Fix escape for StringRegExpression (#2775) (#2776)

* fix

* fmt

* fix

---------

Co-authored-by: shiyuhang <[email protected]>

core/src/test/scala/org/apache/spark/sql/IssueTestSuite.scala

@@ -22,6 +22,16 @@ import org.apache.spark.sql.functions.{col, sum}
 
 class IssueTestSuite extends BaseTiSparkTest {
 
+  test("test like escape") {
+    val dbTable = "tispark_test.like_escape"
+    tidbStmt.execute(s"drop table if exists $dbTable")
+    tidbStmt.execute(s"CREATE TABLE $dbTable (`name` varchar(64) NOT NULL)")
+    tidbStmt.execute(s"insert into $dbTable values('ab%H')")
+    val df = spark.sql(s"select count(*) from $dbTable where name like '%\\%H%'")
+    assert(df.collect().head.get(0) == 1)
+
+  }
+
   test("test tiflash overflow in unsigned bigint") {
     if (!enableTiFlashTest) {
       cancel("tiflash test not enabled")

tikv-client/src/main/java/com/pingcap/tikv/expression/StringRegExpression.java

@@ -86,10 +86,8 @@ public TypedKey getTypedLiteral(int prefixLength) {
 
   @Override
   public List<Expression> getChildren() {
-    // For LIKE statement, an extra ESCAPE parameter is required as the third parameter for
-    // ScalarFunc.
-    // However in Spark ESCAPE is not supported so we simply set this value to zero.
-    return ImmutableList.of(left, reg, Constant.create(0, IntegerType.BIGINT));
+    // LIKE statement use '\' as escape character because Spark use it as escape character too.
+    return ImmutableList.of(left, reg, Constant.create(92, IntegerType.BIGINT));
   }
 
   @Override