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mariadb/sql/sql_union.cc
Vasilii Lakhin 717c12de0e Fix typos in C comments inside sql/
2025-03-14 12:08:56 +04:00

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/* Copyright (c) 2000, 2017, Oracle and/or its affiliates.
Copyright (c) 2010, 2020, MariaDB Corporation.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; version 2 of the License.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1335 USA */
/*
UNION of select's
UNION's were introduced by Monty and Sinisa <sinisa@mysql.com>
*/
#include "mariadb.h"
#include "sql_priv.h"
#include "unireg.h"
#include "sql_union.h"
#include "sql_select.h"
#include "sql_cursor.h"
#include "sql_base.h" // fill_record
#include "filesort.h" // filesort_free_buffers
#include "sql_view.h"
#include "sql_cte.h"
#include "item_windowfunc.h"
select_handler *find_partial_select_handler(THD *thd, SELECT_LEX *select_lex,
SELECT_LEX_UNIT *lex_unit);
bool mysql_union(THD *thd, LEX *lex, select_result *result,
SELECT_LEX_UNIT *unit, ulonglong setup_tables_done_option)
{
DBUG_ENTER("mysql_union");
bool res;
if (!(res= unit->prepare(unit->derived, result, SELECT_NO_UNLOCK |
setup_tables_done_option)))
res= unit->exec();
res|= unit->cleanup();
DBUG_RETURN(res);
}
/***************************************************************************
** store records in temporary table for UNION
***************************************************************************/
int select_unit::prepare(List<Item> &list, SELECT_LEX_UNIT *u)
{
unit= u;
return 0;
}
/**
This called by SELECT_LEX_UNIT::exec when select changed
*/
void select_unit::change_select()
{
uint current_select_number= thd->lex->current_select->select_number;
DBUG_ENTER("select_unit::change_select");
DBUG_PRINT("enter", ("select in unit change: %u -> %u",
curr_sel, current_select_number));
DBUG_ASSERT(curr_sel != current_select_number);
curr_sel= current_select_number;
/* New SELECT processing starts */
DBUG_ASSERT(table->file->inited == 0);
step= thd->lex->current_select->get_linkage();
switch (step)
{
case INTERSECT_TYPE:
prev_step= curr_step;
curr_step= current_select_number;
break;
case EXCEPT_TYPE:
break;
default:
step= UNION_TYPE;
break;
}
DBUG_VOID_RETURN;
}
/**
Fill temporary tables for UNION/EXCEPT/INTERSECT
@Note
UNION:
just add records to the table (with 'counter' field first if INTERSECT
present in the sequence).
EXCEPT:
looks for the record in the table (with 'counter' field first if
INTERSECT present in the sequence) and delete it if found
INTERSECT:
looks for the same record with 'counter' field of previous operation,
put as a 'counter' number of the current SELECT.
We scan the table and remove all records which marked with not last
'counter' after processing all records in send_eof and only if it last
SELECT of sequence of INTERSECTS.
@param values List of record items to process.
@retval 0 - OK
@retval -1 - duplicate
@retval 1 - error
*/
int select_unit::send_data(List<Item> &values)
{
int rc= 0;
int not_reported_error= 0;
if (table->no_rows_with_nulls)
table->null_catch_flags= CHECK_ROW_FOR_NULLS_TO_REJECT;
fill_record(thd, table, table->field + addon_cnt, values, true, false, true);
/* set up initial values for records to be written */
if (addon_cnt && step == UNION_TYPE)
{
DBUG_ASSERT(addon_cnt == 1);
table->field[0]->store((ulonglong) curr_step, 1);
}
if (unlikely(thd->is_error()))
{
rc= 1;
if (unlikely(not_reported_error))
{
DBUG_ASSERT(rc);
table->file->print_error(not_reported_error, MYF(0));
}
return rc;
}
if (table->no_rows_with_nulls)
{
table->null_catch_flags&= ~CHECK_ROW_FOR_NULLS_TO_REJECT;
if (table->null_catch_flags)
{
rc= 0;
if (unlikely(not_reported_error))
{
DBUG_ASSERT(rc);
table->file->print_error(not_reported_error, MYF(0));
}
return rc;
}
}
/* select_unit::change_select() change step & Co correctly for each SELECT */
int find_res;
switch (step)
{
case UNION_TYPE:
/* Errors not related to duplicate key are reported by write_record() */
rc= write_record();
/* no reaction with conversion. rc == -1 (dupp key) is ignored by caller */
if (rc == -2)
rc= 0;
break;
case EXCEPT_TYPE:
/*
The temporary table uses very first index or constrain for
checking unique constrain.
*/
if (!(find_res= table->file->find_unique_row(table->record[0], 0)))
rc= delete_record();
else
rc= not_reported_error= (find_res != 1);
break;
case INTERSECT_TYPE:
/*
The temporary table uses very first index or constrain for
checking unique constrain.
*/
if (!(find_res= table->file->find_unique_row(table->record[0], 0)))
{
DBUG_ASSERT(!table->triggers);
if (table->field[0]->val_int() == prev_step)
{
not_reported_error= update_counter(table->field[0], curr_step);
rc= MY_TEST(not_reported_error);
DBUG_ASSERT(rc != HA_ERR_RECORD_IS_THE_SAME);
}
}
else
rc= not_reported_error= (find_res != 1);
break;
default:
DBUG_ASSERT(0);
}
if (unlikely(not_reported_error))
{
DBUG_ASSERT(rc);
table->file->print_error(not_reported_error, MYF(0));
}
return rc;
}
bool select_unit::send_eof()
{
if (step != INTERSECT_TYPE ||
(thd->lex->current_select->next_select() &&
thd->lex->current_select->next_select()->get_linkage() == INTERSECT_TYPE))
{
/*
it is not INTERSECT or next SELECT in the sequence is INTERSECT so no
need filtering (the last INTERSECT in this sequence of intersects will
filter).
*/
return 0;
}
/*
It is last select in the sequence of INTERSECTs so we should filter out
all records except marked with actual counter.
TODO: as optimization for simple case this could be moved to
'fake_select' WHERE condition
*/
int error;
if (table->file->ha_rnd_init_with_error(1))
return 1;
do
{
error= table->file->ha_rnd_next(table->record[0]);
if (unlikely(error))
{
if (error == HA_ERR_END_OF_FILE)
{
error= 0;
break;
}
break;
}
if (table->field[0]->val_int() != curr_step)
error= delete_record();
} while (!error);
table->file->ha_rnd_end();
if (unlikely(error))
table->file->print_error(error, MYF(0));
return(MY_TEST(error));
}
int select_union_recursive::send_data(List<Item> &values)
{
int rc;
bool save_abort_on_warning= thd->abort_on_warning;
enum_check_fields save_count_cuted_fields= thd->count_cuted_fields;
long save_counter;
/*
For recursive CTE's give warnings for wrong field info
However, we don't do that for CREATE TABLE ... SELECT or INSERT ... SELECT
as the upper level code for these handles setting of abort_on_warning
depending on if 'IGNORE' is used.
*/
if (thd->lex->sql_command != SQLCOM_CREATE_TABLE &&
thd->lex->sql_command != SQLCOM_INSERT_SELECT)
thd->abort_on_warning= thd->is_strict_mode();
thd->count_cuted_fields= CHECK_FIELD_WARN;
save_counter= thd->get_stmt_da()->set_current_row_for_warning(++row_counter);
rc= select_unit::send_data(values);
thd->get_stmt_da()->set_current_row_for_warning(save_counter);
thd->count_cuted_fields= save_count_cuted_fields;
thd->abort_on_warning= save_abort_on_warning;
if (rc == 0 &&
write_err != HA_ERR_FOUND_DUPP_KEY &&
write_err != HA_ERR_FOUND_DUPP_UNIQUE)
{
int err;
DBUG_ASSERT(incr_table->s->reclength == table->s->reclength ||
incr_table->s->reclength == table->s->reclength - MARIA_UNIQUE_HASH_LENGTH);
if ((err= incr_table->file->ha_write_tmp_row(table->record[0])))
{
bool is_duplicate;
rc= create_internal_tmp_table_from_heap(thd, incr_table,
tmp_table_param.start_recinfo,
&tmp_table_param.recinfo,
err, 1, &is_duplicate);
}
}
return rc;
}
bool select_unit::flush()
{
int error;
if (unlikely((error=table->file->extra(HA_EXTRA_NO_CACHE))))
{
table->file->print_error(error, MYF(0));
return 1;
}
return 0;
}
/*
Create a temporary table to store the result of select_union.
SYNOPSIS
select_unit::create_result_table()
thd thread handle
column_types a list of items used to define columns of the
temporary table
is_union_distinct if set, the temporary table will eliminate
duplicates on insert
options create options
table_alias name of the temporary table
bit_fields_as_long convert bit fields to ulonglong
create_table whether to physically create result table
keep_row_order keep rows in order as they were inserted
hidden number of hidden fields (for INTERSECT)
plus one for `ALL`
DESCRIPTION
Create a temporary table that is used to store the result of a UNION,
derived table, or a materialized cursor.
RETURN VALUE
0 The table has been created successfully.
1 create_tmp_table failed.
*/
bool
select_unit::create_result_table(THD *thd_arg, List<Item> *column_types,
bool is_union_distinct, ulonglong options,
const LEX_CSTRING *alias,
bool bit_fields_as_long, bool create_table,
bool keep_row_order,
uint hidden)
{
DBUG_ASSERT(table == 0);
tmp_table_param.init();
tmp_table_param.field_count= column_types->elements;
tmp_table_param.func_count= tmp_table_param.field_count;
tmp_table_param.bit_fields_as_long= bit_fields_as_long;
tmp_table_param.hidden_field_count= hidden;
if (! (table= create_tmp_table(thd_arg, &tmp_table_param, *column_types,
(ORDER*) 0, is_union_distinct, 1,
options, HA_POS_ERROR, alias,
!create_table, keep_row_order)))
return TRUE;
table->keys_in_use_for_query.clear_all();
if (create_table)
{
table->file->extra(HA_EXTRA_WRITE_CACHE);
table->file->extra(HA_EXTRA_IGNORE_DUP_KEY);
}
return FALSE;
}
bool
select_union_recursive::create_result_table(THD *thd_arg,
List<Item> *column_types,
bool is_union_distinct,
ulonglong options,
const LEX_CSTRING *alias,
bool bit_fields_as_long,
bool create_table,
bool keep_row_order,
uint hidden)
{
if (select_unit::create_result_table(thd_arg, column_types,
is_union_distinct, options,
&empty_clex_str, bit_fields_as_long,
create_table, keep_row_order,
hidden))
return true;
incr_table_param.init();
incr_table_param.field_count= incr_table_param.func_count=
column_types->elements;
incr_table_param.bit_fields_as_long= bit_fields_as_long;
if (! (incr_table= create_tmp_table(thd_arg, &incr_table_param, *column_types,
(ORDER*) 0, false, 1,
options, HA_POS_ERROR, &empty_clex_str,
true, keep_row_order)))
return true;
incr_table->keys_in_use_for_query.clear_all();
return false;
}
/*
@brief
Write a record
@retval
-2 conversion happened
-1 found a duplicate key
0 no error
1 if an error is reported
*/
int select_unit::write_record()
{
if (unlikely((write_err= table->file->ha_write_tmp_row(table->record[0]))))
{
if (write_err == HA_ERR_FOUND_DUPP_KEY)
{
/*
Inform upper level that we found a duplicate key, that should not
be counted as part of limit
*/
return -1;
}
bool is_duplicate= false;
/* create_internal_tmp_table_from_heap will generate error if needed */
if (table->file->is_fatal_error(write_err, HA_CHECK_DUP))
{
if (!create_internal_tmp_table_from_heap(thd, table,
tmp_table_param.start_recinfo,
&tmp_table_param.recinfo,
write_err, 1, &is_duplicate))
return -2;
return 1;
}
if (is_duplicate)
return -1;
}
return 0;
}
/*
@brief
Update counter for a record
@retval
0 no error
-1 error occurred
*/
int select_unit::update_counter(Field* counter, longlong value)
{
store_record(table, record[1]);
counter->store(value, 0);
int error= table->file->ha_update_tmp_row(table->record[1],
table->record[0]);
return error;
}
/*
@brief
Try to disable index
@retval
true index is disabled this time
false this time did not disable the index
*/
bool select_unit_ext::disable_index_if_needed(SELECT_LEX *curr_sl)
{
if (is_index_enabled &&
(curr_sl == curr_sl->master_unit()->union_distinct ||
!curr_sl->next_select()) )
{
is_index_enabled= false;
if (table->file->ha_disable_indexes(key_map(0), false))
return false;
table->no_keyread=1;
return true;
}
return false;
}
/*
@brief
Unfold a record
@retval
0 no error
-1 conversion happened
1 error
Note that duplicate keys are ignored (write_record() is returning -1)
*/
int select_unit_ext::unfold_record(ha_rows cnt)
{
DBUG_ASSERT(cnt > 0);
int ret= 0;
while (--cnt)
{
int error= write_record();
if (error == -2)
ret= -1; // Conversion happened
else if (error > 0)
return error;
}
return ret;
}
/*
@brief
Delete a record
@retval
0 no error
1 if an error is reported
*/
int select_unit::delete_record()
{
DBUG_ASSERT(!table->triggers);
table->status|= STATUS_DELETED;
int not_reported_error= table->file->ha_delete_tmp_row(table->record[0]);
return MY_TEST(not_reported_error);
}
/**
Reset and empty the temporary table that stores the materialized query
result.
@note The cleanup performed here is exactly the same as for the two temp
tables of JOIN - exec_tmp_table_[1 | 2].
*/
void select_unit::reset_for_next_ps_execution()
{
table->file->extra(HA_EXTRA_RESET_STATE);
table->file->ha_delete_all_rows();
}
/*
@brief
Set up value needed by send_data() and send_eof()
@detail
- For EXCEPT we will decrease the counter by one
and INTERSECT / UNION we increase the counter.
- For INTERSECT we will modify the second extra field (intersect counter)
and for EXCEPT / UNION we modify the first (duplicate counter)
*/
void select_unit_ext::change_select()
{
select_unit::change_select();
switch(step){
case UNION_TYPE:
increment= 1;
curr_op_type= UNION_DISTINCT;
break;
case EXCEPT_TYPE:
increment= -1;
curr_op_type= EXCEPT_DISTINCT;
break;
case INTERSECT_TYPE:
increment= 1;
curr_op_type= INTERSECT_DISTINCT;
break;
default: DBUG_ASSERT(0);
}
if (!thd->lex->current_select->distinct)
/* change type from DISTINCT to ALL */
curr_op_type= (set_op_type)(curr_op_type + 1);
duplicate_cnt= table->field[addon_cnt - 1];
if (addon_cnt == 2)
additional_cnt= table->field[addon_cnt - 2];
else
additional_cnt= NULL;
}
/*
@brief
Fill temporary tables for operations need extra fields
@detail
- If this operation is not distinct, we try to find it and increase the
counter by "increment" setted in select_unit_ext::change_select().
- If it is distinct, for UNION we write this record; for INTERSECT we
try to find it and increase the intersect counter if found; for EXCEPT
we try to find it and delete that record if found.
*/
int select_unit_ext::send_data(List<Item> &values)
{
int rc= 0;
int not_reported_error= 0;
int find_res;
if (table->no_rows_with_nulls)
table->null_catch_flags= CHECK_ROW_FOR_NULLS_TO_REJECT;
fill_record(thd, table, table->field + addon_cnt, values, true, false, true);
/* set up initial values for records to be written */
if ( step == UNION_TYPE )
{
/* set duplicate counter to 1 */
duplicate_cnt->store((longlong) 1, 1);
/* set the other counter to 0 */
if (curr_op_type == INTERSECT_ALL)
additional_cnt->store((longlong) 0, 1);
}
if (unlikely(thd->is_error()))
{
rc= 1;
if (unlikely(not_reported_error))
{
DBUG_ASSERT(rc);
table->file->print_error(not_reported_error, MYF(0));
}
return rc;
}
if (table->no_rows_with_nulls)
{
table->null_catch_flags&= ~CHECK_ROW_FOR_NULLS_TO_REJECT;
if (table->null_catch_flags)
{
if (unlikely(not_reported_error))
{
DBUG_ASSERT(rc);
table->file->print_error(not_reported_error, MYF(0));
}
return rc;
}
}
switch(curr_op_type)
{
case UNION_ALL:
if (!is_index_enabled ||
(find_res= table->file->find_unique_row(table->record[0], 0)))
{
rc= write_record();
/* no reaction with conversion */
if (rc == -2)
rc= 0;
}
else
{
longlong cnt= duplicate_cnt->val_int() + increment;
not_reported_error= update_counter(duplicate_cnt, cnt);
DBUG_ASSERT(!table->triggers);
rc= MY_TEST(not_reported_error);
}
break;
case EXCEPT_ALL:
if (!(find_res= table->file->find_unique_row(table->record[0], 0)))
{
longlong cnt= duplicate_cnt->val_int() + increment;
if (cnt == 0)
rc= delete_record();
else
{
not_reported_error= update_counter(duplicate_cnt, cnt);
DBUG_ASSERT(!table->triggers);
rc= MY_TEST(not_reported_error);
}
}
break;
case INTERSECT_ALL:
if (!(find_res= table->file->find_unique_row(table->record[0], 0)))
{
longlong cnt= duplicate_cnt->val_int() + increment;
if (cnt <= additional_cnt->val_int())
{
not_reported_error= update_counter(duplicate_cnt, cnt);
DBUG_ASSERT(!table->triggers);
rc= MY_TEST(not_reported_error);
}
}
break;
case UNION_DISTINCT:
rc= write_record();
/* no reaction with conversion */
if (rc == -2)
rc= 0;
break;
case EXCEPT_DISTINCT:
if (!(find_res= table->file->find_unique_row(table->record[0], 0)))
rc= delete_record();
else
rc= not_reported_error= (find_res != 1);
break;
case INTERSECT_DISTINCT:
if (!(find_res= table->file->find_unique_row(table->record[0], 0)))
{
if (additional_cnt->val_int() == prev_step)
{
not_reported_error= update_counter(additional_cnt, curr_step);
rc= MY_TEST(not_reported_error);
DBUG_ASSERT(rc != HA_ERR_RECORD_IS_THE_SAME);
}
else if (additional_cnt->val_int() != curr_step)
rc= delete_record();
}
else
rc= not_reported_error= (find_res != 1);
break;
default:
DBUG_ASSERT(0);
}
if (unlikely(not_reported_error))
{
DBUG_ASSERT(rc);
table->file->print_error(not_reported_error, MYF(0));
}
return rc;
}
/*
@brief
Do post-operation after a operator
@detail
We need to scan in these cases:
- If this operation is DISTINCT and next is ALL,
duplicate counter needs to be set to 1.
- If this operation is INTERSECT ALL and counter needs to be updated.
- If next operation is INTERSECT ALL,
set up the second extra field (called "intersect_counter") to 0.
this extra field counts records in the second operand.
If this operation is equal to "union_distinct" or is the last operation,
we'll disable index. Then if this operation is ALL we'll unfold records.
*/
bool select_unit_ext::send_eof()
{
int error= 0;
SELECT_LEX *curr_sl= thd->lex->current_select;
SELECT_LEX *next_sl= curr_sl->next_select();
bool is_next_distinct= next_sl && next_sl->distinct;
bool is_next_intersect_all=
next_sl &&
next_sl->get_linkage() == INTERSECT_TYPE &&
!next_sl->distinct;
bool need_unfold= (disable_index_if_needed(curr_sl) &&
!curr_sl->distinct);
if (((curr_sl->distinct && !is_next_distinct) ||
curr_op_type == INTERSECT_ALL ||
is_next_intersect_all) &&
!need_unfold)
{
if (!next_sl)
DBUG_ASSERT(curr_op_type != INTERSECT_ALL);
bool need_update_row;
if (unlikely(table->file->ha_rnd_init_with_error(1)))
return 1;
do
{
need_update_row= false;
if (unlikely(error= table->file->ha_rnd_next(table->record[0])))
{
if (error == HA_ERR_END_OF_FILE)
{
error= 0;
break;
}
break;
}
store_record(table, record[1]);
if (curr_sl->distinct && !is_next_distinct)
{
/* set duplicate counter to 1 if next operation is ALL */
duplicate_cnt->store(1, 0);
need_update_row= true;
}
if (is_next_intersect_all)
{
longlong d_cnt_val= duplicate_cnt->val_int();
if (d_cnt_val == 0)
error= delete_record();
else
{
if (curr_op_type == INTERSECT_ALL)
{
longlong a_cnt_val= additional_cnt->val_int();
if (a_cnt_val < d_cnt_val)
d_cnt_val= a_cnt_val;
}
additional_cnt->store(d_cnt_val, 0);
duplicate_cnt->store((longlong)0, 0);
need_update_row= true;
}
}
if (need_update_row)
error= table->file->ha_update_tmp_row(table->record[1],
table->record[0]);
} while (likely(!error));
table->file->ha_rnd_end();
}
/* unfold */
else if (need_unfold)
{
/* unfold if is ALL operation */
ha_rows dup_cnt;
if (unlikely(table->file->ha_rnd_init_with_error(1)))
return 1;
do
{
if (unlikely(error= table->file->ha_rnd_next(table->record[0])))
{
if (error == HA_ERR_END_OF_FILE)
{
error= 0;
break;
}
break;
}
dup_cnt= (ha_rows)duplicate_cnt->val_int();
/* delete record if not exist in the second operand */
if (dup_cnt == 0)
{
error= delete_record();
continue;
}
if (curr_op_type == INTERSECT_ALL)
{
ha_rows add_cnt= (ha_rows)additional_cnt->val_int();
if (dup_cnt > add_cnt && add_cnt > 0)
dup_cnt= (ha_rows)add_cnt;
}
if (dup_cnt == 1)
continue;
duplicate_cnt->store((longlong)1, 0);
if (additional_cnt)
additional_cnt->store((longlong)0, 0);
error= table->file->ha_update_tmp_row(table->record[1],
table->record[0]);
if (unlikely(error))
break;
if ((error= unfold_record(dup_cnt)) == -1)
{
/* restart the scan */
if (unlikely(table->file->ha_rnd_init_with_error(1)))
return 1;
duplicate_cnt= table->field[addon_cnt - 1];
if (addon_cnt == 2)
additional_cnt= table->field[addon_cnt - 2];
else
additional_cnt= NULL;
error= 0;
continue;
}
else if (error > 0)
{
table->file->ha_index_or_rnd_end();
return 1;
}
} while (likely(!error));
table->file->ha_rnd_end();
}
/* Clean up table buffers for the next set operation from pipeline */
if (next_sl)
restore_record(table,s->default_values);
if (unlikely(error))
table->file->print_error(error, MYF(0));
return (MY_TEST(error));
}
void select_union_recursive::reset_for_next_ps_execution()
{
if (table)
{
select_unit::reset_for_next_ps_execution();
free_tmp_table(thd, table);
}
if (incr_table)
{
if (incr_table->is_created())
{
incr_table->file->extra(HA_EXTRA_RESET_STATE);
incr_table->file->ha_delete_all_rows();
}
free_tmp_table(thd, incr_table);
}
List_iterator<TABLE_LIST> it(rec_table_refs);
TABLE_LIST *tbl;
while ((tbl= it++))
{
TABLE *tab= tbl->table;
if (tab->is_created())
{
tab->file->extra(HA_EXTRA_RESET_STATE);
tab->file->ha_delete_all_rows();
}
/*
The table will be closed later in close_thread_tables(),
because it might be used in the statements like
ANALYZE WITH r AS (...) SELECT * from r
where r is defined through recursion.
*/
tab->next= thd->rec_tables;
thd->rec_tables= tab;
tbl->derived_result= 0;
}
row_counter= 0;
}
/**
Replace the current result with new_result and prepare it.
@param new_result New result pointer
@retval FALSE Success
@retval TRUE Error
*/
bool select_union_direct::change_result(select_result *new_result)
{
result= new_result;
return (result->prepare(unit->types, unit) || result->prepare2(NULL));
}
bool select_union_direct::postponed_prepare(List<Item> &types)
{
if (result != NULL)
return (result->prepare(types, unit) || result->prepare2(NULL));
else
return false;
}
bool select_union_direct::send_result_set_metadata(List<Item> &list, uint flags)
{
if (done_send_result_set_metadata)
return false;
done_send_result_set_metadata= true;
/*
Set global offset and limit to be used in send_data(). These can
be variables in prepared statements or stored programs, so they
must be reevaluated for each execution.
*/
offset= unit->global_parameters()->get_offset();
limit= unit->global_parameters()->get_limit();
if (limit + offset >= limit)
limit+= offset;
else
limit= HA_POS_ERROR; /* purecov: inspected */
return result->send_result_set_metadata(unit->types, flags);
}
int select_union_direct::send_data(List<Item> &items)
{
if (!limit)
return false;
limit--;
if (offset)
{
offset--;
return false;
}
send_records++;
fill_record(thd, table, table->field, items, true, false, true);
if (unlikely(thd->is_error()))
return true; /* purecov: inspected */
return result->send_data(unit->item_list);
}
bool select_union_direct::initialize_tables (JOIN *join)
{
if (done_initialize_tables)
return false;
done_initialize_tables= true;
return result->initialize_tables(join);
}
bool select_union_direct::send_eof()
{
// Reset for each SELECT_LEX, so accumulate here
limit_found_rows+= thd->limit_found_rows;
if (unit->thd->lex->current_select == last_select_lex ||
thd->killed == ABORT_QUERY)
{
thd->limit_found_rows= limit_found_rows;
// Reset and make ready for re-execution
done_send_result_set_metadata= false;
done_initialize_tables= false;
return result->send_eof();
}
else
return false;
}
/*
initialization procedures before fake_select_lex preparation()
SYNOPSIS
st_select_lex_unit::init_prepare_fake_select_lex()
thd - thread handler
first_execution - TRUE at the first execution of the union
RETURN
options of SELECT
*/
void
st_select_lex_unit::init_prepare_fake_select_lex(THD *thd_arg,
bool first_execution)
{
thd_arg->lex->current_select= fake_select_lex;
fake_select_lex->table_list.insert(&result_table_list,
&result_table_list.next_local);
fake_select_lex->context.table_list=
fake_select_lex->context.first_name_resolution_table=
fake_select_lex->get_table_list();
/*
The flag fake_select_lex->first_execution indicates whether this is
called at the first execution of the statement, while first_execution
shows whether this is called at the first execution of the union that
may form just a subselect.
*/
if ((fake_select_lex->changed_elements & TOUCHED_SEL_COND) &&
first_execution)
{
for (ORDER *order= global_parameters()->order_list.first;
order;
order= order->next)
order->item= &order->item_ptr;
}
}
bool st_select_lex_unit::prepare_join(THD *thd_arg, SELECT_LEX *sl,
select_result *tmp_result,
ulonglong additional_options,
bool is_union_select)
{
DBUG_ENTER("st_select_lex_unit::prepare_join");
TABLE_LIST *derived= sl->master_unit()->derived;
bool can_skip_order_by;
sl->options|= SELECT_NO_UNLOCK;
JOIN *join= new JOIN(thd_arg, sl->item_list,
(sl->options | thd_arg->variables.option_bits |
additional_options),
tmp_result);
if (!join)
DBUG_RETURN(true);
thd_arg->lex->current_select= sl;
can_skip_order_by= (is_union_select && !(sl->braces &&
sl->limit_params.explicit_limit) &&
!thd->lex->with_rownum);
saved_error= join->prepare(sl->table_list.first,
(derived && derived->merged ? NULL : sl->where),
(can_skip_order_by ? 0 :
sl->order_list.elements) +
sl->group_list.elements,
can_skip_order_by ?
NULL : sl->order_list.first,
can_skip_order_by,
sl->group_list.first,
sl->having,
(is_union_select ? NULL :
thd_arg->lex->proc_list.first),
sl, this);
last_procedure= join->procedure;
if (unlikely(saved_error || (saved_error= thd_arg->is_fatal_error)))
DBUG_RETURN(true);
/*
Remove all references from the select_lex_units to the subqueries that
are inside the ORDER BY clause.
*/
if (can_skip_order_by)
{
for (ORDER *ord= (ORDER *)sl->order_list.first; ord; ord= ord->next)
{
(*ord->item)->walk(&Item::eliminate_subselect_processor, FALSE, NULL);
}
}
DBUG_RETURN(false);
}
/**
Aggregate data type handlers for the "count" leftmost UNION parts.
*/
bool st_select_lex_unit::join_union_type_handlers(THD *thd_arg,
Type_holder *holders,
uint count)
{
DBUG_ENTER("st_select_lex_unit::join_union_type_handlers");
SELECT_LEX *first_sl= first_select(), *sl= first_sl;
for (uint i= 0; i < count ; sl= sl->next_select(), i++)
{
Item *item;
List_iterator_fast<Item> it(sl->item_list);
for (uint pos= 0; (item= it++); pos++)
{
const Type_handler *item_type_handler= item->real_type_handler();
if (sl == first_sl)
holders[pos].set_handler(item_type_handler);
else
{
DBUG_ASSERT(first_sl->item_list.elements == sl->item_list.elements);
if (holders[pos].aggregate_for_result(item_type_handler))
{
my_error(ER_ILLEGAL_PARAMETER_DATA_TYPES2_FOR_OPERATION, MYF(0),
holders[pos].type_handler()->name().ptr(),
item_type_handler->name().ptr(),
"UNION");
DBUG_RETURN(true);
}
}
}
}
DBUG_RETURN(false);
}
/**
Aggregate data type attributes for the "count" leftmost UNION parts.
*/
bool st_select_lex_unit::join_union_type_attributes(THD *thd_arg,
Type_holder *holders,
uint count)
{
DBUG_ENTER("st_select_lex_unit::join_union_type_attributes");
SELECT_LEX *sl, *first_sl= first_select();
uint item_pos;
for (uint pos= 0; pos < first_sl->item_list.elements; pos++)
{
if (holders[pos].alloc_arguments(thd_arg, count))
DBUG_RETURN(true);
}
for (item_pos= 0, sl= first_sl ;
item_pos < count;
sl= sl->next_select(), item_pos++)
{
Item *item_tmp;
List_iterator_fast<Item> itx(sl->item_list);
for (uint holder_pos= 0 ; (item_tmp= itx++); holder_pos++)
{
/*
If the outer query has a GROUP BY clause, an outer reference to this
query block may have been wrapped in a Item_outer_ref, which has not
been fixed yet. An Item_type_holder must be created based on a fixed
Item, so use the inner Item instead.
*/
DBUG_ASSERT(item_tmp->fixed() ||
(item_tmp->type() == Item::REF_ITEM &&
((Item_ref *)(item_tmp))->ref_type() ==
Item_ref::OUTER_REF));
if (!item_tmp->fixed())
item_tmp= item_tmp->real_item();
holders[holder_pos].add_argument(item_tmp);
}
}
for (uint pos= 0; pos < first_sl->item_list.elements; pos++)
{
if (holders[pos].aggregate_attributes(thd_arg))
DBUG_RETURN(true);
}
DBUG_RETURN(false);
}
/**
Join data types for the leftmost "count" UNION parts
and store corresponding Item_type_holder's into "types".
*/
bool st_select_lex_unit::join_union_item_types(THD *thd_arg,
List<Item> &types,
uint count)
{
DBUG_ENTER("st_select_lex_unit::join_union_select_list_types");
SELECT_LEX *first_sl= first_select();
Type_holder *holders;
if (!(holders= new (thd_arg->mem_root)
Type_holder[first_sl->item_list.elements]) ||
join_union_type_handlers(thd_arg, holders, count) ||
join_union_type_attributes(thd_arg, holders, count))
DBUG_RETURN(true);
bool is_recursive= with_element && with_element->is_recursive;
types.empty();
List_iterator_fast<Item> it(first_sl->item_list);
Item *item_tmp;
for (uint pos= 0; (item_tmp= it++); pos++)
{
/*
SQL standard requires forced nullability only for
recursive columns. However type aggregation in our
implementation so far does not differentiate between
recursive and non-recursive columns of a recursive CTE.
TODO: this should be fixed.
*/
bool pos_maybe_null= is_recursive ? true : holders[pos].get_maybe_null();
/* Error's in 'new' will be detected after loop */
types.push_back(new (thd_arg->mem_root)
Item_type_holder(thd_arg,
item_tmp,
holders[pos].type_handler(),
&holders[pos]/*Type_all_attributes*/,
pos_maybe_null));
}
if (unlikely(thd_arg->is_fatal_error))
DBUG_RETURN(true); // out of memory
DBUG_RETURN(false);
}
static bool init_item_int(THD* thd, Item_int* &item)
{
if (!item)
{
item= new (thd->mem_root) Item_int(thd, 0);
if (!item)
return true;
}
else
{
item->value= 0;
}
return false;
}
/**
@brief
Recursive subroutine to be called from find_unit_handler() (see below).
Must not be called directly, only from find_unit_handler().
*/
static select_handler *find_unit_handler_for_lex(THD *thd,
SELECT_LEX *sel_lex,
SELECT_LEX_UNIT* unit)
{
if (!(sel_lex->join))
return nullptr;
for (TABLE_LIST *tbl= sel_lex->join->tables_list; tbl; tbl= tbl->next_local)
{
if (!tbl->table)
continue;
if (tbl->derived)
{
/*
Skip derived table for now as they will be checked
in the subsequent loop
*/
continue;
}
handlerton *ht= tbl->table->file->partition_ht();
if (!ht->create_unit)
continue;
select_handler *sh= ht->create_unit(thd, unit);
if (sh)
return sh;
}
for (SELECT_LEX_UNIT *un= sel_lex->first_inner_unit(); un;
un= un->next_unit())
{
for (SELECT_LEX *sl= un->first_select(); sl; sl= sl->next_select())
{
select_handler *uh= find_unit_handler_for_lex(thd, sl, unit);
if (uh)
return uh;
}
}
return nullptr;
}
/**
@brief
Look for provision of the select_handler interface by a foreign engine.
This interface must support processing UNITs (multiple SELECTs combined
with UNION/EXCEPT/INTERSECT operators)
@param
thd The thread handler
unit UNIT (one or more SELECTs combined with UNION/EXCEPT/INTERSECT
@details
The function checks that this is an upper level UNIT and if so looks
through its tables searching for one whose handlerton owns a
create_unit call-back function. If the call of this function returns
a select_handler interface object then the server will push the
query into this engine.
This is a responsibility of the create_unit call-back function to
check whether the engine can execute the query.
The function recursively scans subqueries (see find_unit_handler_for_lex())
to get down to real tables and process queries like this:
(SELECT a FROM t1 UNION SELECT b FROM t2) UNION
(SELECT c FROM t3 UNION select d FROM t4)
@retval the found select_handler if the search is successful
nullptr otherwise
*/
static select_handler *find_unit_handler(THD *thd,
SELECT_LEX_UNIT *unit)
{
if (unit->outer_select())
return nullptr;
for (SELECT_LEX *sl= unit->first_select(); sl; sl= sl->next_select())
{
select_handler *uh= find_unit_handler_for_lex(thd, sl, unit);
if (uh)
return uh;
}
return nullptr;
}
inline bool st_select_lex_unit::rename_item_list(TABLE_LIST *derived_arg)
{
if (derived_arg->save_original_names(first_select()))
return true;
if (first_select()->set_item_list_names(derived_arg->column_names))
return true;
return false;
}
inline bool st_select_lex_unit::rename_types_list(List<Lex_ident_sys> *newnames)
{
if (item_list.elements != newnames->elements)
{
my_error(ER_INCORRECT_COLUMN_NAME_COUNT, MYF(0));
return true;
}
List_iterator<Lex_ident_sys> it(*newnames);
List_iterator_fast<Item> li(types);
Item *item;
while ((item= li++))
lex_string_set( &item->name, (it++)->str);
return false;
}
bool st_select_lex_unit::prepare(TABLE_LIST *derived_arg,
select_result *sel_result,
ulonglong additional_options)
{
SELECT_LEX *lex_select_save= thd->lex->current_select;
SELECT_LEX *sl, *first_sl= first_select();
bool is_recursive= with_element && with_element->is_recursive;
bool is_rec_result_table_created= false;
uint union_part_count= 0;
select_result *tmp_result;
bool is_union_select;
bool have_except= false, have_intersect= false,
have_except_all_or_intersect_all= false;
bool instantiate_tmp_table= false;
bool use_direct_union_result= false;
bool single_tvc= !first_sl->next_select() && first_sl->tvc;
bool single_tvc_wo_order= single_tvc && !first_sl->order_list.elements;
bool distinct_key= 0;
DBUG_ENTER("st_select_lex_unit::prepare");
DBUG_ASSERT(thd == current_thd);
if (is_recursive && (sl= first_sl->next_select()))
{
SELECT_LEX *next_sl;
for ( ; ; sl= next_sl)
{
next_sl= sl->next_select();
if (!next_sl)
break;
if (next_sl->with_all_modifier != sl->with_all_modifier)
{
my_error(ER_NOT_SUPPORTED_YET, MYF(0),
"mix of ALL and DISTINCT UNION operations in recursive CTE spec");
DBUG_RETURN(TRUE);
}
}
}
describe= additional_options & SELECT_DESCRIBE;
/*
Save fake_select_lex in case we don't need it for anything but
global parameters.
*/
if (saved_fake_select_lex == NULL) // Don't overwrite on PS second prepare
saved_fake_select_lex= fake_select_lex;
/*
result object should be reassigned even if preparing already done for
max/min subquery (ALL/ANY optimization)
*/
result= sel_result;
if (prepared)
{
if (describe)
{
/* fast reinit for EXPLAIN */
for (sl= first_sl; sl; sl= sl->next_select())
{
if (sl->tvc)
{
sl->tvc->result= result;
if (result->prepare(sl->item_list, this))
DBUG_RETURN(TRUE);
sl->tvc->select_options|= SELECT_DESCRIBE;
}
else
{
sl->join->result= result;
lim.clear();
if (!sl->join->procedure &&
result->prepare(sl->join->fields_list, this))
{
DBUG_RETURN(TRUE);
}
sl->join->select_options|= SELECT_DESCRIBE;
sl->join->reinit();
}
}
}
DBUG_RETURN(FALSE);
}
prepared= 1;
saved_error= FALSE;
thd->lex->current_select= sl= first_sl;
found_rows_for_union= first_sl->options & OPTION_FOUND_ROWS;
is_union_select= is_unit_op() || fake_select_lex || single_tvc;
/*
If we are reading UNION output and the UNION is in the
IN/ANY/ALL/EXISTS subquery, then ORDER BY is redundant and hence should
be removed.
Example:
select ... col IN (select col2 FROM t1 union select col3 from t2 ORDER BY 1)
(as for ORDER BY ... LIMIT, it currently not supported inside
IN/ALL/ANY subqueries)
(For non-UNION this removal of ORDER BY clause is done in
check_and_do_in_subquery_rewrites())
*/
if (item && is_unit_op() &&
(item->is_in_predicate() || item->is_exists_predicate()))
{
global_parameters()->order_list.first= NULL;
global_parameters()->order_list.elements= 0;
}
/* will only optimize once */
if (!bag_set_op_optimized && !is_recursive)
{
optimize_bag_operation(false);
}
for (SELECT_LEX *s= first_sl; s; s= s->next_select())
{
switch (s->linkage)
{
case INTERSECT_TYPE:
have_intersect= TRUE;
if (!s->distinct)
have_except_all_or_intersect_all= TRUE;
break;
case EXCEPT_TYPE:
have_except= TRUE;
if (!s->distinct)
have_except_all_or_intersect_all= TRUE;
break;
case DERIVED_TABLE_TYPE:
if (s->distinct)
distinct_key= 1;
break;
default:
break;
}
}
if (is_union_select || is_recursive)
{
if ((single_tvc_wo_order && !fake_select_lex) ||
(is_unit_op() && !union_needs_tmp_table() &&
!have_except && !have_intersect && !single_tvc))
{
if (unlikely(set_direct_union_result(sel_result)))
goto err;
tmp_result= union_result;
fake_select_lex= NULL;
instantiate_tmp_table= false;
use_direct_union_result= true;
}
else
{
if (!is_recursive)
{
/*
class "select_unit_ext" handles query contains EXCEPT ALL and / or
INTERSECT ALL. Others are handled by class "select_unit"
If have EXCEPT ALL or INTERSECT ALL in the query. First operand
should be UNION ALL
*/
if (have_except_all_or_intersect_all)
{
union_result= new (thd->mem_root) select_unit_ext(thd);
first_sl->distinct= false;
}
else
union_result= new (thd->mem_root) select_unit(thd);
}
else
{
with_element->rec_result=
new (thd->mem_root) select_union_recursive(thd);
union_result= with_element->rec_result;
if (fake_select_lex)
{
if (fake_select_lex->order_list.first ||
fake_select_lex->limit_params.explicit_limit)
{
my_error(ER_NOT_SUPPORTED_YET, MYF(0),
"global ORDER_BY/LIMIT in recursive CTE spec");
goto err;
}
fake_select_lex->cleanup();
fake_select_lex= NULL;
}
}
if (!(tmp_result= union_result))
goto err; /* purecov: inspected */
instantiate_tmp_table= true;
}
}
else
tmp_result= sel_result;
sl->context.resolve_in_select_list= TRUE;
if (!is_union_select && !is_recursive)
{
if (sl->tvc)
{
if (sl->tvc->prepare(thd, sl, tmp_result, this))
goto err;
}
else
{
if (prepare_join(thd, first_sl, tmp_result, additional_options,
is_union_select))
goto err;
if (derived_arg && derived_arg->table &&
derived_arg->derived_type == VIEW_ALGORITHM_MERGE &&
derived_arg->table->versioned())
{
/* Got versioning conditions (see vers_setup_conds()), need to update
derived_arg. */
derived_arg->where= first_sl->where;
}
}
types= first_sl->item_list;
goto cont;
}
if (sl->tvc && sl->order_list.elements &&
!sl->tvc->to_be_wrapped_as_with_tail())
{
SELECT_LEX_UNIT *unit= sl->master_unit();
if (thd->lex->context_analysis_only & CONTEXT_ANALYSIS_ONLY_VIEW)
{
unit->fake_select_lex= 0;
unit->saved_fake_select_lex= 0;
}
else
{
if (!unit->first_select()->next_select())
{
if (!unit->fake_select_lex)
{
Query_arena *arena, backup_arena;
arena= thd->activate_stmt_arena_if_needed(&backup_arena);
bool rc= unit->add_fake_select_lex(thd);
if (arena)
thd->restore_active_arena(arena, &backup_arena);
if (rc)
goto err;
}
SELECT_LEX *fake= unit->fake_select_lex;
fake->order_list= sl->order_list;
fake->limit_params= sl->limit_params;
sl->order_list.empty();
sl->limit_params.clear();
if (describe)
fake->options|= SELECT_DESCRIBE;
}
else if (!sl->limit_params.explicit_limit)
sl->order_list.empty();
}
}
for (;sl; sl= sl->next_select(), union_part_count++)
{
if (sl->tvc)
{
if (sl->tvc->to_be_wrapped_as_with_tail() &&
!(thd->lex->context_analysis_only & CONTEXT_ANALYSIS_ONLY_VIEW))
{
st_select_lex *wrapper_sl= wrap_tvc_with_tail(thd, sl);
if (!wrapper_sl)
goto err;
if (sl == first_sl)
first_sl= wrapper_sl;
sl= wrapper_sl;
if (prepare_join(thd, sl, tmp_result, additional_options,
is_union_select))
goto err;
}
else if (sl->tvc->prepare(thd, sl, tmp_result, this))
goto err;
}
else if (prepare_join(thd, sl, tmp_result, additional_options,
is_union_select))
goto err;
/*
setup_tables_done_option should be set only for very first SELECT,
because it protect from second setup_tables call for select-like non
select commands (DELETE/INSERT/...) and they use only very first
SELECT (for union it can be only INSERT ... SELECT).
*/
additional_options&= ~OPTION_SETUP_TABLES_DONE;
/*
Use items list of underlaid select for derived tables to preserve
information about fields lengths and exact types
*/
if (sl == first_sl)
{
if (with_element)
{
if (with_element->process_columns_of_derived_unit(thd, this))
goto err;
if (check_duplicate_names(thd, sl->item_list, 0))
goto err;
}
}
else
{
if (first_sl->item_list.elements != sl->item_list.elements)
{
my_message(ER_WRONG_NUMBER_OF_COLUMNS_IN_SELECT,
ER_THD(thd, ER_WRONG_NUMBER_OF_COLUMNS_IN_SELECT),
MYF(0));
goto err;
}
}
if (is_recursive)
{
if (!with_element->is_anchor(sl))
sl->uncacheable|= UNCACHEABLE_UNITED;
if (!is_rec_result_table_created &&
(!sl->next_select() ||
sl->next_select() == with_element->first_recursive))
{
ulonglong create_options;
create_options= (first_sl->options | thd->variables.option_bits |
TMP_TABLE_ALL_COLUMNS);
// Join data types for all non-recursive parts of a recursive UNION
if (join_union_item_types(thd, types, union_part_count + 1))
goto err;
if (union_result->create_result_table(thd, &types,
(MY_TEST(union_distinct) ||
distinct_key),
create_options,
&derived_arg->alias, false,
instantiate_tmp_table, false,
0))
goto err;
if (have_except_all_or_intersect_all)
{
union_result->init();
}
if (!derived_arg->table)
{
bool res= false;
if ((!derived_arg->is_with_table_recursive_reference() ||
!derived_arg->derived_result) &&
!(derived_arg->derived_result=
new (thd->mem_root) select_unit(thd)))
goto err; // out of memory
thd->create_tmp_table_for_derived= TRUE;
res= derived_arg->derived_result->create_result_table(thd,
&types,
distinct_key,
create_options,
&derived_arg->alias,
FALSE, FALSE,
FALSE, 0);
thd->create_tmp_table_for_derived= FALSE;
if (res)
goto err;
derived_arg->derived_result->set_unit(this);
derived_arg->table= derived_arg->derived_result->table;
if (derived_arg->is_with_table_recursive_reference())
{
/* Here 'derived_arg' is the primary recursive table reference */
derived_arg->with->rec_result->
rec_table_refs.push_back(derived_arg);
}
}
with_element->mark_as_with_prepared_anchor();
is_rec_result_table_created= true;
}
}
}
/*
We need to rename tvc BEFORE Item_holder pushed into result table
below in join_union_item_types().
*/
if (first_select()->tvc && derived_arg && derived_arg->column_names)
if (rename_item_list(derived_arg))
goto err;
// In case of a non-recursive UNION, join data types for all UNION parts.
if (!is_recursive && join_union_item_types(thd, types, union_part_count))
goto err;
cont:
/*
If the query is using select_union_direct, we have postponed
preparation of the underlying select_result until column types
are known.
*/
if (union_result != NULL && union_result->postponed_prepare(types))
DBUG_RETURN(true);
if (is_union_select)
{
/*
Check that it was possible to aggregate
all collations together for UNION.
*/
List_iterator_fast<Item> tp(types);
Item *type;
ulonglong create_options;
uint save_tablenr= 0;
table_map save_map= 0;
uint save_maybe_null= 0;
while ((type= tp++))
{
/*
Test if the aggregated data type is OK for a UNION element.
E.g. in case of string data, DERIVATION_NONE is not allowed.
*/
if (type->type() == Item::TYPE_HOLDER && type->type_handler()->
union_element_finalize(static_cast<Item_type_holder*>(type)))
goto err;
}
/*
Disable the usage of fulltext searches in the last union branch.
This is a temporary 5.x limitation because of the way the fulltext
search functions are handled by the optimizer.
This is manifestation of the more general problems of "taking away"
parts of a SELECT statement post-fix_fields(). This is generally not
doable since various flags are collected in various places (e.g.
SELECT_LEX) that carry information about the presence of certain
expressions or constructs in the parts of the query.
When part of the query is taken away it's not clear how to "divide"
the meaning of these accumulated flags and what to carry over to the
recipient query (SELECT_LEX).
*/
if (global_parameters()->ftfunc_list->elements &&
global_parameters()->order_list.elements &&
global_parameters() != fake_select_lex)
{
ORDER *ord;
Item_func::Functype ft= Item_func::FT_FUNC;
for (ord= global_parameters()->order_list.first; ord; ord= ord->next)
if ((*ord->item)->walk (&Item::find_function_processor, FALSE, &ft))
{
my_error (ER_CANT_USE_OPTION_HERE, MYF(0), "MATCH()");
goto err;
}
}
create_options= (first_sl->options | thd->variables.option_bits |
TMP_TABLE_ALL_COLUMNS);
/*
Force the temporary table to be a MyISAM table if we're going to use
fulltext functions (MATCH ... AGAINST .. IN BOOLEAN MODE) when reading
from it (this should be removed in 5.2 when fulltext search is moved
out of MyISAM).
*/
if (global_parameters()->ftfunc_list->elements)
create_options= create_options | TMP_TABLE_FORCE_MYISAM;
/* extra field counter */
uint hidden= 0;
Item_int *addon_fields[2]= {0};
if (!is_recursive)
{
if (have_except_all_or_intersect_all)
{
/* add duplicate_count */
++hidden;
}
/* add intersect_count */
if (have_intersect)
++hidden;
for(uint i= 0; i< hidden; i++)
{
if (init_item_int(thd, addon_fields[i]) ||
types.push_front(addon_fields[i]))
{
types.empty();
goto err;
}
addon_fields[i]->name.str= i ? "__CNT_1" : "__CNT_2";
addon_fields[i]->name.length= 7;
}
bool error=
union_result->create_result_table(thd, &types,
MY_TEST(union_distinct) ||
have_except_all_or_intersect_all ||
have_intersect || distinct_key,
create_options, &empty_clex_str,
false, instantiate_tmp_table, false,
hidden);
union_result->addon_cnt= hidden;
for (uint i= 0; i < hidden; i++)
types.pop();
if (unlikely(error))
goto err;
}
if (fake_select_lex && !fake_select_lex->first_cond_optimization)
{
save_tablenr= result_table_list.tablenr_exec;
save_map= result_table_list.map_exec;
save_maybe_null= result_table_list.maybe_null_exec;
}
bzero((char*) &result_table_list, sizeof(result_table_list));
result_table_list.db.str= (char*) "";
result_table_list.db.length= 0;
result_table_list.table_name.str= result_table_list.alias.str= "union";
result_table_list.table_name.length= result_table_list.alias.length= sizeof("union")-1;
result_table_list.table= table= union_result->table;
if (fake_select_lex && !fake_select_lex->first_cond_optimization)
{
result_table_list.tablenr_exec= save_tablenr;
result_table_list.map_exec= save_map;
result_table_list.maybe_null_exec= save_maybe_null;
}
thd->lex->current_select= lex_select_save;
if (!item_list.elements)
{
Query_arena *arena, backup_arena;
arena= thd->activate_stmt_arena_if_needed(&backup_arena);
saved_error= table->fill_item_list(&item_list);
for (uint i= 0; i < hidden; i++)
item_list.pop();
if (arena)
thd->restore_active_arena(arena, &backup_arena);
if (unlikely(saved_error))
goto err;
}
else
{
/*
We're in execution of a prepared statement or stored procedure:
reset field items to point at fields from the created temporary table.
*/
table->reset_item_list(&item_list, hidden);
}
if (fake_select_lex != NULL)
{
init_prepare_fake_select_lex(thd, TRUE);
DBUG_ASSERT(fake_select_lex->join == 0);
if (!(fake_select_lex->join= new JOIN(thd, item_list, options, result)))
{
fake_select_lex->table_list.empty();
DBUG_RETURN(TRUE);
}
/*
Fake st_select_lex should have item list for correct ref_array
allocation.
*/
fake_select_lex->item_list= item_list;
thd->lex->current_select= fake_select_lex;
/*
We need to add up n_sum_items in order to make the correct
allocation in setup_ref_array().
*/
fake_select_lex->n_child_sum_items+= global_parameters()->n_sum_items;
fake_select_lex->join->no_const_tables= TRUE;
saved_error= fake_select_lex->join->prepare(
fake_select_lex->table_list.first, 0,
global_parameters()->order_list.elements, // og_num
global_parameters()->order_list.first, // order
false, NULL, NULL, NULL, fake_select_lex, this);
}
/*
Rename types used in result table for union.
*/
if (derived_arg && derived_arg->column_names)
{
if (rename_types_list(derived_arg->column_names))
goto err;
}
if (!thd->lex->is_view_context_analysis())
pushdown_unit= find_unit_handler(thd, this);
if (pushdown_unit)
{
if (prepare_pushdown(use_direct_union_result, sel_result))
goto err;
}
}
if (derived_arg && derived_arg->column_names)
{
if (rename_item_list(derived_arg))
goto err;
}
thd->lex->current_select= lex_select_save;
DBUG_RETURN(saved_error || thd->is_fatal_error);
err:
thd->lex->current_select= lex_select_save;
(void) cleanup();
DBUG_RETURN(TRUE);
}
/**
@brief
Prepare st_select_lex_unit for the pushdown handler processing
@details
Creates and initializes data structures required for processing of the
pushdown handler. Validates fake_select_lex then discards it and sets
direct union result which is necessary for pushed down statements
@return
false - success
true - failure
*/
bool st_select_lex_unit::prepare_pushdown(bool use_direct_union_result,
select_result *sel_result)
{
if (unlikely(pushdown_unit->prepare()))
return true;
if(!use_direct_union_result)
{
/*
Always use select_union_direct result for pushed down units, overwrite
the previous union_result unless select_union_direct is already used
*/
if (unlikely(set_direct_union_result(sel_result)))
return true;
}
return false;
}
bool st_select_lex_unit::set_direct_union_result(select_result *sel_result)
{
SELECT_LEX *last= first_select();
while (last->next_select())
last= last->next_select();
union_result= new (thd->mem_root) select_union_direct(thd, sel_result,
last);
return (union_result == nullptr);
}
/**
@brief
Optimize a sequence of set operations
@param first_sl first select of the level now under processing
@details
The method optimizes with the following rules:
- (1)If a subsequence of INTERSECT contains at least one INTERSECT DISTINCT
or this subsequence is followed by UNION/EXCEPT DISTINCT then all
elements in the subsequence can changed for INTERSECT DISTINCT
- (2)If previous set operation is DISTINCT then EXCEPT ALL can be replaced
for EXCEPT DISTINCT
- (3)If UNION DISTINCT / EXCEPT DISTINCT follows a subsequence of UNION ALL
then all set operations of this subsequence can be replaced for
UNION DISTINCT
For derived table it will look up outer select, and do optimize based on
outer select.
Variable "union_distinct" will be updated in the end.
Not compatible with Oracle Mode.
*/
void st_select_lex_unit::optimize_bag_operation(bool is_outer_distinct)
{
/*
skip run optimize for:
ORACLE MODE
CREATE VIEW
PREPARE ... FROM
recursive
*/
if ((thd->variables.sql_mode & MODE_ORACLE) ||
(thd->lex->context_analysis_only & CONTEXT_ANALYSIS_ONLY_VIEW) ||
(fake_select_lex != NULL && thd->stmt_arena->is_stmt_prepare()) ||
(with_element && with_element->is_recursive ))
return;
DBUG_ASSERT(!bag_set_op_optimized);
SELECT_LEX *sl;
/* INTERSECT subsequence can occur only at the very beginning */
/* The first select with linkage == INTERSECT_TYPE */
SELECT_LEX *intersect_start= NULL;
/* The first select after the INTERSECT subsequence */
SELECT_LEX *intersect_end= NULL;
/*
Will point to the last node before UNION ALL subsequence.
Index can be disable there.
*/
SELECT_LEX *disable_index= NULL;
/*
True if there is a select with:
linkage == INTERSECT_TYPE && distinct==true
*/
bool any_intersect_distinct= false;
SELECT_LEX *prev_sl= first_select();
/* process INTERSECT subsequence in the begining */
for (sl= prev_sl->next_select(); sl; prev_sl= sl, sl= sl->next_select())
{
if (sl->linkage != INTERSECT_TYPE)
{
intersect_end= sl;
break;
}
else
{
if (!intersect_start)
intersect_start= sl;
if (sl->distinct)
{
any_intersect_distinct= true;
disable_index= sl;
}
}
}
/* if subquery only contains INTERSECT and outer is UNION DISTINCT*/
if (!sl && is_outer_distinct)
any_intersect_distinct= true;
/* The first select of the current UNION ALL subsequence */
SELECT_LEX *union_all_start= NULL;
for ( ; sl; prev_sl= sl, sl= sl->next_select())
{
DBUG_ASSERT (sl->linkage != INTERSECT_TYPE);
if (!sl->distinct)
{
if (sl->linkage == UNION_TYPE)
{
if (!union_all_start)
{
union_all_start= sl;
}
}
else
{
DBUG_ASSERT (sl->linkage == EXCEPT_TYPE);
union_all_start= NULL;
if (prev_sl->distinct && prev_sl->is_set_op())
{
sl->distinct= true;
disable_index= sl;
}
}
}
else
{ /* sl->distinct == true */
for (SELECT_LEX *si= union_all_start; si && si != sl; si= si->next_select())
{
si->distinct= true;
}
union_all_start= NULL;
disable_index= sl;
}
}
if (is_outer_distinct)
{
for (SELECT_LEX *si= union_all_start; si && si != sl; si= si->next_select())
{
si->distinct= true;
}
union_all_start= NULL;
}
if (any_intersect_distinct ||
(intersect_end != NULL && intersect_end->distinct))
{
for (sl= intersect_start; sl && sl != intersect_end; sl= sl->next_select())
{
sl->distinct= true;
if (disable_index && disable_index->linkage == INTERSECT_TYPE)
disable_index= sl;
}
}
/*
if disable_index points to a INTERSECT, based on rule 1 we can set it
to the last INTERSECT node.
*/
if (disable_index && disable_index->linkage == INTERSECT_TYPE &&
intersect_end && intersect_end->distinct)
disable_index= intersect_end;
/* union_distinct controls when to disable index */
union_distinct= disable_index;
/* recursive call this function for whole lex tree */
for(sl= first_select(); sl; sl= sl->next_select())
{
if (sl->is_unit_nest() &&
sl->first_inner_unit() &&
!sl->first_inner_unit()->bag_set_op_optimized)
sl->first_inner_unit()->optimize_bag_operation(sl->distinct);
}
/* mark as optimized */
bag_set_op_optimized= true;
}
/**
Run optimization phase.
@return false unit successfully passed optimization phase.
@return TRUE an error occur.
*/
bool st_select_lex_unit::optimize()
{
SELECT_LEX *lex_select_save= thd->lex->current_select;
SELECT_LEX *select_cursor=first_select();
DBUG_ENTER("st_select_lex_unit::optimize");
if (optimized && !uncacheable && !describe)
DBUG_RETURN(false);
if (with_element && with_element->is_recursive && optimize_started)
DBUG_RETURN(false);
optimize_started= true;
if (uncacheable || !item || !item->assigned() || describe)
{
if (item)
item->reset_value_registration();
if (optimized && item)
{
if (item->assigned())
{
item->assigned(0); // We will reinit & reexecute unit
item->reset();
}
if (table->is_created())
{
table->file->ha_delete_all_rows();
table->file->info(HA_STATUS_VARIABLE);
}
/* re-enabling indexes for next subselect iteration */
if ((union_result->force_enable_index_if_needed() || union_distinct))
{
if(table->file->ha_enable_indexes(key_map(table->s->keys), false))
DBUG_ASSERT(0);
else
table->no_keyread= 0;
}
}
for (SELECT_LEX *sl= select_cursor; sl; sl= sl->next_select())
{
if (sl->tvc)
{
sl->tvc->select_options=
(lim.is_unlimited() || sl->braces) ?
sl->options & ~OPTION_FOUND_ROWS : sl->options | found_rows_for_union;
if (sl->tvc->optimize(thd))
{
thd->lex->current_select= lex_select_save;
DBUG_RETURN(TRUE);
}
if (derived)
sl->increase_derived_records(sl->tvc->get_records());
continue;
}
thd->lex->current_select= sl;
if (optimized)
saved_error= sl->join->reinit();
else
{
set_limit(sl);
if (sl == global_parameters() || describe)
{
lim.remove_offset();
/*
We can't use LIMIT at this stage if we are using ORDER BY for the
whole query
*/
if (sl->order_list.first || describe)
lim.set_unlimited();
}
/*
When using braces, SQL_CALC_FOUND_ROWS affects the whole query:
we don't calculate found_rows() per union part.
Otherwise, SQL_CALC_FOUND_ROWS should be done on all sub parts.
*/
sl->join->select_options=
(lim.is_unlimited() || sl->braces) ?
sl->options & ~OPTION_FOUND_ROWS : sl->options | found_rows_for_union;
if (!this->pushdown_unit)
{
/*
If the UNIT hasn't been pushed down to the engine as a whole,
try to push down partial SELECTs of this UNIT separately
*/
sl->pushdown_select= find_partial_select_handler(thd, sl, this);
}
saved_error= sl->join->optimize();
}
if (unlikely(saved_error))
{
thd->lex->current_select= lex_select_save;
DBUG_RETURN(saved_error);
}
}
}
optimized= 1;
thd->lex->current_select= lex_select_save;
DBUG_RETURN(saved_error);
}
bool st_select_lex_unit::exec()
{
DBUG_ENTER("st_select_lex_unit::exec");
if (executed && !uncacheable && !describe)
DBUG_RETURN(FALSE);
if (pushdown_unit)
{
create_explain_query_if_not_exists(thd->lex, thd->mem_root);
if (!executed)
save_union_explain(thd->lex->explain);
DBUG_RETURN(pushdown_unit->execute());
}
DBUG_RETURN(exec_inner());
}
bool st_select_lex_unit::exec_inner()
{
SELECT_LEX *lex_select_save= thd->lex->current_select;
SELECT_LEX *select_cursor=first_select();
ulonglong add_rows=0;
bool first_execution= !executed;
bool was_executed= executed;
executed= 1;
if (!(uncacheable & ~UNCACHEABLE_EXPLAIN) && item &&
!item->with_recursive_reference)
item->make_const();
saved_error= optimize();
create_explain_query_if_not_exists(thd->lex, thd->mem_root);
if (!saved_error && !was_executed)
save_union_explain(thd->lex->explain);
if (unlikely(saved_error))
return saved_error;
if (union_result)
{
union_result->init();
if (uncacheable & UNCACHEABLE_DEPENDENT &&
union_result->table && union_result->table->is_created())
{
union_result->table->file->ha_delete_all_rows();
union_result->table->file->ha_enable_indexes(key_map(table->s->keys), false);
}
}
if (uncacheable || !item || !item->assigned() || describe)
{
if (!fake_select_lex && !(with_element && with_element->is_recursive))
union_result->reset_for_next_ps_execution();
for (SELECT_LEX *sl= select_cursor; sl; sl= sl->next_select())
{
ha_rows records_at_start= 0;
thd->lex->current_select= sl;
if (union_result)
union_result->change_select();
if (fake_select_lex)
{
if (sl != thd->lex->first_select_lex())
fake_select_lex->uncacheable|= sl->uncacheable;
else
fake_select_lex->uncacheable= 0;
}
{
set_limit(sl);
if (sl == global_parameters() || describe)
{
lim.remove_offset();
/*
We can't use LIMIT at this stage if we are using ORDER BY for the
whole query
*/
if (sl->order_list.first || describe)
lim.set_unlimited();
}
/*
When using braces, SQL_CALC_FOUND_ROWS affects the whole query:
we don't calculate found_rows() per union part.
Otherwise, SQL_CALC_FOUND_ROWS should be done on all sub parts.
*/
if (sl->tvc)
{
sl->tvc->select_options=
(lim.is_unlimited() || sl->braces) ?
sl->options & ~OPTION_FOUND_ROWS : sl->options | found_rows_for_union;
saved_error= sl->tvc->optimize(thd);
}
else
{
sl->join->select_options=
(lim.is_unlimited() || sl->braces) ?
sl->options & ~OPTION_FOUND_ROWS : sl->options | found_rows_for_union;
saved_error= sl->join->optimize();
}
}
if (likely(!saved_error))
{
records_at_start= table->file->stats.records;
if (sl->tvc)
sl->tvc->exec(sl);
else
saved_error= sl->join->exec();
if (sl == union_distinct && !have_except_all_or_intersect_all &&
!(with_element && with_element->is_recursive))
{
// This is UNION DISTINCT, so there should be a fake_select_lex
DBUG_ASSERT(fake_select_lex != NULL);
if (table->file->ha_disable_indexes(key_map(0), false))
return true;
table->no_keyread=1;
}
if (likely(!saved_error))
{
if (union_result->flush())
{
thd->lex->current_select= lex_select_save;
return true;
}
}
}
if (unlikely(saved_error))
{
thd->lex->current_select= lex_select_save;
return saved_error;
}
if (fake_select_lex != NULL)
{
/* Needed for the following test and for records_at_start in next loop */
int error= table->file->info(HA_STATUS_VARIABLE);
if (unlikely(error))
{
table->file->print_error(error, MYF(0));
return true;
}
}
if (found_rows_for_union && !sl->braces &&
!lim.is_unlimited())
{
/*
This is a union without braces. Remember the number of rows that
could also have been part of the result set.
We get this from the difference of between total number of possible
rows and actual rows added to the temporary table.
*/
add_rows+= (ulonglong) (thd->limit_found_rows - (ulonglong)
((table->file->stats.records - records_at_start)));
}
if (thd->killed == ABORT_QUERY)
{
/*
Stop execution of the remaining queries in the UNIONS, and produce
the current result.
*/
push_warning_printf(thd, Sql_condition::WARN_LEVEL_WARN,
ER_QUERY_RESULT_INCOMPLETE,
ER_THD(thd, ER_QUERY_RESULT_INCOMPLETE),
"LIMIT ROWS EXAMINED",
thd->lex->limit_rows_examined->val_uint());
thd->reset_killed();
break;
}
}
}
DBUG_EXECUTE_IF("show_explain_probe_union_read",
dbug_serve_apcs(thd, 1););
{
List<Item_func_match> empty_list;
empty_list.empty();
/*
Disable LIMIT ROWS EXAMINED in order to produce the possibly incomplete
result of the UNION without interruption due to exceeding the limit.
*/
thd->lex->limit_rows_examined_cnt= ULONGLONG_MAX;
// Check if EOM
if (fake_select_lex != NULL && likely(!thd->is_fatal_error))
{
/* Send result to 'result' */
saved_error= true;
set_limit(global_parameters());
JOIN *join= fake_select_lex->join;
saved_error= false;
if (!(thd->stmt_arena->is_stmt_prepare() ||
(thd->lex->context_analysis_only & CONTEXT_ANALYSIS_ONLY_VIEW)) &&
first_execution)
{
save_union_explain_part2(thd->lex->explain);
saved_error= mysql_select(thd, &result_table_list,
item_list, NULL,
global_parameters()->order_list.elements,
global_parameters()->order_list.first,
NULL, NULL, NULL,
fake_select_lex->options | SELECT_NO_UNLOCK,
result, this, fake_select_lex);
}
else
{
if (describe)
{
/*
In EXPLAIN command, constant subqueries that do not use any
tables are executed two times:
- 1st time is a real evaluation to get the subquery value
- 2nd time is to produce EXPLAIN output rows.
1st execution sets certain members (e.g. select_result) to perform
subquery execution rather than EXPLAIN line production. In order
to reset them back, we re-do all of the actions (yes it is ugly):
*/ // psergey-todo: is the above really necessary anymore??
saved_error= mysql_select(thd, &result_table_list, item_list, NULL,
global_parameters()->order_list.elements,
global_parameters()->order_list.first,
NULL, NULL, NULL,
fake_select_lex->options | SELECT_NO_UNLOCK,
result, this, fake_select_lex);
}
else
{
saved_error= join->reinit();
if (join->exec())
saved_error= 1;
}
}
fake_select_lex->table_list.empty();
if (likely(!saved_error))
{
thd->limit_found_rows = (ulonglong)table->file->stats.records + add_rows;
}
/*
Mark for slow query log if any of the union parts didn't use
indexes efficiently
*/
}
}
thd->lex->current_select= lex_select_save;
thd->lex->set_limit_rows_examined();
return saved_error;
}
/**
@brief
Execute the union of the specification of a recursive with table
@details
The method is performed only for the units that are specifications
if recursive with table T. If the specification contains an anchor
part then the first call of this method executes only this part
while the following calls execute the recursive part. If there are
no anchors each call executes the whole unit.
Before the excution the method cleans up the temporary table
to where the new rows of the recursive table are sent.
After the execution the unit these rows are copied to the
temporary tables created for recursive references of T.
If the specification if T is restricted (standards compliant)
then these temporary tables are cleaned up before new rows
are copied into them.
@retval
false on success
true on failure
*/
bool st_select_lex_unit::exec_recursive()
{
st_select_lex *lex_select_save= thd->lex->current_select;
st_select_lex *start= with_element->first_recursive;
TABLE *incr_table= with_element->rec_result->incr_table;
st_select_lex *end= NULL;
bool is_unrestricted= with_element->is_unrestricted();
List_iterator_fast<TABLE_LIST> li(with_element->rec_result->rec_table_refs);
TMP_TABLE_PARAM *tmp_table_param= &with_element->rec_result->tmp_table_param;
bool was_executed= executed;
TABLE_LIST *rec_tbl;
DBUG_ENTER("st_select_lex_unit::exec_recursive");
executed= 1;
create_explain_query_if_not_exists(thd->lex, thd->mem_root);
if (!was_executed)
save_union_explain(thd->lex->explain);
if (with_element->level == 0)
{
if (!incr_table->is_created() &&
instantiate_tmp_table(incr_table,
tmp_table_param->keyinfo,
tmp_table_param->start_recinfo,
&tmp_table_param->recinfo,
0))
DBUG_RETURN(1);
incr_table->file->extra(HA_EXTRA_WRITE_CACHE);
incr_table->file->extra(HA_EXTRA_IGNORE_DUP_KEY);
start= first_select();
if (with_element->with_anchor)
end= with_element->first_recursive;
}
else if (unlikely((saved_error= incr_table->file->ha_delete_all_rows())))
goto err;
for (st_select_lex *sl= start ; sl != end; sl= sl->next_select())
{
if (with_element->level)
{
for (TABLE_LIST *derived= with_element->derived_with_rec_ref.first;
derived;
derived= derived->next_with_rec_ref)
{
if (derived->is_materialized_derived())
{
if (derived->table->is_created())
derived->table->file->ha_delete_all_rows();
derived->table->reginfo.join_tab->preread_init_done= false;
}
}
}
thd->lex->current_select= sl;
set_limit(sl);
if (sl->tvc)
sl->tvc->exec(sl);
else
{
saved_error= sl->join->exec();
}
if (likely(!saved_error))
{
if (unlikely(union_result->flush()))
{
thd->lex->current_select= lex_select_save;
DBUG_RETURN(1);
}
}
else
{
thd->lex->current_select= lex_select_save;
goto err;
}
}
incr_table->file->info(HA_STATUS_VARIABLE);
if (with_element->level && incr_table->file->stats.records == 0)
with_element->set_as_stabilized();
else
with_element->level++;
while ((rec_tbl= li++))
{
TABLE *rec_table= rec_tbl->table;
saved_error=
incr_table->insert_all_rows_into_tmp_table(thd, rec_table,
tmp_table_param,
!is_unrestricted);
if (!with_element->rec_result->first_rec_table_to_update)
with_element->rec_result->first_rec_table_to_update= rec_table;
if (with_element->level == 1 && rec_table->reginfo.join_tab)
rec_table->reginfo.join_tab->preread_init_done= true;
}
for (Item_subselect *sq= with_element->sq_with_rec_ref.first;
sq;
sq= sq->next_with_rec_ref)
{
sq->reset();
sq->engine->force_reexecution();
}
thd->lex->current_select= lex_select_save;
err:
thd->lex->set_limit_rows_examined();
DBUG_RETURN(saved_error);
}
bool st_select_lex_unit::cleanup()
{
bool error= 0;
DBUG_ENTER("st_select_lex_unit::cleanup");
if (cleaned)
{
DBUG_RETURN(FALSE);
}
if (with_element && with_element->is_recursive && union_result &&
with_element->rec_outer_references)
{
select_union_recursive *result= with_element->rec_result;
if (++result->cleanup_count == with_element->rec_outer_references)
{
/*
Perform cleanup for with_element and for all with elements
mutually recursive with it.
*/
cleaned= 1;
with_element->get_next_mutually_recursive()->spec->cleanup();
}
else
{
/*
Just increment by 1 cleanup_count for with_element and
for all with elements mutually recursive with it.
*/
With_element *with_elem= with_element;
while ((with_elem= with_elem->get_next_mutually_recursive()) !=
with_element)
with_elem->rec_result->cleanup_count++;
DBUG_RETURN(FALSE);
}
}
columns_are_renamed= false;
cleaned= 1;
for (SELECT_LEX *sl= first_select(); sl; sl= sl->next_select())
error|= sl->cleanup();
if (fake_select_lex)
{
error|= fake_select_lex->cleanup();
/*
There are two cases when we should clean order items:
1. UNION with SELECTs which all enclosed into braces
in this case global_parameters == fake_select_lex
2. UNION where last SELECT is not enclosed into braces
in this case global_parameters == 'last select'
So we should use global_parameters->order_list for
proper order list clean up.
Note: global_parameters and fake_select_lex are always
initialized for UNION
*/
DBUG_ASSERT(global_parameters());
if (global_parameters()->order_list.elements)
{
ORDER *ord;
for (ord= global_parameters()->order_list.first; ord; ord= ord->next)
(*ord->item)->walk (&Item::cleanup_processor, 0, 0);
}
}
if (with_element && with_element->is_recursive)
{
if (union_result)
{
((select_union_recursive *) union_result)->reset_for_next_ps_execution();
delete union_result;
union_result= 0;
}
with_element->mark_as_cleaned();
}
else
{
if (union_result)
{
delete union_result;
union_result=0; // Safety
if (table)
free_tmp_table(thd, table);
table= 0; // Safety
}
}
delete pushdown_unit;
pushdown_unit= nullptr;
DBUG_RETURN(error);
}
void st_select_lex_unit::reinit_exec_mechanism()
{
prepared= optimized= optimized_2= executed= 0;
optimize_started= 0;
if (with_element && with_element->is_recursive)
with_element->reset_recursive_for_exec();
}
/**
Change the select_result object used to return the final result of
the unit, replacing occurences of old_result with new_result.
@param new_result New select_result object
@param old_result Old select_result object
@retval false Success
@retval true Error
*/
bool st_select_lex_unit::change_result(select_result_interceptor *new_result,
select_result_interceptor *old_result)
{
for (SELECT_LEX *sl= first_select(); sl; sl= sl->next_select())
{
if (sl->join)
if (sl->join->change_result(new_result, old_result))
return true; /* purecov: inspected */
}
if (fake_select_lex && fake_select_lex->join)
fake_select_lex->join->change_result(new_result, old_result);
return false;
}
/*
Get column type information for this unit.
SYNOPSIS
st_select_lex_unit::get_column_types()
@param for_cursor if true return the list the fields
retrieved by the cursor
DESCRIPTION
For a single-select the column types are taken
from the list of selected items. For a union this function
assumes that st_select_lex_unit::prepare has been called
and returns the type holders that were created for unioned
column types of all selects.
NOTES
The implementation of this function should be in sync with
st_select_lex_unit::prepare()
*/
List<Item> *st_select_lex_unit::get_column_types(bool for_cursor)
{
SELECT_LEX *sl= first_select();
bool is_procedure= !sl->tvc && sl->join->procedure ;
if (is_procedure)
{
/* Types for "SELECT * FROM t1 procedure analyse()"
are generated during execute */
return &sl->join->procedure_fields_list;
}
if (is_unit_op())
{
DBUG_ASSERT(prepared);
/* Types are generated during prepare */
return &types;
}
return for_cursor ? sl->join->fields : &sl->item_list;
}
static void cleanup_order(ORDER *order)
{
for (; order; order= order->next)
order->counter_used= 0;
}
static void cleanup_window_funcs(List<Item_window_func> &win_funcs)
{
List_iterator_fast<Item_window_func> it(win_funcs);
Item_window_func *win_func;
while ((win_func= it++))
{
Window_spec *win_spec= win_func->window_spec;
if (!win_spec)
continue;
if (win_spec->save_partition_list)
{
win_spec->partition_list= win_spec->save_partition_list;
win_spec->save_partition_list= NULL;
}
if (win_spec->save_order_list)
{
win_spec->order_list= win_spec->save_order_list;
win_spec->save_order_list= NULL;
}
}
}
bool st_select_lex::cleanup()
{
bool error= FALSE;
DBUG_ENTER("st_select_lex::cleanup()");
DBUG_PRINT("info", ("select: %p (%u) JOIN %p",
this, select_number, join));
cleanup_order(order_list.first);
cleanup_order(group_list.first);
cleanup_ftfuncs(this);
cleanup_window_funcs(window_funcs);
if (join)
{
List_iterator<TABLE_LIST> ti(leaf_tables);
TABLE_LIST *tbl;
while ((tbl= ti++))
{
if (tbl->is_recursive_with_table() &&
!tbl->is_with_table_recursive_reference())
{
/*
If query is killed before open_and_process_table() for tbl
is called then 'with' is already set, but 'derived' is not.
*/
st_select_lex_unit *unit= tbl->with->spec;
error|= (bool) error | (uint) unit->cleanup();
}
}
DBUG_ASSERT((st_select_lex*)join->select_lex == this);
error= join->destroy();
delete join;
join= 0;
}
leaf_tables.empty();
for (SELECT_LEX_UNIT *lex_unit= first_inner_unit(); lex_unit ;
lex_unit= lex_unit->next_unit())
{
if (lex_unit->with_element && lex_unit->with_element->is_recursive &&
lex_unit->with_element->rec_outer_references)
continue;
error= (bool) ((uint) error | (uint) lex_unit->cleanup());
}
inner_refs_list.empty();
exclude_from_table_unique_test= FALSE;
hidden_bit_fields= 0;
delete pushdown_select;
pushdown_select= nullptr;
DBUG_RETURN(error);
}
void st_select_lex::cleanup_all_joins(bool full)
{
SELECT_LEX_UNIT *unit;
SELECT_LEX *sl;
DBUG_ENTER("st_select_lex::cleanup_all_joins");
if (join)
join->cleanup(full);
for (unit= first_inner_unit(); unit; unit= unit->next_unit())
{
if (unit->with_element && unit->with_element->is_recursive)
continue;
for (sl= unit->first_select(); sl; sl= sl->next_select())
sl->cleanup_all_joins(full);
}
DBUG_VOID_RETURN;
}
/**
Set exclude_from_table_unique_test for selects of this unit and all
underlying selects.
@note used to exclude materialized derived tables (views) from unique
table check.
*/
void st_select_lex_unit::set_unique_exclude()
{
for (SELECT_LEX *sl= first_select(); sl; sl= sl->next_select())
{
sl->exclude_from_table_unique_test= TRUE;
for (SELECT_LEX_UNIT *unit= sl->first_inner_unit();
unit;
unit= unit->next_unit())
{
unit->set_unique_exclude();
}
}
}
/**
@brief
Check if the derived table is guaranteed to have distinct rows because of
UNION operations used to populate it.
@detail
UNION operation removes duplicate rows from its output. That is, a query like
select * from t1 UNION select * from t2
will not produce duplicate rows in its output, even if table t1 (and/or t2)
contain duplicate rows. EXCEPT and INTERSECT operations also have this
property.
On the other hand, UNION ALL operation doesn't remove duplicates. (The SQL
standard also defines EXCEPT ALL and INTERSECT ALL, but we don't support
them).
st_select_lex_unit computes its value left to right. That is, if there is
a st_select_lex_unit object describing
(select #1) OP1 (select #2) OP2 (select #3)
then ((select #1) OP1 (select #2)) is computed first, and OP2 is computed
second.
How can one tell if st_select_lex_unit is guaranteed to have distinct
output rows? This depends on whether the last operation was duplicate-
removing or not:
- UNION ALL is not duplicate-removing
- all other operations are duplicate-removing
*/
bool st_select_lex_unit::check_distinct_in_union()
{
if (union_distinct && !union_distinct->next_select())
return true;
return false;
}
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