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/* -*- mode: c++; c-basic-offset: 2; indent-tabs-mode: nil; -*-
* vim:expandtab:shiftwidth=2:tabstop=2:smarttab:
*
* Copyright (C) 2008-2009 Sun Microsystems, Inc.
*
* 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
*/
#pragma once
#include <drizzled/memory/sql_alloc.h>
namespace drizzled {
namespace optimizer {
/*
SEL_IMERGE is a list of possible ways to do index merge, i.e. it is
a condition in the following form:
(t_1||t_2||...||t_N) && (next)
where all t_i are optimizer::SEL_TREEs, next is another SEL_IMERGE and no pair
(t_i,t_j) contains SEL_ARGS for the same index.
optimizer::SEL_TREE contained in SEL_IMERGE always has merges=NULL.
This class relies on memory manager to do the cleanup.
*/
class SEL_IMERGE : public memory::SqlAlloc
{
enum { PREALLOCED_TREES= 10};
public:
SEL_TREE *trees_prealloced[PREALLOCED_TREES];
SEL_TREE **trees; /* trees used to do index_merge */
SEL_TREE **trees_next; /* last of these trees */
SEL_TREE **trees_end; /* end of allocated space */
SEL_ARG ***best_keys; /* best keys to read in optimizer::SEL_TREEs */
SEL_IMERGE();
/*
Add optimizer::SEL_TREE to this index_merge without any checks,
NOTES
This function implements the following:
(x_1||...||x_N) || t = (x_1||...||x_N||t), where x_i, t are optimizer::SEL_TREEs
RETURN
0 - OK
-1 - Out of memory.
*/
void or_sel_tree(RangeParameter *param, SEL_TREE *tree);
/*
Perform OR operation on this SEL_IMERGE and supplied optimizer::SEL_TREE new_tree,
combining new_tree with one of the trees in this SEL_IMERGE if they both
have SEL_ARGs for the same key.
SYNOPSIS
or_sel_tree_with_checks()
param Parameter from SqlSelect::test_quick_select
new_tree optimizer::SEL_TREE with type KEY or KEY_SMALLER.
NOTES
This does the following:
(t_1||...||t_k)||new_tree =
either
= (t_1||...||t_k||new_tree)
or
= (t_1||....||(t_j|| new_tree)||...||t_k),
where t_i, y are optimizer::SEL_TREEs.
new_tree is combined with the first t_j it has a SEL_ARG on common
key with. As a consequence of this, choice of keys to do index_merge
read may depend on the order of conditions in WHERE part of the query.
RETURN
0 OK
1 One of the trees was combined with new_tree to optimizer::SEL_TREE::ALWAYS,
and (*this) should be discarded.
-1 An error occurred.
*/
int or_sel_tree_with_checks(RangeParameter&, SEL_TREE&);
/*
Perform OR operation on this index_merge and supplied index_merge list.
RETURN
0 - OK
1 - One of conditions in result is always true and this SEL_IMERGE
should be discarded.
-1 - An error occurred
*/
int or_sel_imerge_with_checks(RangeParameter&, SEL_IMERGE&);
};
} /* namespace optimizer */
} /* namespace drizzled */
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