MWL#67: MRR backport

- Make index condition pushdown be controlled by an @@optimizer_switch flag,
  not by @@engine_condition_pushdown
- Make MRR buffer size be controlled by @@mrr_buffer_size, not 
  by @@read_rnd_buffer_size
- Move parts of code to separate files
- Code cleanup
- Add --sorted_result to some SELECTs in tests.

1 files changed, 70 insertions, 0 deletions

diff --git a/sql/multi_range_read.h b/sql/multi_range_read.h
new file mode 100644
index 00000000000..90e2e4c93d6
--- /dev/null
+++ b/sql/multi_range_read.h
@@ -0,0 +1,70 @@
+/*
+  This file contains declarations for 
+   - Disk-Sweep MultiRangeRead (DS-MRR) implementation
+*/
+
+/**
+  A Disk-Sweep MRR interface implementation
+
+  This implementation makes range (and, in the future, 'ref') scans to read
+  table rows in disk sweeps. 
+  
+  Currently it is used by MyISAM and InnoDB. Potentially it can be used with
+  any table handler that has non-clustered indexes and on-disk rows.
+*/
+
+class DsMrr_impl
+{
+public:
+  typedef void (handler::*range_check_toggle_func_t)(bool on);
+
+  DsMrr_impl()
+    : h2(NULL) {};
+  
+  /*
+    The "owner" handler object (the one that calls dsmrr_XXX functions.
+    It is used to retrieve full table rows by calling rnd_pos().
+  */
+  handler *h;
+  TABLE *table; /* Always equal to h->table */
+private:
+  /* Secondary handler object.  It is used for scanning the index */
+  handler *h2;
+
+  /* Buffer to store rowids, or (rowid, range_id) pairs */
+  uchar *rowids_buf;
+  uchar *rowids_buf_cur;   /* Current position when reading/writing */
+  uchar *rowids_buf_last;  /* When reading: end of used buffer space */
+  uchar *rowids_buf_end;   /* End of the buffer */
+
+  bool dsmrr_eof; /* TRUE <=> We have reached EOF when reading index tuples */
+
+  /* TRUE <=> need range association, buffer holds {rowid, range_id} pairs */
+  bool is_mrr_assoc;
+
+  bool use_default_impl; /* TRUE <=> shortcut all calls to default MRR impl */
+public:
+  void init(handler *h_arg, TABLE *table_arg)
+  {
+    h= h_arg; 
+    table= table_arg;
+  }
+  int dsmrr_init(handler *h, RANGE_SEQ_IF *seq_funcs, void *seq_init_param, 
+                 uint n_ranges, uint mode, HANDLER_BUFFER *buf);
+  void dsmrr_close();
+  int dsmrr_fill_buffer();
+  int dsmrr_next(char **range_info);
+
+  ha_rows dsmrr_info(uint keyno, uint n_ranges, uint keys, uint *bufsz,
+                     uint *flags, COST_VECT *cost);
+
+  ha_rows dsmrr_info_const(uint keyno, RANGE_SEQ_IF *seq, 
+                            void *seq_init_param, uint n_ranges, uint *bufsz,
+                            uint *flags, COST_VECT *cost);
+private:
+  bool choose_mrr_impl(uint keyno, ha_rows rows, uint *flags, uint *bufsz, 
+                       COST_VECT *cost);
+  bool get_disk_sweep_mrr_cost(uint keynr, ha_rows rows, uint flags, 
+                               uint *buffer_size, COST_VECT *cost);
+};
+