mirror of
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246 lines
8.4 KiB
C++
246 lines
8.4 KiB
C++
/* Copyright (C) 2003 MySQL AB
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; version 2 of the License.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */
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/** @file ha_example.h
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@brief
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The ha_example engine is a stubbed storage engine for example purposes only;
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it does nothing at this point. Its purpose is to provide a source
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code illustration of how to begin writing new storage engines; see also
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/storage/example/ha_example.cc.
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@note
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Please read ha_example.cc before reading this file.
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Reminder: The example storage engine implements all methods that are *required*
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to be implemented. For a full list of all methods that you can implement, see
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handler.h.
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@see
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/sql/handler.h and /storage/example/ha_example.cc
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*/
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#ifdef USE_PRAGMA_INTERFACE
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#pragma interface /* gcc class implementation */
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#endif
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/** @brief
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EXAMPLE_SHARE is a structure that will be shared among all open handlers.
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This example implements the minimum of what you will probably need.
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*/
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typedef struct st_example_share {
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char *table_name;
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uint table_name_length,use_count;
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pthread_mutex_t mutex;
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THR_LOCK lock;
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} EXAMPLE_SHARE;
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/** @brief
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Class definition for the storage engine
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*/
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class ha_example: public handler
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{
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THR_LOCK_DATA lock; ///< MySQL lock
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EXAMPLE_SHARE *share; ///< Shared lock info
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public:
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ha_example(handlerton *hton, TABLE_SHARE *table_arg);
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~ha_example()
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{
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}
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/** @brief
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The name that will be used for display purposes.
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*/
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const char *table_type() const { return "EXAMPLE"; }
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/** @brief
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The name of the index type that will be used for display.
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Don't implement this method unless you really have indexes.
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*/
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const char *index_type(uint inx) { return "HASH"; }
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/** @brief
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The file extensions.
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*/
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const char **bas_ext() const;
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/** @brief
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This is a list of flags that indicate what functionality the storage engine
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implements. The current table flags are documented in handler.h
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*/
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ulonglong table_flags() const
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{
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return 0;
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}
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/** @brief
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This is a bitmap of flags that indicates how the storage engine
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implements indexes. The current index flags are documented in
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handler.h. If you do not implement indexes, just return zero here.
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@details
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part is the key part to check. First key part is 0.
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If all_parts is set, MySQL wants to know the flags for the combined
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index, up to and including 'part'.
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*/
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ulong index_flags(uint inx, uint part, bool all_parts) const
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{
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return 0;
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}
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/** @brief
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unireg.cc will call max_supported_record_length(), max_supported_keys(),
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max_supported_key_parts(), uint max_supported_key_length()
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to make sure that the storage engine can handle the data it is about to
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send. Return *real* limits of your storage engine here; MySQL will do
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min(your_limits, MySQL_limits) automatically.
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*/
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uint max_supported_record_length() const { return HA_MAX_REC_LENGTH; }
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/** @brief
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unireg.cc will call this to make sure that the storage engine can handle
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the data it is about to send. Return *real* limits of your storage engine
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here; MySQL will do min(your_limits, MySQL_limits) automatically.
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@details
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There is no need to implement ..._key_... methods if your engine doesn't
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support indexes.
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*/
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uint max_supported_keys() const { return 0; }
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/** @brief
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unireg.cc will call this to make sure that the storage engine can handle
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the data it is about to send. Return *real* limits of your storage engine
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here; MySQL will do min(your_limits, MySQL_limits) automatically.
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@details
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There is no need to implement ..._key_... methods if your engine doesn't
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support indexes.
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*/
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uint max_supported_key_parts() const { return 0; }
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/** @brief
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unireg.cc will call this to make sure that the storage engine can handle
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the data it is about to send. Return *real* limits of your storage engine
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here; MySQL will do min(your_limits, MySQL_limits) automatically.
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@details
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There is no need to implement ..._key_... methods if your engine doesn't
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support indexes.
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*/
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uint max_supported_key_length() const { return 0; }
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/** @brief
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Called in test_quick_select to determine if indexes should be used.
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*/
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virtual double scan_time() { return (double) (stats.records+stats.deleted) / 20.0+10; }
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/** @brief
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This method will never be called if you do not implement indexes.
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*/
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virtual double read_time(ha_rows rows) { return (double) rows / 20.0+1; }
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/*
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Everything below are methods that we implement in ha_example.cc.
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Most of these methods are not obligatory, skip them and
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MySQL will treat them as not implemented
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*/
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/** @brief
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We implement this in ha_example.cc; it's a required method.
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*/
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int open(const char *name, int mode, uint test_if_locked); // required
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/** @brief
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We implement this in ha_example.cc; it's a required method.
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*/
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int close(void); // required
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/** @brief
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We implement this in ha_example.cc. It's not an obligatory method;
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skip it and and MySQL will treat it as not implemented.
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*/
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int write_row(byte * buf);
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/** @brief
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We implement this in ha_example.cc. It's not an obligatory method;
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skip it and and MySQL will treat it as not implemented.
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*/
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int update_row(const byte * old_data, byte * new_data);
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/** @brief
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We implement this in ha_example.cc. It's not an obligatory method;
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skip it and and MySQL will treat it as not implemented.
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*/
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int delete_row(const byte * buf);
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/** @brief
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We implement this in ha_example.cc. It's not an obligatory method;
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skip it and and MySQL will treat it as not implemented.
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*/
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int index_read(byte * buf, const byte * key,
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uint key_len, enum ha_rkey_function find_flag);
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/** @brief
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We implement this in ha_example.cc. It's not an obligatory method;
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skip it and and MySQL will treat it as not implemented.
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*/
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int index_next(byte * buf);
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/** @brief
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We implement this in ha_example.cc. It's not an obligatory method;
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skip it and and MySQL will treat it as not implemented.
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*/
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int index_prev(byte * buf);
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/** @brief
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We implement this in ha_example.cc. It's not an obligatory method;
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skip it and and MySQL will treat it as not implemented.
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*/
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int index_first(byte * buf);
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/** @brief
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We implement this in ha_example.cc. It's not an obligatory method;
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skip it and and MySQL will treat it as not implemented.
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*/
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int index_last(byte * buf);
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/** @brief
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Unlike index_init(), rnd_init() can be called two consecutive times
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without rnd_end() in between (it only makes sense if scan=1). In this
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case, the second call should prepare for the new table scan (e.g if
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rnd_init() allocates the cursor, the second call should position the
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cursor to the start of the table; no need to deallocate and allocate
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it again. This is a required method.
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*/
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int rnd_init(bool scan); //required
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int rnd_end();
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int rnd_next(byte *buf); ///< required
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int rnd_pos(byte * buf, byte *pos); ///< required
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void position(const byte *record); ///< required
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int info(uint); ///< required
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int extra(enum ha_extra_function operation);
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int external_lock(THD *thd, int lock_type); ///< required
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int delete_all_rows(void);
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ha_rows records_in_range(uint inx, key_range *min_key,
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key_range *max_key);
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int delete_table(const char *from);
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int rename_table(const char * from, const char * to);
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int create(const char *name, TABLE *form,
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HA_CREATE_INFO *create_info); ///< required
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THR_LOCK_DATA **store_lock(THD *thd, THR_LOCK_DATA **to,
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enum thr_lock_type lock_type); ///< required
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};
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