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-rw-r--r--sql/handler.h41
1 files changed, 38 insertions, 3 deletions
diff --git a/sql/handler.h b/sql/handler.h
index aabb60e4252..36cb81017c6 100644
--- a/sql/handler.h
+++ b/sql/handler.h
@@ -1358,6 +1358,15 @@ void get_sweep_read_cost(TABLE *table, ha_rows nrows, bool interrupted,
*/
#define HA_MRR_MATERIALIZED_KEYS 256
+#define HA_MRR_IMPLEMENTATION_FLAG1 512
+#define HA_MRR_IMPLEMENTATION_FLAG2 1024
+#define HA_MRR_IMPLEMENTATION_FLAG3 2048
+#define HA_MRR_IMPLEMENTATION_FLAG4 4096
+#define HA_MRR_IMPLEMENTATION_FLAG5 8192
+#define HA_MRR_IMPLEMENTATION_FLAG6 16384
+
+#define HA_MRR_IMPLEMENTATION_FLAGS \
+ (512 | 1024 | 2048 | 4096 | 8192 | 16384)
/*
This is a buffer area that the handler can use to store rows.
@@ -1863,14 +1872,40 @@ public:
virtual ha_rows multi_range_read_info_const(uint keyno, RANGE_SEQ_IF *seq,
void *seq_init_param,
uint n_ranges, uint *bufsz,
- uint *flags, COST_VECT *cost);
+ uint *mrr_mode, COST_VECT *cost);
virtual ha_rows multi_range_read_info(uint keyno, uint n_ranges, uint keys,
uint key_parts, uint *bufsz,
- uint *flags, COST_VECT *cost);
+ uint *mrr_mode, COST_VECT *cost);
virtual int multi_range_read_init(RANGE_SEQ_IF *seq, void *seq_init_param,
- uint n_ranges, uint mode,
+ uint n_ranges, uint mrr_mode,
HANDLER_BUFFER *buf);
virtual int multi_range_read_next(range_id_t *range_info);
+ /*
+ Return string representation of the MRR plan.
+
+ This is intended to be used for EXPLAIN, via the following scenario:
+ 1. SQL layer calls handler->multi_range_read_info().
+ 1.1. Storage engine figures out whether it will use some non-default
+ MRR strategy, sets appropritate bits in *mrr_mode, and returns
+ control to SQL layer
+ 2. SQL layer remembers the returned mrr_mode
+ 3. SQL layer compares various options and choses the final query plan. As
+ a part of that, it makes a choice of whether to use the MRR strategy
+ picked in 1.1
+ 4. EXPLAIN code converts the query plan to its text representation. If MRR
+ strategy is part of the plan, it calls
+ multi_range_read_explain_info(mrr_mode) to get a text representation of
+ the picked MRR strategy.
+
+ @param mrr_mode Mode which was returned by multi_range_read_info[_const]
+ @param str INOUT string to be printed for EXPLAIN
+ @param str_end End of the string buffer. The function is free to put the
+ string into [str..str_end] memory range.
+ */
+ virtual int multi_range_read_explain_info(uint mrr_mode, char *str,
+ size_t size)
+ { return 0; }
+
virtual int read_range_first(const key_range *start_key,
const key_range *end_key,
bool eq_range, bool sorted);