EXPLAIN JSON: Print out the "expensive constant condition" attached to joins.

1 files changed, 52 insertions, 0 deletions

diff --git a/mysql-test/r/explain_json.result b/mysql-test/r/explain_json.result
index 0824132de05..e1135298924 100644
--- a/mysql-test/r/explain_json.result
+++ b/mysql-test/r/explain_json.result
@@ -551,6 +551,7 @@ EXPLAIN
 {
   "query_block": {
     "select_id": 1,
+    "const_condition": "1",
     "table": {
       "table_name": "t1",
       "access_type": "ALL",
@@ -778,3 +779,54 @@ EXPLAIN
   }
 }
 DROP TABLE t1,t2;
+#
+# Join's constant expression
+#
+create table t0(a int);
+insert into t0 values (0),(1),(2),(3),(4),(5),(6),(7),(8),(9);
+create table t1(a int, b int);
+insert into t1 select tbl1.a+10*tbl2.a, 1234 from t0 tbl1, t0 tbl2;
+explain format=json 
+select * from t0 
+where 
+20000 > all (select max(tbl1.a + tbl2.a)
+from t1 tbl1, t1 tbl2 where tbl1.b=tbl2.b);
+EXPLAIN
+{
+  "query_block": {
+    "select_id": 1,
+    "const_condition": "<not>(<in_optimizer>(20000,(<max>(subquery#2) >= 20000)))",
+    "table": {
+      "table_name": "t0",
+      "access_type": "ALL",
+      "rows": 10,
+      "filtered": 100
+    },
+    "subqueries": [
+      {
+        "query_block": {
+          "select_id": 2,
+          "table": {
+            "table_name": "tbl1",
+            "access_type": "ALL",
+            "rows": 100,
+            "filtered": 100
+          },
+          "block-nl-join": {
+            "table": {
+              "table_name": "tbl2",
+              "access_type": "ALL",
+              "rows": 100,
+              "filtered": 100
+            },
+            "buffer_type": "flat",
+            "join_type": "BNL",
+            "attached_condition": "(tbl2.b = tbl1.b)"
+          }
+        }
+      }
+    ]
+  }
+}
+drop table t1;
+drop table t0;