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Range optimizer fix:

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If cost(full_scan_on_shortest_covering_index) < cost(best_range_scan) <  cost(full_table_scan)
  use full_scan_on_shortest_covering_index
(before this fix best_range_scan was used)
This commit is contained in:
unknown
2004-06-22 04:47:28 +04:00
parent 6c50d995c1
commit b482176b6d
14 changed files with 36 additions and 36 deletions
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22
sql/opt_range.cc
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@ -1614,6 +1614,17 @@ int SQL_SELECT::test_quick_select(THD *thd, key_map keys_to_use,
}
param.key_parts_end=key_parts;
/* Calculate cost of full index read for the shortest covering index */
if (!head->used_keys.is_clear_all())
{
int key_for_use= find_shortest_key(head, &head->used_keys);
double key_read_time= get_index_only_read_time(&param, records,
key_for_use);
DBUG_PRINT("info", ("'all'+'using index' scan will be using key %d, "
"read time %g", key_for_use, key_read_time));
if (key_read_time < read_time)
read_time= key_read_time;
}
if ((tree=get_mm_tree(&param,cond)))
{
@ -1676,17 +1687,6 @@ int SQL_SELECT::test_quick_select(THD *thd, key_map keys_to_use,
TABLE_READ_PLAN *best_conj_trp= NULL, *new_conj_trp;
LINT_INIT(new_conj_trp); /* no empty index_merge lists possible */
/* Calculate cost of full index read for the shortest covering index */
if (!head->used_keys.is_clear_all())
{
int key_for_use= find_shortest_key(head, &head->used_keys);
double key_read_time= get_index_only_read_time(&param, records,
key_for_use);
DBUG_PRINT("info", ("'all'+'using index' scan will be using key %d, "
"read time %g", key_for_use, key_read_time));
if (key_read_time < read_time)
read_time= key_read_time;
}
DBUG_PRINT("info",("No range reads possible,"
" trying to construct index_merge"));