release/src/router/mysql/storage/innobase/include/btr0cur.ic

   1 /******************************************************
   2 The index tree cursor
   3
   4 (c) 1994-1996 Innobase Oy
   5
   6 Created 10/16/1994 Heikki Tuuri
   7 *******************************************************/
   8
   9 #include "btr0btr.h"
  10
  11 #ifdef UNIV_DEBUG
  12 # define LIMIT_OPTIMISTIC_INSERT_DEBUG(NREC, CODE)\
  13 if (btr_cur_limit_optimistic_insert_debug\
  14     && (NREC) >= (ulint)btr_cur_limit_optimistic_insert_debug) {\
  15         CODE;\
  16 }
  17 #else
  18 # define LIMIT_OPTIMISTIC_INSERT_DEBUG(NREC, CODE)
  19 #endif /* UNIV_DEBUG */
  20
  21 /*************************************************************
  22 Returns the page cursor component of a tree cursor. */
  23 UNIV_INLINE
  24 page_cur_t*
  25 btr_cur_get_page_cur(
  26 /*=================*/
  27                                 /* out: pointer to page cursor component */
  28         btr_cur_t*      cursor) /* in: tree cursor */
  29 {
  30         return(&(cursor->page_cur));
  31 }
  32
  33 /*************************************************************
  34 Returns the record pointer of a tree cursor. */
  35 UNIV_INLINE
  36 rec_t*
  37 btr_cur_get_rec(
  38 /*============*/
  39                                 /* out: pointer to record */
  40         btr_cur_t*      cursor) /* in: tree cursor */
  41 {
  42         return(page_cur_get_rec(&(cursor->page_cur)));
  43 }
  44
  45 /*************************************************************
  46 Invalidates a tree cursor by setting record pointer to NULL. */
  47 UNIV_INLINE
  48 void
  49 btr_cur_invalidate(
  50 /*===============*/
  51         btr_cur_t*      cursor) /* in: tree cursor */
  52 {
  53         page_cur_invalidate(&(cursor->page_cur));
  54 }
  55
  56 /*************************************************************
  57 Returns the page of a tree cursor. */
  58 UNIV_INLINE
  59 page_t*
  60 btr_cur_get_page(
  61 /*=============*/
  62                                 /* out: pointer to page */
  63         btr_cur_t*      cursor) /* in: tree cursor */
  64 {
  65         return(buf_frame_align(page_cur_get_rec(&(cursor->page_cur))));
  66 }
  67
  68 /*************************************************************
  69 Returns the index of a cursor. */
  70 UNIV_INLINE
  71 dict_index_t*
  72 btr_cur_get_index(
  73 /*==============*/
  74                                 /* out: index */
  75         btr_cur_t*      cursor) /* in: B-tree cursor */
  76 {
  77         return(cursor->index);
  78 }
  79
  80 /*************************************************************
  81 Positions a tree cursor at a given record. */
  82 UNIV_INLINE
  83 void
  84 btr_cur_position(
  85 /*=============*/
  86         dict_index_t*   index,  /* in: index */
  87         rec_t*          rec,    /* in: record in tree */
  88         btr_cur_t*      cursor) /* in: cursor */
  89 {
  90         page_cur_position(rec, btr_cur_get_page_cur(cursor));
  91
  92         cursor->index = index;
  93 }
  94
  95 /*************************************************************************
  96 Checks if compressing an index page where a btr cursor is placed makes
  97 sense. */
  98 UNIV_INLINE
  99 ibool
 100 btr_cur_compress_recommendation(
 101 /*============================*/
 102                                 /* out: TRUE if compression is recommended */
 103         btr_cur_t*      cursor, /* in: btr cursor */
 104         mtr_t*          mtr)    /* in: mtr */
 105 {
 106         page_t*         page;
 107
 108         ut_ad(mtr_memo_contains(mtr, buf_block_align(btr_cur_get_rec(cursor)),
 109                                 MTR_MEMO_PAGE_X_FIX));
 110
 111         page = btr_cur_get_page(cursor);
 112
 113         LIMIT_OPTIMISTIC_INSERT_DEBUG(page_get_n_recs(page) * 2,
 114                                       return(FALSE));
 115
 116         if ((page_get_data_size(page) < BTR_CUR_PAGE_COMPRESS_LIMIT)
 117             || ((btr_page_get_next(page, mtr) == FIL_NULL)
 118                 && (btr_page_get_prev(page, mtr) == FIL_NULL))) {
 119
 120                 /* The page fillfactor has dropped below a predefined
 121                 minimum value OR the level in the B-tree contains just
 122                 one page: we recommend compression if this is not the
 123                 root page. */
 124
 125                 return(dict_index_get_page(cursor->index)
 126                        != buf_frame_get_page_no(page));
 127         }
 128
 129         return(FALSE);
 130 }
 131
 132 /*************************************************************************
 133 Checks if the record on which the cursor is placed can be deleted without
 134 making tree compression necessary (or, recommended). */
 135 UNIV_INLINE
 136 ibool
 137 btr_cur_can_delete_without_compress(
 138 /*================================*/
 139                                 /* out: TRUE if can be deleted without
 140                                 recommended compression */
 141         btr_cur_t*      cursor, /* in: btr cursor */
 142         ulint           rec_size,/* in: rec_get_size(btr_cur_get_rec(cursor))*/
 143         mtr_t*          mtr)    /* in: mtr */
 144 {
 145         page_t*         page;
 146
 147         ut_ad(mtr_memo_contains(mtr, buf_block_align(btr_cur_get_rec(cursor)),
 148                                 MTR_MEMO_PAGE_X_FIX));
 149
 150         page = btr_cur_get_page(cursor);
 151
 152         if ((page_get_data_size(page) - rec_size < BTR_CUR_PAGE_COMPRESS_LIMIT)
 153             || ((btr_page_get_next(page, mtr) == FIL_NULL)
 154                 && (btr_page_get_prev(page, mtr) == FIL_NULL))
 155             || (page_get_n_recs(page) < 2)) {
 156
 157                 /* The page fillfactor will drop below a predefined
 158                 minimum value, OR the level in the B-tree contains just
 159                 one page, OR the page will become empty: we recommend
 160                 compression if this is not the root page. */
 161
 162                 return(dict_index_get_page(cursor->index)
 163                        == buf_frame_get_page_no(page));
 164         }
 165
 166         return(TRUE);
 167 }