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/* Copyright (C) 2003 MySQL AB
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 Street, Fifth Floor, Boston, MA 02110-1301, USA */
#ifndef NdbIndexStat_H
#define NdbIndexStat_H
#include <ndb_global.h>
#include <NdbDictionary.hpp>
#include <NdbError.hpp>
class NdbIndexImpl;
class NdbIndexScanOperation;
/*
* Statistics for an ordered index.
*/
class NdbIndexStat {
public:
NdbIndexStat(const NdbDictionary::Index* index);
~NdbIndexStat();
/*
* Allocate memory for cache. Argument is minimum number of stat
* entries and applies to lower and upper bounds separately. More
* entries may fit (keys have variable size). If not used, db is
* contacted always.
*/
int alloc_cache(Uint32 entries);
/*
* Flags for records_in_range.
*/
enum {
RR_UseDb = 1, // contact db
RR_NoUpdate = 2 // but do not update cache
};
/*
* Estimate how many index records need to be scanned. The scan
* operation must be prepared with lock mode LM_CommittedRead and must
* have the desired bounds set. The routine may use local cache or
* may contact db by executing the operation.
*
* If returned count is zero then db was contacted and the count is
* exact. Otherwise the count is approximate. If cache is used then
* caller must provide estimated number of table rows. It will be
* multiplied by a percentage obtained from the cache (result zero is
* returned as 1).
*/
int records_in_range(const NdbDictionary::Index* index,
NdbIndexScanOperation* op,
Uint64 table_rows,
Uint64* count,
int flags);
/*
* Get latest error.
*/
const NdbError& getNdbError() const;
private:
/*
* There are 2 areas: start keys and end keys. An area has pointers
* at beginning and entries at end. Pointers are sorted by key.
*
* A pointer contains entry offset and also entry timestamp. An entry
* contains the key and percentage of rows _not_ satisfying the bound
* i.e. less than start key or greater than end key.
*
* A key is an array of index key bounds. Each has type (0-4) in
* first word followed by data with AttributeHeader.
*
* Stat update comes as pair of start and end key and associated
* percentages. Stat query takes best match of start and end key from
* each area separately. Rows in range percentage is then computed by
* excluding the two i.e. as 100 - (start key pct + end key pct).
*
* TODO use more compact key format
*/
struct Pointer;
friend struct Pointer;
struct Entry;
friend struct Entry;
struct Area;
friend struct Area;
struct Pointer {
Uint16 m_pos;
Uint16 m_seq;
};
struct Entry {
float m_pct;
Uint32 m_keylen;
};
STATIC_CONST( EntrySize = sizeof(Entry) >> 2 );
STATIC_CONST( PointerSize = sizeof(Pointer) >> 2 );
struct Area {
Uint32* m_data;
Uint32 m_offset;
Uint32 m_free;
Uint16 m_entries;
Uint8 m_idir;
Uint8 pad1;
Area() {}
Pointer& get_pointer(unsigned i) const {
return *(Pointer*)&m_data[i];
}
Entry& get_entry(unsigned i) const {
return *(Entry*)&m_data[get_pointer(i).m_pos];
}
Uint32 get_pos(const Entry& e) const {
return (const Uint32*)&e - m_data;
}
unsigned get_firstpos() const {
return PointerSize * m_entries + m_free;
}
};
const NdbIndexImpl& m_index;
Uint32 m_areasize;
Uint16 m_seq;
Area m_area[2];
Uint32* m_cache;
NdbError m_error;
#ifdef VM_TRACE
void stat_verify();
#endif
int stat_cmpkey(const Area& a, const Uint32* key1, Uint32 keylen1,
const Uint32* key2, Uint32 keylen2);
int stat_search(const Area& a, const Uint32* key, Uint32 keylen,
Uint32* idx, bool* match);
int stat_oldest(const Area& a);
int stat_delete(Area& a, Uint32 k);
int stat_update(const Uint32* key1, Uint32 keylen1,
const Uint32* key2, Uint32 keylen2, const float pct[2]);
int stat_select(const Uint32* key1, Uint32 keylen1,
const Uint32* key2, Uint32 keylen2, float pct[2]);
void set_error(int code);
};
#endif
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