Backport into MariaDB-5.2 the following:

WL#2474 "Multi Range Read: Change the default MRR implementation to implement new MRR interface"
WL#2475 "Batched range read functions for MyISAM/InnoDb"
        "Index condition pushdown for MyISAM/InnoDB"
- Adjust test results (checked)
- Code cleanup.

8 files changed, 35 insertions, 159 deletions

diff --git a/sql/ds_mrr.cc b/sql/ds_mrr.cc
index 7a0fc65b8f5..0bf63e95a1f 100644
--- a/sql/ds_mrr.cc
+++ b/sql/ds_mrr.cc
@@ -950,8 +950,15 @@ void push_index_cond(JOIN_TAB *tab, uint keyno, bool other_tbls_ok)
     ((tab->table->file->index_flags(keyno, 0, 1) &
       HA_DO_INDEX_COND_PUSHDOWN) &&
      tab->join->thd->variables.engine_condition_pushdown);
-  // psergey:
-  //
+
+  /*
+    Do not try index condition pushdown on indexes which have partially-covered
+    columns. Unpacking from a column prefix into index tuple is not a supported 
+    operation in some engines, see e.g. MySQL BUG#42991.
+    TODO: a better solution would be not to consider partially-covered columns
+    as parts of the index and still produce/check index condition for
+    fully-covered index columns.
+  */
   KEY *key_info= tab->table->key_info + keyno;
   for (uint kp= 0; kp < key_info->key_parts; kp++)
   {
@@ -961,7 +968,7 @@ void push_index_cond(JOIN_TAB *tab, uint keyno, bool other_tbls_ok)
       break;
     }
   }
-  // :psergey
+
   /*
     When WL#5116 is done this DBUG statement must be removed. It's just a
     temporary hack to allow us to discriminate whether a test failure relates
@@ -984,7 +991,8 @@ void push_index_cond(JOIN_TAB *tab, uint keyno, bool other_tbls_ok)
       Item *idx_remainder_cond= 0;
       tab->pre_idx_push_select_cond= tab->select_cond;
 #if 0
-      // The following is only needed for BKA:
+      /* 
+        psergey: enable the below when we backport BKA: */
       /*
         For BKA cache we store condition to special BKA cache field
         because evaluation of the condition requires additional operations
diff --git a/sql/ds_mrr.h b/sql/ds_mrr.h
index 02abe72a4c1..12e2c955f0a 100644
--- a/sql/ds_mrr.h
+++ b/sql/ds_mrr.h
@@ -1,4 +1,8 @@
-
+/*
+  This file contains declarations for 
+   - Disk-Sweep MultiRangeRead (DS-MRR) implementation
+   - Index Condition Pushdown helper functions
+*/
 
 /**
   A Disk-Sweep MRR interface implementation
@@ -65,4 +69,5 @@ private:
                                uint *buffer_size, COST_VECT *cost);
 };
 
+void push_index_cond(JOIN_TAB *tab, uint keyno, bool other_tbls_ok);
 
diff --git a/sql/ha_ndbcluster.cc b/sql/ha_ndbcluster.cc
index c6b48c5b744..edfec934b2a 100644
--- a/sql/ha_ndbcluster.cc
+++ b/sql/ha_ndbcluster.cc
@@ -8702,6 +8702,8 @@ ha_ndbcluster::null_value_index_search(KEY_MULTI_RANGE *ranges,
   DBUG_RETURN(FALSE);
 }
 
+#if 0 
+/* MRR/NDB is disabled, for details see method declarations in ha_ndbcluster.h */
 int
 ha_ndbcluster::read_multi_range_first(KEY_MULTI_RANGE **found_range_p,
                                       KEY_MULTI_RANGE *ranges, 
@@ -9074,6 +9076,7 @@ found_next:
   m_multi_range_result_ptr += reclength;
   DBUG_RETURN(0);
 }
+#endif 
 
 int
 ha_ndbcluster::setup_recattr(const NdbRecAttr* curr)
diff --git a/sql/ha_ndbcluster.h b/sql/ha_ndbcluster.h
index f3651ebeca9..9e6d697492a 100644
--- a/sql/ha_ndbcluster.h
+++ b/sql/ha_ndbcluster.h
@@ -259,10 +259,20 @@ class ha_ndbcluster: public handler
   /**
    * Multi range stuff
    */
+#if 0 
+  /*
+    MRR/NDB is disabled in MariaDB. This is because in MariaDB, we've
+    backported
+     - the latest version of MRR interface (BKA needs this)
+     - the latest version of DS-MRR implementation
+    but didn't backport the latest version MRR/NDB implementation.
+
+  */
   int read_multi_range_first(KEY_MULTI_RANGE **found_range_p,
                              KEY_MULTI_RANGE*ranges, uint range_count,
                              bool sorted, HANDLER_BUFFER *buffer);
   int read_multi_range_next(KEY_MULTI_RANGE **found_range_p);
+#endif  
   bool null_value_index_search(KEY_MULTI_RANGE *ranges,
 			       KEY_MULTI_RANGE *end_range,
 			       HANDLER_BUFFER *buffer);
diff --git a/sql/handler.cc b/sql/handler.cc
index 3f4fec8f23a..fe3639a0e00 100644
--- a/sql/handler.cc
+++ b/sql/handler.cc
@@ -4193,136 +4193,6 @@ double handler::index_only_read_time(uint keynr, double records)
   return read_time;
 }
 
-#if 0 
-// psergey-mrr
-
-/**
-  Read the first row of a multi-range set.
-
-  @param found_range_p       Returns a pointer to the element in 'ranges' that
-                             corresponds to the returned row.
-  @param ranges              An array of KEY_MULTI_RANGE range descriptions.
-  @param range_count         Number of ranges in 'ranges'.
-  @param sorted	      If result should be sorted per key.
-  @param buffer              A HANDLER_BUFFER for internal handler usage.
-
-  @note
-    - Record is read into table->record[0].
-    - *found_range_p returns a valid value only if read_multi_range_first()
-    returns 0.
-    - Sorting is done within each range. If you want an overall sort, enter
-    'ranges' with sorted ranges.
-
-  @retval
-    0			OK, found a row
-  @retval
-    HA_ERR_END_OF_FILE	No rows in range
-  @retval
-    \#			Error code
-*/
-int handler::read_multi_range_first(KEY_MULTI_RANGE **found_range_p,
-                                    KEY_MULTI_RANGE *ranges, uint range_count,
-                                    bool sorted, HANDLER_BUFFER *buffer)
-{
-  int result= HA_ERR_END_OF_FILE;
-  DBUG_ENTER("handler::read_multi_range_first");
-  multi_range_sorted= sorted;
-  multi_range_buffer= buffer;
-
-  table->mark_columns_used_by_index_no_reset(active_index, table->read_set);
-  table->column_bitmaps_set(table->read_set, table->write_set);
-
-  for (multi_range_curr= ranges, multi_range_end= ranges + range_count;
-       multi_range_curr < multi_range_end;
-       multi_range_curr++)
-  {
-    result= read_range_first(multi_range_curr->start_key.keypart_map ?
-                             &multi_range_curr->start_key : 0,
-                             multi_range_curr->end_key.keypart_map ?
-                             &multi_range_curr->end_key : 0,
-                             test(multi_range_curr->range_flag & EQ_RANGE),
-                             multi_range_sorted);
-    if (result != HA_ERR_END_OF_FILE)
-      break;
-  }
-
-  *found_range_p= multi_range_curr;
-  DBUG_PRINT("exit",("result %d", result));
-  DBUG_RETURN(result);
-}
-
-
-/**
-  Read the next row of a multi-range set.
-
-  @param found_range_p       Returns a pointer to the element in 'ranges' that
-                             corresponds to the returned row.
-
-  @note
-    - Record is read into table->record[0].
-    - *found_range_p returns a valid value only if read_multi_range_next()
-    returns 0.
-
-  @retval
-    0			OK, found a row
-  @retval
-    HA_ERR_END_OF_FILE	No (more) rows in range
-  @retval
-    \#			Error code
-*/
-int handler::read_multi_range_next(KEY_MULTI_RANGE **found_range_p)
-{
-  int result;
-  DBUG_ENTER("handler::read_multi_range_next");
-
-  /* We should not be called after the last call returned EOF. */
-  DBUG_ASSERT(multi_range_curr < multi_range_end);
-
-  do
-  {
-    /* Save a call if there can be only one row in range. */
-    if (multi_range_curr->range_flag != (UNIQUE_RANGE | EQ_RANGE))
-    {
-      result= read_range_next();
-
-      /* On success or non-EOF errors jump to the end. */
-      if (result != HA_ERR_END_OF_FILE)
-        break;
-    }
-    else
-    {
-      if (was_semi_consistent_read())
-        goto scan_it_again;
-      /*
-        We need to set this for the last range only, but checking this
-        condition is more expensive than just setting the result code.
-      */
-      result= HA_ERR_END_OF_FILE;
-    }
-
-    multi_range_curr++;
-scan_it_again:
-    /* Try the next range(s) until one matches a record. */
-    for (; multi_range_curr < multi_range_end; multi_range_curr++)
-    {
-      result= read_range_first(multi_range_curr->start_key.keypart_map ?
-                               &multi_range_curr->start_key : 0,
-                               multi_range_curr->end_key.keypart_map ?
-                               &multi_range_curr->end_key : 0,
-                               test(multi_range_curr->range_flag & EQ_RANGE),
-                               multi_range_sorted);
-      if (result != HA_ERR_END_OF_FILE)
-        break;
-    }
-  }
-  while ((result == HA_ERR_END_OF_FILE) &&
-         (multi_range_curr < multi_range_end));
-
-  *found_range_p= multi_range_curr;
-  DBUG_PRINT("exit",("handler::read_multi_range_next: result %d", result));
-  DBUG_RETURN(result);
-}
-#endif
 
 /**
   Read first row between two ranges.
diff --git a/sql/handler.h b/sql/handler.h
index 2ad7d61b03b..ed7426b0811 100644
--- a/sql/handler.h
+++ b/sql/handler.h
@@ -1290,15 +1290,6 @@ public:
 
   ha_statistics stats;
 
-  /** The following are for read_multi_range */
-//////psergey: was: 
-#if 0
-  bool multi_range_sorted;
-  KEY_MULTI_RANGE *multi_range_curr;
-  KEY_MULTI_RANGE *multi_range_end;
-  HANDLER_BUFFER *multi_range_buffer;
-#endif
-//////psergey
   /** MultiRangeRead-related members: */
   range_seq_t mrr_iter;    /* Interator to traverse the range sequence */
   RANGE_SEQ_IF mrr_funcs;  /* Range sequence traversal functions */
@@ -1311,7 +1302,6 @@ public:
   bool mrr_have_range;
   /** Current range (the one we're now returning rows from) */
   KEY_MULTI_RANGE mrr_cur_range;
-//////psergey
 
   /** The following are for read_range() */
   key_range save_end_range, *end_range;
@@ -1744,13 +1734,6 @@ public:
       update_index_statistics();
     return error;
   }
-#if 0
-  virtual int read_multi_range_first(KEY_MULTI_RANGE **found_range_p,
-                                     KEY_MULTI_RANGE *ranges, uint range_count,
-                                     bool sorted, HANDLER_BUFFER *buffer);
-  virtual int read_multi_range_next(KEY_MULTI_RANGE **found_range_p);
-#endif 
-  //psergey-mrr: 
   virtual ha_rows multi_range_read_info_const(uint keyno, RANGE_SEQ_IF *seq,
                                               void *seq_init_param, 
                                               uint n_ranges, uint *bufsz,
@@ -1761,7 +1744,6 @@ public:
                                     uint n_ranges, uint mode,
                                     HANDLER_BUFFER *buf);
   virtual int multi_range_read_next(char **range_info);
-  //psergey-mrr: ends
   virtual int read_range_first(const key_range *start_key,
                                const key_range *end_key,
                                bool eq_range, bool sorted);
diff --git a/sql/sql_select.cc b/sql/sql_select.cc
index 434afe8fd69..4ea391cbfa0 100644
--- a/sql/sql_select.cc
+++ b/sql/sql_select.cc
@@ -16734,11 +16734,12 @@ static void select_describe(JOIN *join, bool need_tmp_table, bool need_order,
         if (keyno != MAX_KEY && keyno == table->file->pushed_idx_cond_keyno &&
             table->file->pushed_idx_cond)
           extra.append(STRING_WITH_LEN("; Using index condition"));
-        /**
-        psergey-mrr:
+        /*
+        psergey: enable the below when we backport BKA:
+
         else if (tab->cache_idx_cond)
           extra.append(STRING_WITH_LEN("; Using index condition(BKA)"));
-        **/
+        */
         if (quick_type == QUICK_SELECT_I::QS_TYPE_ROR_UNION || 
             quick_type == QUICK_SELECT_I::QS_TYPE_ROR_INTERSECT ||
             quick_type == QUICK_SELECT_I::QS_TYPE_INDEX_MERGE)
diff --git a/sql/sql_select.h b/sql/sql_select.h
index 0a6702a8135..4945d433fac 100644
--- a/sql/sql_select.h
+++ b/sql/sql_select.h
@@ -780,7 +780,4 @@ inline bool optimizer_flag(THD *thd, uint flag)
 
 void eliminate_tables(JOIN *join);
 
-/// psergey-mrr:
-void push_index_cond(JOIN_TAB *tab, uint keyno, bool other_tbls_ok);
-