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ChangeSet@stripped, 2006-10-16 19:30:19+03:00, gkodinov@stripped +4 -0
Bug #22342: No results returned for query using max and group by
When using index for group by and range access the server isolates
a set of ranges based on the conditions over the key parts of the
index used. Then it uses only the ranges over the GROUP BY fields to
jump from one group to another. Since the GROUP BY fields may form a
prefix over the index, we may use only a prefix of the ranges produced
by the range optimizer.
Each range contains a notion on whether it includes its border values.
The problem is that when using a range prefix, the last range is open
because it assumes that there is a range on the next keypart. Thus when
we use a prefix range as it is, it excludes all border values.
The solution is when ignoring the suffix of the range conditions
(to jump over the GROUP BY prefix only) the server must change the
remaining intervals so they always contain their borders, e.g.
if the whole range was :
(1,-inf) <= (<group_by_col>,<min_max_arg_col>) < (1, 3) we must make
(1) <= (<group_by_col>) <= (1) because (a,b) < (c1,c2) means :
a < c1 OR (a = c1 AND b < c2).
mysql-test/r/group_min_max.result@stripped, 2006-10-16 19:30:12+03:00, gkodinov@stripped +20 -0
Bug #22342: No results returned for query using max and group by
- test case
mysql-test/t/group_min_max.test@stripped, 2006-10-16 19:30:13+03:00, gkodinov@stripped +16 -0
Bug #22342: No results returned for query using max and group by
- test case
sql/opt_range.cc@stripped, 2006-10-16 19:30:14+03:00, gkodinov@stripped +37 -0
Bug #22342: No results returned for query using max and group by
- open the intervals for prefix select when there are more conditions
than used for the prefix search.
sql/opt_range.h@stripped, 2006-10-16 19:30:14+03:00, gkodinov@stripped +2 -0
Bug #22342: No results returned for query using max and group by
- open the intervals for prefix select when there are more conditions
than used for the prefix search.
# 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: gkodinov
# Host: macbook.gmz
# Root: /Users/kgeorge/mysql/work/B22342-5.0-opt
--- 1.225/sql/opt_range.cc 2006-10-16 19:30:35 +03:00
+++ 1.226/sql/opt_range.cc 2006-10-16 19:30:35 +03:00
@@ -8374,6 +8374,7 @@ TRP_GROUP_MIN_MAX::make_quick(PARAM *par
quick->quick_prefix_select= NULL;
quick->update_key_stat();
+ quick->adjust_prefix_ranges();
DBUG_RETURN(quick);
}
@@ -8600,6 +8601,42 @@ bool QUICK_GROUP_MIN_MAX_SELECT::add_ran
if (insert_dynamic(&min_max_ranges, (gptr)&range))
return TRUE;
return FALSE;
+}
+
+
+/*
+ Opens the ranges if there are more conditions in quick_prefix_select than
+ the ones used for jumping through the prefixes.
+
+ SYNOPSIS
+ QUICK_GROUP_MIN_MAX_SELECT::adjust_prefix_ranges()
+
+ NOTES
+ quick_prefix_select is made over the conditions on the whole key.
+ It defines a number of ranges of length x.
+ However when jumping through the prefixes we use only the the first
+ few most significant keyparts in the range key. However if there
+ are more keyparts to follow the ones we are using we must make the
+ condition on the key inclusive (because x < "ab" means
+ x[0] < 'a' OR (x[0] == 'a' AND x[1] < 'b').
+ To achive the above we must turn off the NEAR_MIN/NEAR_MAX
+*/
+void QUICK_GROUP_MIN_MAX_SELECT::adjust_prefix_ranges ()
+{
+ if (quick_prefix_select &&
+ group_prefix_len < quick_prefix_select->max_used_key_length)
+ {
+ DYNAMIC_ARRAY *arr;
+ uint inx;
+
+ for (inx= 0, arr= &quick_prefix_select->ranges; inx < arr->elements; inx++)
+ {
+ QUICK_RANGE *range;
+
+ get_dynamic(arr, (gptr)&range, inx);
+ range->flag &= ~(NEAR_MIN | NEAR_MAX);
+ }
+ }
}
--- 1.62/sql/opt_range.h 2006-10-16 19:30:35 +03:00
+++ 1.63/sql/opt_range.h 2006-10-16 19:30:35 +03:00
@@ -294,6 +294,7 @@ protected:
friend class QUICK_SELECT_DESC;
friend class QUICK_INDEX_MERGE_SELECT;
friend class QUICK_ROR_INTERSECT_SELECT;
+ friend class QUICK_GROUP_MIN_MAX_SELECT;
DYNAMIC_ARRAY ranges; /* ordered array of range ptrs */
QUICK_RANGE **cur_range; /* current element in ranges */
@@ -642,6 +643,7 @@ public:
~QUICK_GROUP_MIN_MAX_SELECT();
bool add_range(SEL_ARG *sel_range);
void update_key_stat();
+ void adjust_prefix_ranges();
bool alloc_buffers();
int init();
int reset();
--- 1.25/mysql-test/r/group_min_max.result 2006-10-16 19:30:35 +03:00
+++ 1.26/mysql-test/r/group_min_max.result 2006-10-16 19:30:35 +03:00
@@ -2142,3 +2142,23 @@ t1;
id2 id3 id5 id4 id3 id6 id5 id1
1 1 1 1 1 1 1 1
DROP TABLE t1,t2,t3,t4,t5,t6;
+CREATE TABLE t1 (a int, b int, PRIMARY KEY (a,b), KEY b (b));
+INSERT INTO t1 VALUES (1,1),(1,2);
+explain SELECT MAX(b), a FROM t1 WHERE b < 2 AND a = 1 GROUP BY a;
+id select_type table type possible_keys key key_len ref rows Extra
+1 SIMPLE t1 range PRIMARY,b PRIMARY 8 NULL 2 Using where; Using index for group-by
+SELECT MAX(b), a FROM t1 WHERE b < 2 AND a = 1 GROUP BY a;
+MAX(b) a
+1 1
+SELECT MIN(b), a FROM t1 WHERE b > 1 AND a = 1 GROUP BY a;
+MIN(b) a
+2 1
+CREATE TABLE t2 (a int, b int, c int, PRIMARY KEY (a,b,c));
+INSERT INTO t2 SELECT a,b,b FROM t1;
+explain SELECT MIN(c) FROM t2 WHERE b = 2 and a = 1 and c > 1 GROUP BY a;
+id select_type table type possible_keys key key_len ref rows Extra
+1 SIMPLE t2 range PRIMARY PRIMARY 12 NULL 2 Using where; Using index for group-by
+SELECT MIN(c) FROM t2 WHERE b = 2 and a = 1 and c > 1 GROUP BY a;
+MIN(c)
+2
+DROP TABLE t1,t2;
--- 1.23/mysql-test/t/group_min_max.test 2006-10-16 19:30:35 +03:00
+++ 1.24/mysql-test/t/group_min_max.test 2006-10-16 19:30:35 +03:00
@@ -794,3 +794,19 @@ SELECT * FROM
t1;
DROP TABLE t1,t2,t3,t4,t5,t6;
+
+#
+# Bug#22342: No results returned for query using max and group by
+#
+CREATE TABLE t1 (a int, b int, PRIMARY KEY (a,b), KEY b (b));
+INSERT INTO t1 VALUES (1,1),(1,2);
+
+explain SELECT MAX(b), a FROM t1 WHERE b < 2 AND a = 1 GROUP BY a;
+SELECT MAX(b), a FROM t1 WHERE b < 2 AND a = 1 GROUP BY a;
+SELECT MIN(b), a FROM t1 WHERE b > 1 AND a = 1 GROUP BY a;
+CREATE TABLE t2 (a int, b int, c int, PRIMARY KEY (a,b,c));
+INSERT INTO t2 SELECT a,b,b FROM t1;
+explain SELECT MIN(c) FROM t2 WHERE b = 2 and a = 1 and c > 1 GROUP BY a;
+SELECT MIN(c) FROM t2 WHERE b = 2 and a = 1 and c > 1 GROUP BY a;
+
+DROP TABLE t1,t2;
| Thread |
|---|
| • bk commit into 5.0 tree (gkodinov:1.2278) BUG#22342 | kgeorge | 16 Oct |
