diff options
Diffstat (limited to 'sql/examples/ha_example.h')
-rw-r--r-- | sql/examples/ha_example.h | 87 |
1 files changed, 57 insertions, 30 deletions
diff --git a/sql/examples/ha_example.h b/sql/examples/ha_example.h index 2228f04284a..dc8f265c16e 100644 --- a/sql/examples/ha_example.h +++ b/sql/examples/ha_example.h @@ -14,13 +14,17 @@ along with this program; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */ -/* +/* Please read ha_exmple.cc before reading this file. Please keep in mind that the example storage engine implements all methods that are required to be implemented. handler.h has a full list of methods that you can implement. */ +#ifdef __GNUC__ +#pragma interface /* gcc class implementation */ +#endif + /* EXAMPLE_SHARE is a structure that will be shared amoung all open handlers The example implements the minimum of what you will probably need. @@ -44,56 +48,68 @@ public: ha_example(TABLE *table): handler(table) { } - ~ha_example() + ~ha_example() { } /* The name that will be used for display purposes */ - const char *table_type() const { return "EXAMPLE"; } - /* The name of the index type that will be used for display */ - const char *index_type(uint inx) { return "NONE"; } + const char *table_type() const { return "EXAMPLE"; } + /* + The name of the index type that will be used for display + don't implement this method unless you really have indexes + */ + const char *index_type(uint inx) { return "HASH"; } const char **bas_ext() const; - /* - This is a list of flags that says what the storage engine + /* + This is a list of flags that says what the storage engine implements. The current table flags are documented in - table_flags. + handler.h */ ulong table_flags() const { return 0; } - /* - This is a list of flags that says how the storage engine + /* + This is a list of flags that says how the storage engine implements indexes. The current index flags are documented in - handler.h. If you do not implement indexes, just return zero + handler.h. If you do not implement indexes, just return zero here. */ - ulong index_flags(uint inx) const + ulong index_flags(uint inx, uint part) const { return 0; } - /* + /* unireg.cc will call the following to make sure that the storage engine can handle the data it is about to send. + + Return *real* limits of your storage engine here. MySQL will do + min(your_limits, MySQL_limits) automatically + + There is no need to implement ..._key_... methods if you don't suport + indexes. */ - uint max_record_length() const { return HA_MAX_REC_LENGTH; } - uint max_keys() const { return 0; } - uint max_key_parts() const { return 0; } - uint max_key_length() const { return 0; } + uint max_supported_record_length() const { return HA_MAX_REC_LENGTH; } + uint max_supported_keys() const { return 0; } + uint max_supported_key_parts() const { return 0; } + uint max_supported_key_length() const { return 0; } /* Called in test_quick_select to determine if indexes should be used. */ virtual double scan_time() { return (double) (records+deleted) / 20.0+10; } - /* + /* The next method will never be called if you do not implement indexes. */ virtual double read_time(ha_rows rows) { return (double) rows / 20.0+1; } - virtual bool fast_key_read() { return 1;} - /* + /* Everything below are methods that we implment in ha_example.cc. + + Most of these methods are not obligatory, skip them and + MySQL will treat them as not implemented */ - int open(const char *name, int mode, uint test_if_locked); - int close(void); + int open(const char *name, int mode, uint test_if_locked); // required + int close(void); // required + int write_row(byte * buf); int update_row(const byte * old_data, byte * new_data); int delete_row(const byte * buf); @@ -105,21 +121,32 @@ public: int index_prev(byte * buf); int index_first(byte * buf); int index_last(byte * buf); - int rnd_init(bool scan=1); - int rnd_next(byte *buf); - int rnd_pos(byte * buf, byte *pos); - void position(const byte *record); - void info(uint); + /* + unlike index_init(), rnd_init() can be called two times + without rnd_end() in between (it only makes sense if scan=1). + then the second call should prepare for the new table scan + (e.g if rnd_init allocates the cursor, second call should + position it to the start of the table, no need to deallocate + and allocate it again + */ + int rnd_init(bool scan); //required + int rnd_end(); + int rnd_next(byte *buf); //required + int rnd_pos(byte * buf, byte *pos); //required + void position(const byte *record); //required + void info(uint); //required + int extra(enum ha_extra_function operation); int reset(void); - int external_lock(THD *thd, int lock_type); + int external_lock(THD *thd, int lock_type); //required int delete_all_rows(void); ha_rows records_in_range(uint inx, key_range *min_key, key_range *max_key); int delete_table(const char *from); int rename_table(const char * from, const char * to); - int create(const char *name, TABLE *form, HA_CREATE_INFO *create_info); + int create(const char *name, TABLE *form, + HA_CREATE_INFO *create_info); //required THR_LOCK_DATA **store_lock(THD *thd, THR_LOCK_DATA **to, - enum thr_lock_type lock_type); + enum thr_lock_type lock_type); //required }; |