index_range_scan.h

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#ifndef SQL_RANGE_OPTIMIZER_INDEX_RANGE_SCAN_H_
#define SQL_RANGE_OPTIMIZER_INDEX_RANGE_SCAN_H_
 
#include <sys/types.h>
#include <memory>
 
#include "my_bitmap.h"
#include "my_inttypes.h"
#include "sql/field.h"
#include "sql/handler.h"
#include "sql/range_optimizer/range_optimizer.h"
#include "sql/range_optimizer/rowid_capable_row_iterator.h"
 
class KEY_PART_INFO;
class RANGE_OPT_PARAM;
class SEL_ARG;
class SEL_ROOT;
class String;
class THD;
struct KEY_MULTI_RANGE;
struct MEM_ROOT;
struct TABLE;
 
/*
  MRR range sequence, array<QUICK_RANGE> implementation: sequence traversal
  context.
*/
struct QUICK_RANGE_SEQ_CTX {
  Quick_ranges::const_iterator first;
  Quick_ranges::const_iterator cur;
  Quick_ranges::const_iterator last;
};
 
/*
  Quick select that does a range scan on a single key. The records are
  returned in key order if ::need_sorted_output() has been called.
*/
class IndexRangeScanIterator : public RowIDCapableRowIterator {
 protected:
  handler *file;
 
  uint index; /* Index this quick select uses */
 
  /* Members to deal with case when this quick select is a ROR-merged scan */
  bool in_ror_merged_scan;
 
  // TODO: pre-allocate space to avoid malloc/free for small number of columns.
  MY_BITMAP column_bitmap;
 
  friend uint quick_range_seq_next(range_seq_t rseq, KEY_MULTI_RANGE *range);
  friend range_seq_t quick_range_seq_init(void *init_param, uint n_ranges,
                                          uint flags);
  friend class IndexMergeIterator;
  friend class RowIDIntersectionIterator;
 
  Bounds_checked_array<QUICK_RANGE *> ranges; /* ordered array of range ptrs */
  bool free_file; /* TRUE <=> this->file is "owned" by this quick select */
 
  /* Range pointers to be used when not using MRR interface */
  QUICK_RANGE **cur_range; /* current element in ranges  */
  QUICK_RANGE *last_range;
 
  /* Members needed to use the MRR interface */
  QUICK_RANGE_SEQ_CTX qr_traversal_ctx;
 
  uint mrr_flags;    /* Flags to be used with MRR interface */
  uint mrr_buf_size; /* copy from thd->variables.read_rnd_buff_size */
  HANDLER_BUFFER *mrr_buf_desc; /* the handler buffer */
 
  /* Info about index we're scanning */
  KEY_PART_INFO *key_part_info;
 
  const bool need_rows_in_rowid_order;
  const bool reuse_handler;
 
 private:
  MEM_ROOT *mem_root;
  bool inited = false;
  const double m_expected_rows;
  ha_rows *m_examined_rows;
 
  int cmp_next(QUICK_RANGE *range);
  int cmp_prev(QUICK_RANGE *range);
  bool row_in_ranges();
  bool shared_init();
  bool shared_reset();
  bool init_ror_merged_scan();
 
 public:
  IndexRangeScanIterator(THD *thd, TABLE *table, ha_rows *examined_rows,
                         double expected_rows, uint index_arg,
                         bool need_rows_in_rowid_order, bool reuse_handler,
                         MEM_ROOT *return_mem_root, uint mrr_flags,
                         uint mrr_buf_size,
                         Bounds_checked_array<QUICK_RANGE *> ranges);
  ~IndexRangeScanIterator() override;
 
  IndexRangeScanIterator(const IndexRangeScanIterator &) = delete;
 
  /* Default move ctor used by ReverseIndexRangeScanIterator */
  IndexRangeScanIterator(IndexRangeScanIterator &&) = default;
 
  bool Init() override;
  int Read() override;
  void UnlockRow() override {
    // Override TableRowIterator::UnlockRow(), since we may use
    // a different handler from m_table->file.
    file->unlock_row();
  }
 
  uint get_mrr_flags() const { return mrr_flags; }
  uchar *last_rowid() const override {
    assert(need_rows_in_rowid_order);
    return file->ref;
  }
};
 
bool InitIndexRangeScan(TABLE *table, handler *file, int index,
                        unsigned mrr_flags, bool in_ror_merged_scan,
                        MY_BITMAP *column_bitmap);
 
range_seq_t quick_range_seq_init(void *init_param, uint, uint);
uint quick_range_seq_next(range_seq_t rseq, KEY_MULTI_RANGE *range);
 
#endif  // SQL_RANGE_OPTIMIZER_INDEX_RANGE_SCAN_H_