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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
*/
/* classes to use when handling where clause */
#pragma once
#include <drizzled/field.h>
#include <drizzled/item/sum.h>
#include <drizzled/table_reference.h>
#include <queue>
#include <boost/dynamic_bitset.hpp>
namespace drizzled {
typedef struct st_key_part
{
uint16_t key;
uint16_t part;
/* See KeyPartInfo for meaning of the next two: */
uint16_t store_length;
uint16_t length;
uint8_t null_bit;
/**
Keypart flags (0 when this structure is used by partition pruning code
for fake partitioning index description)
*/
uint8_t flag;
Field *field;
} KEY_PART;
namespace optimizer {
/**
Quick select interface.
This class is a parent for all QUICK_*_SELECT classes.
The usage scenario is as follows:
1. Create quick select
quick= new QUICK_XXX_SELECT(...);
2. Perform lightweight initialization. This can be done in 2 ways:
2.a: Regular initialization
if (quick->init())
{
//the only valid action after failed init() call is delete
delete quick;
}
2.b: Special initialization for quick selects merged by QUICK_ROR_*_SELECT
if (quick->init_ror_merged_scan())
delete quick;
3. Perform zero, one, or more scans.
while (...)
{
// initialize quick select for scan. This may allocate
// buffers and/or prefetch rows.
if (quick->reset())
{
//the only valid action after failed reset() call is delete
delete quick;
//abort query
}
// perform the scan
do
{
res= quick->get_next();
} while (res && ...)
}
4. Delete the select:
delete quick;
*/
class QuickSelectInterface
{
public:
bool sorted;
ha_rows records; /**< estimate of # of records to be retrieved */
double read_time; /**< time to perform this retrieval */
Table *head;
/**
Index this quick select uses, or MAX_KEY for quick selects
that use several indexes
*/
uint32_t index;
/**
Total length of first used_key_parts parts of the key.
Applicable if index!= MAX_KEY.
*/
uint32_t max_used_key_length;
/**
Maximum number of (first) key parts this quick select uses for retrieval.
eg. for "(key1p1=c1 AND key1p2=c2) OR key1p1=c2" used_key_parts == 2.
Applicable if index!= MAX_KEY.
For QUICK_GROUP_MIN_MAX_SELECT it includes MIN/MAX argument keyparts.
*/
uint32_t used_key_parts;
/**
* The rowid of last row retrieved by this quick select. This is used only when
* doing ROR-index_merge selects
*/
unsigned char *last_rowid;
/**
* Table record buffer used by this quick select.
*/
unsigned char *record;
QuickSelectInterface();
virtual ~QuickSelectInterface(){};
/**
* Do post-constructor initialization.
*
* @details
*
* Performs initializations that should have been in constructor if
* it was possible to return errors from constructors. The join optimizer may
* create and then delete quick selects without retrieving any rows so init()
* must not contain any IO or CPU intensive code.
*
* If init() call fails the only valid action is to delete this quick select,
* reset() and get_next() must not be called.
*
* @retval
* 0 OK
* @retval
* other Error code
*/
virtual int init() = 0;
/**
* Initializes quick select for row retrieval.
*
* @details
*
* Should be called when it is certain that row retrieval will be
* necessary. This call may do heavyweight initialization like buffering first
* N records etc. If reset() call fails get_next() must not be called.
* Note that reset() may be called several times if
* - the quick select is executed in a subselect
* - a JOIN buffer is used
*
* @retval
* 0 OK
* @retval
* other Error code
*/
virtual int reset(void) = 0;
/** Gets next record to retrieve */
virtual int get_next() = 0;
/** Range end should be called when we have looped over the whole index */
virtual void range_end() {}
virtual bool reverse_sorted() const = 0;
virtual bool unique_key_range() const
{
return false;
}
enum
{
QS_TYPE_RANGE= 0,
QS_TYPE_INDEX_MERGE= 1,
QS_TYPE_RANGE_DESC= 2,
QS_TYPE_ROR_INTERSECT= 4,
QS_TYPE_ROR_UNION= 5,
QS_TYPE_GROUP_MIN_MAX= 6
};
/** Returns the type of this quick select - one of the QS_TYPE_* values */
virtual int get_type() const = 0;
/**
* Initialize this quick select as a merged scan inside a ROR-union or a ROR-
* intersection scan. The caller must not additionally call init() if this
* function is called.
*
* @param If true, the quick select may use table->Cursor,
* otherwise it must create and use a separate Cursor
* object.
*
* @retval
* 0 Ok
* @retval
* other Error
*/
virtual int init_ror_merged_scan(bool)
{
assert(0);
return 1;
}
/**
* Save ROWID of last retrieved row in file->ref. This used in ROR-merging.
*/
virtual void save_last_pos(){};
/**
* Append comma-separated list of keys this quick select uses to key_names;
* append comma-separated list of corresponding used lengths to used_lengths.
*
* @note This is used by during explain plan.
*/
virtual void add_keys_and_lengths(std::string *key_names,
std::string *used_lengths)=0;
/**
* Append text representation of quick select structure (what and how is
* merged) to str. The result is added to "Extra" field in EXPLAIN output.
*
* @note
*
* This function is implemented only by quick selects that merge other quick
* selects output and/or can produce output suitable for merging.
*/
virtual void add_info_string(std::string *)
{}
/**
* Returns true if any index used by this quick select
* uses field which is marked in passed bitmap.
*/
virtual bool is_keys_used(const boost::dynamic_bitset<>& fields);
};
/**
* MRR range sequence, array<QuickRange> implementation: sequence traversal
* context.
*/
typedef struct st_quick_range_seq_ctx
{
QuickRange **first;
QuickRange **cur;
QuickRange **last;
} QuickRangeSequenceContext;
range_seq_t quick_range_seq_init(void *init_param, uint32_t n_ranges, uint32_t flags);
uint32_t quick_range_seq_next(range_seq_t rseq, KEY_MULTI_RANGE *range);
/**
* Executor class for SELECT statements.
*
* @details
*
* The QuickSelectInterface member variable is the implementor
* of the SELECT execution.
*/
class SqlSelect : public memory::SqlAlloc
{
public:
QuickSelectInterface *quick; /**< If quick-select used */
COND *cond; /**< where condition */
Table *head;
internal::IO_CACHE *file; /**< Positions to used records */
ha_rows records; /**< Records in use if read from file */
double read_time; /**< Time to read rows */
key_map quick_keys; /**< Possible quick keys */
key_map needed_reg; /**< Possible quick keys after prev tables. */
table_map const_tables;
table_map read_tables;
bool free_cond;
SqlSelect();
~SqlSelect();
void cleanup();
bool check_quick(Session *session, bool force_quick_range, ha_rows limit);
bool skip_record();
int test_quick_select(Session *session, key_map keys, table_map prev_tables,
ha_rows limit, bool force_quick_range,
bool ordered_output);
};
QuickRangeSelect *get_quick_select_for_ref(Session *session,
Table *table,
table_reference_st *ref,
ha_rows records);
/*
Create a QuickRangeSelect from given key and SEL_ARG tree for that key.
SYNOPSIS
get_quick_select()
param
idx Index of used key in param->key.
key_tree SEL_ARG tree for the used key
mrr_flags MRR parameter for quick select
mrr_buf_size MRR parameter for quick select
parent_alloc If not NULL, use it to allocate memory for
quick select data. Otherwise use quick->alloc.
NOTES
The caller must call QUICK_SELECT::init for returned quick select.
CAUTION! This function may change session->mem_root to a memory::Root which will be
deallocated when the returned quick select is deleted.
RETURN
NULL on error
otherwise created quick select
*/
QuickRangeSelect *get_quick_select(Parameter *param,
uint32_t index,
SEL_ARG *key_tree,
uint32_t mrr_flags,
uint32_t mrr_buf_size,
memory::Root *alloc);
uint32_t get_index_for_order(Table *table, Order *order, ha_rows limit);
SqlSelect *make_select(Table *head,
table_map const_tables,
table_map read_tables,
COND *conds,
bool allow_null_cond,
int *error);
bool get_quick_keys(Parameter *param,
QuickRangeSelect *quick,
KEY_PART *key,
SEL_ARG *key_tree,
unsigned char *min_key,
uint32_t min_key_flag,
unsigned char *max_key,
uint32_t max_key_flag);
} /* namespace optimizer */
} /* namespace drizzled */
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