement argument since the null_value may be read
without any preceding call to val_*().
We are replacing the argument of Item_func_set_user_var after
its value has been read. The argument's null_value should be
set by now, so we must set it explicitly for the replacement
argument since the null_value may be read without any
preceeding call to val_*().
*/
new_field->update_null_value();
List<Item> list;
Expand Down

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