expression: make collation work with json type (#37211)

close #31640
pingcap · Aug 19, 2022 · d6ebc60 · d6ebc60
1 parent 7d401c5
commit d6ebc60
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Showing 4 changed files with 58 additions and 13 deletions.
diff --git a/cmd/explaintest/r/collation_agg_func_disabled.result b/cmd/explaintest/r/collation_agg_func_disabled.result
@@ -263,13 +263,13 @@ min(d)
 desc format='brief' select min(d collate utf8mb4_bin) from tt;
 id	estRows	task	access object	operator info
 StreamAgg	1.00	root		funcs:min(Column#8)->Column#6
-└─Projection	1.00	root		cast(collation_agg_func.tt.d, json BINARY)->Column#8
+└─Projection	1.00	root		cast(collation_agg_func.tt.d, longtext CHARACTER SET utf8mb4 COLLATE utf8mb4_bin)->Column#8
   └─Projection	1.00	root		collation_agg_func.tt.d
     └─TopN	1.00	root		Column#7, offset:0, count:1
-      └─Projection	1.00	root		collation_agg_func.tt.d, cast(collation_agg_func.tt.d, json BINARY)->Column#7
+      └─Projection	1.00	root		collation_agg_func.tt.d, cast(collation_agg_func.tt.d, longtext CHARACTER SET utf8mb4 COLLATE utf8mb4_bin)->Column#7
         └─TableReader	1.00	root		data:TopN
-          └─TopN	1.00	cop[tikv]		cast(collation_agg_func.tt.d, json BINARY), offset:0, count:1
-            └─Selection	8000.00	cop[tikv]		not(isnull(cast(cast(collation_agg_func.tt.d, json BINARY), var_string(4294967295))))
+          └─TopN	1.00	cop[tikv]		cast(collation_agg_func.tt.d, longtext CHARACTER SET utf8mb4 COLLATE utf8mb4_bin), offset:0, count:1
+            └─Selection	8000.00	cop[tikv]		not(isnull(cast(collation_agg_func.tt.d, longtext CHARACTER SET utf8mb4 COLLATE utf8mb4_bin)))
               └─TableFullScan	10000.00	cop[tikv]	table:tt	keep order:false, stats:pseudo
 select min(d collate utf8mb4_bin) from tt;
 min(d collate utf8mb4_bin)
@@ -288,13 +288,13 @@ max(d)
 desc format='brief' select max(d collate utf8mb4_bin) from tt;
 id	estRows	task	access object	operator info
 StreamAgg	1.00	root		funcs:max(Column#8)->Column#6
-└─Projection	1.00	root		cast(collation_agg_func.tt.d, json BINARY)->Column#8
+└─Projection	1.00	root		cast(collation_agg_func.tt.d, longtext CHARACTER SET utf8mb4 COLLATE utf8mb4_bin)->Column#8
   └─Projection	1.00	root		collation_agg_func.tt.d
     └─TopN	1.00	root		Column#7:desc, offset:0, count:1
-      └─Projection	1.00	root		collation_agg_func.tt.d, cast(collation_agg_func.tt.d, json BINARY)->Column#7
+      └─Projection	1.00	root		collation_agg_func.tt.d, cast(collation_agg_func.tt.d, longtext CHARACTER SET utf8mb4 COLLATE utf8mb4_bin)->Column#7
         └─TableReader	1.00	root		data:TopN
-          └─TopN	1.00	cop[tikv]		cast(collation_agg_func.tt.d, json BINARY):desc, offset:0, count:1
-            └─Selection	8000.00	cop[tikv]		not(isnull(cast(cast(collation_agg_func.tt.d, json BINARY), var_string(4294967295))))
+          └─TopN	1.00	cop[tikv]		cast(collation_agg_func.tt.d, longtext CHARACTER SET utf8mb4 COLLATE utf8mb4_bin):desc, offset:0, count:1
+            └─Selection	8000.00	cop[tikv]		not(isnull(cast(collation_agg_func.tt.d, longtext CHARACTER SET utf8mb4 COLLATE utf8mb4_bin)))
               └─TableFullScan	10000.00	cop[tikv]	table:tt	keep order:false, stats:pseudo
 select max(d collate utf8mb4_bin) from tt;
 max(d collate utf8mb4_bin)

diff --git a/cmd/explaintest/r/collation_agg_func_enabled.result b/cmd/explaintest/r/collation_agg_func_enabled.result
@@ -258,9 +258,19 @@ select min(d) from tt;
 min(d)
 {"A": "A"}
 desc format='brief' select min(d collate utf8mb4_bin) from tt;
-Error 1253: COLLATION 'utf8mb4_bin' is not valid for CHARACTER SET 'binary'
+id	estRows	task	access object	operator info
+StreamAgg	1.00	root		funcs:min(Column#8)->Column#6
+└─Projection	1.00	root		cast(collation_agg_func.tt.d, longtext CHARACTER SET utf8mb4 COLLATE utf8mb4_bin)->Column#8
+  └─Projection	1.00	root		collation_agg_func.tt.d
+    └─TopN	1.00	root		Column#7, offset:0, count:1
+      └─Projection	1.00	root		collation_agg_func.tt.d, cast(collation_agg_func.tt.d, longtext CHARACTER SET utf8mb4 COLLATE utf8mb4_bin)->Column#7
+        └─TableReader	1.00	root		data:TopN
+          └─TopN	1.00	cop[tikv]		cast(collation_agg_func.tt.d, longtext CHARACTER SET utf8mb4 COLLATE utf8mb4_bin), offset:0, count:1
+            └─Selection	8000.00	cop[tikv]		not(isnull(cast(collation_agg_func.tt.d, longtext CHARACTER SET utf8mb4 COLLATE utf8mb4_bin)))
+              └─TableFullScan	10000.00	cop[tikv]	table:tt	keep order:false, stats:pseudo
 select min(d collate utf8mb4_bin) from tt;
-Error 1253: COLLATION 'utf8mb4_bin' is not valid for CHARACTER SET 'binary'
+min(d collate utf8mb4_bin)
+{"A": "A"}
 desc format='brief' select max(d) from tt;
 id	estRows	task	access object	operator info
 StreamAgg	1.00	root		funcs:max(collation_agg_func.tt.d)->Column#6
@@ -273,8 +283,18 @@ select max(d) from tt;
 max(d)
 {"c": "c"}
 desc format='brief' select max(d collate utf8mb4_bin) from tt;
-Error 1253: COLLATION 'utf8mb4_bin' is not valid for CHARACTER SET 'binary'
+id	estRows	task	access object	operator info
+StreamAgg	1.00	root		funcs:max(Column#8)->Column#6
+└─Projection	1.00	root		cast(collation_agg_func.tt.d, longtext CHARACTER SET utf8mb4 COLLATE utf8mb4_bin)->Column#8
+  └─Projection	1.00	root		collation_agg_func.tt.d
+    └─TopN	1.00	root		Column#7:desc, offset:0, count:1
+      └─Projection	1.00	root		collation_agg_func.tt.d, cast(collation_agg_func.tt.d, longtext CHARACTER SET utf8mb4 COLLATE utf8mb4_bin)->Column#7
+        └─TableReader	1.00	root		data:TopN
+          └─TopN	1.00	cop[tikv]		cast(collation_agg_func.tt.d, longtext CHARACTER SET utf8mb4 COLLATE utf8mb4_bin):desc, offset:0, count:1
+            └─Selection	8000.00	cop[tikv]		not(isnull(cast(collation_agg_func.tt.d, longtext CHARACTER SET utf8mb4 COLLATE utf8mb4_bin)))
+              └─TableFullScan	10000.00	cop[tikv]	table:tt	keep order:false, stats:pseudo
 select max(d collate utf8mb4_bin) from tt;
-Error 1253: COLLATION 'utf8mb4_bin' is not valid for CHARACTER SET 'binary'
+max(d collate utf8mb4_bin)
+{"c": "c"}
 drop database collation_agg_func;
 use test
diff --git a/expression/integration_test.go b/expression/integration_test.go
@@ -7385,6 +7385,21 @@ func TestImcompleteDateFunc(t *testing.T) {
 	tk.MustQuery("select YEARWEEK('1998-00-11')").Check(testkit.Rows("<nil>"))
 }
 
+func TestIssue31640(t *testing.T) {
+	store := testkit.CreateMockStore(t)
+	tk := testkit.NewTestKit(t, store)
+
+	tk.MustExec("use test")
+	tk.MustExec("create table t(a json);")
+	tk.MustExec(`insert into t values ('"a"'), ('"B"'), ('"c"'), ('"D"'), ('{"a": 1}'), ('1'), ('{"b": 2}'), ('[1, 2]'), ('[3, 4]');`)
+	tk.MustQuery("select min(a) from t;").Check(testkit.Rows("1"))
+	tk.MustQuery("select max(a) from t;").Check(testkit.Rows("[3, 4]"))
+	tk.MustQuery("select min(a collate utf8mb4_bin) from t;").Check(testkit.Rows("\"B\""))
+	tk.MustQuery("select max(a collate utf8mb4_bin) from t;").Check(testkit.Rows("{\"b\": 2}"))
+	tk.MustQuery("select min(a collate utf8mb4_unicode_ci) from t;").Check(testkit.Rows("\"a\""))
+	tk.MustQuery("select max(a collate utf8mb4_unicode_ci) from t;").Check(testkit.Rows("1"))
+}
+
 func TestIssue36279(t *testing.T) {
 	store := testkit.CreateMockStore(t)
 	tk := testkit.NewTestKit(t, store)

diff --git a/planner/core/expression_rewriter.go b/planner/core/expression_rewriter.go
@@ -1203,21 +1203,31 @@ func (er *expressionRewriter) Leave(originInNode ast.Node) (retNode ast.Node, ok
 				break
 			}
 			chs := arg.GetType().GetCharset()
+			// if the field is json, the charset is always utf8mb4.
+			if arg.GetType().GetType() == mysql.TypeJSON {
+				chs = mysql.UTF8MB4Charset
+			}
 			if chs != "" && collInfo.CharsetName != chs {
 				er.err = charset.ErrCollationCharsetMismatch.GenWithStackByArgs(collInfo.Name, chs)
 				break
 			}
 		}
 		// SetCollationExpr sets the collation explicitly, even when the evaluation type of the expression is non-string.
-		if _, ok := arg.(*expression.Column); ok {
+		if _, ok := arg.(*expression.Column); ok || arg.GetType().GetType() == mysql.TypeJSON {
 			if arg.GetType().GetType() == mysql.TypeEnum || arg.GetType().GetType() == mysql.TypeSet {
 				er.err = ErrNotSupportedYet.GenWithStackByArgs("use collate clause for enum or set")
 				break
 			}
 			// Wrap a cast here to avoid changing the original FieldType of the column expression.
 			exprType := arg.GetType().Clone()
+			// if arg type is json, we should cast it to longtext if there is collate clause.
+			if arg.GetType().GetType() == mysql.TypeJSON {
+				exprType = types.NewFieldType(mysql.TypeLongBlob)
+				exprType.SetCharset(mysql.UTF8MB4Charset)
+			}
 			exprType.SetCollate(v.Collate)
 			casted := expression.BuildCastFunction(er.sctx, arg, exprType)
+			arg = casted
 			er.ctxStackPop(1)
 			er.ctxStackAppend(casted, types.EmptyName)
 		} else {