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btr0cur.c:

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


innobase/btr/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
This commit is contained in:
unknown 2002-10-16 00:05:14 +03:00
parent e24c5ce701
commit 09ab0dded2
1 changed files with 36 additions and 8 deletions
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44
innobase/btr/btr0cur.c
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@ -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;
@ -2589,10 +2590,13 @@ 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;
for (i = 0; ; i++) {
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);
slot1 = path1 + i;
@ -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);
}
divergence_level = i;
} else if (diverged && !diverged_lot) {
if (slot1->nth_rec < slot1->n_recs
|| slot2->nth_rec > 1) {
diverged_lot = TRUE;
divergence_level = i;
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) {
diverged = TRUE;
} else if (diverged) {
n_rows = (n_rows * (slot1->n_recs + slot2->n_recs))
/ 2;
}