index_skip_scan_plan.h

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#ifndef SQL_RANGE_OPTIMIZER_INDEX_SKIP_SCAN_PLAN_H_
#define SQL_RANGE_OPTIMIZER_INDEX_SKIP_SCAN_PLAN_H_
 
#include <sys/types.h>
 
#include "my_base.h"
#include "sql/range_optimizer/range_optimizer.h"
 
class KEY;
class KEY_PART_INFO;
class Opt_trace_object;
class RANGE_OPT_PARAM;
class SEL_ARG;
class SEL_ROOT;
class SEL_TREE;
struct MEM_ROOT;
 
/*
  This is an array of array of equality constants with length
  eq_prefix_key_parts.
 
  For example, an equality predicate like "a IN (1, 2) AND b IN (2, 3, 4)",
  eq_prefixes will contain:
 
  [
    { eq_key_prefixes = array[1, 2], cur_eq_prefix = ... },
    { eq_key_prefixes = array[2, 3, 4], cur_eq_prefix = ... }
  ]
 */
struct EQPrefix {
  Bounds_checked_array<uchar *> eq_key_prefixes;
 
  /*
     During skip scan, we will have to iterate through all possible
     equality prefixes. This is the product of all the elements in
     eq_prefix_elements. In the above example, there are 2 x 3 = 6 possible
     equality prefixes.
 
     To track which prefix we are on, we use cur_eq_prefix. For example,
     if both EQPrefixes have the value 1 here, it indicates that the current
     equality prefix is (2, 3).
   */
  unsigned cur_eq_prefix;
};
 
/**
  Logically a part of AccessPath::index_skip_scan(), but is too large,
  so split out into its own struct.
 */
struct IndexSkipScanParameters {
  KEY *index_info;           ///< The index chosen for data access
  uint eq_prefix_len;        ///< Length of the equality prefix
  uint eq_prefix_key_parts;  ///< Number of key parts in the equality prefix
  EQPrefix *eq_prefixes;     ///< Array of equality constants (IN list)
  KEY_PART_INFO *range_key_part;  ///< The key part matching the range condition
  uint used_key_parts;            ///< Number of index keys used for skip scan
  double read_cost;               ///< Total cost of read
  uint index;                     ///< Position of chosen index
 
  uchar *min_range_key;
  uchar *max_range_key;
  uchar *min_search_key;
  uchar *max_search_key;
  uint range_cond_flag;
  uint range_key_len;
  uint num_output_rows;
 
  // The sub-tree corresponding to the range condition
  // (on key part C - for more details see description of get_best_skip_scan()).
  //
  // Does not necessarily live as long as the AccessPath, so used for tracing
  // only.
  const SEL_ARG *range_part_tracing_only;
 
  SEL_ROOT *index_range_tree;   ///< The sub-tree corresponding to index_info
  bool has_aggregate_function;  ///< TRUE if there are aggregate functions.
};
 
Mem_root_array<AccessPath *> get_all_skip_scans(THD *thd,
                                                RANGE_OPT_PARAM *param,
                                                SEL_TREE *tree,
                                                enum_order order_direction,
                                                bool skip_records_in_range,
                                                bool force_skip_scan);
AccessPath *get_best_skip_scan(THD *thd, RANGE_OPT_PARAM *param, SEL_TREE *tree,
                               enum_order order_direction,
                               bool skip_records_in_range,
                               bool force_skip_scan);
 
void trace_basic_info_index_skip_scan(THD *thd, const AccessPath *path,
                                      const RANGE_OPT_PARAM *param,
                                      Opt_trace_object *trace_object);
 
#ifndef NDEBUG
void dbug_dump_index_skip_scan(int indent, bool verbose,
                               const AccessPath *path);
#endif
 
#endif  // SQL_RANGE_OPTIMIZER_INDEX_SKIP_SCAN_PLAN_H_