page0types.h

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/** @file include/page0types.h
 Index page routines

 Created 2/2/1994 Heikki Tuuri
 *******************************************************/

#ifndef page0types_h
#define page0types_h

#include "dict0types.h"
#include "fsp0types.h"
#include "mtr0types.h"
#include "univ.i"
#include "ut0new.h"

#include <map>

/*                      PAGE HEADER
                        ===========

Index page header starts at the first offset left free by the FIL-module */

typedef byte page_header_t;

/** index page header starts at this offset */
constexpr uint32_t PAGE_HEADER = FSEG_PAGE_DATA;

/*-----------------------------*/
/** number of slots in page directory */
constexpr uint32_t PAGE_N_DIR_SLOTS = 0;
/** pointer to record heap top */
constexpr uint32_t PAGE_HEAP_TOP = 2;
/** number of records in the heap, bit 15=flag: new-style compact page format */
constexpr uint32_t PAGE_N_HEAP = 4;
/** pointer to start of page free record list */
constexpr uint32_t PAGE_FREE = 6;
/** number of bytes in deleted records */
constexpr uint32_t PAGE_GARBAGE = 8;
/** pointer to the last inserted record, or NULL if this info has been reset by
 a delete, for example */
constexpr uint32_t PAGE_LAST_INSERT = 10;
/** last insert direction: PAGE_LEFT, ... */
constexpr uint32_t PAGE_DIRECTION = 12;
/** number of consecutive inserts to the same direction */
constexpr uint32_t PAGE_N_DIRECTION = 14;
/** number of user records on the page */
constexpr uint32_t PAGE_N_RECS = 16;
/** highest id of a trx which may have modified a record on the page; trx_id_t;
defined only in secondary indexes and in the insert buffer tree */
constexpr uint32_t PAGE_MAX_TRX_ID = 18;
/** end of private data structure of the page header which are set in a page
create */
constexpr uint32_t PAGE_HEADER_PRIV_END = 26;
/*----*/
/** level of the node in an index tree; the leaf level is the level 0.
This field should not be written to after page creation. */
constexpr uint32_t PAGE_LEVEL = 26;
/** index id where the page belongs. This field should not be written to after
 page creation. */
constexpr uint32_t PAGE_INDEX_ID = 28;
/** file segment header for the leaf pages in a B-tree: defined only on the root
 page of a B-tree, but not in the root of an ibuf tree */
constexpr uint32_t PAGE_BTR_SEG_LEAF = 36;
constexpr uint32_t PAGE_BTR_IBUF_FREE_LIST = PAGE_BTR_SEG_LEAF;
constexpr uint32_t PAGE_BTR_IBUF_FREE_LIST_NODE = PAGE_BTR_SEG_LEAF;
/* in the place of PAGE_BTR_SEG_LEAF and _TOP
there is a free list base node if the page is
the root page of an ibuf tree, and at the same
place is the free list node if the page is in
a free list */
constexpr uint32_t PAGE_BTR_SEG_TOP = 36 + FSEG_HEADER_SIZE;
/* file segment header for the non-leaf pages
in a B-tree: defined only on the root page of
a B-tree, but not in the root of an ibuf
tree */
/*----*/
/** start of data on the page */
constexpr uint32_t PAGE_DATA = PAGE_HEADER + 36 + 2 * FSEG_HEADER_SIZE;

/** offset of the page infimum record on an
old-style page */
#define PAGE_OLD_INFIMUM (PAGE_DATA + 1 + REC_N_OLD_EXTRA_BYTES)

/** offset of the page supremum record on an
old-style page */
#define PAGE_OLD_SUPREMUM (PAGE_DATA + 2 + 2 * REC_N_OLD_EXTRA_BYTES + 8)

/** offset of the page supremum record end on an old-style page */
#define PAGE_OLD_SUPREMUM_END (PAGE_OLD_SUPREMUM + 9)

/** offset of the page infimum record on a new-style compact page */
#define PAGE_NEW_INFIMUM (PAGE_DATA + REC_N_NEW_EXTRA_BYTES)

/** offset of the page supremum record on a new-style compact page */
#define PAGE_NEW_SUPREMUM (PAGE_DATA + 2 * REC_N_NEW_EXTRA_BYTES + 8)

/** offset of the page supremum record end on a new-style compact page */
#define PAGE_NEW_SUPREMUM_END (PAGE_NEW_SUPREMUM + 8)

/*-----------------------------*/

/* Heap numbers */
/** Page infimum */
constexpr ulint PAGE_HEAP_NO_INFIMUM = 0;
/** Page supremum */
constexpr ulint PAGE_HEAP_NO_SUPREMUM = 1;

/** First user record in creation (insertion) order, not necessarily collation
order; this record may have been deleted */
constexpr ulint PAGE_HEAP_NO_USER_LOW = 2;

/* Directions of cursor movement */

enum cursor_direction_t : uint8_t {
  PAGE_LEFT = 1,
  PAGE_RIGHT = 2,
  PAGE_SAME_REC = 3,
  PAGE_SAME_PAGE = 4,
  PAGE_NO_DIRECTION = 5
};

/** Eliminates a name collision on HP-UX */
#define page_t ib_page_t
/** Type of the index page */
typedef byte page_t;
/** Index page cursor */
struct page_cur_t;

/** Compressed index page */
typedef byte page_zip_t;

/* The following definitions would better belong to page0zip.h,
but we cannot include page0zip.h from rem0rec.ic, because
page0*.h includes rem0rec.h and may include rem0rec.ic. */

/** Number of bits needed for representing different compressed page sizes */
constexpr uint8_t PAGE_ZIP_SSIZE_BITS = 3;

/** Maximum compressed page shift size */
constexpr uint32_t PAGE_ZIP_SSIZE_MAX =
    UNIV_ZIP_SIZE_SHIFT_MAX - UNIV_ZIP_SIZE_SHIFT_MIN + 1;

/* Make sure there are enough bits available to store the maximum zip
ssize, which is the number of shifts from 512. */
static_assert(PAGE_ZIP_SSIZE_MAX < (1 << PAGE_ZIP_SSIZE_BITS),
              "PAGE_ZIP_SSIZE_MAX >= (1 << PAGE_ZIP_SSIZE_BITS)");

/* Page cursor search modes; the values must be in this order! */
enum page_cur_mode_t {
  PAGE_CUR_UNSUPP = 0,
  PAGE_CUR_G = 1,
  PAGE_CUR_GE = 2,
  PAGE_CUR_L = 3,
  PAGE_CUR_LE = 4,

  /*      PAGE_CUR_LE_OR_EXTENDS = 5,*/ /* This is a search mode used in
                                   "column LIKE 'abc%' ORDER BY column DESC";
                                   we have to find strings which are <= 'abc' or
                                   which extend it */

  /* These search mode is for search R-tree index. */
  PAGE_CUR_CONTAIN = 7,
  PAGE_CUR_INTERSECT = 8,
  PAGE_CUR_WITHIN = 9,
  PAGE_CUR_DISJOINT = 10,
  PAGE_CUR_MBR_EQUAL = 11,
  PAGE_CUR_RTREE_INSERT = 12,
  PAGE_CUR_RTREE_LOCATE = 13,
  PAGE_CUR_RTREE_GET_FATHER = 14
};

/** Compressed page descriptor */
struct page_zip_des_t {
  /** Compressed page data */
  page_zip_t *data;

#ifdef UNIV_DEBUG
  /** Start offset of modification log */
  uint16_t m_start;
  /** Allocated externally, not from the buffer pool */
  bool m_external;
#endif /* UNIV_DEBUG */

  /** End offset of modification log */
  uint16_t m_end;

  /** Number of externally stored columns on the page; the maximum is 744
  on a 16 KiB page */
  uint16_t n_blobs;

  /** true if the modification log is not empty.  */
  bool m_nonempty;

  /** 0 or compressed page shift size; the size in bytes is:
  (UNIV_ZIP_SIZE_MIN * >> 1) << ssize. */
  uint8_t ssize;
};

/** Compression statistics for a given page size */
struct page_zip_stat_t {
  /** Number of page compressions */
  ulint compressed;
  /** Number of successful page compressions */
  ulint compressed_ok;
  /** Number of page decompressions */
  ulint decompressed;
  /** Duration of page compressions */
  std::chrono::microseconds compress_time;
  /** Duration of page decompressions */
  std::chrono::microseconds decompress_time;
  page_zip_stat_t()
      : /* Initialize members to 0 so that when we do
        stlmap[key].compressed++ and element with "key" does not
        exist it gets inserted with zeroed members. */
        compressed(0),
        compressed_ok(0),
        decompressed(0),
        compress_time{},
        decompress_time{} {}
};

/** Compression statistics types */
typedef std::map<index_id_t, page_zip_stat_t, std::less<index_id_t>,
                 ut::allocator<std::pair<const index_id_t, page_zip_stat_t>>>
    page_zip_stat_per_index_t;

/** Statistics on compression, indexed by page_zip_des_t::ssize - 1 */
extern page_zip_stat_t page_zip_stat[PAGE_ZIP_SSIZE_MAX];
/** Statistics on compression, indexed by dict_index_t::id */
extern page_zip_stat_per_index_t page_zip_stat_per_index;

/** Write the "deleted" flag of a record on a compressed page.  The flag must
 already have been written on the uncompressed page. */
void page_zip_rec_set_deleted(
    page_zip_des_t *page_zip, /*!< in/out: compressed page */
    const byte *rec,          /*!< in: record on the uncompressed page */
    bool flag);               /*!< in: the deleted flag (nonzero=true) */

/** Write the "owned" flag of a record on a compressed page.  The n_owned field
 must already have been written on the uncompressed page.
@param[in,out] page_zip Compressed page
@param[in] rec Record on the uncompressed page
@param[in] flag The owned flag (nonzero=true) */
void page_zip_rec_set_owned(page_zip_des_t *page_zip, const byte *rec,
                            ulint flag);

/** Shift the dense page directory when a record is deleted.
@param[in,out]  page_zip        compressed page
@param[in]      rec             deleted record
@param[in]      index           index of rec
@param[in]      offsets         rec_get_offsets(rec)
@param[in]      free            previous start of the free list */
void page_zip_dir_delete(page_zip_des_t *page_zip, byte *rec,
                         dict_index_t *index, const ulint *offsets,
                         const byte *free);

/** Add a slot to the dense page directory.
@param[in,out]  page_zip      Compressed page
@param[in]      is_clustered  Nonzero for clustered index, zero for others */
void page_zip_dir_add_slot(page_zip_des_t *page_zip, bool is_clustered);

#endif