From: Date: January 29 2007 3:07pm Subject: bk commit into 5.1 tree (mhansson:1.2409) BUG#20604 List-Archive: http://lists.mysql.com/commits/18946 X-Bug: 20604 Message-Id: <20070129140717.E400A21D82@linux-st28.site> Below is the list of changes that have just been committed into a local 5.1 repository of martin. When martin does a push these changes will be propagated to the main repository and, within 24 hours after the push, to the public repository. For information on how to access the public repository see http://dev.mysql.com/doc/mysql/en/installing-source-tree.html ChangeSet@stripped, 2007-01-29 15:07:11+01:00, mhansson@stripped +5 -0 BUG#20604: FORCE INDEX uses keys disabled by ALTER TABLE The function that checks whether we can use keys for aggregates, find_key_for_maxmin(), assumes that keys disabled by ALTER TABLE ... DISABLE KEYS are not in the set table->keys_in_use_for_query. I.E., if a key is in this set, the optimizer assumes it is free to use it. The bug is that keys disabled with ALTER TABLE ... DISABLE KEYS still appear in table->keys_in_use_for_query When the TABLE object has been initialized with setup_tables(). Before setup_tables is called, however, keys that are disabled in the aforementioned way are not included in TABLE::keys_in_use_for_query. The provided patch changes the code that updates keys_is_use_for_query so that it assumes that keys_is_use_for_query already takes into account all disabled keys, and generally all keys that should be used by the query. mysql-test/r/key.result@stripped, 2007-01-29 15:07:08+01:00, mhansson@stripped +7 -0 Test for BUG#20604. The important part of the test is the explain output that tests what indexes are used. mysql-test/t/key.test@stripped, 2007-01-29 15:07:08+01:00, mhansson@stripped +11 -0 The minimal test case that reveals the bug. The optimizer for aggregates relies on keys disabled with ALTER TABLE ... DISABLE KEYS not being in the set TABLE::keys_in_use_for_query. When the execution engine tries to use a disabled index, MyISAM returns an error. sql/sql_base.cc@stripped, 2007-01-29 15:07:08+01:00, mhansson@stripped +6 -1 Exclude the keys disabled by ALTER TABLE ... DISABLE_KEYS from TABLE::keys_in_use_for_query, and in general, don't introduce any new keys. We may not know why keys have been removed at previous stages. sql/sql_select.cc@stripped, 2007-01-29 15:07:08+01:00, mhansson@stripped +6 -5 The intersection operation between table->s->keys_in_use and table->keys_in_use_for_query is no longer necessary. We can trust that the latter is a subset of the former. sql/table.h@stripped, 2007-01-29 15:07:09+01:00, mhansson@stripped +21 -2 Added comments to TABLE_SHARE::keys_in_use and TABLE::keys_in_use_for_query. # This is a BitKeeper patch. What follows are the unified diffs for the # set of deltas contained in the patch. The rest of the patch, the part # that BitKeeper cares about, is below these diffs. # User: mhansson # Host: linux-st28.site # Root: /home/martin/mysql/src/5.1o-bug20604-tp --- 1.372/sql/sql_base.cc 2007-01-24 16:51:05 +01:00 +++ 1.373/sql/sql_base.cc 2007-01-29 15:07:08 +01:00 @@ -5462,7 +5462,12 @@ bool setup_tables(THD *thd, Name_resolut get_key_map_from_key_list(&map, table, table_list->use_index); if (map.is_set_all()) DBUG_RETURN(1); - table->keys_in_use_for_query=map; + /* + Don't introduce keys in keys_in_use_for_query that weren't there + before. FORCE/USE INDEX should not add keys, it should only remove + all keys except the key(s) specified in the hint. + */ + table->keys_in_use_for_query.intersect(map); } if (table_list->ignore_index) { --- 1.485/sql/sql_select.cc 2007-01-25 00:30:31 +01:00 +++ 1.486/sql/sql_select.cc 2007-01-29 15:07:08 +01:00 @@ -12262,13 +12262,14 @@ test_if_skip_sort_order(JOIN_TAB *tab,OR DBUG_ENTER("test_if_skip_sort_order"); LINT_INIT(ref_key_parts); + /* Check which keys can be used to resolve ORDER BY. */ + usable_keys= table->keys_in_use_for_query; + /* - Check which keys can be used to resolve ORDER BY. - We must not try to use disabled keys. + Keys disabled by ALTER TABLE ... DISABLE KEYS should have already + been taken into account. */ - usable_keys= table->s->keys_in_use; - /* we must not consider keys that are disabled by IGNORE INDEX */ - usable_keys.intersect(table->keys_in_use_for_query); + DBUG_ASSERT(usable_keys.is_subset(table->s->keys_in_use)); for (ORDER *tmp_order=order; tmp_order ; tmp_order=tmp_order->next) { --- 1.158/sql/table.h 2007-01-15 10:39:27 +01:00 +++ 1.159/sql/table.h 2007-01-29 15:07:09 +01:00 @@ -158,7 +158,12 @@ typedef struct st_table_share LEX_STRING path; /* Path to .frm file (from datadir) */ LEX_STRING normalized_path; /* unpack_filename(path) */ LEX_STRING connect_string; - key_map keys_in_use; /* Keys in use for table */ + + /* + Set of keys in use, implemented as a Bitmap. + Excludes keys disabled by ALTER TABLE ... DISABLE KEYS. + */ + key_map keys_in_use; key_map keys_for_keyread; ha_rows min_rows, max_rows; /* create information */ ulong avg_row_length; /* create information */ @@ -313,7 +318,21 @@ struct st_table { byte *write_row_record; /* Used as optimisation in THD::write_row */ byte *insert_values; /* used by INSERT ... UPDATE */ - key_map quick_keys, used_keys, keys_in_use_for_query, merge_keys; + key_map quick_keys, used_keys; + + /* + A set of keys that can be used in the query that references this + table + + All indexes disabled on the table's TABLE_SHARE (see TABLE::s) will be + subtracted from this set upon instantiation. Thus for any TABLE t it holds + that t.keys_in_use_for_query is a subset of t.s.keys_in_use. Generally we + must not introduce any new keys here (see setup_tables). + + The set is implemented as a bitmap. + */ + key_map keys_in_use_for_query; + key_map merge_keys; KEY *key_info; /* data of keys in database */ Field *next_number_field; /* Set if next_number is activated */ --- 1.40/mysql-test/r/key.result 2006-08-11 23:06:20 +02:00 +++ 1.41/mysql-test/r/key.result 2007-01-29 15:07:08 +01:00 @@ -482,3 +482,10 @@ alter table t1 drop index i3, drop index alter table t1 add index i3 (c3), add index i2 (c2), add unique index i1 (c1); ERROR 23000: Duplicate entry '1' for key 'i1' drop table t1; +CREATE TABLE t1( a TINYINT, KEY(a) ) ENGINE=MyISAM; +INSERT INTO t1 VALUES( 1 ); +ALTER TABLE t1 DISABLE KEYS; +EXPLAIN SELECT MAX(a) FROM t1 FORCE INDEX(a); +id select_type table type possible_keys key key_len ref rows Extra +1 SIMPLE t1 system NULL NULL NULL NULL 1 +drop table t1; --- 1.31/mysql-test/t/key.test 2006-07-20 20:41:52 +02:00 +++ 1.32/mysql-test/t/key.test 2007-01-29 15:07:08 +01:00 @@ -442,3 +442,14 @@ alter table t1 drop index i3, drop index alter table t1 add index i3 (c3), add index i2 (c2), add unique index i1 (c1); drop table t1; + +# +# Bug #20604: Test for disabled keys with aggregate functions and FORCE INDEX. +# + +CREATE TABLE t1( a TINYINT, KEY(a) ) ENGINE=MyISAM; +INSERT INTO t1 VALUES( 1 ); +ALTER TABLE t1 DISABLE KEYS; +EXPLAIN SELECT MAX(a) FROM t1 FORCE INDEX(a); + +drop table t1;