mariadb/sql/handler.h

/* Copyright (C) 2000,2004 MySQL AB & MySQL Finland AB & TCX DataKonsult 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; 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA */


/* Definitions for parameters to do with handler-routines */

#ifdef USE_PRAGMA_INTERFACE
#pragma interface			/* gcc class implementation */
#endif

#include <ft_global.h>
#include <keycache.h>

#ifndef NO_HASH
#define NO_HASH				/* Not yet implemented */
#endif

#define USING_TRANSACTIONS

// the following is for checking tables

#define HA_ADMIN_ALREADY_DONE	  1
#define HA_ADMIN_OK               0
#define HA_ADMIN_NOT_IMPLEMENTED -1
#define HA_ADMIN_FAILED		 -2
#define HA_ADMIN_CORRUPT         -3
#define HA_ADMIN_INTERNAL_ERROR  -4
#define HA_ADMIN_INVALID         -5
#define HA_ADMIN_REJECT          -6
#define HA_ADMIN_TRY_ALTER       -7
#define HA_ADMIN_WRONG_CHECKSUM  -8
#define HA_ADMIN_NOT_BASE_TABLE  -9
#define HA_ADMIN_NEEDS_UPGRADE  -10
#define HA_ADMIN_NEEDS_ALTER    -11
#define HA_ADMIN_NEEDS_CHECK    -12

/* Bits in table_flags() to show what database can do */

/*
  Can switch index during the scan with ::rnd_same() - not used yet.
  see mi_rsame/heap_rsame/myrg_rsame
*/
#define HA_READ_RND_SAME       (1 << 0)
#define HA_TABLE_SCAN_ON_INDEX (1 << 2) /* No separate data/index file */
#define HA_REC_NOT_IN_SEQ      (1 << 3) /* ha_info don't return recnumber;
                                           It returns a position to ha_r_rnd */
#define HA_CAN_GEOMETRY        (1 << 4)
/*
  Reading keys in random order is as fast as reading keys in sort order
  (Used in records.cc to decide if we should use a record cache and by
  filesort to decide if we should sort key + data or key + pointer-to-row
*/
#define HA_FAST_KEY_READ       (1 << 5)
#define HA_NULL_IN_KEY         (1 << 7) /* One can have keys with NULL */
#define HA_DUPP_POS            (1 << 8) /* ha_position() gives dup row */
#define HA_NO_BLOBS            (1 << 9) /* Doesn't support blobs */
#define HA_CAN_INDEX_BLOBS     (1 << 10)
#define HA_AUTO_PART_KEY       (1 << 11) /* auto-increment in multi-part key */
#define HA_REQUIRE_PRIMARY_KEY (1 << 12) /* .. and can't create a hidden one */
#define HA_NOT_EXACT_COUNT     (1 << 13)
/*
  INSERT_DELAYED only works with handlers that uses MySQL internal table
  level locks
*/
#define HA_CAN_INSERT_DELAYED  (1 << 14)
#define HA_PRIMARY_KEY_IN_READ_INDEX (1 << 15)
/*
  If HA_PRIMARY_KEY_ALLOW_RANDOM_ACCESS is set, it means that the engine can
  do this: the position of an arbitrary record can be retrieved using
  position() when the table has a primary key, effectively allowing random
  access on the table based on a given record.
*/ 
#define HA_PRIMARY_KEY_ALLOW_RANDOM_ACCESS (1 << 16) 
#define HA_NOT_DELETE_WITH_CACHE (1 << 18)
#define HA_NO_PREFIX_CHAR_KEYS (1 << 20)
#define HA_CAN_FULLTEXT        (1 << 21)
#define HA_CAN_SQL_HANDLER     (1 << 22)
#define HA_NO_AUTO_INCREMENT   (1 << 23)
#define HA_HAS_CHECKSUM        (1 << 24)
/* Table data are stored in separate files (for lower_case_table_names) */
#define HA_FILE_BASED	       (1 << 26)
#define HA_NO_VARCHAR	       (1 << 27)
#define HA_CAN_BIT_FIELD       (1 << 28) /* supports bit fields */
#define HA_NEED_READ_RANGE_BUFFER (1 << 29) /* for read_multi_range */
#define HA_ANY_INDEX_MAY_BE_UNIQUE (1 << 30)
#define HA_NO_COPY_ON_ALTER    (1 << 31)

/* Flags for partition handlers */
#define HA_CAN_PARTITION       (1 << 0) /* Partition support */
#define HA_CAN_UPDATE_PARTITION_KEY (1 << 1)
#define HA_CAN_PARTITION_UNIQUE (1 << 2)
#define HA_USE_AUTO_PARTITION (1 << 3)


/* bits in index_flags(index_number) for what you can do with index */
#define HA_READ_NEXT            1       /* TODO really use this flag */
#define HA_READ_PREV            2       /* supports ::index_prev */
#define HA_READ_ORDER           4       /* index_next/prev follow sort order */
#define HA_READ_RANGE           8       /* can find all records in a range */
#define HA_ONLY_WHOLE_INDEX	16	/* Can't use part key searches */
#define HA_KEYREAD_ONLY         64	/* Support HA_EXTRA_KEYREAD */

/*
  bits in alter_table_flags:
*/
/*
  These bits are set if different kinds of indexes can be created
  off-line without re-create of the table (but with a table lock).
*/
#define HA_ONLINE_ADD_INDEX_NO_WRITES           (1L << 0) /*add index w/lock*/
#define HA_ONLINE_DROP_INDEX_NO_WRITES          (1L << 1) /*drop index w/lock*/
#define HA_ONLINE_ADD_UNIQUE_INDEX_NO_WRITES    (1L << 2) /*add unique w/lock*/
#define HA_ONLINE_DROP_UNIQUE_INDEX_NO_WRITES   (1L << 3) /*drop uniq. w/lock*/
#define HA_ONLINE_ADD_PK_INDEX_NO_WRITES        (1L << 4) /*add prim. w/lock*/
#define HA_ONLINE_DROP_PK_INDEX_NO_WRITES       (1L << 5) /*drop prim. w/lock*/
/*
  These are set if different kinds of indexes can be created on-line
  (without a table lock). If a handler is capable of one or more of
  these, it should also set the corresponding *_NO_WRITES bit(s).
*/
#define HA_ONLINE_ADD_INDEX                     (1L << 6) /*add index online*/
#define HA_ONLINE_DROP_INDEX                    (1L << 7) /*drop index online*/
#define HA_ONLINE_ADD_UNIQUE_INDEX              (1L << 8) /*add unique online*/
#define HA_ONLINE_DROP_UNIQUE_INDEX             (1L << 9) /*drop uniq. online*/
#define HA_ONLINE_ADD_PK_INDEX                  (1L << 10)/*add prim. online*/
#define HA_ONLINE_DROP_PK_INDEX                 (1L << 11)/*drop prim. online*/
/*
  HA_PARTITION_FUNCTION_SUPPORTED indicates that the function is
  supported at all.
  HA_FAST_CHANGE_PARTITION means that optimised variants of the changes
  exists but they are not necessarily done online.

  HA_ONLINE_DOUBLE_WRITE means that the handler supports writing to both
  the new partition and to the old partitions when updating through the
  old partitioning schema while performing a change of the partitioning.
  This means that we can support updating of the table while performing
  the copy phase of the change. For no lock at all also a double write
  from new to old must exist and this is not required when this flag is
  set.
  This is actually removed even before it was introduced the first time.
  The new idea is that handlers will handle the lock level already in
  store_lock for ALTER TABLE partitions.

  HA_PARTITION_ONE_PHASE is a flag that can be set by handlers that take
  care of changing the partitions online and in one phase. Thus all phases
  needed to handle the change are implemented inside the storage engine.
  The storage engine must also support auto-discovery since the frm file
  is changed as part of the change and this change must be controlled by
  the storage engine. A typical engine to support this is NDB (through
  WL #2498).
*/
#define HA_PARTITION_FUNCTION_SUPPORTED         (1L << 12)
#define HA_FAST_CHANGE_PARTITION                (1L << 13)
#define HA_PARTITION_ONE_PHASE                  (1L << 14)

/*
  Index scan will not return records in rowid order. Not guaranteed to be
  set for unordered (e.g. HASH) indexes.
*/
#define HA_KEY_SCAN_NOT_ROR     128 

/* operations for disable/enable indexes */
#define HA_KEY_SWITCH_NONUNIQ      0
#define HA_KEY_SWITCH_ALL          1
#define HA_KEY_SWITCH_NONUNIQ_SAVE 2
#define HA_KEY_SWITCH_ALL_SAVE     3

/*
  Note: the following includes binlog and closing 0.
  so: innodb + bdb + ndb + binlog + myisam + myisammrg + archive +
      example + csv + heap + blackhole + federated + 0
  (yes, the sum is deliberately inaccurate)
*/
#define MAX_HA 15

/*
  Parameters for open() (in register form->filestat)
  HA_GET_INFO does an implicit HA_ABORT_IF_LOCKED
*/

#define HA_OPEN_KEYFILE		1
#define HA_OPEN_RNDFILE		2
#define HA_GET_INDEX		4
#define HA_GET_INFO		8	/* do a ha_info() after open */
#define HA_READ_ONLY		16	/* File opened as readonly */
/* Try readonly if can't open with read and write */
#define HA_TRY_READ_ONLY	32
#define HA_WAIT_IF_LOCKED	64	/* Wait if locked on open */
#define HA_ABORT_IF_LOCKED	128	/* skip if locked on open.*/
#define HA_BLOCK_LOCK		256	/* unlock when reading some records */
#define HA_OPEN_TEMPORARY	512

	/* Errors on write which is recoverable  (Key exist) */
#define HA_WRITE_SKIP 121		/* Duplicate key on write */
#define HA_READ_CHECK 123		/* Update with is recoverable */
#define HA_CANT_DO_THAT 131		/* Databasehandler can't do it */

	/* Some key definitions */
#define HA_KEY_NULL_LENGTH	1
#define HA_KEY_BLOB_LENGTH	2

#define HA_LEX_CREATE_TMP_TABLE	1
#define HA_LEX_CREATE_IF_NOT_EXISTS 2
#define HA_OPTION_NO_CHECKSUM	(1L << 17)
#define HA_OPTION_NO_DELAY_KEY_WRITE (1L << 18)
#define HA_MAX_REC_LENGTH	65535

/* Table caching type */
#define HA_CACHE_TBL_NONTRANSACT 0
#define HA_CACHE_TBL_NOCACHE     1
#define HA_CACHE_TBL_ASKTRANSACT 2
#define HA_CACHE_TBL_TRANSACT    4

/* Options of START TRANSACTION statement (and later of SET TRANSACTION stmt) */
#define MYSQL_START_TRANS_OPT_WITH_CONS_SNAPSHOT 1

enum legacy_db_type
{
  DB_TYPE_UNKNOWN=0,DB_TYPE_DIAB_ISAM=1,
  DB_TYPE_HASH,DB_TYPE_MISAM,DB_TYPE_PISAM,
  DB_TYPE_RMS_ISAM, DB_TYPE_HEAP, DB_TYPE_ISAM,
  DB_TYPE_MRG_ISAM, DB_TYPE_MYISAM, DB_TYPE_MRG_MYISAM,
  DB_TYPE_BERKELEY_DB, DB_TYPE_INNODB,
  DB_TYPE_GEMINI, DB_TYPE_NDBCLUSTER,
  DB_TYPE_EXAMPLE_DB, DB_TYPE_ARCHIVE_DB, DB_TYPE_CSV_DB,
  DB_TYPE_FEDERATED_DB,
  DB_TYPE_BLACKHOLE_DB,
  DB_TYPE_PARTITION_DB,
  DB_TYPE_BINLOG,
  DB_TYPE_DEFAULT=127 // Must be last
};

enum row_type { ROW_TYPE_NOT_USED=-1, ROW_TYPE_DEFAULT, ROW_TYPE_FIXED,
		ROW_TYPE_DYNAMIC, ROW_TYPE_COMPRESSED,
		ROW_TYPE_REDUNDANT, ROW_TYPE_COMPACT };

enum enum_binlog_func {
  BFN_RESET_LOGS=        1,
  BFN_RESET_SLAVE=       2,
  BFN_BINLOG_WAIT=       3,
  BFN_BINLOG_END=        4,
  BFN_BINLOG_PURGE_FILE= 5
};

enum enum_binlog_command {
  LOGCOM_CREATE_TABLE,
  LOGCOM_ALTER_TABLE,
  LOGCOM_RENAME_TABLE,
  LOGCOM_DROP_TABLE,
  LOGCOM_CREATE_DB,
  LOGCOM_ALTER_DB,
  LOGCOM_DROP_DB
};

/* struct to hold information about the table that should be created */

/* Bits in used_fields */
#define HA_CREATE_USED_AUTO             (1L << 0)
#define HA_CREATE_USED_RAID             (1L << 1) //RAID is no longer availble
#define HA_CREATE_USED_UNION            (1L << 2)
#define HA_CREATE_USED_INSERT_METHOD    (1L << 3)
#define HA_CREATE_USED_MIN_ROWS         (1L << 4)
#define HA_CREATE_USED_MAX_ROWS         (1L << 5)
#define HA_CREATE_USED_AVG_ROW_LENGTH   (1L << 6)
#define HA_CREATE_USED_PACK_KEYS        (1L << 7)
#define HA_CREATE_USED_CHARSET          (1L << 8)
#define HA_CREATE_USED_DEFAULT_CHARSET  (1L << 9)
#define HA_CREATE_USED_DATADIR          (1L << 10)
#define HA_CREATE_USED_INDEXDIR         (1L << 11)
#define HA_CREATE_USED_ENGINE           (1L << 12)
#define HA_CREATE_USED_CHECKSUM         (1L << 13)
#define HA_CREATE_USED_DELAY_KEY_WRITE  (1L << 14)
#define HA_CREATE_USED_ROW_FORMAT       (1L << 15)
#define HA_CREATE_USED_COMMENT          (1L << 16)
#define HA_CREATE_USED_PASSWORD         (1L << 17)
#define HA_CREATE_USED_CONNECTION       (1L << 18)

typedef ulonglong my_xid; // this line is the same as in log_event.h
#define MYSQL_XID_PREFIX "MySQLXid"
#define MYSQL_XID_PREFIX_LEN 8 // must be a multiple of 8
#define MYSQL_XID_OFFSET (MYSQL_XID_PREFIX_LEN+sizeof(server_id))
#define MYSQL_XID_GTRID_LEN (MYSQL_XID_OFFSET+sizeof(my_xid))

#define XIDDATASIZE 128
#define MAXGTRIDSIZE 64
#define MAXBQUALSIZE 64

#define COMPATIBLE_DATA_YES 0
#define COMPATIBLE_DATA_NO  1

struct xid_t {
  long formatID;
  long gtrid_length;
  long bqual_length;
  char data[XIDDATASIZE];  // not \0-terminated !

  bool eq(struct xid_t *xid)
  { return eq(xid->gtrid_length, xid->bqual_length, xid->data); }
  bool eq(long g, long b, const char *d)
  { return g == gtrid_length && b == bqual_length && !memcmp(d, data, g+b); }
  void set(struct xid_t *xid)
  { memcpy(this, xid, xid->length()); }
  void set(long f, const char *g, long gl, const char *b, long bl)
  {
    formatID= f;
    memcpy(data, g, gtrid_length= gl);
    memcpy(data+gl, b, bqual_length= bl);
  }
  void set(ulonglong xid)
  {
    my_xid tmp;
    formatID= 1;
    set(MYSQL_XID_PREFIX_LEN, 0, MYSQL_XID_PREFIX);
    memcpy(data+MYSQL_XID_PREFIX_LEN, &server_id, sizeof(server_id));
    tmp= xid;
    memcpy(data+MYSQL_XID_OFFSET, &tmp, sizeof(tmp));
    gtrid_length=MYSQL_XID_GTRID_LEN;
  }
  void set(long g, long b, const char *d)
  {
    formatID= 1;
    gtrid_length= g;
    bqual_length= b;
    memcpy(data, d, g+b);
  }
  bool is_null() { return formatID == -1; }
  void null() { formatID= -1; }
  my_xid quick_get_my_xid()
  {
    my_xid tmp;
    memcpy(&tmp, data+MYSQL_XID_OFFSET, sizeof(tmp));
    return tmp;
  }
  my_xid get_my_xid()
  {
    return gtrid_length == MYSQL_XID_GTRID_LEN && bqual_length == 0 &&
           !memcmp(data+MYSQL_XID_PREFIX_LEN, &server_id, sizeof(server_id)) &&
           !memcmp(data, MYSQL_XID_PREFIX, MYSQL_XID_PREFIX_LEN) ?
           quick_get_my_xid() : 0;
  }
  uint length()
  {
    return sizeof(formatID)+sizeof(gtrid_length)+sizeof(bqual_length)+
           gtrid_length+bqual_length;
  }
  byte *key()
  {
    return (byte *)&gtrid_length;
  }
  uint key_length()
  {
    return sizeof(gtrid_length)+sizeof(bqual_length)+gtrid_length+bqual_length;
  }
};
typedef struct xid_t XID;

/* for recover() handlerton call */
#define MIN_XID_LIST_SIZE  128
#ifdef SAFEMALLOC
#define MAX_XID_LIST_SIZE  256
#else
#define MAX_XID_LIST_SIZE  (1024*128)
#endif

/*
  These structures are used to pass information from a set of SQL commands
  on add/drop/change tablespace definitions to the proper hton.
*/
#define UNDEF_NODEGROUP 65535
enum ts_command_type
{
  TS_CMD_NOT_DEFINED = -1,
  CREATE_TABLESPACE = 0,
  ALTER_TABLESPACE = 1,
  CREATE_LOGFILE_GROUP = 2,
  ALTER_LOGFILE_GROUP = 3,
  DROP_TABLESPACE = 4,
  DROP_LOGFILE_GROUP = 5,
  CHANGE_FILE_TABLESPACE = 6,
  ALTER_ACCESS_MODE_TABLESPACE = 7
};

enum ts_alter_tablespace_type
{
  TS_ALTER_TABLESPACE_TYPE_NOT_DEFINED = -1,
  ALTER_TABLESPACE_ADD_FILE = 1,
  ALTER_TABLESPACE_DROP_FILE = 2
};

enum tablespace_access_mode
{
  TS_NOT_DEFINED= -1,
  TS_READ_ONLY = 0,
  TS_READ_WRITE = 1,
  TS_NOT_ACCESSIBLE = 2
};

class st_alter_tablespace : public Sql_alloc
{
  public:
  const char *tablespace_name;
  const char *logfile_group_name;
  enum ts_command_type ts_cmd_type;
  enum ts_alter_tablespace_type ts_alter_tablespace_type;
  const char *data_file_name;
  const char *undo_file_name;
  const char *redo_file_name;
  ulonglong extent_size;
  ulonglong undo_buffer_size;
  ulonglong redo_buffer_size;
  ulonglong initial_size;
  ulonglong autoextend_size;
  ulonglong max_size;
  uint nodegroup_id;
  enum legacy_db_type storage_engine;
  bool wait_until_completed;
  const char *ts_comment;
  enum tablespace_access_mode ts_access_mode;
  st_alter_tablespace()
  {
    tablespace_name= NULL;
    logfile_group_name= "DEFAULT_LG"; //Default log file group
    ts_cmd_type= TS_CMD_NOT_DEFINED;
    data_file_name= NULL;
    undo_file_name= NULL;
    redo_file_name= NULL;
    extent_size= 1024*1024;        //Default 1 MByte
    undo_buffer_size= 8*1024*1024; //Default 8 MByte
    redo_buffer_size= 8*1024*1024; //Default 8 MByte
    initial_size= 128*1024*1024;   //Default 128 MByte
    autoextend_size= 0;            //No autoextension as default
    max_size= 0;                   //Max size == initial size => no extension
    storage_engine= DB_TYPE_UNKNOWN;
    nodegroup_id= UNDEF_NODEGROUP;
    wait_until_completed= TRUE;
    ts_comment= NULL;
    ts_access_mode= TS_NOT_DEFINED;
  }
};

/* The handler for a table type.  Will be included in the TABLE structure */

struct st_table;
typedef struct st_table TABLE;
typedef struct st_table_share TABLE_SHARE;
struct st_foreign_key_info;
typedef struct st_foreign_key_info FOREIGN_KEY_INFO;
typedef bool (stat_print_fn)(THD *thd, const char *type, uint type_len,
                             const char *file, uint file_len,
                             const char *status, uint status_len);
enum ha_stat_type { HA_ENGINE_STATUS, HA_ENGINE_LOGS, HA_ENGINE_MUTEX };

/*
  handlerton is a singleton structure - one instance per storage engine -
  to provide access to storage engine functionality that works on the
  "global" level (unlike handler class that works on a per-table basis)

  usually handlerton instance is defined statically in ha_xxx.cc as

  static handlerton { ... } xxx_hton;

  savepoint_*, prepare, recover, and *_by_xid pointers can be 0.
*/
typedef struct
{
  /*
    handlerton structure version
   */
  const int interface_version;
/* last version change: 0x0001 in 5.1.6 */
#define MYSQL_HANDLERTON_INTERFACE_VERSION 0x0001


  /*
    storage engine name as it should be printed to a user
  */
  const char *name;

  /*
    Historical marker for if the engine is available of not 
  */
  SHOW_COMP_OPTION state;

  /*
    A comment used by SHOW to describe an engine.
  */
  const char *comment;

  /*
    Historical number used for frm file to determine the correct storage engine.
    This is going away and new engines will just use "name" for this.
  */
  enum legacy_db_type db_type;
  /* 
    Method that initizlizes a storage engine
  */
  bool (*init)();

  /*
    each storage engine has it's own memory area (actually a pointer)
    in the thd, for storing per-connection information.
    It is accessed as

      thd->ha_data[xxx_hton.slot]

   slot number is initialized by MySQL after xxx_init() is called.
   */
   uint slot;
   /*
     to store per-savepoint data storage engine is provided with an area
     of a requested size (0 is ok here).
     savepoint_offset must be initialized statically to the size of
     the needed memory to store per-savepoint information.
     After xxx_init it is changed to be an offset to savepoint storage
     area and need not be used by storage engine.
     see binlog_hton and binlog_savepoint_set/rollback for an example.
   */
   uint savepoint_offset;
   /*
     handlerton methods:

     close_connection is only called if
     thd->ha_data[xxx_hton.slot] is non-zero, so even if you don't need
     this storage area - set it to something, so that MySQL would know
     this storage engine was accessed in this connection
   */
   int  (*close_connection)(THD *thd);
   /*
     sv points to an uninitialized storage area of requested size
     (see savepoint_offset description)
   */
   int  (*savepoint_set)(THD *thd, void *sv);
   /*
     sv points to a storage area, that was earlier passed
     to the savepoint_set call
   */
   int  (*savepoint_rollback)(THD *thd, void *sv);
   int  (*savepoint_release)(THD *thd, void *sv);
   /*
     'all' is true if it's a real commit, that makes persistent changes
     'all' is false if it's not in fact a commit but an end of the
     statement that is part of the transaction.
     NOTE 'all' is also false in auto-commit mode where 'end of statement'
     and 'real commit' mean the same event.
   */
   int  (*commit)(THD *thd, bool all);
   int  (*rollback)(THD *thd, bool all);
   int  (*prepare)(THD *thd, bool all);
   int  (*recover)(XID *xid_list, uint len);
   int  (*commit_by_xid)(XID *xid);
   int  (*rollback_by_xid)(XID *xid);
   void *(*create_cursor_read_view)();
   void (*set_cursor_read_view)(void *);
   void (*close_cursor_read_view)(void *);
   handler *(*create)(TABLE_SHARE *table);
   void (*drop_database)(char* path);
   int (*panic)(enum ha_panic_function flag);
   int (*start_consistent_snapshot)(THD *thd);
   bool (*flush_logs)();
   bool (*show_status)(THD *thd, stat_print_fn *print, enum ha_stat_type stat);
   uint (*partition_flags)();
   uint (*alter_table_flags)(uint flags);
   int (*alter_tablespace)(THD *thd, st_alter_tablespace *ts_info);
   int (*fill_files_table)(THD *thd,
                           struct st_table_list *tables,
                           class Item *cond);
   uint32 flags;                                /* global handler flags */
   /* 
      Handlerton functions are not set in the different storage
      engines static initialization.  They are initialized at handler init.
      Thus, leave them last in the struct.
   */
   int (*binlog_func)(THD *thd, enum_binlog_func fn, void *arg);
   void (*binlog_log_query)(THD *thd, enum_binlog_command binlog_command,
                            const char *query, uint query_length,
                            const char *db, const char *table_name);
} handlerton;

extern const handlerton default_hton;

struct show_table_alias_st {
  const char *alias;
  enum legacy_db_type type;
};

/* Possible flags of a handlerton */
#define HTON_NO_FLAGS                 0
#define HTON_CLOSE_CURSORS_AT_COMMIT (1 << 0)
#define HTON_ALTER_NOT_SUPPORTED     (1 << 1) //Engine does not support alter
#define HTON_CAN_RECREATE            (1 << 2) //Delete all is used fro truncate
#define HTON_HIDDEN                  (1 << 3) //Engine does not appear in lists
#define HTON_FLUSH_AFTER_RENAME      (1 << 4)
#define HTON_NOT_USER_SELECTABLE     (1 << 5)

typedef struct st_thd_trans
{
  /* number of entries in the ht[] */
  uint        nht;
  /* true is not all entries in the ht[] support 2pc */
  bool        no_2pc;
  /* storage engines that registered themselves for this transaction */
  handlerton *ht[MAX_HA];
} THD_TRANS;

enum enum_tx_isolation { ISO_READ_UNCOMMITTED, ISO_READ_COMMITTED,
			 ISO_REPEATABLE_READ, ISO_SERIALIZABLE};


enum ndb_distribution { ND_KEYHASH= 0, ND_LINHASH= 1 };

typedef struct {
  uint32 start_part;
  uint32 end_part;
} part_id_range;


/**
 * An enum and a struct to handle partitioning and subpartitioning.
 */
enum partition_type {
  NOT_A_PARTITION= 0,
  RANGE_PARTITION,
  HASH_PARTITION,
  LIST_PARTITION
};

enum partition_state {
  PART_NORMAL= 0,
  PART_IS_DROPPED= 1,
  PART_TO_BE_DROPPED= 2,
  PART_TO_BE_ADDED= 3,
  PART_TO_BE_REORGED= 4,
  PART_REORGED_DROPPED= 5,
  PART_CHANGED= 6,
  PART_IS_CHANGED= 7,
  PART_IS_ADDED= 8
};

typedef struct {
  ulonglong data_file_length;
  ulonglong max_data_file_length;
  ulonglong index_file_length;
  ulonglong delete_length;
  ha_rows records;
  ulong mean_rec_length;
  time_t create_time;
  time_t check_time;
  time_t update_time;
  ulonglong check_sum;
} PARTITION_INFO;

#define UNDEF_NODEGROUP 65535
class Item;

class partition_element :public Sql_alloc {
public:
  List<partition_element> subpartitions;
  List<longlong> list_val_list;
  ulonglong part_max_rows;
  ulonglong part_min_rows;
  char *partition_name;
  char *tablespace_name;
  longlong range_value;
  char* part_comment;
  char* data_file_name;
  char* index_file_name;
  handlerton *engine_type;
  enum partition_state part_state;
  uint16 nodegroup_id;
  
  partition_element()
  : part_max_rows(0), part_min_rows(0), partition_name(NULL),
    tablespace_name(NULL), range_value(0), part_comment(NULL),
    data_file_name(NULL), index_file_name(NULL),
    engine_type(NULL),part_state(PART_NORMAL),
    nodegroup_id(UNDEF_NODEGROUP)
  {
    subpartitions.empty();
    list_val_list.empty();
  }
  ~partition_element() {}
};

typedef struct {
  longlong list_value;
  uint32 partition_id;
} LIST_PART_ENTRY;

class partition_info;

typedef int (*get_part_id_func)(partition_info *part_info,
                                 uint32 *part_id,
                                 longlong *func_value);
typedef uint32 (*get_subpart_id_func)(partition_info *part_info);


struct st_partition_iter;
#define NOT_A_PARTITION_ID ((uint32)-1)

/*
  A "Get next" function for partition iterator.
  SYNOPSIS
    partition_iter_func()
      part_iter  Partition iterator, you call only "iter.get_next(&iter)"

  RETURN 
    NOT_A_PARTITION_ID if there are no more partitions.
    [sub]partition_id  of the next partition
*/

typedef uint32 (*partition_iter_func)(st_partition_iter* part_iter);


/*
  Partition set iterator. Used to enumerate a set of [sub]partitions
  obtained in partition interval analysis (see get_partitions_in_range_iter).

  For the user, the only meaningful field is get_next, which may be used as
  follows:
             part_iterator.get_next(&part_iterator);
  
  Initialization is done by any of the following calls:
    - get_partitions_in_range_iter-type function call
    - init_single_partition_iterator()
    - init_all_partitions_iterator()
  Cleanup is not needed.
*/

typedef struct st_partition_iter
{
  partition_iter_func get_next;
  
  struct st_part_num_range
  {
    uint32 start;
    uint32 end;
  };

  struct st_field_value_range
  {
    longlong start;
    longlong end;
  };

  union
  {
    struct st_part_num_range     part_nums;
    struct st_field_value_range  field_vals;
  };
  partition_info *part_info;
} PARTITION_ITERATOR;


/*
  Get an iterator for set of partitions that match given field-space interval

  SYNOPSIS
    get_partitions_in_range_iter()
      part_info   Partitioning info
      is_subpart  
      min_val     Left edge,  field value in opt_range_key format.
      max_val     Right edge, field value in opt_range_key format. 
      flags       Some combination of NEAR_MIN, NEAR_MAX, NO_MIN_RANGE,
                  NO_MAX_RANGE.
      part_iter   Iterator structure to be initialized

  DESCRIPTION
    Functions with this signature are used to perform "Partitioning Interval
    Analysis". This analysis is applicable for any type of [sub]partitioning 
    by some function of a single fieldX. The idea is as follows:
    Given an interval "const1 <=? fieldX <=? const2", find a set of partitions
    that may contain records with value of fieldX within the given interval.

    The min_val, max_val and flags parameters specify the interval.
    The set of partitions is returned by initializing an iterator in *part_iter

  NOTES
    There are currently two functions of this type:
     - get_part_iter_for_interval_via_walking
     - get_part_iter_for_interval_via_mapping

  RETURN 
    0 - No matching partitions, iterator not initialized
    1 - Some partitions would match, iterator intialized for traversing them
   -1 - All partitions would match, iterator not initialized
*/

typedef int (*get_partitions_in_range_iter)(partition_info *part_info,
                                            bool is_subpart,
                                            char *min_val, char *max_val,
                                            uint flags,
                                            PARTITION_ITERATOR *part_iter);


class partition_info : public Sql_alloc
{
public:
  /*
   * Here comes a set of definitions needed for partitioned table handlers.
   */
  List<partition_element> partitions;
  List<partition_element> temp_partitions;

  List<char> part_field_list;
  List<char> subpart_field_list;
  
  /* 
    If there is no subpartitioning, use only this func to get partition ids.
    If there is subpartitioning, use the this func to get partition id when
    you have both partition and subpartition fields.
  */
  get_part_id_func get_partition_id;

  /* Get partition id when we don't have subpartition fields */
  get_part_id_func get_part_partition_id;

  /* 
    Get subpartition id when we have don't have partition fields by we do
    have subpartition ids.
    Mikael said that for given constant tuple 
    {subpart_field1, ..., subpart_fieldN} the subpartition id will be the
    same in all subpartitions
  */
  get_subpart_id_func get_subpartition_id;
 
  /* NULL-terminated array of fields used in partitioned expression */
  Field **part_field_array;
  /* NULL-terminated array of fields used in subpartitioned expression */
  Field **subpart_field_array;

  /* 
    Array of all fields used in partition and subpartition expression,
    without duplicates, NULL-terminated.
  */
  Field **full_part_field_array;

  Item *part_expr;
  Item *subpart_expr;

  Item *item_free_list;
  
  /* 
    A bitmap of partitions used by the current query. 
    Usage pattern:
    * The handler->extra(HA_EXTRA_RESET) call at query start/end sets all
      partitions to be unused.
    * Before index/rnd_init(), partition pruning code sets the bits for used
      partitions.
  */
  MY_BITMAP used_partitions;

  union {
    longlong *range_int_array;
    LIST_PART_ENTRY *list_array;
  };
  
  /********************************************
   * INTERVAL ANALYSIS
   ********************************************/
  /*
    Partitioning interval analysis function for partitioning, or NULL if 
    interval analysis is not supported for this kind of partitioning.
  */
  get_partitions_in_range_iter get_part_iter_for_interval;
  /*
    Partitioning interval analysis function for subpartitioning, or NULL if
    interval analysis is not supported for this kind of partitioning.
  */
  get_partitions_in_range_iter get_subpart_iter_for_interval;
  
  /*
    Valid iff
    get_part_iter_for_interval=get_part_iter_for_interval_via_walking:
      controls how we'll process "field < C" and "field > C" intervals.
      If the partitioning function F is strictly increasing, then for any x, y
      "x < y" => "F(x) < F(y)" (*), i.e. when we get interval "field < C" 
      we can perform partition pruning on the equivalent "F(field) < F(C)".

      If the partitioning function not strictly increasing (it is simply
      increasing), then instead of (*) we get "x < y" => "F(x) <= F(y)"
      i.e. for interval "field < C" we can perform partition pruning for
      "F(field) <= F(C)".
  */
  bool range_analysis_include_bounds;
  /********************************************
   * INTERVAL ANALYSIS ENDS 
   ********************************************/
  
  char* part_info_string;

  char *part_func_string;
  char *subpart_func_string;

  uchar *part_state;

  partition_element *curr_part_elem;
  partition_element *current_partition;
  /*
    These key_map's are used for Partitioning to enable quick decisions
    on whether we can derive more information about which partition to
    scan just by looking at what index is used.
  */
  key_map all_fields_in_PF, all_fields_in_PPF, all_fields_in_SPF;
  key_map some_fields_in_PF;

  handlerton *default_engine_type;
  Item_result part_result_type;
  partition_type part_type;
  partition_type subpart_type;

  uint part_info_len;
  uint part_state_len;
  uint part_func_len;
  uint subpart_func_len;

  uint no_parts;
  uint no_subparts;
  uint count_curr_subparts;

  uint part_error_code;

  uint no_list_values;

  uint no_part_fields;
  uint no_subpart_fields;
  uint no_full_part_fields;

  /*
    This variable is used to calculate the partition id when using
    LINEAR KEY/HASH. This functionality is kept in the MySQL Server
    but mainly of use to handlers supporting partitioning.
  */
  uint16 linear_hash_mask;

  bool use_default_partitions;
  bool use_default_no_partitions;
  bool use_default_subpartitions;
  bool use_default_no_subpartitions;
  bool default_partitions_setup;
  bool defined_max_value;
  bool list_of_part_fields;
  bool list_of_subpart_fields;
  bool linear_hash_ind;
  bool fixed;
  bool from_openfrm;

  partition_info()
  : get_partition_id(NULL), get_part_partition_id(NULL),
    get_subpartition_id(NULL),
    part_field_array(NULL), subpart_field_array(NULL),
    full_part_field_array(NULL),
    part_expr(NULL), subpart_expr(NULL), item_free_list(NULL),
    list_array(NULL),
    part_info_string(NULL),
    part_func_string(NULL), subpart_func_string(NULL),
    part_state(NULL),
    curr_part_elem(NULL), current_partition(NULL),
    default_engine_type(NULL),
    part_result_type(INT_RESULT),
    part_type(NOT_A_PARTITION), subpart_type(NOT_A_PARTITION),
    part_info_len(0), part_state_len(0),
    part_func_len(0), subpart_func_len(0),
    no_parts(0), no_subparts(0),
    count_curr_subparts(0), part_error_code(0),
    no_list_values(0), no_part_fields(0), no_subpart_fields(0),
    no_full_part_fields(0), linear_hash_mask(0),
    use_default_partitions(TRUE),
    use_default_no_partitions(TRUE),
    use_default_subpartitions(TRUE),
    use_default_no_subpartitions(TRUE),
    default_partitions_setup(FALSE),
    defined_max_value(FALSE),
    list_of_part_fields(FALSE), list_of_subpart_fields(FALSE),
    linear_hash_ind(FALSE),
    fixed(FALSE),
    from_openfrm(FALSE)
  {
    all_fields_in_PF.clear_all();
    all_fields_in_PPF.clear_all();
    all_fields_in_SPF.clear_all();
    some_fields_in_PF.clear_all();
    partitions.empty();
    temp_partitions.empty();
    part_field_list.empty();
    subpart_field_list.empty();
  }
  ~partition_info() {}
};


#ifdef WITH_PARTITION_STORAGE_ENGINE
uint32 get_next_partition_id_range(struct st_partition_iter* part_iter);

/* Initialize the iterator to return a single partition with given part_id */

static inline void init_single_partition_iterator(uint32 part_id,
                                           PARTITION_ITERATOR *part_iter)
{
  part_iter->part_nums.start= part_id;
  part_iter->part_nums.end= part_id+1;
  part_iter->get_next= get_next_partition_id_range;
}

/* Initialize the iterator to enumerate all partitions */
static inline
void init_all_partitions_iterator(partition_info *part_info,
                                  PARTITION_ITERATOR *part_iter)
{
  part_iter->part_nums.start= 0;
  part_iter->part_nums.end= part_info->no_parts;
  part_iter->get_next= get_next_partition_id_range;
}

/*
  Answers the question if subpartitioning is used for a certain table
  SYNOPSIS
    is_sub_partitioned()
    part_info          A reference to the partition_info struct
  RETURN VALUE
    Returns true if subpartitioning used and false otherwise
  DESCRIPTION
    A routine to check for subpartitioning for improved readability of code
*/
static inline
bool is_sub_partitioned(partition_info *part_info)
{ return (part_info->subpart_type == NOT_A_PARTITION ?  FALSE : TRUE); }


/*
  Returns the total number of partitions on the leaf level.
  SYNOPSIS
    get_tot_partitions()
    part_info          A reference to the partition_info struct
  RETURN VALUE
    Returns the number of partitions
  DESCRIPTION
    A routine to check for number of partitions for improved readability
    of code
*/
static inline
uint get_tot_partitions(partition_info *part_info)
{
  return part_info->no_parts *
         (is_sub_partitioned(part_info) ? part_info->no_subparts : 1);
}


#endif

typedef struct st_ha_create_information
{
  CHARSET_INFO *table_charset, *default_table_charset;
  LEX_STRING connect_string;
  const char *comment,*password, *tablespace;
  const char *data_file_name, *index_file_name;
  const char *alias;
  ulonglong max_rows,min_rows;
  ulonglong auto_increment_value;
  ulong table_options;
  ulong avg_row_length;
  ulong used_fields;
  SQL_LIST merge_list;
  handlerton *db_type;
  enum row_type row_type;
  uint null_bits;                       /* NULL bits at start of record */
  uint options;				/* OR of HA_CREATE_ options */
  uint merge_insert_method;
  uint extra_size;                      /* length of extra data segment */
  bool table_existed;			/* 1 in create if table existed */
  bool frm_only;                        /* 1 if no ha_create_table() */
  bool varchar;                         /* 1 if table has a VARCHAR */
  bool store_on_disk;                   /* 1 if table stored on disk */
} HA_CREATE_INFO;



typedef struct st_savepoint SAVEPOINT;
extern ulong savepoint_alloc_size;

/* Forward declaration for condition pushdown to storage engine */
typedef class Item COND;

typedef struct st_ha_check_opt
{
  ulong sort_buffer_size;
  uint flags;       /* isam layer flags (e.g. for myisamchk) */
  uint sql_flags;   /* sql layer flags - for something myisamchk cannot do */
  KEY_CACHE *key_cache;	/* new key cache when changing key cache */
  void init();
} HA_CHECK_OPT;


#ifdef WITH_PARTITION_STORAGE_ENGINE
bool is_partition_in_list(char *part_name, List<char> list_part_names);
char *are_partitions_in_table(partition_info *new_part_info,
                              partition_info *old_part_info);
bool check_reorganise_list(partition_info *new_part_info,
                           partition_info *old_part_info,
                           List<char> list_part_names);
bool set_up_defaults_for_partitioning(partition_info *part_info,
                                      handler *file,
                                      ulonglong max_rows,
                                      uint start_no);
handler *get_ha_partition(partition_info *part_info);
int get_parts_for_update(const byte *old_data, byte *new_data,
                         const byte *rec0, partition_info *part_info,
                         uint32 *old_part_id, uint32 *new_part_id,
                         longlong *func_value);
int get_part_for_delete(const byte *buf, const byte *rec0,
                        partition_info *part_info, uint32 *part_id);
bool check_partition_info(partition_info *part_info,handlerton **eng_type,
                          handler *file, ulonglong max_rows);
bool fix_partition_func(THD *thd, const char *name, TABLE *table,
                        bool create_table_ind);
char *generate_partition_syntax(partition_info *part_info,
                                uint *buf_length, bool use_sql_alloc,
                                bool write_all);
bool partition_key_modified(TABLE *table, List<Item> &fields);
void prune_partition_set(const TABLE *table, part_id_range *part_spec);
void get_partition_set(const TABLE *table, byte *buf, const uint index,
                       const key_range *key_spec,
                       part_id_range *part_spec);
void get_full_part_id_from_key(const TABLE *table, byte *buf,
                               KEY *key_info,
                               const key_range *key_spec,
                               part_id_range *part_spec);
bool mysql_unpack_partition(THD *thd, const uchar *part_buf,
                            uint part_info_len,
                            uchar *part_state, uint part_state_len,
                            TABLE *table, bool is_create_table_ind,
                            handlerton *default_db_type);
void make_used_partitions_str(partition_info *part_info, String *parts_str);
uint32 get_list_array_idx_for_endpoint(partition_info *part_info,
                                       bool left_endpoint,
                                       bool include_endpoint);
uint32 get_partition_id_range_for_endpoint(partition_info *part_info,
                                           bool left_endpoint,
                                           bool include_endpoint);
#endif


/*
  This is a buffer area that the handler can use to store rows.
  'end_of_used_area' should be kept updated after calls to
  read-functions so that other parts of the code can use the
  remaining area (until next read calls is issued).
*/

typedef struct st_handler_buffer
{
  const byte *buffer;         /* Buffer one can start using */
  const byte *buffer_end;     /* End of buffer */
  byte *end_of_used_area;     /* End of area that was used by handler */
} HANDLER_BUFFER;

typedef struct system_status_var SSV;

class handler :public Sql_alloc
{
#ifdef WITH_PARTITION_STORAGE_ENGINE
 friend class ha_partition;
#endif
 protected:
  struct st_table_share *table_share;   /* The table definition */
  struct st_table *table;               /* The current open table */

  virtual int index_init(uint idx, bool sorted) { active_index=idx; return 0; }
  virtual int index_end() { active_index=MAX_KEY; return 0; }
  /*
    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
  */
  virtual int rnd_init(bool scan) =0;
  virtual int rnd_end() { return 0; }

  void ha_statistic_increment(ulong SSV::*offset) const;


private:
  virtual int reset() { return extra(HA_EXTRA_RESET); }
public:
  const handlerton *ht;                 /* storage engine of this handler */
  byte *ref;				/* Pointer to current row */
  byte *dupp_ref;			/* Pointer to dupp row */
  ulonglong data_file_length;		/* Length off data file */
  ulonglong max_data_file_length;	/* Length off data file */
  ulonglong index_file_length;
  ulonglong max_index_file_length;
  ulonglong delete_length;		/* Free bytes */
  ulonglong auto_increment_value;
  ha_rows records;			/* Records in table */
  ha_rows deleted;			/* Deleted records */
  ulong mean_rec_length;		/* physical reclength */
  time_t create_time;			/* When table was created */
  time_t check_time;
  time_t update_time;

  /* The following are for read_multi_range */
  bool multi_range_sorted;
  KEY_MULTI_RANGE *multi_range_curr;
  KEY_MULTI_RANGE *multi_range_end;
  HANDLER_BUFFER *multi_range_buffer;

  /* The following are for read_range() */
  key_range save_end_range, *end_range;
  KEY_PART_INFO *range_key_part;
  int key_compare_result_on_equal;
  bool eq_range;

  uint errkey;				/* Last dup key */
  uint sortkey, key_used_on_scan;
  uint active_index;
  /* Length of ref (1-8 or the clustered key length) */
  uint ref_length;
  uint block_size;			/* index block size */
  FT_INFO *ft_handler;
  enum {NONE=0, INDEX, RND} inited;
  bool  auto_increment_column_changed;
  bool implicit_emptied;                /* Can be !=0 only if HEAP */
  const COND *pushed_cond;
  MY_BITMAP *read_set;
  MY_BITMAP *write_set;

  handler(const handlerton *ht_arg, TABLE_SHARE *share_arg)
    :table_share(share_arg), ht(ht_arg),
    ref(0), data_file_length(0), max_data_file_length(0), index_file_length(0),
    delete_length(0), auto_increment_value(0),
    records(0), deleted(0), mean_rec_length(0),
    create_time(0), check_time(0), update_time(0),
    key_used_on_scan(MAX_KEY), active_index(MAX_KEY),
    ref_length(sizeof(my_off_t)), block_size(0),
    ft_handler(0), inited(NONE), implicit_emptied(0),
    pushed_cond(NULL)
    {}
  virtual ~handler(void)
  {
    /* TODO: DBUG_ASSERT(inited == NONE); */
  }
  /*
    Check whether a handler allows to lock the table.

    SYNOPSIS
      check_if_locking_is_allowed()
        thd     Handler of the thread, trying to lock the table
        table   Table handler to check
        count   Number of locks already granted to the table

    DESCRIPTION
      Check whether a handler allows to lock the table. For instance,
      MyISAM does not allow to lock mysql.proc along with other tables.
      This limitation stems from the fact that MyISAM does not support
      row-level locking and we have to add this limitation to avoid
      deadlocks.

    RETURN
      TRUE      Locking is allowed
      FALSE     Locking is not allowed. The error was thrown.
  */
  virtual bool check_if_locking_is_allowed(uint sql_command,
                                           ulong type, TABLE *table,
                                           uint count,
                                           bool called_by_logger_thread)
  {
    return TRUE;
  }
  virtual int ha_initialise();
  int ha_open(TABLE *table, const char *name, int mode, int test_if_locked);
  bool update_auto_increment();
  virtual void print_error(int error, myf errflag);
  virtual bool get_error_message(int error, String *buf);
  uint get_dup_key(int error);
  void change_table_ptr(TABLE *table_arg, TABLE_SHARE *share)
  {
    table= table_arg;
    table_share= share;
  }
  virtual double scan_time()
    { return ulonglong2double(data_file_length) / IO_SIZE + 2; }
  virtual double read_time(uint index, uint ranges, ha_rows rows)
 { return rows2double(ranges+rows); }
  virtual const key_map *keys_to_use_for_scanning() { return &key_map_empty; }
  virtual bool has_transactions(){ return 0;}
  virtual uint extra_rec_buf_length() const { return 0; }
  
  /*
    Return upper bound of current number of records in the table
    (max. of how many records one will retrieve when doing a full table scan)
    If upper bound is not known, HA_POS_ERROR should be returned as a max
    possible upper bound.
  */
  virtual ha_rows estimate_rows_upper_bound()
  { return records+EXTRA_RECORDS; }

  /*
    Get the row type from the storage engine.  If this method returns
    ROW_TYPE_NOT_USED, the information in HA_CREATE_INFO should be used.
  */
  virtual enum row_type get_row_type() const { return ROW_TYPE_NOT_USED; }

  virtual const char *index_type(uint key_number) { DBUG_ASSERT(0); return "";}

  int ha_index_init(uint idx, bool sorted)
  {
    DBUG_ENTER("ha_index_init");
    DBUG_ASSERT(inited==NONE);
    inited=INDEX;
    DBUG_RETURN(index_init(idx, sorted));
  }
  int ha_index_end()
  {
    DBUG_ENTER("ha_index_end");
    DBUG_ASSERT(inited==INDEX);
    inited=NONE;
    DBUG_RETURN(index_end());
  }
  int ha_rnd_init(bool scan)
  {
    DBUG_ENTER("ha_rnd_init");
    DBUG_ASSERT(inited==NONE || (inited==RND && scan));
    inited=RND;
    DBUG_RETURN(rnd_init(scan));
  }
  int ha_rnd_end()
  {
    DBUG_ENTER("ha_rnd_end");
    DBUG_ASSERT(inited==RND);
    inited=NONE;
    DBUG_RETURN(rnd_end());
  }
  int ha_reset()
  {
    DBUG_ENTER("ha_reset");
    ha_clear_all_set();
    DBUG_RETURN(reset());
  }
    
  /* this is necessary in many places, e.g. in HANDLER command */
  int ha_index_or_rnd_end()
  {
    return inited == INDEX ? ha_index_end() : inited == RND ? ha_rnd_end() : 0;
  }
  /*
    These are a set of routines used to enable handlers to only read/write
    partial lists of the fields in the table. The bit vector is maintained
    by the server part and is used by the handler at calls to read/write
    data in the table.
    It replaces the use of query id's for this purpose. The benefit is that
    the handler can also set bits in the read/write set if it has special
    needs and it is also easy for other parts of the server to interact
    with the handler (e.g. the replication part for row-level logging).
    The routines are all part of the general handler and are not possible
    to override by a handler. A handler can however set/reset bits by
    calling these routines.

    The methods ha_retrieve_all_cols and ha_retrieve_all_pk are made
    virtual to handle InnoDB specifics. If InnoDB doesn't need the
    extra parameters HA_EXTRA_RETRIEVE_ALL_COLS and
    HA_EXTRA_RETRIEVE_PRIMARY_KEY anymore then these methods need not be
    virtual anymore.
  */
  virtual int ha_retrieve_all_cols();
  virtual int ha_retrieve_all_pk();
  void ha_set_all_bits_in_read_set()
  {
    DBUG_ENTER("ha_set_all_bits_in_read_set");
    bitmap_set_all(read_set);
    DBUG_VOID_RETURN;
  }
  void ha_set_all_bits_in_write_set()
  {
    DBUG_ENTER("ha_set_all_bits_in_write_set");
    bitmap_set_all(write_set);
    DBUG_VOID_RETURN;
  }
  void ha_set_bit_in_read_set(uint fieldnr)
  {
    DBUG_ENTER("ha_set_bit_in_read_set");
    DBUG_PRINT("info", ("fieldnr = %d", fieldnr));
    bitmap_set_bit(read_set, fieldnr);
    DBUG_VOID_RETURN;
  }
  void ha_clear_bit_in_read_set(uint fieldnr)
  {
    DBUG_ENTER("ha_clear_bit_in_read_set");
    DBUG_PRINT("info", ("fieldnr = %d", fieldnr));
    bitmap_clear_bit(read_set, fieldnr);
    DBUG_VOID_RETURN;
  }
  void ha_set_bit_in_write_set(uint fieldnr)
  {
    DBUG_ENTER("ha_set_bit_in_write_set");
    DBUG_PRINT("info", ("fieldnr = %d", fieldnr));
    bitmap_set_bit(write_set, fieldnr);
    DBUG_VOID_RETURN;
  }
  void ha_clear_bit_in_write_set(uint fieldnr)
  {
    DBUG_ENTER("ha_clear_bit_in_write_set");
    DBUG_PRINT("info", ("fieldnr = %d", fieldnr));
    bitmap_clear_bit(write_set, fieldnr);
    DBUG_VOID_RETURN;
  }
  void ha_set_bit_in_rw_set(uint fieldnr, bool write_op)
  {
    DBUG_ENTER("ha_set_bit_in_rw_set");
    DBUG_PRINT("info", ("Set bit %u in read set", fieldnr));
    bitmap_set_bit(read_set, fieldnr);
    if (!write_op) {
      DBUG_VOID_RETURN;
    }
    else
    {
      DBUG_PRINT("info", ("Set bit %u in read and write set", fieldnr));
      bitmap_set_bit(write_set, fieldnr);
    }
    DBUG_VOID_RETURN;
  }
  bool ha_get_bit_in_read_set(uint fieldnr)
  {
    bool bit_set=bitmap_is_set(read_set,fieldnr);
    DBUG_ENTER("ha_get_bit_in_read_set");
    DBUG_PRINT("info", ("bit %u = %u", fieldnr, bit_set));
    DBUG_RETURN(bit_set);
  }
  bool ha_get_bit_in_write_set(uint fieldnr)
  {
    bool bit_set=bitmap_is_set(write_set,fieldnr);
    DBUG_ENTER("ha_get_bit_in_write_set");
    DBUG_PRINT("info", ("bit %u = %u", fieldnr, bit_set));
    DBUG_RETURN(bit_set);
  }
  bool ha_get_all_bit_in_read_set()
  {
    bool all_bits_set= bitmap_is_set_all(read_set);
    DBUG_ENTER("ha_get_all_bit_in_read_set");
    DBUG_PRINT("info", ("all bits set = %u", all_bits_set));
    DBUG_RETURN(all_bits_set);
  }
  bool ha_get_all_bit_in_read_clear()
  {
    bool all_bits_set= bitmap_is_clear_all(read_set);
    DBUG_ENTER("ha_get_all_bit_in_read_clear");
    DBUG_PRINT("info", ("all bits clear = %u", all_bits_set));
    DBUG_RETURN(all_bits_set);
  }
  bool ha_get_all_bit_in_write_set()
  {
    bool all_bits_set= bitmap_is_set_all(write_set);
    DBUG_ENTER("ha_get_all_bit_in_write_set");
    DBUG_PRINT("info", ("all bits set = %u", all_bits_set));
    DBUG_RETURN(all_bits_set);
  }
  bool ha_get_all_bit_in_write_clear()
  {
    bool all_bits_set= bitmap_is_clear_all(write_set);
    DBUG_ENTER("ha_get_all_bit_in_write_clear");
    DBUG_PRINT("info", ("all bits clear = %u", all_bits_set));
    DBUG_RETURN(all_bits_set);
  }
  void ha_set_primary_key_in_read_set();
  int ha_allocate_read_write_set(ulong no_fields);
  void ha_clear_all_set();
  uint get_index(void) const { return active_index; }
  virtual int open(const char *name, int mode, uint test_if_locked)=0;
  virtual int close(void)=0;
  virtual int ha_write_row(byte * buf);
  virtual int ha_update_row(const byte * old_data, byte * new_data);
  virtual int ha_delete_row(const byte * buf);
  /*
    If the handler does it's own injection of the rows, this member function
    should return 'true'.
  */
  virtual bool is_injective() const { return false; }
  
  /*
    SYNOPSIS
      start_bulk_update()
    RETURN
      0   Bulk update used by handler
      1   Bulk update not used, normal operation used
  */
  virtual bool start_bulk_update() { return 1; }
  /*
    SYNOPSIS
      start_bulk_delete()
    RETURN
      0   Bulk delete used by handler
      1   Bulk delete not used, normal operation used
  */
  virtual bool start_bulk_delete() { return 1; }
  /*
    SYNOPSIS
    This method is similar to update_row, however the handler doesn't need
    to execute the updates at this point in time. The handler can be certain
    that another call to bulk_update_row will occur OR a call to
    exec_bulk_update before the set of updates in this query is concluded.

      bulk_update_row()
        old_data       Old record
        new_data       New record
        dup_key_found  Number of duplicate keys found
    RETURN
      0   Bulk delete used by handler
      1   Bulk delete not used, normal operation used
  */
  virtual int bulk_update_row(const byte *old_data, byte *new_data,
                              uint *dup_key_found)
  {
    DBUG_ASSERT(FALSE);
    return HA_ERR_WRONG_COMMAND;
  }
  /*
    SYNOPSIS
    After this call all outstanding updates must be performed. The number
    of duplicate key errors are reported in the duplicate key parameter.
    It is allowed to continue to the batched update after this call, the
    handler has to wait until end_bulk_update with changing state.

      exec_bulk_update()
        dup_key_found       Number of duplicate keys found
    RETURN
      0           Success
      >0          Error code
  */
  virtual int exec_bulk_update(uint *dup_key_found)
  {
    DBUG_ASSERT(FALSE);
    return HA_ERR_WRONG_COMMAND;
  }
  /*
    SYNOPSIS
    Perform any needed clean-up, no outstanding updates are there at the
    moment.

      end_bulk_update()
    RETURN
      Nothing
  */
  virtual void end_bulk_update() { return; }
  /*
    SYNOPSIS
    Execute all outstanding deletes and close down the bulk delete.

      end_bulk_delete()
    RETURN
    0             Success
    >0            Error code
  */
  virtual int end_bulk_delete()
  {
    DBUG_ASSERT(FALSE);
    return HA_ERR_WRONG_COMMAND;
  }
  virtual int index_read(byte * buf, const byte * key,
			 uint key_len, enum ha_rkey_function find_flag)
   { return  HA_ERR_WRONG_COMMAND; }
  virtual int index_read_idx(byte * buf, uint index, const byte * key,
			     uint key_len, enum ha_rkey_function find_flag);
  virtual int index_next(byte * buf)
   { return  HA_ERR_WRONG_COMMAND; }
  virtual int index_prev(byte * buf)
   { return  HA_ERR_WRONG_COMMAND; }
  virtual int index_first(byte * buf)
   { return  HA_ERR_WRONG_COMMAND; }
  virtual int index_last(byte * buf)
   { return  HA_ERR_WRONG_COMMAND; }
  virtual int index_next_same(byte *buf, const byte *key, uint keylen);
  virtual int index_read_last(byte * buf, const byte * key, uint key_len)
   { return (my_errno=HA_ERR_WRONG_COMMAND); }
  virtual int read_multi_range_first(KEY_MULTI_RANGE **found_range_p,
                                     KEY_MULTI_RANGE *ranges, uint range_count,
                                     bool sorted, HANDLER_BUFFER *buffer);
  virtual int read_multi_range_next(KEY_MULTI_RANGE **found_range_p);
  virtual int read_range_first(const key_range *start_key,
                               const key_range *end_key,
                               bool eq_range, bool sorted);
  virtual int read_range_next();
  int compare_key(key_range *range);
  virtual int ft_init() { return HA_ERR_WRONG_COMMAND; }
  void ft_end() { ft_handler=NULL; }
  virtual FT_INFO *ft_init_ext(uint flags, uint inx,String *key)
    { return NULL; }
  virtual int ft_read(byte *buf) { return HA_ERR_WRONG_COMMAND; }
  virtual int rnd_next(byte *buf)=0;
  virtual int rnd_pos(byte * buf, byte *pos)=0;
  virtual int read_first_row(byte *buf, uint primary_key);
  /*
    The following function is only needed for tables that may be temporary
    tables during joins
  */
  virtual int restart_rnd_next(byte *buf, byte *pos)
    { return HA_ERR_WRONG_COMMAND; }
  virtual int rnd_same(byte *buf, uint inx)
    { return HA_ERR_WRONG_COMMAND; }
  virtual ha_rows records_in_range(uint inx, key_range *min_key,
                                   key_range *max_key)
    { return (ha_rows) 10; }
  virtual void position(const byte *record)=0;
  virtual void info(uint)=0; // see my_base.h for full description
  virtual void get_dynamic_partition_info(PARTITION_INFO *stat_info,
                                          uint part_id);
  virtual int extra(enum ha_extra_function operation)
  { return 0; }
  virtual int extra_opt(enum ha_extra_function operation, ulong cache_size)
  { return extra(operation); }
  virtual int external_lock(THD *thd, int lock_type) { return 0; }
  /*
    In an UPDATE or DELETE, if the row under the cursor was locked by another
    transaction, and the engine used an optimistic read of the last
    committed row value under the cursor, then the engine returns 1 from this
    function. MySQL must NOT try to update this optimistic value. If the
    optimistic value does not match the WHERE condition, MySQL can decide to
    skip over this row. Currently only works for InnoDB. This can be used to
    avoid unnecessary lock waits.

    If this method returns nonzero, it will also signal the storage
    engine that the next read will be a locking re-read of the row.
  */
  virtual bool was_semi_consistent_read() { return 0; }
  /*
    Tell the engine whether it should avoid unnecessary lock waits.
    If yes, in an UPDATE or DELETE, if the row under the cursor was locked
    by another transaction, the engine may try an optimistic read of
    the last committed row value under the cursor.
  */
  virtual void try_semi_consistent_read(bool) {}
  virtual void unlock_row() {}
  virtual int start_stmt(THD *thd, thr_lock_type lock_type) {return 0;}
  /*
    This is called to delete all rows in a table
    If the handler don't support this, then this function will
    return HA_ERR_WRONG_COMMAND and MySQL will delete the rows one
    by one.
  */
  virtual int delete_all_rows()
  { return (my_errno=HA_ERR_WRONG_COMMAND); }
  virtual ulonglong get_auto_increment();
  virtual void restore_auto_increment();

  /*
    Reset the auto-increment counter to the given value, i.e. the next row
    inserted will get the given value. This is called e.g. after TRUNCATE
    is emulated by doing a 'DELETE FROM t'. HA_ERR_WRONG_COMMAND is
    returned by storage engines that don't support this operation.
  */
  virtual int reset_auto_increment(ulonglong value)
  { return HA_ERR_WRONG_COMMAND; }

  virtual void update_create_info(HA_CREATE_INFO *create_info) {}
protected:
  /* to be implemented in handlers */

  /* admin commands - called from mysql_admin_table */
  virtual int check(THD* thd, HA_CHECK_OPT* check_opt)
  { return HA_ADMIN_NOT_IMPLEMENTED; }

  /*
     in these two methods check_opt can be modified
     to specify CHECK option to use to call check()
     upon the table
  */
  virtual int check_for_upgrade(HA_CHECK_OPT *check_opt)
  { return 0; }
public:
  int ha_check_for_upgrade(HA_CHECK_OPT *check_opt);
  int check_old_types();
  /* to be actually called to get 'check()' functionality*/
  int ha_check(THD *thd, HA_CHECK_OPT *check_opt);
   
  virtual int backup(THD* thd, HA_CHECK_OPT* check_opt)
  { return HA_ADMIN_NOT_IMPLEMENTED; }
  /*
    restore assumes .frm file must exist, and that generate_table() has been
    called; It will just copy the data file and run repair.
  */
  virtual int restore(THD* thd, HA_CHECK_OPT* check_opt)
  { return HA_ADMIN_NOT_IMPLEMENTED; }
protected:
  virtual int repair(THD* thd, HA_CHECK_OPT* check_opt)
  { return HA_ADMIN_NOT_IMPLEMENTED; }
public:
  int ha_repair(THD* thd, HA_CHECK_OPT* check_opt);
  virtual int optimize(THD* thd, HA_CHECK_OPT* check_opt)
  { return HA_ADMIN_NOT_IMPLEMENTED; }
  virtual int analyze(THD* thd, HA_CHECK_OPT* check_opt)
  { return HA_ADMIN_NOT_IMPLEMENTED; }
  virtual int assign_to_keycache(THD* thd, HA_CHECK_OPT* check_opt)
  { return HA_ADMIN_NOT_IMPLEMENTED; }
  virtual int preload_keys(THD* thd, HA_CHECK_OPT* check_opt)
  { return HA_ADMIN_NOT_IMPLEMENTED; }
  /* end of the list of admin commands */

  virtual bool check_and_repair(THD *thd) { return HA_ERR_WRONG_COMMAND; }
  virtual int dump(THD* thd, int fd = -1) { return HA_ERR_WRONG_COMMAND; }
  virtual int disable_indexes(uint mode) { return HA_ERR_WRONG_COMMAND; }
  virtual int enable_indexes(uint mode) { return HA_ERR_WRONG_COMMAND; }
  virtual int indexes_are_disabled(void) {return 0;}
  virtual void start_bulk_insert(ha_rows rows) {}
  virtual int end_bulk_insert() {return 0; }
  virtual int discard_or_import_tablespace(my_bool discard)
  {return HA_ERR_WRONG_COMMAND;}
  virtual int net_read_dump(NET* net) { return HA_ERR_WRONG_COMMAND; }
  virtual char *update_table_comment(const char * comment)
  { return (char*) comment;}
  virtual void append_create_info(String *packet) {}
  /*
    SYNOPSIS
      is_fk_defined_on_table_or_index()
      index            Index to check if foreign key uses it
    RETURN VALUE
       TRUE            Foreign key defined on table or index
       FALSE           No foreign key defined
    DESCRIPTION
      If index == MAX_KEY then a check for table is made and if index <
      MAX_KEY then a check is made if the table has foreign keys and if
      a foreign key uses this index (and thus the index cannot be dropped).
  */
  virtual bool is_fk_defined_on_table_or_index(uint index)
  { return FALSE; }
  virtual char* get_foreign_key_create_info()
  { return(NULL);}  /* gets foreign key create string from InnoDB */
  virtual char* get_tablespace_name(THD *thd)
  { return(NULL);}  /* gets tablespace name from handler */
  /* used in ALTER TABLE; 1 if changing storage engine is allowed */
  virtual bool can_switch_engines() { return 1; }
  /* used in REPLACE; is > 0 if table is referred by a FOREIGN KEY */
  virtual int get_foreign_key_list(THD *thd, List<FOREIGN_KEY_INFO> *f_key_list)
  { return 0; }
  virtual uint referenced_by_foreign_key() { return 0;}
  virtual void init_table_handle_for_HANDLER()
  { return; }       /* prepare InnoDB for HANDLER */
  virtual void free_foreign_key_create_info(char* str) {}
  /* The following can be called without an open handler */
  virtual const char *table_type() const =0;
  virtual const char **bas_ext() const =0;
  virtual ulong table_flags(void) const =0;
#ifdef WITH_PARTITION_STORAGE_ENGINE
  virtual int get_default_no_partitions(ulonglong max_rows) { return 1;}
  virtual void set_auto_partitions(partition_info *part_info) { return; }
  virtual bool get_no_parts(const char *name,
                            uint *no_parts)
  {
    *no_parts= 0;
    return 0;
  }
  virtual void set_part_info(partition_info *part_info) {return;}
#endif
  virtual ulong index_flags(uint idx, uint part, bool all_parts) const =0;

  virtual int add_index(TABLE *table_arg, KEY *key_info, uint num_of_keys)
  { return (HA_ERR_WRONG_COMMAND); }
  virtual int prepare_drop_index(TABLE *table_arg, uint *key_num,
                                 uint num_of_keys)
  { return (HA_ERR_WRONG_COMMAND); }
  virtual int final_drop_index(TABLE *table_arg)
  { return (HA_ERR_WRONG_COMMAND); }

  uint max_record_length() const
  { return min(HA_MAX_REC_LENGTH, max_supported_record_length()); }
  uint max_keys() const
  { return min(MAX_KEY, max_supported_keys()); }
  uint max_key_parts() const
  { return min(MAX_REF_PARTS, max_supported_key_parts()); }
  uint max_key_length() const
  { return min(MAX_KEY_LENGTH, max_supported_key_length()); }
  uint max_key_part_length() const
  { return min(MAX_KEY_LENGTH, max_supported_key_part_length()); }

  virtual uint max_supported_record_length() const { return HA_MAX_REC_LENGTH; }
  virtual uint max_supported_keys() const { return 0; }
  virtual uint max_supported_key_parts() const { return MAX_REF_PARTS; }
  virtual uint max_supported_key_length() const { return MAX_KEY_LENGTH; }
  virtual uint max_supported_key_part_length() const { return 255; }
  virtual uint min_record_length(uint options) const { return 1; }

  virtual bool low_byte_first() const { return 1; }
  virtual uint checksum() const { return 0; }
  virtual bool is_crashed() const  { return 0; }
  virtual bool auto_repair() const { return 0; }

  /*
    default rename_table() and delete_table() rename/delete files with a
    given name and extensions from bas_ext()
  */
  virtual int rename_table(const char *from, const char *to);
  virtual int delete_table(const char *name);
  virtual void drop_table(const char *name);
  
  virtual int create(const char *name, TABLE *form, HA_CREATE_INFO *info)=0;
  virtual int create_handler_files(const char *name) { return FALSE;}

  virtual int change_partitions(HA_CREATE_INFO *create_info,
                                const char *path,
                                ulonglong *copied,
                                ulonglong *deleted,
                                const void *pack_frm_data,
                                uint pack_frm_len)
  { return HA_ERR_WRONG_COMMAND; }
  virtual int drop_partitions(const char *path)
  { return HA_ERR_WRONG_COMMAND; }
  virtual int rename_partitions(const char *path)
  { return HA_ERR_WRONG_COMMAND; }
  virtual int optimize_partitions(THD *thd)
  { return HA_ERR_WRONG_COMMAND; }
  virtual int analyze_partitions(THD *thd)
  { return HA_ERR_WRONG_COMMAND; }
  virtual int check_partitions(THD *thd)
  { return HA_ERR_WRONG_COMMAND; }
  virtual int repair_partitions(THD *thd)
  { return HA_ERR_WRONG_COMMAND; }

  /* lock_count() can be more than one if the table is a MERGE */
  virtual uint lock_count(void) const { return 1; }
  virtual THR_LOCK_DATA **store_lock(THD *thd,
				     THR_LOCK_DATA **to,
				     enum thr_lock_type lock_type)=0;

  /* Type of table for caching query */
  virtual uint8 table_cache_type() { return HA_CACHE_TBL_NONTRANSACT; }
  /* ask handler about permission to cache table when query is to be cached */
  virtual my_bool register_query_cache_table(THD *thd, char *table_key,
					     uint key_length,
					     qc_engine_callback 
					     *engine_callback,
					     ulonglong *engine_data)
  {
    *engine_callback= 0;
    return 1;
  }
 /*
  RETURN
    true  Primary key (if there is one) is clustered key covering all fields
    false otherwise
 */
 virtual bool primary_key_is_clustered() { return FALSE; }

 virtual int cmp_ref(const byte *ref1, const byte *ref2)
 {
   return memcmp(ref1, ref2, ref_length);
 }
 
 /*
   Condition pushdown to storage engines
 */

 /*
   Push condition down to the table handler.
   SYNOPSIS
     cond_push()
     cond   Condition to be pushed. The condition tree must not be            
     modified by the by the caller.
   RETURN
     The 'remainder' condition that caller must use to filter out records.
     NULL means the handler will not return rows that do not match the
     passed condition.
   NOTES
   The pushed conditions form a stack (from which one can remove the
   last pushed condition using cond_pop).
   The table handler filters out rows using (pushed_cond1 AND pushed_cond2 
   AND ... AND pushed_condN)
   or less restrictive condition, depending on handler's capabilities.
   
   handler->extra(HA_EXTRA_RESET) call empties the condition stack.
   Calls to rnd_init/rnd_end, index_init/index_end etc do not affect the
   condition stack.
 */ 
 virtual const COND *cond_push(const COND *cond) { return cond; };
 /*
   Pop the top condition from the condition stack of the handler instance.
   SYNOPSIS
     cond_pop()
     Pops the top if condition stack, if stack is not empty
 */
 virtual void cond_pop() { return; };
 virtual bool check_if_incompatible_data(HA_CREATE_INFO *create_info,
					 uint table_changes)
 { return COMPATIBLE_DATA_NO; }

private:

  /*
    Row-level primitives for storage engines. 
    These should be overridden by the storage engine class. To call
    these methods, use the corresponding 'ha_*' method above.
  */
  friend int ndb_add_binlog_index(THD *, void *);

  virtual int write_row(byte *buf __attribute__((unused))) 
  { 
    return HA_ERR_WRONG_COMMAND; 
  }

  virtual int update_row(const byte *old_data __attribute__((unused)),
                         byte *new_data __attribute__((unused)))
  { 
    return HA_ERR_WRONG_COMMAND; 
  }

  virtual int delete_row(const byte *buf __attribute__((unused)))
  { 
    return HA_ERR_WRONG_COMMAND; 
  }
};

	/* Some extern variables used with handlers */

extern handlerton *sys_table_types[];
extern const char *ha_row_type[];
extern TYPELIB tx_isolation_typelib;
extern TYPELIB myisam_stats_method_typelib;
extern ulong total_ha, total_ha_2pc;

	/* Wrapper functions */
#define ha_commit_stmt(thd) (ha_commit_trans((thd), FALSE))
#define ha_rollback_stmt(thd) (ha_rollback_trans((thd), FALSE))
#define ha_commit(thd) (ha_commit_trans((thd), TRUE))
#define ha_rollback(thd) (ha_rollback_trans((thd), TRUE))

/* lookups */
handlerton *ha_resolve_by_name(THD *thd, LEX_STRING *name);
handlerton *ha_resolve_by_legacy_type(THD *thd, enum legacy_db_type db_type);
const char *ha_get_storage_engine(enum legacy_db_type db_type);
handler *get_new_handler(TABLE_SHARE *share, MEM_ROOT *alloc,
                         handlerton *db_type);
handlerton *ha_checktype(THD *thd, enum legacy_db_type database_type,
                          bool no_substitute, bool report_error);


static inline enum legacy_db_type ha_legacy_type(const handlerton *db_type)
{
  return (db_type == NULL) ? DB_TYPE_UNKNOWN : db_type->db_type;
}

static inline const char *ha_resolve_storage_engine_name(const handlerton *db_type)
{
  return db_type == NULL ? "UNKNOWN" : db_type->name;
}

static inline bool ha_check_storage_engine_flag(const handlerton *db_type, uint32 flag)
{
  return db_type == NULL ? FALSE : test(db_type->flags & flag);
}

static inline bool ha_storage_engine_is_enabled(const handlerton *db_type)
{
  return (db_type && db_type->create) ?
         (db_type->state == SHOW_OPTION_YES) : FALSE;
}

/* basic stuff */
int ha_init(void);
int ha_register_builtin_plugins();
int ha_initialize_handlerton(handlerton *hton);

TYPELIB *ha_known_exts(void);
int ha_panic(enum ha_panic_function flag);
void ha_close_connection(THD* thd);
bool ha_flush_logs(handlerton *db_type);
void ha_drop_database(char* path);
int ha_create_table(THD *thd, const char *path,
                    const char *db, const char *table_name,
                    HA_CREATE_INFO *create_info,
		    bool update_create_info);
int ha_delete_table(THD *thd, handlerton *db_type, const char *path,
                    const char *db, const char *alias, bool generate_warning);

/* statistics and info */
bool ha_show_status(THD *thd, handlerton *db_type, enum ha_stat_type stat);

/* discovery */
int ha_create_table_from_engine(THD* thd, const char *db, const char *name);
int ha_discover(THD* thd, const char* dbname, const char* name,
                const void** frmblob, uint* frmlen);
int ha_find_files(THD *thd,const char *db,const char *path,
                  const char *wild, bool dir,List<char>* files);
int ha_table_exists_in_engine(THD* thd, const char* db, const char* name);

/* key cache */
int ha_init_key_cache(const char *name, KEY_CACHE *key_cache);
int ha_resize_key_cache(KEY_CACHE *key_cache);
int ha_change_key_cache_param(KEY_CACHE *key_cache);
int ha_change_key_cache(KEY_CACHE *old_key_cache, KEY_CACHE *new_key_cache);
int ha_end_key_cache(KEY_CACHE *key_cache);

/* report to InnoDB that control passes to the client */
int ha_release_temporary_latches(THD *thd);

/* transactions: interface to handlerton functions */
int ha_start_consistent_snapshot(THD *thd);
int ha_commit_or_rollback_by_xid(XID *xid, bool commit);
int ha_commit_one_phase(THD *thd, bool all);
int ha_rollback_trans(THD *thd, bool all);
int ha_prepare(THD *thd);
int ha_recover(HASH *commit_list);

/* transactions: these functions never call handlerton functions directly */
int ha_commit_trans(THD *thd, bool all);
int ha_autocommit_or_rollback(THD *thd, int error);
int ha_enable_transaction(THD *thd, bool on);

/* savepoints */
int ha_rollback_to_savepoint(THD *thd, SAVEPOINT *sv);
int ha_savepoint(THD *thd, SAVEPOINT *sv);
int ha_release_savepoint(THD *thd, SAVEPOINT *sv);

/* these are called by storage engines */
void trans_register_ha(THD *thd, bool all, handlerton *ht);

/*
  Storage engine has to assume the transaction will end up with 2pc if
   - there is more than one 2pc-capable storage engine available
   - in the current transaction 2pc was not disabled yet
*/
#define trans_need_2pc(thd, all)                   ((total_ha_2pc > 1) && \
        !((all ? &thd->transaction.all : &thd->transaction.stmt)->no_2pc))

/* semi-synchronous replication */
int ha_repl_report_sent_binlog(THD *thd, char *log_file_name,
                               my_off_t end_offset);
int ha_repl_report_replication_stop(THD *thd);

#ifdef HAVE_NDB_BINLOG
int ha_reset_logs(THD *thd);
int ha_binlog_index_purge_file(THD *thd, const char *file);
void ha_reset_slave(THD *thd);
void ha_binlog_log_query(THD *thd, const handlerton *db_type,
                         enum_binlog_command binlog_command,
                         const char *query, uint query_length,
                         const char *db, const char *table_name);
void ha_binlog_wait(THD *thd);
int ha_binlog_end(THD *thd);
#else
#define ha_reset_logs(a) 0
#define ha_binlog_index_purge_file(a,b) 0
#define ha_reset_slave(a)
#define ha_binlog_log_query(a,b,c,d,e,f,g);
#define ha_binlog_wait(a)
#define ha_binlog_end(a) 0
#endif