btr_cur_t;

/** B-tree cursor */
typedef struct btr_cur_struct        btr_cur_t;

/** The tree cursor: the definition appears here only for the compiler
to know struct size! */
struct btr_cur_struct {
    dict_index_t*    index;        /*!< index where positioned */
    page_cur_t    page_cur;    /*!< page cursor */
    purge_node_t*    purge_node;    /*!< purge node, for BTR_DELETE */
    buf_block_t*    left_block;    /*!< this field is used to store
                    a pointer to the left neighbor
                    page, in the cases
                    BTR_SEARCH_PREV and
                    BTR_MODIFY_PREV */
    /*------------------------------*/
    que_thr_t*    thr;        /*!< this field is only used
                    when btr_cur_search_to_nth_level
                    is called for an index entry
                    insertion: the calling query
                    thread is passed here to be
                    used in the insert buffer */
    /*------------------------------*/
    /** The following fields are used in
    btr_cur_search_to_nth_level to pass information: */
    /* @{ */
    enum btr_cur_method    flag;    /*!< Search method used */
    ulint        tree_height;    /*!< Tree height if the search is done
                    for a pessimistic insert or update
                    operation */
    ulint        up_match;    /*!< If the search mode was PAGE_CUR_LE,
                    the number of matched fields to the
                    the first user record to the right of
                    the cursor record after
                    btr_cur_search_to_nth_level;
                    for the mode PAGE_CUR_GE, the matched
                    fields to the first user record AT THE
                    CURSOR or to the right of it;
                    NOTE that the up_match and low_match
                    values may exceed the correct values
                    for comparison to the adjacent user
                    record if that record is on a
                    different leaf page! (See the note in
                    row_ins_duplicate_key.) */
    ulint        up_bytes;    /*!< number of matched bytes to the
                    right at the time cursor positioned;
                    only used internally in searches: not
                    defined after the search */
    ulint        low_match;    /*!< if search mode was PAGE_CUR_LE,
                    the number of matched fields to the
                    first user record AT THE CURSOR or
                    to the left of it after
                    btr_cur_search_to_nth_level;
                    NOT defined for PAGE_CUR_GE or any
                    other search modes; see also the NOTE
                    in up_match! */
    ulint        low_bytes;    /*!< number of matched bytes to the
                    right at the time cursor positioned;
                    only used internally in searches: not
                    defined after the search */
    ulint        n_fields;    /*!< prefix length used in a hash
                    search if hash_node != NULL */
    ulint        n_bytes;    /*!< hash prefix bytes if hash_node !=
                    NULL */
    ulint        fold;        /*!< fold value used in the search if
                    flag is BTR_CUR_HASH */
    /* @} */
    btr_path_t*    path_arr;    /*!< in estimating the number of
                    rows in range, we store in this array
                    information of the path through
                    the tree */
};