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dc9107df2a
There always was a one-to-one mapping between dict_tree_t and dict_index_t. This saves 6 machine words per B-tree index in the data dictionary cache plus the memory allocation overhead. We save one mem_heap_t object per index (15 machine words). Considering the internal fragmentation of the buddy allocator in mem_area_alloc(), this should save 32 machine words per index (128 bytes on 32-bit systems and 256 bytes on 64-bit systems). (Bug #20877) struct dict_tree_struct, dict_tree_t: Remove. struct dict_index_struct: Add page and lock. dict_tree_create(): Remove. Replace the invocation with assignment to index->page and a call to rw_lock_create(&index->lock). dict_tree_free(): Remove. Replace the invocation wtih a call to rw_lock_free(&index->lock). dict_index_get_tree(): Remove. dict_tree_get_space_reserve(): Rename to dict_index_get_space_reserve() and remove the parameter, which was unused. btr_level_list_remove(): Remove the unused parameter "tree". Replace the occurrences of "tree" with "index" in names of variables, functions and data types, e.g. "dict_tree_t tree" becomes "dict_index_t index". Remove local variables "tree" or "index" of functions that needed both "tree" and "index".
154 lines
4.1 KiB
Text
154 lines
4.1 KiB
Text
/******************************************************
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The index tree cursor
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(c) 1994-1996 Innobase Oy
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Created 10/16/1994 Heikki Tuuri
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*******************************************************/
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#include "btr0btr.h"
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/*************************************************************
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Returns the page cursor component of a tree cursor. */
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UNIV_INLINE
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page_cur_t*
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btr_cur_get_page_cur(
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/*=================*/
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/* out: pointer to page cursor component */
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btr_cur_t* cursor) /* in: tree cursor */
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{
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return(&(cursor->page_cur));
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}
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/*************************************************************
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Returns the record pointer of a tree cursor. */
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UNIV_INLINE
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rec_t*
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btr_cur_get_rec(
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/*============*/
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/* out: pointer to record */
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btr_cur_t* cursor) /* in: tree cursor */
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{
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return(page_cur_get_rec(&(cursor->page_cur)));
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}
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/*************************************************************
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Invalidates a tree cursor by setting record pointer to NULL. */
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UNIV_INLINE
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void
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btr_cur_invalidate(
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/*===============*/
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btr_cur_t* cursor) /* in: tree cursor */
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{
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page_cur_invalidate(&(cursor->page_cur));
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}
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/*************************************************************
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Returns the page of a tree cursor. */
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UNIV_INLINE
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page_t*
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btr_cur_get_page(
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/*=============*/
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/* out: pointer to page */
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btr_cur_t* cursor) /* in: tree cursor */
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{
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return(buf_frame_align(page_cur_get_rec(&(cursor->page_cur))));
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}
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/*************************************************************
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Returns the index of a cursor. */
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UNIV_INLINE
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dict_index_t*
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btr_cur_get_index(
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/*==============*/
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/* out: index */
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btr_cur_t* cursor) /* in: B-tree cursor */
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{
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return(cursor->index);
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}
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/*************************************************************
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Positions a tree cursor at a given record. */
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UNIV_INLINE
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void
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btr_cur_position(
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/*=============*/
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dict_index_t* index, /* in: index */
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rec_t* rec, /* in: record in tree */
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btr_cur_t* cursor) /* in: cursor */
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{
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page_cur_position(rec, btr_cur_get_page_cur(cursor));
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cursor->index = index;
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}
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/*************************************************************************
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Checks if compressing an index page where a btr cursor is placed makes
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sense. */
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UNIV_INLINE
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ibool
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btr_cur_compress_recommendation(
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/*============================*/
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/* out: TRUE if compression is recommended */
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btr_cur_t* cursor, /* in: btr cursor */
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mtr_t* mtr) /* in: mtr */
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{
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page_t* page;
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ut_ad(mtr_memo_contains(mtr, buf_block_align(btr_cur_get_rec(cursor)),
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MTR_MEMO_PAGE_X_FIX));
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page = btr_cur_get_page(cursor);
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if ((page_get_data_size(page) < BTR_CUR_PAGE_COMPRESS_LIMIT)
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|| ((btr_page_get_next(page, mtr) == FIL_NULL)
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&& (btr_page_get_prev(page, mtr) == FIL_NULL))) {
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/* The page fillfactor has dropped below a predefined
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minimum value OR the level in the B-tree contains just
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one page: we recommend compression if this is not the
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root page. */
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return(dict_index_get_page(cursor->index)
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!= buf_frame_get_page_no(page));
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}
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return(FALSE);
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}
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/*************************************************************************
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Checks if the record on which the cursor is placed can be deleted without
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making tree compression necessary (or, recommended). */
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UNIV_INLINE
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ibool
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btr_cur_can_delete_without_compress(
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/*================================*/
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/* out: TRUE if can be deleted without
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recommended compression */
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btr_cur_t* cursor, /* in: btr cursor */
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ulint rec_size,/* in: rec_get_size(btr_cur_get_rec(cursor))*/
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mtr_t* mtr) /* in: mtr */
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{
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page_t* page;
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ut_ad(mtr_memo_contains(mtr, buf_block_align(btr_cur_get_rec(cursor)),
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MTR_MEMO_PAGE_X_FIX));
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page = btr_cur_get_page(cursor);
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if ((page_get_data_size(page) - rec_size < BTR_CUR_PAGE_COMPRESS_LIMIT)
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|| ((btr_page_get_next(page, mtr) == FIL_NULL)
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&& (btr_page_get_prev(page, mtr) == FIL_NULL))
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|| (page_get_n_recs(page) < 2)) {
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/* The page fillfactor will drop below a predefined
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minimum value, OR the level in the B-tree contains just
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one page, OR the page will become empty: we recommend
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compression if this is not the root page. */
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return(dict_index_get_page(cursor->index)
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== buf_frame_get_page_no(page));
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}
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return(TRUE);
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}
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