/** Set next page@param[in]next_page_nonext page no */

void PageBulk::setNext(page_no_t next_page_no) {

btr_page_set_next(m_page, nullptr, next_page_no, m_mtr);

}

/** Set previous page@param[in]prev_page_noprevious page no */

void PageBulk::setPrev(page_no_t prev_page_no) {

btr_page_set_prev(m_page, nullptr, prev_page_no, m_mtr);

}

双向

/** Sets the previous index page field. */

UNIV_INLINE

void btr_page_set_prev(

page_t *page, /*!< in: index page */

page_zip_des_t *page_zip, /*!< in: compressed page whose uncompressed

part will be updated, or NULL */

page_no_t prev, /*!< in: previous page number */

mtr_t *mtr) /*!< in: mini-transaction handle */

{

ut_ad(page != NULL);

ut_ad(mtr != NULL);

if (page_zip) {

mach_write_to_4(page + FIL_PAGE_PREV, prev);

page_zip_write_header(page_zip, page + FIL_PAGE_PREV, 4, mtr);

} else {

mlog_write_ulint(page + FIL_PAGE_PREV, prev, MLOG_4BYTES, mtr);

}

}

/** Sets the next index page field. */

UNIV_INLINE

void btr_page_set_next(

page_t *page, /*!< in: index page */

page_zip_des_t *page_zip, /*!< in: compressed page whose uncompressed

part will be updated, or NULL */

page_no_t next, /*!< in: next page number */

mtr_t *mtr) /*!< in: mini-transaction handle */

{

ut_ad(page != NULL);

ut_ad(mtr != NULL);

if (page_zip) {

mach_write_to_4(page + FIL_PAGE_NEXT, next);

page_zip_write_header(page_zip, page + FIL_PAGE_NEXT, 4, mtr);

} else {

mlog_write_ulint(page + FIL_PAGE_NEXT, next, MLOG_4BYTES, mtr);

}

}

双向更新

/** if there is a 'natural' predecessor of the page, its offset.

Otherwise FIL_NULL. This field is not set on BLOB pages, which are stored as a

singly-linked list. See also FIL_PAGE_NEXT. */

#define FIL_PAGE_PREV 8

/** On page 0 of the tablespace, this is the server version ID */

#define FIL_PAGE_SRV_VERSION 8

/** if there is a 'natural' successor of the page, its offset. Otherwise

FIL_NULL. B-tree index pages(FIL_PAGE_TYPE contains FIL_PAGE_INDEX) on the

same PAGE_LEVEL are maintained as a doubly linked list via FIL_PAGE_PREV and

FIL_PAGE_NEXT in the collation order of the smallest user record on each

page. */

#define FIL_PAGE_NEXT 12

注意：This field is not set on BLOB pages, which are stored as a singly-linked list. See also FIL_PAGE_NEXT. */

也就是BLOB页是单向的，

页：

数据页

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