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mariadb/sql/sql_derived.cc
Kent Boortz 9da00ebec9 Updated/added copyright headers
2011-06-30 17:46:53 +02:00

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/* Copyright (c) 2002, 2011, Oracle and/or its affiliates. All rights reserved.
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 02110-1301 USA */
/*
Derived tables
These were introduced by Sinisa <sinisa@mysql.com>
*/
#include "my_global.h" /* NO_EMBEDDED_ACCESS_CHECKS */
#include "sql_priv.h"
#include "unireg.h"
#include "sql_derived.h"
#include "sql_select.h"
#include "sql_view.h" // check_duplicate_names
#include "sql_acl.h" // SELECT_ACL
/*
Call given derived table processor (preparing or filling tables)
SYNOPSIS
mysql_handle_derived()
lex LEX for this thread
processor procedure of derived table processing
RETURN
FALSE OK
TRUE Error
*/
bool
mysql_handle_derived(LEX *lex, bool (*processor)(THD*, LEX*, TABLE_LIST*))
{
bool res= FALSE;
if (lex->derived_tables)
{
lex->thd->derived_tables_processing= TRUE;
for (SELECT_LEX *sl= lex->all_selects_list;
sl;
sl= sl->next_select_in_list())
{
for (TABLE_LIST *cursor= sl->get_table_list();
cursor;
cursor= cursor->next_local)
{
if ((res= (*processor)(lex->thd, lex, cursor)))
goto out;
}
if (lex->describe)
{
/*
Force join->join_tmp creation, because we will use this JOIN
twice for EXPLAIN and we have to have unchanged join for EXPLAINing
*/
sl->uncacheable|= UNCACHEABLE_EXPLAIN;
sl->master_unit()->uncacheable|= UNCACHEABLE_EXPLAIN;
}
}
}
out:
lex->thd->derived_tables_processing= FALSE;
return res;
}
/**
@brief Create temporary table structure (but do not fill it).
@param thd Thread handle
@param lex LEX for this thread
@param orig_table_list TABLE_LIST for the upper SELECT
@details
This function is called before any command containing derived tables is
executed. Currently the function is used for derived tables, i.e.
- Anonymous derived tables, or
- Named derived tables (aka views) with the @c TEMPTABLE algorithm.
The table reference, contained in @c orig_table_list, is updated with the
fields of a new temporary table.
Derived tables are stored in @c thd->derived_tables and closed by
close_thread_tables().
This function is part of the procedure that starts in
open_and_lock_tables(), a procedure that - among other things - introduces
new table and table reference objects (to represent derived tables) that
don't exist in the privilege database. This means that normal privilege
checking cannot handle them. Hence this function does some extra tricks in
order to bypass normal privilege checking, by exploiting the fact that the
current state of privilege verification is attached as GRANT_INFO structures
on the relevant TABLE and TABLE_REF objects.
For table references, the current state of accrued access is stored inside
TABLE_LIST::grant. Hence this function must update the state of fulfilled
privileges for the new TABLE_LIST, an operation which is normally performed
exclusively by the table and database access checking functions,
check_access() and check_grant(), respectively. This modification is done
for both views and anonymous derived tables: The @c SELECT privilege is set
as fulfilled by the user. However, if a view is referenced and the table
reference is queried against directly (see TABLE_LIST::referencing_view),
the state of privilege checking (GRANT_INFO struct) is copied as-is to the
temporary table.
This function implements a signature called "derived table processor", and
is passed as a function pointer to mysql_handle_derived().
@note This function sets @c SELECT_ACL for @c TEMPTABLE views as well as
anonymous derived tables, but this is ok since later access checking will
distinguish between them.
@see mysql_handle_derived(), mysql_derived_filling(), GRANT_INFO
@return
false OK
true Error
*/
bool mysql_derived_prepare(THD *thd, LEX *lex, TABLE_LIST *orig_table_list)
{
SELECT_LEX_UNIT *unit= orig_table_list->derived;
ulonglong create_options;
DBUG_ENTER("mysql_derived_prepare");
bool res= FALSE;
if (unit)
{
SELECT_LEX *first_select= unit->first_select();
TABLE *table= 0;
select_union *derived_result;
/* prevent name resolving out of derived table */
for (SELECT_LEX *sl= first_select; sl; sl= sl->next_select())
sl->context.outer_context= 0;
if (!(derived_result= new select_union))
DBUG_RETURN(TRUE); // out of memory
lex->context_analysis_only|= CONTEXT_ANALYSIS_ONLY_DERIVED;
// st_select_lex_unit::prepare correctly work for single select
if ((res= unit->prepare(thd, derived_result, 0)))
goto exit;
lex->context_analysis_only&= ~CONTEXT_ANALYSIS_ONLY_DERIVED;
if ((res= check_duplicate_names(unit->types, 0)))
goto exit;
create_options= (first_select->options | thd->variables.option_bits |
TMP_TABLE_ALL_COLUMNS);
/*
Temp table is created so that it hounours if UNION without ALL is to be
processed
As 'distinct' parameter we always pass FALSE (0), because underlying
query will control distinct condition by itself. Correct test of
distinct underlying query will be is_union &&
!unit->union_distinct->next_select() (i.e. it is union and last distinct
SELECT is last SELECT of UNION).
*/
if ((res= derived_result->create_result_table(thd, &unit->types, FALSE,
create_options,
orig_table_list->alias)))
goto exit;
table= derived_result->table;
exit:
/* Hide "Unknown column" or "Unknown function" error */
if (orig_table_list->view)
{
if (thd->is_error() &&
(thd->stmt_da->sql_errno() == ER_BAD_FIELD_ERROR ||
thd->stmt_da->sql_errno() == ER_FUNC_INEXISTENT_NAME_COLLISION ||
thd->stmt_da->sql_errno() == ER_SP_DOES_NOT_EXIST))
{
thd->clear_error();
my_error(ER_VIEW_INVALID, MYF(0), orig_table_list->db,
orig_table_list->table_name);
}
}
/*
if it is preparation PS only or commands that need only VIEW structure
then we do not need real data and we can skip execution (and parameters
is not defined, too)
*/
if (res)
{
if (table)
free_tmp_table(thd, table);
delete derived_result;
}
else
{
if (!thd->fill_derived_tables())
{
delete derived_result;
derived_result= NULL;
}
orig_table_list->derived_result= derived_result;
orig_table_list->table= table;
orig_table_list->table_name= table->s->table_name.str;
orig_table_list->table_name_length= table->s->table_name.length;
table->derived_select_number= first_select->select_number;
table->s->tmp_table= NON_TRANSACTIONAL_TMP_TABLE;
#ifndef NO_EMBEDDED_ACCESS_CHECKS
if (orig_table_list->referencing_view)
table->grant= orig_table_list->grant;
else
table->grant.privilege= SELECT_ACL;
#endif
orig_table_list->db= (char *)"";
orig_table_list->db_length= 0;
// Force read of table stats in the optimizer
table->file->info(HA_STATUS_VARIABLE);
/* Add new temporary table to list of open derived tables */
table->next= thd->derived_tables;
thd->derived_tables= table;
}
}
else if (orig_table_list->merge_underlying_list)
orig_table_list->set_underlying_merge();
DBUG_RETURN(res);
}
/*
fill derived table
SYNOPSIS
mysql_derived_filling()
thd Thread handle
lex LEX for this thread
unit node that contains all SELECT's for derived tables
orig_table_list TABLE_LIST for the upper SELECT
IMPLEMENTATION
Derived table is resolved with temporary table. It is created based on the
queries defined. After temporary table is filled, if this is not EXPLAIN,
then the entire unit / node is deleted. unit is deleted if UNION is used
for derived table and node is deleted is it is a simple SELECT.
If you use this function, make sure it's not called at prepare.
Due to evaluation of LIMIT clause it can not be used at prepared stage.
RETURN
FALSE OK
TRUE Error
*/
bool mysql_derived_filling(THD *thd, LEX *lex, TABLE_LIST *orig_table_list)
{
TABLE *table= orig_table_list->table;
SELECT_LEX_UNIT *unit= orig_table_list->derived;
bool res= FALSE;
/*check that table creation pass without problem and it is derived table */
if (table && unit)
{
SELECT_LEX *first_select= unit->first_select();
select_union *derived_result= orig_table_list->derived_result;
SELECT_LEX *save_current_select= lex->current_select;
if (unit->is_union())
{
// execute union without clean up
res= unit->exec();
}
else
{
unit->set_limit(first_select);
if (unit->select_limit_cnt == HA_POS_ERROR)
first_select->options&= ~OPTION_FOUND_ROWS;
lex->current_select= first_select;
res= mysql_select(thd, &first_select->ref_pointer_array,
first_select->table_list.first,
first_select->with_wild,
first_select->item_list, first_select->where,
(first_select->order_list.elements+
first_select->group_list.elements),
first_select->order_list.first,
first_select->group_list.first,
first_select->having, (ORDER*) NULL,
(first_select->options | thd->variables.option_bits |
SELECT_NO_UNLOCK),
derived_result, unit, first_select);
}
if (!res)
{
/*
Here we entirely fix both TABLE_LIST and list of SELECT's as
there were no derived tables
*/
if (derived_result->flush())
res= TRUE;
}
lex->current_select= save_current_select;
}
return res;
}
/**
Cleans up the SELECT_LEX_UNIT for the derived table (if any).
*/
bool mysql_derived_cleanup(THD *thd, LEX *lex, TABLE_LIST *derived)
{
SELECT_LEX_UNIT *unit= derived->derived;
if (unit)
unit->cleanup();
return false;
}
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