Commit 3652fe78 authored by heikki@hundin.mysql.fi's avatar heikki@hundin.mysql.fi
Browse files

btr0cur.c: 

  Fix bug: range estimator exaggerated small range size greatly if the paths in the B-tree happened to branch on a high level
parent b2fb75b5

innobase/btr/btr0cur.c

+36 −8
Original line number Diff line number Diff line
@@ -2547,6 +2547,7 @@ btr_estimate_n_rows_in_range( 
	btr_path_t*	slot1;

	btr_path_t*	slot2;

	ibool		diverged;

	ibool           diverged_lot;

	ulint           divergence_level;           

	ib_longlong	n_rows;

	ulint		i;
@@ -2589,9 +2590,12 @@ btr_estimate_n_rows_in_range( 
	/* We have the path information for the range in path1 and path2 */



	n_rows = 1;

	diverged = FALSE;

	divergence_level = 1000000;

	

	diverged = FALSE;           /* This becomes true when the path is not

				    the same any more */

	diverged_lot = FALSE;       /* This becomes true when the paths are

				    not the same or adjacent any more */

	divergence_level = 1000000; /* This is the level where paths diverged

				    a lot */ 

       	for (i = 0; ; i++) {

		ut_ad(i < BTR_PATH_ARRAY_N_SLOTS);
@@ -2620,7 +2624,7 @@ btr_estimate_n_rows_in_range( 
				then we estimate all rows are in the range */

			  

			        if (n_rows == 0) {

			                n_rows = index->table->stat_n_rows;

				        n_rows = index->table->stat_n_rows / 2;

			        }

			}
@@ -2629,8 +2633,15 @@ btr_estimate_n_rows_in_range( 


		if (!diverged && slot1->nth_rec != slot2->nth_rec) {



			diverged = TRUE;



			if (slot1->nth_rec < slot2->nth_rec) {

				n_rows = slot2->nth_rec - slot1->nth_rec;



				if (n_rows > 1) {

				          diverged_lot = TRUE;

					  divergence_level = i;

				}

			} else {

				/* Maybe the tree has changed between

				searches */
@@ -2638,10 +2649,27 @@ btr_estimate_n_rows_in_range( 
				return(10);

			}



		} else if (diverged && !diverged_lot) {



		        if (slot1->nth_rec < slot1->n_recs

		            || slot2->nth_rec > 1) {



		                diverged_lot = TRUE;

				divergence_level = i;



			diverged = TRUE;

		} else if (diverged) {

				n_rows = 0;



		                if (slot1->nth_rec < slot1->n_recs) {

				        n_rows += slot1->n_recs

					             - slot1->nth_rec;

				}



				if (slot2->nth_rec > 1) {

				        n_rows += slot2->nth_rec - 1;

				}

      			}

		} else if (diverged_lot) {



			n_rows = (n_rows * (slot1->n_recs + slot2->n_recs))

									/ 2;

		}