fixs for A/R

5 files changed, 55 insertions, 48 deletions

diff --git a/storage/innobase/btr/btr0cur.cc b/storage/innobase/btr/btr0cur.cc
index 255ab481b44..07d70688976 100644
--- a/storage/innobase/btr/btr0cur.cc
+++ b/storage/innobase/btr/btr0cur.cc
@@ -2850,14 +2850,17 @@ btr_cur_open_at_index_side(
 /**********************************************************************//**
 Positions a cursor at a randomly chosen position within a B-tree.
 @return true if the index is available and we have put the cursor, false
-if the index is unavailable */
+if the index is unavailable. Cursor->page_cur->rec can be null if
+simulate_uniform=true, which means that no record is chosen in the
+generated tree path. The caller should retry a call, that will
+try a new tree path */
 bool
 btr_cur_open_at_rnd_pos(
-	dict_index_t*	index,		/*!< in: index */
-	ulint		latch_mode,     /*!< in: BTR_SEARCH_LEAF, ... */
-	btr_cur_t*	cursor,		/*!< in/out: B-tree cursor */
-	mtr_t*		mtr,            /*!< in: mtr */
-        bool* probability_correctness)  /*!< out: flag for A/R check */
+	dict_index_t*	index,	    /*!< in: index */
+	ulint		latch_mode, /*!< in: BTR_SEARCH_LEAF, ... */
+	btr_cur_t*	cursor,	    /*!< in/out: B-tree cursor */
+	mtr_t*		mtr,        /*!< in: mtr */
+        bool simulate_uniform)      /*!< in: flag for uniform simulation */
 {
 	page_cur_t*	page_cursor;
 	ulint		node_ptr_max_size = srv_page_size / 2;
@@ -2869,11 +2872,10 @@ btr_cur_open_at_rnd_pos(
 	ulint		n_blocks = 0;
 	ulint		n_releases = 0;
 	mem_heap_t*	heap		= NULL;
+        bool            start_move_down = true;
+        double          p = 1.0;
 	rec_offs	offsets_[REC_OFFS_NORMAL_SIZE];
 	rec_offs*	offsets		= offsets_;
-        *probability_correctness = true;
-        bool start_move_down = true;
-        double p = 1.0;
 	rec_offs_init(offsets_);
 
 	ut_ad(!index->is_spatial());
@@ -3041,14 +3043,18 @@ btr_cur_open_at_rnd_pos(
 				}
 			}
 		}
-                if(!start_move_down) {
-                    ulint n_recs = page_get_n_recs(block->page.frame);
-                    double max_fanout = (double)srv_page_size /
-                                (REC_N_NEW_EXTRA_BYTES + 1);
-                    p *= (double)n_recs / max_fanout;
-                } else {
-                  start_move_down= false;
+
+                if(simulate_uniform) {
+                        if(!start_move_down) {
+                                ulint n_recs = page_get_n_recs(block->page.frame);
+                                double max_fanout = (double)srv_page_size /
+                                                   (REC_N_NEW_EXTRA_BYTES + 1);
+                                p *= (double)n_recs / max_fanout;
+                        } else {
+                                start_move_down= false;
+                        }
                 }
+
                 page_cur_open_on_rnd_user_rec(block, page_cursor);
 
 		if (height == 0) {
@@ -3145,8 +3151,8 @@ btr_cur_open_at_rnd_pos(
 	}
 
         double rand_uniform = (double)(rand() / (double(RAND_MAX)));
-        if(rand_uniform < p)
-          *probability_correctness = false;
+        if(simulate_uniform&& rand_uniform < p)
+                page_cursor->rec = NULL;
 
 	return err == DB_SUCCESS;
 }
diff --git a/storage/innobase/handler/ha_innodb.cc b/storage/innobase/handler/ha_innodb.cc
index 3ea5968d50d..e0480cfa4ba 100644
--- a/storage/innobase/handler/ha_innodb.cc
+++ b/storage/innobase/handler/ha_innodb.cc
@@ -9527,35 +9527,28 @@ ha_innobase::sample_next(
   rec_offs_init(offsets_);
 
   dict_index_t*	index= innobase_get_index(MAX_KEY);
-  bool probability_correctness;
   do {
     mtr.start();
-    res= btr_pcur_open_at_rnd_pos(index, BTR_SEARCH_LEAF, pcur, &mtr, &probability_correctness);
+    res= btr_pcur_open_at_rnd_pos(index, BTR_SEARCH_LEAF, pcur, &mtr, true);
     mtr.commit();
     if(!res)
     {
       return HA_ERR_KEY_NOT_FOUND;
     }
-  } while (!probability_correctness);
-
-  rec= btr_pcur_get_rec(pcur);
+  } while (!(rec= btr_pcur_get_rec(pcur)));
 
   mem_heap_t*	heap= NULL;
+  auto _ = make_scope_exit([heap]() { if(heap) mem_heap_free(heap); });
+
   offsets= rec_get_offsets(rec, index, offsets, index->n_core_fields, ULINT_UNDEFINED, &heap);
   ut_ad(offsets);
   if (!offsets)
-  {
-    if (heap)
-      mem_heap_free(heap);
     return HA_ERR_INTERNAL_ERROR;
-  }
 
   res= row_sel_store_mysql_rec(
       buf, m_prebuilt, rec, NULL, true,
       index, offsets);
 
-  if(heap)
-    mem_heap_free(heap);
   return res ? 0 : HA_ERR_INTERNAL_ERROR;
 }
 
diff --git a/storage/innobase/include/btr0cur.h b/storage/innobase/include/btr0cur.h
index e9f4b2599d3..25bc8a40752 100644
--- a/storage/innobase/include/btr0cur.h
+++ b/storage/innobase/include/btr0cur.h
@@ -208,14 +208,16 @@ btr_cur_open_at_index_side(
 /**********************************************************************//**
 Positions a cursor at a randomly chosen position within a B-tree.
 @return true if the index is available and we have put the cursor, false
-if the index is unavailable */
+if the index is unavailable. Cursor->page_cur->rec can be null if
+simulate_uniform=true,which means that no record is chosen in the generated
+tree path. The caller should retry a call, that will try a new tree path */
 bool
 btr_cur_open_at_rnd_pos(
-	dict_index_t*	index,		       /*!< in: index */
-	ulint		latch_mode,	       /*!< in: BTR_SEARCH_LEAF, ... */
-	btr_cur_t*	cursor,		       /*!< in/out: B-tree cursor */
-	mtr_t*		mtr,                   /*!< in: mtr */
-        bool* probability_correctness = NULL); /*!< out: flag for A/R check */
+	dict_index_t*	index,	        /*!< in: index */
+	ulint		latch_mode,     /*!< in: BTR_SEARCH_LEAF, ... */
+	btr_cur_t*	cursor,         /*!< in/out: B-tree cursor */
+	mtr_t*		mtr,            /*!< in: mtr */
+        bool simulate_uniform= false);  /*!< in: flag for uniform simulation */
 /*************************************************************//**
 Tries to perform an insert to a page in an index tree, next to cursor.
 It is assumed that mtr holds an x-latch on the page. The operation does
diff --git a/storage/innobase/include/btr0pcur.h b/storage/innobase/include/btr0pcur.h
index 121da578800..bd45f57225e 100644
--- a/storage/innobase/include/btr0pcur.h
+++ b/storage/innobase/include/btr0pcur.h
@@ -201,15 +201,18 @@ btr_pcur_open_on_user_rec(
 /**********************************************************************//**
 Positions a cursor at a randomly chosen position within a B-tree.
 @return true if the index is available and we have put the cursor, false
-if the index is unavailable */
+if the index is unavailable. Cursor->btr_cur->page_cur->rec can be null if
+simulate_uniform=true, which means that no record is chosen in the
+generated tree path. The caller should retry a call, that will
+try a new tree path */
 UNIV_INLINE
 bool
 btr_pcur_open_at_rnd_pos(
-	dict_index_t*	index,		/*!< in: index */
-	ulint		latch_mode,	/*!< in: BTR_SEARCH_LEAF, ... */
-	btr_pcur_t*	cursor,		/*!< in/out: B-tree pcur */
-	mtr_t*		mtr,		/*!< in: mtr */
-	bool* probability_correctness = NULL); /*!< out: flag for A/R check */
+	dict_index_t*	index,	       /*!< in: index */
+	ulint		latch_mode,    /*!< in: BTR_SEARCH_LEAF, ... */
+	btr_pcur_t*	cursor,	       /*!< in/out: B-tree pcur */
+	mtr_t*		mtr,	       /*!< in: mtr */
+	bool simulate_uniform= false); /*!< in: flag for uniform simulation */
 /**************************************************************//**
 Frees the possible memory heap of a persistent cursor and sets the latch
 mode of the persistent cursor to BTR_NO_LATCHES.
diff --git a/storage/innobase/include/btr0pcur.inl b/storage/innobase/include/btr0pcur.inl
index 4ca256733e0..84fb1b4fa13 100644
--- a/storage/innobase/include/btr0pcur.inl
+++ b/storage/innobase/include/btr0pcur.inl
@@ -480,15 +480,18 @@ btr_pcur_open_at_index_side(
 /**********************************************************************//**
 Positions a cursor at a randomly chosen position within a B-tree.
 @return true if the index is available and we have put the cursor, false
-if the index is unavailable */
+if the index is unavailable. Cursor->btr_cur->page_cur->rec can be null if
+simulate_uniform=true, which means that no record is chosen in the
+generated tree path. The caller should retry a call, that will
+try a new tree path */
 UNIV_INLINE
 bool
 btr_pcur_open_at_rnd_pos(
-	dict_index_t*	index,		/*!< in: index */
-	ulint		latch_mode,	/*!< in: BTR_SEARCH_LEAF, ... */
-	btr_pcur_t*	cursor,		/*!< in/out: B-tree pcur */
-	mtr_t*		mtr,		/*!< in: mtr */
-	bool* probability_correctness) /*!< out: flag for A/R check */
+	dict_index_t*	index,	    /*!< in: index */
+	ulint		latch_mode, /*!< in: BTR_SEARCH_LEAF, ... */
+	btr_pcur_t*	cursor,	    /*!< in/out: B-tree pcur */
+	mtr_t*		mtr,	    /*!< in: mtr */
+	bool simulate_uniform)      /*!< in: flag for uniform simulation */
 {
 	/* Initialize the cursor */
 
@@ -501,7 +504,7 @@ btr_pcur_open_at_rnd_pos(
 
 	available = btr_cur_open_at_rnd_pos(index, latch_mode,
 					    btr_pcur_get_btr_cur(cursor),
-					    mtr, probability_correctness);
+					    mtr, simulate_uniform);
 	cursor->pos_state = BTR_PCUR_IS_POSITIONED;
 	cursor->old_stored = false;