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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
*
* 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; either version 2 of the License, or
* (at your option) any later version.
*
* 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
*/
/**
* @file
*
* Defines the JoinTable class which is the primary class
* used in the nested loops join implementation.
*/
#ifndef DRIZZLED_JOINTABLE_H
#define DRIZZLED_JOINTABLE_H
#include <drizzled/enum_nested_loop_state.h>
#include <drizzled/table_reference.h>
#include <drizzled/opt_range.h>
#include <drizzled/join_cache.h>
/* Values for JoinTable::packed_info */
#define TAB_INFO_HAVE_VALUE 1
#define TAB_INFO_USING_INDEX 2
#define TAB_INFO_USING_WHERE 4
#define TAB_INFO_FULL_SCAN_ON_NULL 8
class KeyUse;
class Table;
class SQL_SELECT;
/** Description of a join type */
enum join_type
{
JT_UNKNOWN,
JT_SYSTEM,
JT_CONST,
JT_EQ_REF,
JT_REF,
JT_MAYBE_REF,
JT_ALL,
JT_RANGE,
JT_NEXT,
JT_REF_OR_NULL,
JT_UNIQUE_SUBQUERY,
JT_INDEX_SUBQUERY,
JT_INDEX_MERGE
};
class JoinTable
{
public:
JoinTable() {} /* Remove gcc warning */
Table *table;
KeyUse *keyuse; /**< pointer to first used key */
SQL_SELECT *select;
COND *select_cond;
QUICK_SELECT_I *quick;
/**
The value of select_cond before we've attempted to do Index Condition
Pushdown. We may need to restore everything back if we first choose one
index but then reconsider (see test_if_skip_sort_order() for such
scenarios).
NULL means no index condition pushdown was performed.
*/
Item *pre_idx_push_select_cond;
Item **on_expr_ref; /**< pointer to the associated on expression */
COND_EQUAL *cond_equal; /**< multiple equalities for the on expression */
JoinTable *first_inner; /**< first inner table for including outerjoin */
bool found; /**< true after all matches or null complement */
bool not_null_compl;/**< true before null complement is added */
JoinTable *last_inner; /**< last table table for embedding outer join */
JoinTable *first_upper; /**< first inner table for embedding outer join */
JoinTable *first_unmatched; /**< used for optimization purposes only */
/* Special content for EXPLAIN 'Extra' column or NULL if none */
const char *info;
/*
Bitmap of TAB_INFO_* bits that encodes special line for EXPLAIN 'Extra'
column, or 0 if there is no info.
*/
uint32_t packed_info;
Read_record_func read_first_record;
Next_select_func next_select;
READ_RECORD read_record;
/*
Currently the following two fields are used only for a [NOT] IN subquery
if it is executed by an alternative full table scan when the left operand of
the subquery predicate is evaluated to NULL.
*/
Read_record_func save_read_first_record; /**< to save read_first_record */
int (*save_read_record) (READ_RECORD *); /**< to save read_record.read_record */
double worst_seeks;
key_map const_keys; /**< Keys with constant part */
key_map checked_keys; /**< Keys checked in find_best */
key_map needed_reg;
key_map keys; /**< all keys with can be used */
/** Either #rows in the table or 1 for const table. */
ha_rows records;
/**
Number of records that will be scanned (yes scanned, not returned) by the
best 'independent' access method, i.e. table scan or QUICK_*_SELECT)
*/
ha_rows found_records;
/**
Cost of accessing the table using "ALL" or range/index_merge access
method (but not 'index' for some reason), i.e. this matches method which
E(#records) is in found_records.
*/
ha_rows read_time;
table_map dependent;
table_map key_dependent;
uint32_t use_quick;
uint32_t index;
uint32_t status; /**< Save status for cache */
uint32_t used_fields; /**< Number of used fields in join set */
uint32_t used_fieldlength; /**< Not sure... */
uint32_t used_blobs; /**< Number of BLOB fields in join set */
enum join_type type; /**< Access pattern or join type... */
bool cached_eq_ref_table;
bool eq_ref_table;
bool not_used_in_distinct;
/** True if index-based access method must return records in order */
bool sorted;
/**
If it's not 0 the number stored this field indicates that the index
scan has been chosen to access the table data and we expect to scan
this number of rows for the table.
*/
ha_rows limit;
table_reference_st ref;
JOIN_CACHE cache;
JOIN *join;
/**
ptr - this join tab should do an InsideOut scan. Points
to the tab for which we'll need to check tab->found_match.
NULL - Not an insideout scan.
*/
JoinTable *insideout_match_tab;
unsigned char *insideout_buf; /**< Buffer to save index tuple to be able to skip dups */
/** Used by InsideOut scan. Just set to true when have found a row. */
bool found_match;
enum
{
/* If set, the rowid of this table must be put into the temptable. */
KEEP_ROWID=1,
/*
If set, one should call h->position() to obtain the rowid,
otherwise, the rowid is assumed to already be in h->ref
(this is because join caching and filesort() save the rowid and then
put it back into h->ref)
*/
CALL_POSITION=2
};
/** A set of flags from the above enum */
int rowid_keep_flags;
/** Bitmap of nested joins this table is part of */
nested_join_map embedding_map;
void cleanup();
inline bool is_using_loose_index_scan()
{
return (select && select->quick &&
(select->quick->get_type() ==
QUICK_SELECT_I::QS_TYPE_GROUP_MIN_MAX));
}
void readCachedRecord();
};
#endif /* DRIZZLED_JOINTABLE_H */
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