Merge pull request #8526 from dolthub/nicktobey/unionshcema

Avoid comparing `sql.Types` in `dolt diff`

go/cmd/dolt/commands/diff.go

@@ -1401,7 +1401,12 @@ func diffRows(
 		toSch = pkSch.Schema
 	}
 
-	unionSch := unionSchemas(fromSch, toSch)
+	var unionSch sql.Schema
+	if fromSch.Equals(toSch) {
+		unionSch = fromSch
+	} else {
+		unionSch = unionSchemas(fromSch, toSch)
+	}
 
 	// We always instantiate a RowWriter in case the diffWriter needs it to close off any work from schema output
 	rowWriter, err := dw.RowWriter(fromTableInfo, toTableInfo, tableSummary, unionSch)
@@ -1561,13 +1566,13 @@ func unionSchemas(s1 sql.Schema, s2 sql.Schema) sql.Schema {
 //
 // Note this is only for printing the diff. This is not robust for other purposes.
 func chooseMostFlexibleType(origA, origB sql.Type) sql.Type {
-	if origA == origB {
-		return origA
-	}
-
 	at := origA.Type()
 	bt := origB.Type()
 
+	if at == bt {
+		return origA
+	}
+
 	// If both are numbers, we'll take the float.
 	if sqltypes.IsIntegral(at) && sqltypes.IsFloat(bt) {
 		return origB

integration-tests/bats/diff.bats

@@ -1966,3 +1966,125 @@ SQL
   [[ "$output" =~ "t1" ]] || false
   [[ "$output" =~ "t2" ]] || false
 }
+
+
+@test "diff: enum data change" {
+    dolt sql <<SQL
+drop table test;
+create table test (pk int primary key, size ENUM('x-small', 'small', 'medium', 'large', 'x-large'));
+insert into test values (1,'x-small');
+insert into test values (2,'small');
+insert into test values (3,'medium');
+SQL
+    dolt add .
+    dolt commit -am "First commit"
+
+    dolt sql <<SQL
+insert into test values (4,'large');
+delete from test where pk = 1;
+update test set size = 'x-large' where pk = 2;
+SQL
+
+    run dolt diff
+
+    EXPECTED=$(cat <<'EOF'
++---+----+---------+
+|   | pk | size    |
++---+----+---------+
+| - | 1  | x-small |
+| < | 2  | small   |
+| > | 2  | x-large |
+| + | 4  | large   |
++---+----+---------+
+EOF
+)
+
+    [ "$status" -eq 0 ]
+    [[ "$output" =~ "$EXPECTED" ]] || false
+
+    run dolt diff --data --schema
+    [ "$status" -eq 0 ]
+    [[ "$output" =~ "$EXPECTED" ]] || false
+
+    run dolt diff --data
+    [[ "$output" =~ "$EXPECTED" ]] || false
+}
+
+@test "diff: enum and schema changes" {
+    dolt sql <<SQL
+drop table test;
+create table test (pk int primary key, size ENUM('x-small', 'small', 'medium', 'large', 'x-large'));
+insert into test values (1,'x-small');
+insert into test values (2,'small');
+insert into test values (3,'medium');
+SQL
+    dolt add .
+    dolt commit -am "First commit"
+
+    dolt sql <<SQL
+alter table test add column c1 int;
+insert into test values (4,'large',1);
+delete from test where pk = 1;
+update test set size = 'x-large' where pk = 2;
+SQL
+
+    run dolt diff
+
+    EXPECTED=$(cat <<'EOF'
+ CREATE TABLE `test` (
+   `pk` int NOT NULL,
+   `size` enum('x-small','small','medium','large','x-large'),
++  `c1` int,
+   PRIMARY KEY (`pk`)
+ ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_bin;
++---+----+---------+------+
+|   | pk | size    | c1   |
++---+----+---------+------+
+| - | 1  | x-small | NULL |
+| < | 2  | small   | NULL |
+| > | 2  | x-large | NULL |
+| + | 4  | large   | 1    |
++---+----+---------+------+
+EOF
+)
+
+    [ "$status" -eq 0 ]
+    [[ "$output" =~ "$EXPECTED" ]] || false
+
+    run dolt diff --data --schema
+    [ "$status" -eq 0 ]
+    [[ "$output" =~ "$EXPECTED" ]] || false
+
+    run dolt diff --schema
+
+    EXPECTED=$(cat <<'EOF'
+ CREATE TABLE `test` (
+   `pk` int NOT NULL,
+   `size` enum('x-small','small','medium','large','x-large'),
++  `c1` int,
+   PRIMARY KEY (`pk`)
+ ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_bin;
+EOF
+)
+
+    [[ "$output" =~ "$EXPECTED" ]] || false
+    # Count the line numbers to make sure there are no data changes output
+    [ "${#lines[@]}" -eq 9 ]
+
+    run dolt diff --data
+    EXPECTED=$(cat <<'EOF'
++---+----+---------+------+
+|   | pk | size    | c1   |
++---+----+---------+------+
+| - | 1  | x-small | NULL |
+| < | 2  | small   | NULL |
+| > | 2  | x-large | NULL |
+| + | 4  | large   | 1    |
++---+----+---------+------+
+EOF
+)
+
+    [[ "$output" =~ "$EXPECTED" ]] || false
+    # Count the line numbers to make sure there are no schema changes output
+    [ "${#lines[@]}" -eq 11 ]
+}