sql: fix where condition without brackets problem (#372)

tests/basic/run.sh

@@ -40,6 +40,27 @@ expected=$(seq 3 9)
 echo "expected ${expected}, actual ${actual}"
 [ "$actual" = "$expected" ]
 
+# Test for OR WHERE case. Better dump MySQL here because Dumpling has some special handle for concurrently dump TiDB tables.
+export DUMPLING_TEST_PORT=3306
+run_sql "drop database if exists \`$DB_NAME\`;"
+run_sql "create database \`$DB_NAME\`;"
+run_sql "create table \`$DB_NAME\`.\`$TABLE_NAME\` (a int primary key, b int);"
+
+seq 0 99 | xargs -I_ run_sql "insert into \`$DB_NAME\`.\`$TABLE_NAME\` (a,b) values (_, 99-_);"
+run_sql "analyze table \`$DB_NAME\`.\`$TABLE_NAME\`;"
+run_dumpling --where "b <= 4 or b >= 95" -f "$DB_NAME.$TABLE_NAME" --rows 10
+
+actual=$(grep -w "(.*)" ${DUMPLING_OUTPUT_DIR}/${DB_NAME}.${TABLE_NAME}.000000000.sql | cut -c2-2)
+expected=$(seq 0 4)
+echo "expected ${DUMPLING_OUTPUT_DIR}/${DB_NAME}.${TABLE_NAME}.000000000.sql ${expected}, actual ${actual}"
+[ "$actual" = "$expected" ]
+actual=$(grep -w "(.*)" ${DUMPLING_OUTPUT_DIR}/${DB_NAME}.${TABLE_NAME}.000000009.sql | cut -c2-3)
+expected=$(seq 95 99)
+echo "expected ${DUMPLING_OUTPUT_DIR}/${DB_NAME}.${TABLE_NAME}.000000009.sql ${expected}, actual ${actual}"
+[ "$actual" = "$expected" ]
+
+seq 1 8 | xargs -I\? file_not_exist ${DUMPLING_OUTPUT_DIR}/${DB_NAME}.${TABLE_NAME}.00000000\?.sql
+
 # Test for specifying --filetype sql with --sql, should report an error
 set +e
 run_dumpling --sql "select * from \`$DB_NAME\`.\`$TABLE_NAME\`" --filetype sql > ${DUMPLING_OUTPUT_DIR}/dumpling.log

v4/export/sql.go

@@ -1069,18 +1069,24 @@ func parseSnapshotToTSO(pool *sql.DB, snapshot string) (uint64, error) {
 func buildWhereCondition(conf *Config, where string) string {
 	var query strings.Builder
 	separator := "WHERE"
+	leftBracket := " "
+	rightBracket := " "
+	if conf.Where != "" && where != "" {
+		leftBracket = " ("
+		rightBracket = ") "
+	}
 	if conf.Where != "" {
 		query.WriteString(separator)
-		query.WriteByte(' ')
+		query.WriteString(leftBracket)
 		query.WriteString(conf.Where)
-		query.WriteByte(' ')
+		query.WriteString(rightBracket)
 		separator = "AND"
-		query.WriteByte(' ')
 	}
 	if where != "" {
 		query.WriteString(separator)
-		query.WriteString(" ")
+		query.WriteString(leftBracket)
 		query.WriteString(where)
+		query.WriteString(rightBracket)
 	}
 	return query.String()
 }

v4/export/sql_test.go

@@ -828,6 +828,43 @@ func TestBuildPartitionClauses(t *testing.T) {
 	}
 }
 
+func TestBuildWhereCondition(t *testing.T) {
+	t.Parallel()
+
+	conf := DefaultConfig()
+	testCases := []struct {
+		confWhere     string
+		chunkWhere    string
+		expectedWhere string
+	}{
+		{
+			"",
+			"",
+			"",
+		},
+		{
+			"a >= 1000000 and a <= 2000000",
+			"",
+			"WHERE a >= 1000000 and a <= 2000000 ",
+		},
+		{
+			"",
+			"(`a`>1 and `a`<3)or(`a`=1 and(`b`>=2))or(`a`=3 and(`b`<4))",
+			"WHERE (`a`>1 and `a`<3)or(`a`=1 and(`b`>=2))or(`a`=3 and(`b`<4)) ",
+		},
+		{
+			"a >= 1000000 and a <= 2000000",
+			"(`a`>1 and `a`<3)or(`a`=1 and(`b`>=2))or(`a`=3 and(`b`<4))",
+			"WHERE (a >= 1000000 and a <= 2000000) AND ((`a`>1 and `a`<3)or(`a`=1 and(`b`>=2))or(`a`=3 and(`b`<4))) ",
+		},
+	}
+	for _, testCase := range testCases {
+		conf.Where = testCase.confWhere
+		where := buildWhereCondition(conf, testCase.chunkWhere)
+		require.Equal(t, testCase.expectedWhere, where)
+	}
+}
+
 func TestBuildRegionQueriesWithoutPartition(t *testing.T) {
 	t.Parallel()