Patch for push of wl1354 Partitioning

1 files changed, 916 insertions, 0 deletions

diff --git a/sql/ha_partition.h b/sql/ha_partition.h
new file mode 100644
index 00000000000..e78cff4cdbb
--- /dev/null
+++ b/sql/ha_partition.h
@@ -0,0 +1,916 @@
+/* Copyright (C) 2005 MySQL AB
+
+  This program is free software; you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation; 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 */
+
+#ifdef __GNUC__
+#pragma interface				/* gcc class implementation */
+#endif
+
+/*
+  PARTITION_SHARE is a structure that will be shared amoung all open handlers
+  The partition implements the minimum of what you will probably need.
+*/
+
+typedef struct st_partition_share
+{
+  char *table_name;
+  uint table_name_length, use_count;
+  pthread_mutex_t mutex;
+  THR_LOCK lock;
+} PARTITION_SHARE;
+
+
+#define PARTITION_BYTES_IN_POS 2
+class ha_partition :public handler
+{
+private:
+  enum partition_index_scan_type
+  {
+    partition_index_read= 0,
+    partition_index_first= 1,
+    partition_index_last= 2,
+    partition_no_index_scan= 3
+  };
+  /* Data for the partition handler */
+  char *m_file_buffer;                  // Buffer with names
+  char *m_name_buffer_ptr;		// Pointer to first partition name
+  uchar *m_engine_array;                // Array of types of the handlers
+  handler **m_file;                     // Array of references to handler inst.
+  partition_info *m_part_info;          // local reference to partition
+  byte *m_start_key_ref;                // Reference of start key in current
+                                        // index scan info
+  Field **m_part_field_array;           // Part field array locally to save acc
+  byte *m_ordered_rec_buffer;           // Row and key buffer for ord. idx scan
+  KEY *m_curr_key_info;                 // Current index
+  byte *m_rec0;                         // table->record[0]
+  QUEUE queue;                          // Prio queue used by sorted read
+  /*
+    Since the partition handler is a handler on top of other handlers, it
+    is necessary to keep information about what the underlying handler
+    characteristics is. It is not possible to keep any handler instances
+    for this since the MySQL Server sometimes allocating the handler object
+    without freeing them.
+  */
+  u_long m_table_flags;
+  u_long m_low_byte_first;
+
+  uint m_tot_parts;                      // Total number of partitions;
+  uint m_last_part;                      // Last file that we update,write
+  int m_lock_type;                       // Remembers type of last
+                                         // external_lock
+  part_id_range m_part_spec;             // Which parts to scan
+  uint m_scan_value;                     // Value passed in rnd_init
+                                         // call
+  uint m_ref_length;                     // Length of position in this
+                                         // handler object
+  key_range m_start_key;                 // index read key range
+  enum partition_index_scan_type m_index_scan_type;// What type of index
+                                                   // scan
+  uint m_top_entry;                      // Which partition is to
+                                         // deliver next result
+  uint m_rec_length;                     // Local copy of record length
+
+  bool m_ordered;                        // Ordered/Unordered index scan
+  bool m_has_transactions;               // Can we support transactions
+  bool m_pkey_is_clustered;              // Is primary key clustered
+  bool m_create_handler;                 // Handler used to create table
+  bool m_is_sub_partitioned;             // Is subpartitioned
+  bool m_ordered_scan_ongoing;
+  bool m_use_bit_array;
+
+  /*
+    We keep track if all underlying handlers are MyISAM since MyISAM has a
+    great number of extra flags not needed by other handlers.
+  */
+  bool m_myisam;                         // Are all underlying handlers
+                                         // MyISAM
+  /*
+    We keep track of InnoDB handlers below since it requires proper setting
+    of query_id in fields at index_init and index_read calls.
+  */
+  bool m_innodb;                        // Are all underlying handlers
+                                        // InnoDB
+  /*
+    When calling extra(HA_EXTRA_CACHE) we do not pass this to the underlying
+    handlers immediately. Instead we cache it and call the underlying
+    immediately before starting the scan on the partition. This is to
+    prevent allocating a READ CACHE for each partition in parallel when
+    performing a full table scan on MyISAM partitioned table.
+    This state is cleared by extra(HA_EXTRA_NO_CACHE).
+  */
+  bool m_extra_cache;
+  uint m_extra_cache_size;
+
+  void init_handler_variables();
+  /*
+    Variables for lock structures.
+  */
+  THR_LOCK_DATA lock;                   /* MySQL lock */
+  PARTITION_SHARE *share;               /* Shared lock info */
+
+public:
+  /*
+    -------------------------------------------------------------------------
+    MODULE create/delete handler object
+    -------------------------------------------------------------------------
+    Object create/delete methode. The normal called when a table object
+    exists. There is also a method to create the handler object with only
+    partition information. This is used from mysql_create_table when the
+    table is to be created and the engine type is deduced to be the
+    partition handler.
+    -------------------------------------------------------------------------
+  */
+    ha_partition(TABLE * table);
+    ha_partition(partition_info * part_info);
+   ~ha_partition();
+  /*
+    A partition handler has no characteristics in itself. It only inherits
+    those from the underlying handlers. Here we set-up those constants to
+    enable later calls of the methods to retrieve constants from the under-
+    lying handlers. Returns false if not successful.
+  */
+  int ha_initialise();
+
+  /*
+    -------------------------------------------------------------------------
+    MODULE meta data changes
+    -------------------------------------------------------------------------
+    Meta data routines to CREATE, DROP, RENAME table and often used at
+    ALTER TABLE (update_create_info used from ALTER TABLE and SHOW ..).
+
+    update_table_comment is used in SHOW TABLE commands to provide a
+    chance for the handler to add any interesting comments to the table
+    comments not provided by the users comment.
+
+    create_handler_files is called before opening a new handler object
+    with openfrm to call create. It is used to create any local handler
+    object needed in opening the object in openfrm
+    -------------------------------------------------------------------------
+  */
+  virtual int delete_table(const char *from);
+  virtual int rename_table(const char *from, const char *to);
+  virtual int create(const char *name, TABLE * form,
+		     HA_CREATE_INFO * create_info);
+  virtual int create_handler_files(const char *name);
+  virtual void update_create_info(HA_CREATE_INFO * create_info);
+  virtual char *update_table_comment(const char *comment);
+private:
+  /*
+    delete_table, rename_table and create uses very similar logic which
+    is packed into this routine.
+  */
+    uint del_ren_cre_table(const char *from,
+			   const char *to= NULL,
+			   TABLE * table_arg= NULL,
+			   HA_CREATE_INFO * create_info= NULL);
+  /*
+    One method to create the table_name.par file containing the names of the
+    underlying partitions, their engine and the number of partitions.
+    And one method to read it in.
+  */
+  bool create_handler_file(const char *name);
+  bool get_from_handler_file(const char *name);
+  bool new_handlers_from_part_info();
+  bool create_handlers();
+  void clear_handler_file();
+  void set_up_table_before_create(TABLE * table_arg, HA_CREATE_INFO * info,
+				  uint part_id);
+  partition_element *find_partition_element(uint part_id);
+public:
+
+  /*
+    -------------------------------------------------------------------------
+    MODULE open/close object
+    -------------------------------------------------------------------------
+    Open and close handler object to ensure all underlying files and
+    objects allocated and deallocated for query handling is handled
+    properly.
+    -------------------------------------------------------------------------
+
+    A handler object is opened as part of its initialisation and before
+    being used for normal queries (not before meta-data changes always.
+    If the object was opened it will also be closed before being deleted.
+  */
+  virtual int open(const char *name, int mode, uint test_if_locked);
+  virtual int close(void);
+
+  /*
+    -------------------------------------------------------------------------
+    MODULE start/end statement
+    -------------------------------------------------------------------------
+    This module contains methods that are used to understand start/end of
+    statements, transaction boundaries, and aid for proper concurrency
+    control.
+    The partition handler need not implement abort and commit since this
+    will be handled by any underlying handlers implementing transactions.
+    There is only one call to each handler type involved per transaction
+    and these go directly to the handlers supporting transactions
+    currently InnoDB, BDB and NDB).
+    -------------------------------------------------------------------------
+  */
+  virtual THR_LOCK_DATA **store_lock(THD * thd, THR_LOCK_DATA ** to,
+				     enum thr_lock_type lock_type);
+  virtual int external_lock(THD * thd, int lock_type);
+  /*
+    When table is locked a statement is started by calling start_stmt
+    instead of external_lock
+  */
+  virtual int start_stmt(THD * thd);
+  /*
+    Lock count is number of locked underlying handlers (I assume)
+  */
+  virtual uint lock_count(void) const;
+  /*
+    Call to unlock rows not to be updated in transaction
+  */
+  virtual void unlock_row();
+
+  /*
+    -------------------------------------------------------------------------
+    MODULE change record
+    -------------------------------------------------------------------------
+    This part of the handler interface is used to change the records
+    after INSERT, DELETE, UPDATE, REPLACE method calls but also other
+    special meta-data operations as ALTER TABLE, LOAD DATA, TRUNCATE.
+    -------------------------------------------------------------------------
+
+    These methods are used for insert (write_row), update (update_row)
+    and delete (delete_row). All methods to change data always work on
+    one row at a time. update_row and delete_row also contains the old
+    row.
+    delete_all_rows will delete all rows in the table in one call as a
+    special optimisation for DELETE from table;
+
+    Bulk inserts are supported if all underlying handlers support it.
+    start_bulk_insert and end_bulk_insert is called before and after a
+    number of calls to write_row.
+    Not yet though.
+  */
+  virtual int write_row(byte * buf);
+  virtual int update_row(const byte * old_data, byte * new_data);
+  virtual int delete_row(const byte * buf);
+  virtual int delete_all_rows(void);
+  virtual void start_bulk_insert(ha_rows rows);
+  virtual int end_bulk_insert();
+
+  /*
+    -------------------------------------------------------------------------
+    MODULE full table scan
+    -------------------------------------------------------------------------
+    This module is used for the most basic access method for any table
+    handler. This is to fetch all data through a full table scan. No
+    indexes are needed to implement this part.
+    It contains one method to start the scan (rnd_init) that can also be
+    called multiple times (typical in a nested loop join). Then proceeding
+    to the next record (rnd_next) and closing the scan (rnd_end).
+    To remember a record for later access there is a method (position)
+    and there is a method used to retrieve the record based on the stored
+    position.
+    The position can be a file position, a primary key, a ROWID dependent
+    on the handler below.
+    -------------------------------------------------------------------------
+  */
+  /*
+    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
+  */
+  virtual int rnd_init(bool scan);
+  virtual int rnd_end();
+  virtual int rnd_next(byte * buf);
+  virtual int rnd_pos(byte * buf, byte * pos);
+  virtual void position(const byte * record);
+
+  /*
+    -------------------------------------------------------------------------
+    MODULE index scan
+    -------------------------------------------------------------------------
+    This part of the handler interface is used to perform access through
+    indexes. The interface is defined as a scan interface but the handler
+    can also use key lookup if the index is a unique index or a primary
+    key index.
+    Index scans are mostly useful for SELECT queries but are an important
+    part also of UPDATE, DELETE, REPLACE and CREATE TABLE table AS SELECT
+    and so forth.
+    Naturally an index is needed for an index scan and indexes can either
+    be ordered, hash based. Some ordered indexes can return data in order
+    but not necessarily all of them.
+    There are many flags that define the behavior of indexes in the
+    various handlers. These methods are found in the optimizer module.
+    -------------------------------------------------------------------------
+
+    index_read is called to start a scan of an index. The find_flag defines
+    the semantics of the scan. These flags are defined in
+    include/my_base.h
+    index_read_idx is the same but also initializes index before calling doing
+    the same thing as index_read. Thus it is similar to index_init followed
+    by index_read. This is also how we implement it.
+
+    index_read/index_read_idx does also return the first row. Thus for
+    key lookups, the index_read will be the only call to the handler in
+    the index scan.
+
+    index_init initializes an index before using it and index_end does
+    any end processing needed.
+  */
+  virtual int index_read(byte * buf, const byte * key,
+			 uint key_len, enum ha_rkey_function find_flag);
+  virtual int index_read_idx(byte * buf, uint idx, const byte * key,
+			     uint key_len, enum ha_rkey_function find_flag);
+  virtual int index_init(uint idx, bool sorted);
+  virtual int index_end();
+
+  /*
+    These methods are used to jump to next or previous entry in the index
+    scan. There are also methods to jump to first and last entry.
+  */
+  virtual int index_next(byte * buf);
+  virtual int index_prev(byte * buf);
+  virtual int index_first(byte * buf);
+  virtual int index_last(byte * buf);
+  virtual int index_next_same(byte * buf, const byte * key, uint keylen);
+  virtual int index_read_last(byte * buf, const byte * key, uint keylen);
+
+  /*
+    read_first_row is virtual method but is only implemented by
+    handler.cc, no storage engine has implemented it so neither
+    will the partition handler.
+    
+    virtual int read_first_row(byte *buf, uint primary_key);
+  */
+
+  /*
+    We don't implement multi read range yet, will do later.
+    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();
+
+private:
+  int common_index_read(byte * buf, const byte * key,
+			uint key_len, enum ha_rkey_function find_flag);
+  int common_first_last(byte * buf);
+  int partition_scan_set_up(byte * buf, bool idx_read_flag);
+  int handle_unordered_next(byte * buf, bool next_same);
+  int handle_unordered_scan_next_partition(byte * buf);
+  byte *queue_buf(uint part_id)
+    {
+      return (m_ordered_rec_buffer +
+              (part_id * (m_rec_length + PARTITION_BYTES_IN_POS)));
+    }
+  byte *rec_buf(uint part_id)
+    {
+      return (queue_buf(part_id) +
+              PARTITION_BYTES_IN_POS);
+    }
+  int handle_ordered_index_scan(byte * buf);
+  int handle_ordered_next(byte * buf, bool next_same);
+  int handle_ordered_prev(byte * buf);
+  void return_top_record(byte * buf);
+  void include_partition_fields_in_used_fields();
+public:
+  /*
+    -------------------------------------------------------------------------
+    MODULE information calls
+    -------------------------------------------------------------------------
+    This calls are used to inform the handler of specifics of the ongoing
+    scans and other actions. Most of these are used for optimisation
+    purposes.
+    -------------------------------------------------------------------------
+  */
+  virtual void info(uint);
+  virtual int extra(enum ha_extra_function operation);
+  virtual int extra_opt(enum ha_extra_function operation, ulong cachesize);
+  virtual int reset(void);
+
+private:
+  static const uint NO_CURRENT_PART_ID= 0xFFFFFFFF;
+  int loop_extra(enum ha_extra_function operation);
+  void late_extra_cache(uint partition_id);
+  void late_extra_no_cache(uint partition_id);
+  void prepare_extra_cache(uint cachesize);
+public:
+
+  /*
+    -------------------------------------------------------------------------
+    MODULE optimiser support
+    -------------------------------------------------------------------------
+    -------------------------------------------------------------------------
+  */
+
+  /*
+    NOTE !!!!!!
+     -------------------------------------------------------------------------
+     -------------------------------------------------------------------------
+     One important part of the public handler interface that is not depicted in
+     the methods is the attribute records
+
+     which is defined in the base class. This is looked upon directly and is
+     set by calling info(HA_STATUS_INFO) ?
+     -------------------------------------------------------------------------
+  */
+
+  /*
+    keys_to_use_for_scanning can probably be implemented as the
+    intersection of all underlying handlers if mixed handlers are used.
+    This method is used to derive whether an index can be used for
+    index-only scanning when performing an ORDER BY query.
+    Only called from one place in sql_select.cc
+  */
+  virtual const key_map *keys_to_use_for_scanning();
+
+  /*
+    Called in test_quick_select to determine if indexes should be used.
+  */
+  virtual double scan_time();
+
+  /*
+    The next method will never be called if you do not implement indexes.
+  */
+  virtual double read_time(uint index, uint ranges, ha_rows rows);
+  /*
+    For the given range how many records are estimated to be in this range.
+    Used by optimiser to calculate cost of using a particular index.
+  */
+  virtual ha_rows records_in_range(uint inx, key_range * min_key,
+				   key_range * max_key);
+
+  /*
+    Upper bound of number records returned in scan is sum of all
+    underlying handlers.
+  */
+  virtual ha_rows estimate_rows_upper_bound();
+
+  /*
+    table_cache_type is implemented by the underlying handler but all
+    underlying handlers must have the same implementation for it to work.
+  */
+  virtual uint8 table_cache_type();
+
+  /*
+    -------------------------------------------------------------------------
+    MODULE print messages
+    -------------------------------------------------------------------------
+    This module contains various methods that returns text messages for
+    table types, index type and error messages.
+    -------------------------------------------------------------------------
+  */
+  /*
+    The name of the index type that will be used for display
+    Here we must ensure that all handlers use the same index type
+    for each index created.
+  */
+  virtual const char *index_type(uint inx);
+
+  /* The name of the table type that will be used for display purposes */
+  virtual const char *table_type() const
+  { return "PARTITION"; }
+
+  /*
+     Handler specific error messages
+  */
+  virtual void print_error(int error, myf errflag);
+  virtual bool get_error_message(int error, String * buf);
+  /*
+   -------------------------------------------------------------------------
+    MODULE handler characteristics
+    -------------------------------------------------------------------------
+    This module contains a number of methods defining limitations and
+    characteristics of the handler. The partition handler will calculate
+    this characteristics based on underlying handler characteristics.
+    -------------------------------------------------------------------------
+
+    This is a list of flags that says what the storage engine
+    implements. The current table flags are documented in handler.h
+    The partition handler will support whatever the underlying handlers
+    support except when specifically mentioned below about exceptions
+    to this rule.
+
+    HA_READ_RND_SAME:
+    Not currently used. (Means that the handler supports the rnd_same() call)
+    (MyISAM, HEAP)
+
+    HA_TABLE_SCAN_ON_INDEX:
+    Used to avoid scanning full tables on an index. If this flag is set then
+    the handler always has a primary key (hidden if not defined) and this
+    index is used for scanning rather than a full table scan in all
+    situations.
+    (InnoDB, BDB, Federated)
+
+    HA_REC_NOT_IN_SEQ:
+    This flag is set for handlers that cannot guarantee that the rows are
+    returned accroding to incremental positions (0, 1, 2, 3...).
+    This also means that rnd_next() should return HA_ERR_RECORD_DELETED
+    if it finds a deleted row.
+    (MyISAM (not fixed length row), BDB, HEAP, NDB, InooDB)
+
+    HA_CAN_GEOMETRY:
+    Can the storage engine handle spatial data.
+    Used to check that no spatial attributes are declared unless
+    the storage engine is capable of handling it.
+    (MyISAM)
+
+    HA_FAST_KEY_READ:
+    Setting this flag indicates that the handler is equally fast in
+    finding a row by key as by position.
+    This flag is used in a very special situation in conjunction with
+    filesort's. For further explanation see intro to init_read_record.
+    (BDB, HEAP, InnoDB)
+
+    HA_NULL_IN_KEY:
+    Is NULL values allowed in indexes.
+    If this is not allowed then it is not possible to use an index on a
+    NULLable field.
+    (BDB, HEAP, MyISAM, NDB, InnoDB)
+
+    HA_DUPP_POS:
+    Tells that we can the position for the conflicting duplicate key
+    record is stored in table->file->dupp_ref. (insert uses rnd_pos() on
+    this to find the duplicated row)
+    (MyISAM)
+
+    HA_CAN_INDEX_BLOBS:
+    Is the storage engine capable of defining an index of a prefix on
+    a BLOB attribute.
+    (BDB, Federated, MyISAM, InnoDB)
+
+    HA_AUTO_PART_KEY:
+    Auto increment fields can be part of a multi-part key. For second part
+    auto-increment keys, the auto_incrementing is done in handler.cc
+    (BDB, Federated, MyISAM, NDB)
+
+    HA_REQUIRE_PRIMARY_KEY:
+    Can't define a table without primary key (and cannot handle a table
+    with hidden primary key)
+    (No handler has this limitation currently)
+
+    HA_NOT_EXACT_COUNT:
+    Does the counter of records after the info call specify an exact
+    value or not. If it doesn't this flag is set.
+    Only MyISAM and HEAP uses exact count.
+    (MyISAM, HEAP, BDB, InnoDB, NDB, Federated)
+
+    HA_CAN_INSERT_DELAYED:
+    Can the storage engine support delayed inserts.
+    To start with the partition handler will not support delayed inserts.
+    Further investigation needed.
+    (HEAP, MyISAM)
+
+    HA_PRIMARY_KEY_IN_READ_INDEX:
+    This parameter is set when the handler will also return the primary key
+    when doing read-only-key on another index.
+
+    HA_NOT_DELETE_WITH_CACHE:
+    Seems to be an old MyISAM feature that is no longer used. No handler
+    has it defined but it is checked in init_read_record.
+    Further investigation needed.
+    (No handler defines it)
+
+    HA_NO_PREFIX_CHAR_KEYS:
+    Indexes on prefixes of character fields is not allowed.
+    (NDB)
+
+    HA_CAN_FULLTEXT:
+    Does the storage engine support fulltext indexes
+    The partition handler will start by not supporting fulltext indexes.
+    (MyISAM)
+
+    HA_CAN_SQL_HANDLER:
+    Can the HANDLER interface in the MySQL API be used towards this
+    storage engine.
+    (MyISAM, InnoDB)
+
+    HA_NO_AUTO_INCREMENT:
+    Set if the storage engine does not support auto increment fields.
+    (Currently not set by any handler)
+
+    HA_HAS_CHECKSUM:
+    Special MyISAM feature. Has special SQL support in CREATE TABLE.
+    No special handling needed by partition handler.
+    (MyISAM)
+
+    HA_FILE_BASED:
+    Should file names always be in lower case (used by engines
+    that map table names to file names.
+    Since partition handler has a local file this flag is set.
+    (BDB, Federated, MyISAM)
+
+    HA_CAN_BIT_FIELD:
+    Is the storage engine capable of handling bit fields?
+    (MyISAM, NDB)
+
+    HA_NEED_READ_RANGE_BUFFER:
+    Is Read Multi-Range supported => need multi read range buffer
+    This parameter specifies whether a buffer for read multi range
+    is needed by the handler. Whether the handler supports this
+    feature or not is dependent of whether the handler implements
+    read_multi_range* calls or not. The only handler currently
+    supporting this feature is NDB so the partition handler need
+    not handle this call. There are methods in handler.cc that will
+    transfer those calls into index_read and other calls in the
+    index scan module.
+    (NDB)
+  */
+  virtual ulong table_flags() const
+  { return m_table_flags; }
+  /*
+    HA_CAN_PARTITION:
+    Used by storage engines that can handle partitioning without this
+    partition handler
+    (Partition, NDB)
+
+    HA_CAN_UPDATE_PARTITION_KEY:
+    Set if the handler can update fields that are part of the partition
+    function.
+
+    HA_CAN_PARTITION_UNIQUE:
+    Set if the handler can handle unique indexes where the fields of the
+    unique key are not part of the fields of the partition function. Thus
+    a unique key can be set on all fields.
+  */
+  virtual ulong partition_flags() const
+  { return HA_CAN_PARTITION; }
+
+  /*
+    This is a bitmap 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
+    here.
+
+    part is the key part to check. First key part is 0
+    If all_parts it's set, MySQL want to know the flags for the combined
+    index up to and including 'part'.
+
+    HA_READ_NEXT:
+    Does the index support read next, this is assumed in the server
+    code and never checked so all indexes must support this.
+    Note that the handler can be used even if it doesn't have any index.
+    (BDB, HEAP, MyISAM, Federated, NDB, InnoDB)
+
+    HA_READ_PREV:
+    Can the index be used to scan backwards.
+    (BDB, HEAP, MyISAM, NDB, InnoDB)
+
+    HA_READ_ORDER:
+    Can the index deliver its record in index order. Typically true for
+    all ordered indexes and not true for hash indexes.
+    In first step this is not true for partition handler until a merge
+    sort has been implemented in partition handler.
+    Used to set keymap part_of_sortkey
+    This keymap is only used to find indexes usable for resolving an ORDER BY
+    in the query. Thus in most cases index_read will work just fine without
+    order in result production. When this flag is set it is however safe to
+    order all output started by index_read since most engines do this. With
+    read_multi_range calls there is a specific flag setting order or not
+    order so in those cases ordering of index output can be avoided.
+    (BDB, InnoDB, HEAP, MyISAM, NDB)
+
+    HA_READ_RANGE:
+    Specify whether index can handle ranges, typically true for all
+    ordered indexes and not true for hash indexes.
+    Used by optimiser to check if ranges (as key >= 5) can be optimised
+    by index.
+    (BDB, InnoDB, NDB, MyISAM, HEAP)
+
+    HA_ONLY_WHOLE_INDEX:
+    Can't use part key searches. This is typically true for hash indexes
+    and typically not true for ordered indexes.
+    (Federated, NDB, HEAP)
+
+    HA_KEYREAD_ONLY:
+    Does the storage engine support index-only scans on this index.
+    Enables use of HA_EXTRA_KEYREAD and HA_EXTRA_NO_KEYREAD
+    Used to set key_map keys_for_keyread and to check in optimiser for
+    index-only scans.  When doing a read under HA_EXTRA_KEYREAD the handler
+    only have to fill in the columns the key covers. If
+    HA_PRIMARY_KEY_IN_READ_INDEX is set then also the PRIMARY KEY columns
+    must be updated in the row.
+    (BDB, InnoDB, MyISAM)
+  */
+  virtual ulong index_flags(uint inx, uint part, bool all_parts) const
+  {
+    return m_file[0]->index_flags(inx, part, all_parts);
+  }
+
+  /*
+     extensions of table handler files
+  */
+  virtual const char **bas_ext() const;
+  /*
+    unireg.cc will call the following to make sure that the storage engine
+    can handle the data it is about to send.
+
+    The maximum supported values is the minimum of all handlers in the table
+  */
+  uint min_of_the_max_uint(uint (handler::*operator_func)(void) const) const; 
+  virtual uint max_supported_record_length() const;
+  virtual uint max_supported_keys() const;
+  virtual uint max_supported_key_parts() const;
+  virtual uint max_supported_key_length() const;
+  virtual uint max_supported_key_part_length() const;
+
+  /*
+    All handlers in a partitioned table must have the same low_byte_first
+  */
+  virtual bool low_byte_first() const
+  { return m_low_byte_first; }
+
+  /*
+    The extra record buffer length is the maximum needed by all handlers.
+    The minimum record length is the maximum of all involved handlers.
+  */
+  virtual uint extra_rec_buf_length() const;
+  virtual uint min_record_length(uint options) const;
+
+  /*
+    Transactions on the table is supported if all handlers below support
+    transactions.
+  */
+  virtual bool has_transactions()
+  { return m_has_transactions; }
+
+  /*
+    Primary key is clustered can only be true if all underlying handlers have
+    this feature.
+  */
+  virtual bool primary_key_is_clustered()
+  { return m_pkey_is_clustered; }
+
+  /*
+    -------------------------------------------------------------------------
+    MODULE compare records
+    -------------------------------------------------------------------------
+    cmp_ref checks if two references are the same. For most handlers this is
+    a simple memcmp of the reference. However some handlers use primary key
+    as reference and this can be the same even if memcmp says they are
+    different. This is due to character sets and end spaces and so forth.
+    For the partition handler the reference is first two bytes providing the
+    partition identity of the referred record and then the reference of the
+    underlying handler.
+    Thus cmp_ref for the partition handler always returns FALSE for records
+    not in the same partition and uses cmp_ref on the underlying handler
+    to check whether the rest of the reference part is also the same.
+    -------------------------------------------------------------------------
+  */
+  virtual int cmp_ref(const byte * ref1, const byte * ref2);
+  /*
+    -------------------------------------------------------------------------
+    MODULE auto increment
+    -------------------------------------------------------------------------
+    This module is used to handle the support of auto increments.
+
+    This variable in the handler is used as part of the handler interface
+    It is maintained by the parent handler object and should not be
+    touched by child handler objects (see handler.cc for its use).
+
+    auto_increment_column_changed
+     -------------------------------------------------------------------------
+  */
+  virtual void restore_auto_increment();
+  virtual ulonglong get_auto_increment();
+
+  /*
+     -------------------------------------------------------------------------
+     MODULE initialise handler for HANDLER call
+     -------------------------------------------------------------------------
+     This method is a special InnoDB method called before a HANDLER query.
+     -------------------------------------------------------------------------
+  */
+  virtual void init_table_handle_for_HANDLER();
+
+  /*
+    The remainder of this file defines the handler methods not implemented
+    by the partition handler
+  */
+
+  /*
+    -------------------------------------------------------------------------
+    MODULE foreign key support
+    -------------------------------------------------------------------------
+    The following methods are used to implement foreign keys as supported by
+    InnoDB. Implement this ??
+    get_foreign_key_create_info is used by SHOW CREATE TABLE to get a textual
+    description of how the CREATE TABLE part to define FOREIGN KEY's is done.
+    free_foreign_key_create_info is used to free the memory area that provided
+    this description.
+    -------------------------------------------------------------------------
+
+    virtual char* get_foreign_key_create_info()
+    virtual void free_foreign_key_create_info(char* str)
+
+    virtual int get_foreign_key_list(THD *thd,
+    List<FOREIGN_KEY_INFO> *f_key_list)
+    virtual uint referenced_by_foreign_key()
+  */
+
+  /*
+    -------------------------------------------------------------------------
+    MODULE fulltext index
+    -------------------------------------------------------------------------
+    Fulltext stuff not yet.
+    -------------------------------------------------------------------------
+    virtual int ft_init() { return HA_ERR_WRONG_COMMAND; }
+    virtual FT_INFO *ft_init_ext(uint flags,uint inx,const byte *key,
+    uint keylen)
+    { return NULL; }
+    virtual int ft_read(byte *buf) { return HA_ERR_WRONG_COMMAND; }
+  */
+
+  /*
+     -------------------------------------------------------------------------
+     MODULE restart full table scan at position (MyISAM)
+     -------------------------------------------------------------------------
+     The following method is only used by MyISAM when used as
+     temporary tables in a join.
+     virtual int restart_rnd_next(byte *buf, byte *pos);
+  */
+
+  /*
+    -------------------------------------------------------------------------
+    MODULE on-line ALTER TABLE
+    -------------------------------------------------------------------------
+    These methods are in the handler interface but never used (yet)
+    They are to be used by on-line alter table add/drop index:
+    -------------------------------------------------------------------------
+    virtual ulong index_ddl_flags(KEY *wanted_index) const
+    virtual int add_index(TABLE *table_arg,KEY *key_info,uint num_of_keys);
+    virtual int drop_index(TABLE *table_arg,uint *key_num,uint num_of_keys);
+  */
+
+  /*
+    -------------------------------------------------------------------------
+    MODULE tablespace support
+    -------------------------------------------------------------------------
+    Admin of table spaces is not applicable to the partition handler (InnoDB)
+    This means that the following method is not implemented:
+    -------------------------------------------------------------------------
+    virtual int discard_or_import_tablespace(my_bool discard)
+  */
+
+  /*
+    -------------------------------------------------------------------------
+    MODULE admin MyISAM
+    -------------------------------------------------------------------------
+    Admin commands not supported currently (almost purely MyISAM routines)
+    This means that the following methods are not implemented:
+    -------------------------------------------------------------------------
+
+    virtual int check(THD* thd, HA_CHECK_OPT *check_opt);
+    virtual int backup(TD* thd, HA_CHECK_OPT *check_opt);
+    virtual int restore(THD* thd, HA_CHECK_OPT *check_opt);
+    virtual int repair(THD* thd, HA_CHECK_OPT *check_opt);
+    virtual int optimize(THD* thd, HA_CHECK_OPT *check_opt);
+    virtual int analyze(THD* thd, HA_CHECK_OPT *check_opt);
+    virtual int assign_to_keycache(THD* thd, HA_CHECK_OPT *check_opt);
+    virtual int preload_keys(THD *thd, HA_CHECK_OPT *check_opt);
+    virtual bool check_and_repair(THD *thd);
+    virtual int dump(THD* thd, int fd = -1);
+    virtual int net_read_dump(NET* net);
+    virtual uint checksum() const;
+    virtual bool is_crashed() const;
+    virtual bool auto_repair() const;
+
+    -------------------------------------------------------------------------
+    MODULE enable/disable indexes
+    -------------------------------------------------------------------------
+    Enable/Disable Indexes are not supported currently (Heap, MyISAM)
+    This means that the following methods are not implemented:
+    -------------------------------------------------------------------------
+    virtual int disable_indexes(uint mode);
+    virtual int enable_indexes(uint mode);
+    virtual int indexes_are_disabled(void);
+  */
+
+  /*
+    -------------------------------------------------------------------------
+    MODULE append_create_info
+    -------------------------------------------------------------------------
+    append_create_info is only used by MyISAM MERGE tables and the partition
+    handler will not support this handler as underlying handler.
+    Implement this??
+    -------------------------------------------------------------------------
+    virtual void append_create_info(String *packet)
+  */
+};