mirror/mariadb
1
0
Fork 0
mirror of https://github.com/MariaDB/server.git synced 2025-01-31 02:51:44 +01:00
Code Issues Projects Releases Packages Wiki Activity Actions

Merge heikki@work.mysql.com:/home/my/mysql

Browse source 
into donna.mysql.fi:/home/heikki/mysqln
This commit is contained in:
heikki@donna.mysql.fi 2002-02-03 15:15:13 +02:00
commit 4f3e7f68f5
2 changed files with 19 additions and 17 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

20
innobase/btr/btr0cur.c
View file

@ -2552,6 +2552,7 @@ btr_estimate_number_of_different_key_vals(
ulint total_external_size = 0;
ulint i;
ulint j;
ulint add_on;
mtr_t mtr;
n_cols = dict_index_get_n_unique(index);
@ -2624,8 +2625,25 @@ btr_estimate_number_of_different_key_vals(
+ not_empty_flag)
/ (BTR_KEY_VAL_ESTIMATE_N_PAGES
+ total_external_size);
}
/* If the tree is small, smaller than <
10 * BTR_KEY_VAL_ESTIMATE_N_PAGES + total_external_size, then
the above estimate is ok. For bigger trees it is common that we
do not see any borders between key values in the few pages
we pick. But still there may be BTR_KEY_VAL_ESTIMATE_N_PAGES
different key values, or even more. Let us try to approximate
that: */
add_on = index->stat_n_leaf_pages /
(10 * (BTR_KEY_VAL_ESTIMATE_N_PAGES + total_external_size));
if (add_on > BTR_KEY_VAL_ESTIMATE_N_PAGES) {
add_on = BTR_KEY_VAL_ESTIMATE_N_PAGES;
}
index->stat_n_diff_key_vals[j] += add_on;
}
mem_free(n_diff);
}

16
sql/ha_innobase.cc
View file

@ -3130,22 +3130,6 @@ ha_innobase::info(
rec_per_key = 1;
}
/* Since the MySQL optimizer is often too
pessimistic in the assumption that a table
does not fit in the buffer pool, we
increase the attractiveness of indexes
by assuming the selectivity of any prefix
of an index is 1 / 100 or better.
(Actually, we should look at the table
size, and if the table is smaller than
the buffer pool, we should uniformly
increase the attractiveness of indexes,
regardless of the estimated selectivity.) */
if (rec_per_key > records / 100) {
rec_per_key = records / 100;
}
table->key_info[i].rec_per_key[j]
= rec_per_key;
}