WIP

Checking whether the join cardinality estimates are accurate
should only be done when the order by limit optimization is
enabled.

mysql-test/include/join_cardinality.inc

@@ -2,42 +2,42 @@
 --echo # BASIC CASES
 --echo #
 
-EXPLAIN SELECT * FROM t1 WHERE t1.b <> 10;
+EXPLAIN SELECT * FROM t1 WHERE t1.b <> 10 ORDER BY t1.c LIMIT 5;
 SELECT JSON_DETAILED(JSON_EXTRACT(trace, '$**.cardinality_accurate'))
 FROM INFORMATION_SCHEMA.OPTIMIZER_TRACE;
 
-EXPLAIN SELECT * FROM t1 WHERE t1.b > 10;
+EXPLAIN SELECT * FROM t1 WHERE t1.b > 10 ORDER BY t1.c LIMIT 5;
 SELECT JSON_DETAILED(JSON_EXTRACT(trace, '$**.cardinality_accurate'))
 FROM INFORMATION_SCHEMA.OPTIMIZER_TRACE;
 
-EXPLAIN SELECT * FROM t1 WHERE t1.b < 10;
+EXPLAIN SELECT * FROM t1 WHERE t1.b < 10 ORDER BY t1.c LIMIT 5;
 SELECT JSON_DETAILED(JSON_EXTRACT(trace, '$**.cardinality_accurate'))
 FROM INFORMATION_SCHEMA.OPTIMIZER_TRACE;
 
-EXPLAIN SELECT * FROM t1 WHERE t1.b = 10;
+EXPLAIN SELECT * FROM t1 WHERE t1.b = 10 ORDER BY t1.c LIMIT 5;
 SELECT JSON_DETAILED(JSON_EXTRACT(trace, '$**.cardinality_accurate'))
 FROM INFORMATION_SCHEMA.OPTIMIZER_TRACE;
 
-EXPLAIN SELECT * FROM t1 WHERE t1.b+2 = 10;
+EXPLAIN SELECT * FROM t1 WHERE t1.b+2 = 10 ORDER BY t1.c LIMIT 5;
 SELECT JSON_DETAILED(JSON_EXTRACT(trace, '$**.cardinality_accurate'))
 FROM INFORMATION_SCHEMA.OPTIMIZER_TRACE;
 
-EXPLAIN SELECT * FROM t1 WHERE a IN (1,2,3);
+EXPLAIN SELECT * FROM t1 WHERE a IN (1,2,3) ORDER BY t1.c LIMIT 5;
 SELECT JSON_DETAILED(JSON_EXTRACT(trace, '$**.cardinality_accurate'))
 FROM INFORMATION_SCHEMA.OPTIMIZER_TRACE;
 
-EXPLAIN SELECT * FROM t1 WHERE a BETWEEN 1 and 5;
+EXPLAIN SELECT * FROM t1 WHERE a BETWEEN 1 and 5 ORDER BY t1.c LIMIT 5;
 SELECT JSON_DETAILED(JSON_EXTRACT(trace, '$**.cardinality_accurate'))
 FROM INFORMATION_SCHEMA.OPTIMIZER_TRACE;
 
 --echo # Equi-join condition
-EXPLAIN SELECT * FROM t1,t2 WHERE t1.a=t2.b;
+EXPLAIN SELECT * FROM t1,t2 WHERE t1.a=t2.b ORDER BY t1.c LIMIT 5;
 SELECT JSON_DETAILED(JSON_EXTRACT(trace, '$**.cardinality_accurate'))
 FROM INFORMATION_SCHEMA.OPTIMIZER_TRACE;
 
 --echo # CASE where selectivity estimates are not accurate
 
-EXPLAIN SELECT * FROM t1 WHERE abs(t1.b) = 10;
+EXPLAIN SELECT * FROM t1 WHERE abs(t1.b) = 10 ORDER BY t1.c LIMIT 5;
 SELECT JSON_DETAILED(JSON_EXTRACT(trace, '$**.cardinality_accurate'))
 FROM INFORMATION_SCHEMA.OPTIMIZER_TRACE;
 
@@ -46,7 +46,7 @@ FROM INFORMATION_SCHEMA.OPTIMIZER_TRACE;
 --echo # selectivity for the predicate t1.c=10
 --echo #
 
-EXPLAIN SELECT * FROM t1 WHERE t1.c = 10;
+EXPLAIN SELECT * FROM t1 WHERE t1.c = 10 ORDER BY t1.a LIMIT 5;
 SELECT JSON_DETAILED(JSON_EXTRACT(trace, '$**.cardinality_accurate'))
 FROM INFORMATION_SCHEMA.OPTIMIZER_TRACE;
 
@@ -54,15 +54,16 @@ FROM INFORMATION_SCHEMA.OPTIMIZER_TRACE;
 --echo # BASIC CASES FOR AND CONJUNCT
 --echo #
 
-EXPLAIN SELECT * FROM t1 WHERE a >= 5 and b <= 6;
+EXPLAIN SELECT * FROM t1 WHERE a >= 5 and b <= 6 ORDER BY t1.c LIMIT 5;
 SELECT JSON_DETAILED(JSON_EXTRACT(trace, '$**.cardinality_accurate'))
 FROM INFORMATION_SCHEMA.OPTIMIZER_TRACE;
 
-EXPLAIN SELECT * FROM t1 WHERE a BETWEEN 1 AND 5 AND b <= 6;
+EXPLAIN SELECT * FROM t1 WHERE a BETWEEN 1 AND 5 AND b <= 6
+ORDER BY t1.c LIMIT 5;
 SELECT JSON_DETAILED(JSON_EXTRACT(trace, '$**.cardinality_accurate'))
 FROM INFORMATION_SCHEMA.OPTIMIZER_TRACE;
 
-EXPLAIN SELECT * FROM t1,t2 WHERE t1.a > 5 AND t2.b < 10;
+EXPLAIN SELECT * FROM t1,t2 WHERE t1.a > 5 AND t2.b < 10 ORDER BY t1.c LIMIT 5;
 SELECT JSON_DETAILED(JSON_EXTRACT(trace, '$**.cardinality_accurate'))
 FROM INFORMATION_SCHEMA.OPTIMIZER_TRACE;
 
@@ -70,22 +71,24 @@ FROM INFORMATION_SCHEMA.OPTIMIZER_TRACE;
 --echo # BASIC CASES FOR OR CONJUNCT
 --echo #
 
-EXPLAIN SELECT * FROM t1 WHERE a >= 5 OR a <= 2;
+EXPLAIN SELECT * FROM t1 WHERE a >= 5 OR a <= 2 ORDER BY t1.c LIMIT 5;
 SELECT JSON_DETAILED(JSON_EXTRACT(trace, '$**.cardinality_accurate'))
 FROM INFORMATION_SCHEMA.OPTIMIZER_TRACE;
 
-EXPLAIN SELECT * FROM t1 WHERE a BETWEEN 1 AND 5 OR a <= 0;
+EXPLAIN SELECT * FROM t1 WHERE a BETWEEN 1 AND 5 OR a <= 0
+ORDER BY t1.c LIMIT 5;
 SELECT JSON_DETAILED(JSON_EXTRACT(trace, '$**.cardinality_accurate'))
 FROM INFORMATION_SCHEMA.OPTIMIZER_TRACE;
 
 --echo # The cardinality here would be not accurate because for the
 --echo # OR conjunct all predicates can't be resolved to one column
 
-EXPLAIN SELECT * FROM t1,t2 WHERE t1.a > 5 OR t2.b < 10;
+EXPLAIN SELECT * FROM t1,t2 WHERE t1.a > 5 OR t2.b < 10
+ORDER BY t1.c LIMIT 5;
 SELECT JSON_DETAILED(JSON_EXTRACT(trace, '$**.cardinality_accurate'))
 FROM INFORMATION_SCHEMA.OPTIMIZER_TRACE;
 
-EXPLAIN SELECT * FROM t1 WHERE a >= 5 OR b <= 6;
+EXPLAIN SELECT * FROM t1 WHERE a >= 5 OR b <= 6 ORDER BY t1.c LIMIT 5;
 SELECT JSON_DETAILED(JSON_EXTRACT(trace, '$**.cardinality_accurate'))
 FROM INFORMATION_SCHEMA.OPTIMIZER_TRACE;
 
@@ -93,15 +96,18 @@ FROM INFORMATION_SCHEMA.OPTIMIZER_TRACE;
 --echo # COMPLEX CASES WITH AND-OR CONJUNCTS
 --echo #
 
-EXPLAIN SELECT * from t1,t2 WHERE t1.a=t2.b and (t1.a > 5 or t1.a < 10);
+EXPLAIN SELECT * from t1,t2 WHERE t1.a=t2.b and (t1.a > 5 or t1.a < 10)
+ORDER BY t1.c LIMIT 5;
 SELECT JSON_DETAILED(JSON_EXTRACT(trace, '$**.cardinality_accurate'))
 FROM INFORMATION_SCHEMA.OPTIMIZER_TRACE;
 
-EXPLAIN SELECT * from t1,t2 WHERE t1.a=t2.b and (t1.a > 5 or t2.b < 10);
+EXPLAIN SELECT * from t1,t2 WHERE t1.a=t2.b and (t1.a > 5 or t2.b < 10)
+ORDER BY t1.c LIMIT 5;
 SELECT JSON_DETAILED(JSON_EXTRACT(trace, '$**.cardinality_accurate'))
 FROM INFORMATION_SCHEMA.OPTIMIZER_TRACE;
 
-EXPLAIN SELECT * from t1,t2 WHERE t1.a=t2.b and (t1.a > 5 or t2.a < 10);
+EXPLAIN SELECT * from t1,t2 WHERE t1.a=t2.b and (t1.a > 5 or t2.a < 10)
+ORDER BY t1.c LIMIT 5;
 SELECT JSON_DETAILED(JSON_EXTRACT(trace, '$**.cardinality_accurate'))
 FROM INFORMATION_SCHEMA.OPTIMIZER_TRACE;
 
@@ -109,11 +115,13 @@ EXPLAIN SELECT * FROM t1
 WHERE ((t1.a > 20  and t1.a < 30) or (t1.a > 40 and t1.a < 50)) AND
 ((t1.a > 25 and t1.a < 35) or (t1.a > 45 and t1.a < 55)) OR
 ((t1.a > 120 and t1.a < 130) or (t1.a > 140 and t1.a < 150)) AND
-((t1.a > 125 and t1.a < 135) or (t1.a > 145 and t1.a < 155));
+((t1.a > 125 and t1.a < 135) or (t1.a > 145 and t1.a < 155))
+ORDER BY t1.c LIMIT 5;
 SELECT JSON_DETAILED(JSON_EXTRACT(trace, '$**.cardinality_accurate'))
 FROM INFORMATION_SCHEMA.OPTIMIZER_TRACE;
 
-EXPLAIN EXTENDED SELECT * from t1  WHERE ((t1.a IS NULL) or (t1.a = 5));
+EXPLAIN EXTENDED SELECT * from t1  WHERE ((t1.a IS NULL) or (t1.a = 5))
+ORDER BY t1.c LIMIT 5;
 SELECT JSON_DETAILED(JSON_EXTRACT(trace, '$**.cardinality_accurate'))
 FROM INFORMATION_SCHEMA.OPTIMIZER_TRACE;
 
@@ -121,16 +129,19 @@ FROM INFORMATION_SCHEMA.OPTIMIZER_TRACE;
 --echo # Test with subquery
 --echo #
 
-EXPLAIN SELECT * from t1  WHERE t1.a = (select t2.a from t2 limit 1);
+EXPLAIN SELECT * from t1  WHERE t1.a = (select t2.a from t2 limit 1)
+ORDER BY t1.c LIMIT 5;
 SELECT JSON_DETAILED(JSON_EXTRACT(trace, '$**.cardinality_accurate'))
 FROM INFORMATION_SCHEMA.OPTIMIZER_TRACE;
 
 EXPLAIN SELECT * from t1
-WHERE t1.a = (select t2.a from t2 where t1.b=t2.b limit 1);
+WHERE t1.a = (select t2.a from t2 where t1.b=t2.b limit 1)
+ORDER BY t1.c LIMIT 5;
 SELECT JSON_DETAILED(JSON_EXTRACT(trace, '$**.cardinality_accurate'))
 FROM INFORMATION_SCHEMA.OPTIMIZER_TRACE;
 
 EXPLAIN SELECT * from t1
-WHERE t1.a = (select t2.a from t2 where t2.b > 10 limit 1) AND abs(t1.b)= 11;
+WHERE t1.a = (select t2.a from t2 where t2.b > 10 limit 1) AND abs(t1.b)= 11
+ORDER BY t1.c LIMIT 5;
 SELECT JSON_DETAILED(JSON_EXTRACT(trace, '$**.cardinality_accurate'))
 FROM INFORMATION_SCHEMA.OPTIMIZER_TRACE;

sql/sql_select.cc

@@ -8486,7 +8486,7 @@ choose_plan(JOIN *join, table_map join_tables)
 
   Json_writer_object wrapper(thd);
 
-  if (join->conds && (join->sort_nest_possible || thd->trace_started()))
+  if (join->conds && join->sort_nest_possible)
   {
     bool cardinality_accurate;
     SAME_FIELD arg= {NULL, FALSE};