bk commit into 5.1 tree (mhansson:1.2518) BUG#28570

[mhansson]

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ChangeSet@stripped, 2007-06-04 13:55:30+03:00, mhansson@stripped +4 -0
  bug#28570: handler::index_read() is called with different find_flag when ORDER BY is
used
  
  Problem 1: When called with a range representing a ref access, the handler calls the 
  engine with the find flag HA_READ_KEY_OR_NEXT when it should use HA_READ_KEY_EXACT,
which 
  causes lock waits on InnoDB. This happens when ORDER BY is used along with an equality
  predicate.
  
  Problem 2: The range analysis module does not correctly signal to the handler that a 
  range represents a ref (EQ_RANGE flag)
  
  Problem 2 fixed by setting EQ_RANGE for all range accesses that represent an equality 
  predicate. 
  
  Problem 1 fixed by making the handler call the storage engine with HA_READ_KEY_EXACT
when
  a range really represents a ref.

  mysql-test/r/innodb_mysql.result@stripped, 2007-06-04 13:55:22+03:00,
mhansson@stripped +18 -0
    bug#28570: Test Result

  mysql-test/t/innodb_mysql.test@stripped, 2007-06-04 13:55:22+03:00, mhansson@stripped
+30 -0
    bug#28570: Test Case

  sql/handler.cc@stripped, 2007-06-04 13:55:22+03:00, mhansson@stripped +7 -1
    bug#28570: Added case to read only exact match for the search key if the range is the 
    interval [x, x], which is more efficient on MyISAM, and avoids lock wait on InnoDB.

  sql/opt_range.cc@stripped, 2007-06-04 13:55:22+03:00, mhansson@stripped +1 -2
    bug#28570: Removed the criterion that key has to be unique (HA_NOSAME) in order for
the 
    EQ_RANGE flag to be set. It is sufficient that the range represents a ref access.

# 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-bug28570

--- 1.309/sql/handler.cc	2007-05-24 14:11:20 +03:00
+++ 1.310/sql/handler.cc	2007-06-04 13:55:22 +03:00
@@ -3204,7 +3204,8 @@ int handler::read_multi_range_next(KEY_M
     read_range_first()
     start_key		Start key. Is 0 if no min range
     end_key		End key.  Is 0 if no max range
-    eq_range_arg	Set to 1 if start_key == end_key		
+    eq_range_arg	Set to 1 if start_key == end_key and the range endpoints
+			will not change during execution.
     sorted		Set to 1 if result should be sorted per key
 
   NOTES
@@ -3235,6 +3236,11 @@ int handler::read_range_first(const key_
 
   if (!start_key)			// Read first record
     result= index_first(table->record[0]);
+  else if(eq_range_arg)
+    result= index_read(table->record[0],
+                       start_key->key,
+                       start_key->keypart_map,
+                       HA_READ_KEY_EXACT);
   else
     result= index_read(table->record[0],
 		       start_key->key,

--- 1.274/sql/opt_range.cc	2007-05-24 01:39:21 +03:00
+++ 1.275/sql/opt_range.cc	2007-06-04 13:55:22 +03:00
@@ -7805,8 +7805,7 @@ QUICK_RANGE_SELECT *get_quick_select_for
   range->min_keypart_map= range->max_keypart_map=
     make_prev_keypart_map(ref->key_parts);
   range->flag= ((ref->key_length == key_info->key_length &&
-		 (key_info->flags & (HA_NOSAME | HA_END_SPACE_KEY)) ==
-		 HA_NOSAME) ? EQ_RANGE : 0);
+		 (key_info->flags & HA_END_SPACE_KEY) == 0) ? EQ_RANGE : 0);
 
   if (!(quick->key_parts=key_part=(KEY_PART *)
 	alloc_root(&quick->alloc,sizeof(KEY_PART)*ref->key_parts)))

--- 1.34/mysql-test/r/innodb_mysql.result	2007-05-29 15:57:28 +03:00
+++ 1.35/mysql-test/r/innodb_mysql.result	2007-06-04 13:55:22 +03:00
@@ -818,3 +818,21 @@ alter table t2 modify i int default 4, r
 unlock tables;
 drop table t1;
 End of 5.1 tests
+CREATE TABLE t1 (
+a INT,
+b INT,
+KEY (b)
+) ENGINE=InnoDB;
+INSERT INTO t1 VALUES (1,10), (2,10), (2,20), (3,30);
+START TRANSACTION;
+SELECT * FROM t1 WHERE b=20 FOR UPDATE;
+a	b
+2	20
+START TRANSACTION;
+SELECT * FROM t1 WHERE b=10 ORDER BY A FOR UPDATE;
+a	b
+1	10
+2	10
+ROLLBACK;
+ROLLBACK;
+DROP TABLE t1;

--- 1.3/mysql-test/t/innodb_mysql.test	2006-09-18 17:55:52 +03:00
+++ 1.4/mysql-test/t/innodb_mysql.test	2007-06-04 13:55:22 +03:00
@@ -12,3 +12,33 @@ let $other_engine_type= MEMORY;
 let $test_foreign_keys= 1;
 
 --source include/mix1.inc
+
+#
+# Bug #28570: handler::index_read() is called with different find_flag when 
+# ORDER BY is used
+#
+
+CREATE TABLE t1 (
+  a INT,
+  b INT,
+  KEY (b)
+) ENGINE=InnoDB;
+
+INSERT INTO t1 VALUES (1,10), (2,10), (2,20), (3,30);
+
+START TRANSACTION;
+SELECT * FROM t1 WHERE b=20 FOR UPDATE;
+
+--connect (conn2, localhost, root,,test)
+
+# This statement gives a "failed: 1205: Lock wait timeout exceeded; try 
+# restarting transaction" message when the bug is present.
+START TRANSACTION;
+SELECT * FROM t1 WHERE b=10 ORDER BY A FOR UPDATE;
+ROLLBACK;
+
+--disconnect conn2
+--connection default
+
+ROLLBACK;
+DROP TABLE t1;