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