[SPARK-28077][SQL] Support ANSI SQL OVERLAY function.

## What changes were proposed in this pull request? The `OVERLAY` function is a `ANSI` `SQL`. For example: ``` SELECT OVERLAY('abcdef' PLACING '45' FROM 4); SELECT OVERLAY('yabadoo' PLACING 'daba' FROM 5); SELECT OVERLAY('yabadoo' PLACING 'daba' FROM 5 FOR 0); SELECT OVERLAY('babosa' PLACING 'ubb' FROM 2 FOR 4); ``` The results of the above four `SQL` are: ``` abc45f yabadaba yabadabadoo bubba ``` Note: If the input string is null, then the result is null too. There are some mainstream database support the syntax. **PostgreSQL:** https://www.postgresql.org/docs/11/functions-string.html **Vertica:** https://www.vertica.com/docs/9.2.x/HTML/Content/Authoring/SQLReferenceManual/Functions/String/OVERLAY.htm?zoom_highlight=overlay **Oracle:** https://docs.oracle.com/en/database/oracle/oracle-database/19/arpls/UTL_RAW.html#GUID-342E37E7-FE43-4CE1-A0E9-7DAABD000369 **DB2:** https://www.ibm.com/support/knowledgecenter/SSGMCP_5.3.0/com.ibm.cics.rexx.doc/rexx/overlay.html There are some show of the PR on my production environment. ``` spark-sql> SELECT OVERLAY('abcdef' PLACING '45' FROM 4); abc45f Time taken: 6.385 seconds, Fetched 1 row(s) spark-sql> SELECT OVERLAY('yabadoo' PLACING 'daba' FROM 5); yabadaba Time taken: 0.191 seconds, Fetched 1 row(s) spark-sql> SELECT OVERLAY('yabadoo' PLACING 'daba' FROM 5 FOR 0); yabadabadoo Time taken: 0.186 seconds, Fetched 1 row(s) spark-sql> SELECT OVERLAY('babosa' PLACING 'ubb' FROM 2 FOR 4); bubba Time taken: 0.151 seconds, Fetched 1 row(s) spark-sql> SELECT OVERLAY(null PLACING '45' FROM 4); NULL Time taken: 0.22 seconds, Fetched 1 row(s) spark-sql> SELECT OVERLAY(null PLACING 'daba' FROM 5); NULL Time taken: 0.157 seconds, Fetched 1 row(s) spark-sql> SELECT OVERLAY(null PLACING 'daba' FROM 5 FOR 0); NULL Time taken: 0.254 seconds, Fetched 1 row(s) spark-sql> SELECT OVERLAY(null PLACING 'ubb' FROM 2 FOR 4); NULL Time taken: 0.159 seconds, Fetched 1 row(s) ``` ## How was this patch tested? Exists UT and new UT. Closes apache#24918 from beliefer/ansi-sql-overlay. Lead-authored-by: gengjiaan <[email protected]> Co-authored-by: Jiaan Geng <[email protected]> Signed-off-by: Takuya UESHIN <[email protected]>
kpathak13 · Jun 28, 2019 · 832ff87 · 832ff87
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diff --git a/docs/sql-keywords.md b/docs/sql-keywords.md
@@ -194,12 +194,14 @@ Below is a list of all the keywords in Spark SQL.
   <tr><td>OUTPUTFORMAT</td><td>non-reserved</td><td>non-reserved</td><td>non-reserved</td></tr>
   <tr><td>OVER</td><td>non-reserved</td><td>non-reserved</td><td>non-reserved</td></tr>
   <tr><td>OVERLAPS</td><td>reserved</td><td>non-reserved</td><td>reserved</td></tr>
+  <tr><td>OVERLAY</td><td>non-reserved</td><td>non-reserved</td><td>non-reserved</td></tr>
   <tr><td>OVERWRITE</td><td>non-reserved</td><td>non-reserved</td><td>non-reserved</td></tr>
   <tr><td>PARTITION</td><td>non-reserved</td><td>non-reserved</td><td>reserved</td></tr>
   <tr><td>PARTITIONED</td><td>non-reserved</td><td>non-reserved</td><td>non-reserved</td></tr>
   <tr><td>PARTITIONS</td><td>non-reserved</td><td>non-reserved</td><td>non-reserved</td></tr>
   <tr><td>PERCENT</td><td>non-reserved</td><td>non-reserved</td><td>non-reserved</td></tr>
   <tr><td>PIVOT</td><td>non-reserved</td><td>non-reserved</td><td>non-reserved</td></tr>
+  <tr><td>PLACING</td><td>non-reserved</td><td>non-reserved</td><td>non-reserved</td></tr>
   <tr><td>POSITION</td><td>non-reserved</td><td>non-reserved</td><td>reserved</td></tr>
   <tr><td>PRECEDING</td><td>non-reserved</td><td>non-reserved</td><td>non-reserved</td></tr>
   <tr><td>PRIMARY</td><td>reserved</td><td>non-reserved</td><td>reserved</td></tr>

diff --git a/sql/catalyst/src/main/antlr4/org/apache/spark/sql/catalyst/parser/SqlBase.g4 b/sql/catalyst/src/main/antlr4/org/apache/spark/sql/catalyst/parser/SqlBase.g4
@@ -705,6 +705,8 @@ primaryExpression
       ((FOR | ',') len=valueExpression)? ')'                                                   #substring
     | TRIM '(' trimOption=(BOTH | LEADING | TRAILING)? (trimStr=valueExpression)?
        FROM srcStr=valueExpression ')'                                                         #trim
+    | OVERLAY '(' input=valueExpression PLACING replace=valueExpression
+      FROM position=valueExpression (FOR length=valueExpression)? ')'                          #overlay
     ;
 
 constant
@@ -1002,6 +1004,7 @@ ansiNonReserved
     | OUT
     | OUTPUTFORMAT
     | OVER
+    | OVERLAY
     | OVERWRITE
     | PARTITION
     | PARTITIONED
@@ -1253,12 +1256,14 @@ nonReserved
     | OUTPUTFORMAT
     | OVER
     | OVERLAPS
+    | OVERLAY
     | OVERWRITE
     | PARTITION
     | PARTITIONED
     | PARTITIONS
     | PERCENTLIT
     | PIVOT
+    | PLACING
     | POSITION
     | PRECEDING
     | PRIMARY
@@ -1509,12 +1514,14 @@ OUTER: 'OUTER';
 OUTPUTFORMAT: 'OUTPUTFORMAT';
 OVER: 'OVER';
 OVERLAPS: 'OVERLAPS';
+OVERLAY: 'OVERLAY';
 OVERWRITE: 'OVERWRITE';
 PARTITION: 'PARTITION';
 PARTITIONED: 'PARTITIONED';
 PARTITIONS: 'PARTITIONS';
 PERCENTLIT: 'PERCENT';
 PIVOT: 'PIVOT';
+PLACING: 'PLACING';
 POSITION: 'POSITION';
 PRECEDING: 'PRECEDING';
 PRIMARY: 'PRIMARY';

diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/FunctionRegistry.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/FunctionRegistry.scala
@@ -348,6 +348,7 @@ object FunctionRegistry {
     expression[RegExpReplace]("regexp_replace"),
     expression[StringRepeat]("repeat"),
     expression[StringReplace]("replace"),
+    expression[Overlay]("overlay"),
     expression[RLike]("rlike"),
     expression[StringRPad]("rpad"),
     expression[StringTrimRight]("rtrim"),

diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/Expression.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/Expression.scala
@@ -68,6 +68,7 @@ import org.apache.spark.sql.types._
  * - [[UnaryExpression]]: an expression that has one child.
  * - [[BinaryExpression]]: an expression that has two children.
  * - [[TernaryExpression]]: an expression that has three children.
+ * - [[QuaternaryExpression]]: an expression that has four children.
  * - [[BinaryOperator]]: a special case of [[BinaryExpression]] that requires two children to have
  *                       the same output data type.
  *
@@ -757,6 +758,111 @@ abstract class TernaryExpression extends Expression {
   }
 }
 
+/**
+ * An expression with four inputs and one output. The output is by default evaluated to null
+ * if any input is evaluated to null.
+ */
+abstract class QuaternaryExpression extends Expression {
+
+  override def foldable: Boolean = children.forall(_.foldable)
+
+  override def nullable: Boolean = children.exists(_.nullable)
+
+  /**
+   * Default behavior of evaluation according to the default nullability of QuaternaryExpression.
+   * If subclass of QuaternaryExpression override nullable, probably should also override this.
+   */
+  override def eval(input: InternalRow): Any = {
+    val exprs = children
+    val value1 = exprs(0).eval(input)
+    if (value1 != null) {
+      val value2 = exprs(1).eval(input)
+      if (value2 != null) {
+        val value3 = exprs(2).eval(input)
+        if (value3 != null) {
+          val value4 = exprs(3).eval(input)
+          if (value4 != null) {
+            return nullSafeEval(value1, value2, value3, value4)
+          }
+        }
+      }
+    }
+    null
+  }
+
+  /**
+   * Called by default [[eval]] implementation.  If subclass of QuaternaryExpression keep the
+   *  default nullability, they can override this method to save null-check code.  If we need
+   *  full control of evaluation process, we should override [[eval]].
+   */
+  protected def nullSafeEval(input1: Any, input2: Any, input3: Any, input4: Any): Any =
+    sys.error(s"QuaternaryExpressions must override either eval or nullSafeEval")
+
+  /**
+   * Short hand for generating quaternary evaluation code.
+   * If either of the sub-expressions is null, the result of this computation
+   * is assumed to be null.
+   *
+   * @param f accepts four variable names and returns Java code to compute the output.
+   */
+  protected def defineCodeGen(
+    ctx: CodegenContext,
+    ev: ExprCode,
+    f: (String, String, String, String) => String): ExprCode = {
+    nullSafeCodeGen(ctx, ev, (eval1, eval2, eval3, eval4) => {
+      s"${ev.value} = ${f(eval1, eval2, eval3, eval4)};"
+    })
+  }
+
+  /**
+   * Short hand for generating quaternary evaluation code.
+   * If either of the sub-expressions is null, the result of this computation
+   * is assumed to be null.
+   *
+   * @param f function that accepts the 4 non-null evaluation result names of children
+   *          and returns Java code to compute the output.
+   */
+  protected def nullSafeCodeGen(
+    ctx: CodegenContext,
+    ev: ExprCode,
+    f: (String, String, String, String) => String): ExprCode = {
+    val firstGen = children(0).genCode(ctx)
+    val secondGen = children(1).genCode(ctx)
+    val thridGen = children(2).genCode(ctx)
+    val fourthGen = children(3).genCode(ctx)
+    val resultCode = f(firstGen.value, secondGen.value, thridGen.value, fourthGen.value)
+
+    if (nullable) {
+      val nullSafeEval =
+        firstGen.code + ctx.nullSafeExec(children(0).nullable, firstGen.isNull) {
+          secondGen.code + ctx.nullSafeExec(children(1).nullable, secondGen.isNull) {
+            thridGen.code + ctx.nullSafeExec(children(2).nullable, thridGen.isNull) {
+              fourthGen.code + ctx.nullSafeExec(children(3).nullable, fourthGen.isNull) {
+                s"""
+                  ${ev.isNull} = false; // resultCode could change nullability.
+                  $resultCode
+                """
+              }
+            }
+          }
+      }
+
+      ev.copy(code = code"""
+        boolean ${ev.isNull} = true;
+        ${CodeGenerator.javaType(dataType)} ${ev.value} = ${CodeGenerator.defaultValue(dataType)};
+        $nullSafeEval""")
+    } else {
+      ev.copy(code = code"""
+        ${firstGen.code}
+        ${secondGen.code}
+        ${thridGen.code}
+        ${fourthGen.code}
+        ${CodeGenerator.javaType(dataType)} ${ev.value} = ${CodeGenerator.defaultValue(dataType)};
+        $resultCode""", isNull = FalseLiteral)
+    }
+  }
+}
+
 /**
  * A trait used for resolving nullable flags, including `nullable`, `containsNull` of [[ArrayType]]
  * and `valueContainsNull` of [[MapType]], containsNull, valueContainsNull flags of the output date

diff --git a/...catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/stringExpressions.scala b/...catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/stringExpressions.scala
@@ -32,6 +32,7 @@ import org.apache.spark.sql.catalyst.expressions.codegen._
 import org.apache.spark.sql.catalyst.expressions.codegen.Block._
 import org.apache.spark.sql.catalyst.util.{ArrayData, GenericArrayData, TypeUtils}
 import org.apache.spark.sql.types._
+import org.apache.spark.unsafe.UTF8StringBuilder
 import org.apache.spark.unsafe.types.{ByteArray, UTF8String}
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////
@@ -454,6 +455,69 @@ case class StringReplace(srcExpr: Expression, searchExpr: Expression, replaceExp
   override def prettyName: String = "replace"
 }
 
+object Overlay {
+
+  def calculate(input: UTF8String, replace: UTF8String, pos: Int, len: Int): UTF8String = {
+    val builder = new UTF8StringBuilder
+    builder.append(input.substringSQL(1, pos - 1))
+    builder.append(replace)
+    // If you specify length, it must be a positive whole number or zero.
+    // Otherwise it will be ignored.
+    // The default value for length is the length of replace.
+    val length = if (len >= 0) {
+      len
+    } else {
+      replace.numChars
+    }
+    builder.append(input.substringSQL(pos + length, Int.MaxValue))
+    builder.build()
+  }
+}
+
+// scalastyle:off line.size.limit
+@ExpressionDescription(
+  usage = "_FUNC_(input, replace, pos[, len]) - Replace `input` with `replace` that starts at `pos` and is of length `len`.",
+  examples = """
+    Examples:
+      > SELECT _FUNC_('Spark SQL' PLACING '_' FROM 6);
+       Spark_SQL
+      > SELECT _FUNC_('Spark SQL' PLACING 'CORE' FROM 7);
+       Spark CORE
+      > SELECT _FUNC_('Spark SQL' PLACING 'ANSI ' FROM 7 FOR 0);
+       Spark ANSI SQL
+      > SELECT _FUNC_('Spark SQL' PLACING 'tructured' FROM 2 FOR 4);
+       Structured SQL
+  """)
+// scalastyle:on line.size.limit
+case class Overlay(input: Expression, replace: Expression, pos: Expression, len: Expression)
+  extends QuaternaryExpression with ImplicitCastInputTypes with NullIntolerant {
+
+  def this(str: Expression, replace: Expression, pos: Expression) = {
+    this(str, replace, pos, Literal.create(-1, IntegerType))
+  }
+
+  override def dataType: DataType = StringType
+
+  override def inputTypes: Seq[AbstractDataType] =
+    Seq(StringType, StringType, IntegerType, IntegerType)
+
+  override def children: Seq[Expression] = input :: replace :: pos :: len :: Nil
+
+  override def nullSafeEval(inputEval: Any, replaceEval: Any, posEval: Any, lenEval: Any): Any = {
+    val inputStr = inputEval.asInstanceOf[UTF8String]
+    val replaceStr = replaceEval.asInstanceOf[UTF8String]
+    val position = posEval.asInstanceOf[Int]
+    val length = lenEval.asInstanceOf[Int]
+    Overlay.calculate(inputStr, replaceStr, position, length)
+  }
+
+  override def doGenCode(ctx: CodegenContext, ev: ExprCode): ExprCode = {
+    defineCodeGen(ctx, ev, (input, replace, pos, len) =>
+      "org.apache.spark.sql.catalyst.expressions.Overlay" +
+        s".calculate($input, $replace, $pos, $len);")
+  }
+}
+
 object StringTranslate {
 
   def buildDict(matchingString: UTF8String, replaceString: UTF8String)

diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/parser/AstBuilder.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/parser/AstBuilder.scala
@@ -1421,6 +1421,20 @@ class AstBuilder(conf: SQLConf) extends SqlBaseBaseVisitor[AnyRef] with Logging
     }
   }
 
+  /**
+   * Create a Overlay expression.
+   */
+  override def visitOverlay(ctx: OverlayContext): Expression = withOrigin(ctx) {
+    val input = expression(ctx.input)
+    val replace = expression(ctx.replace)
+    val position = expression(ctx.position)
+    val lengthOpt = Option(ctx.length).map(expression)
+    lengthOpt match {
+      case Some(length) => Overlay(input, replace, position, length)
+      case None => new Overlay(input, replace, position)
+    }
+  }
+
   /**
    * Create a (windowed) Function expression.
    */

diff --git a/...yst/src/test/scala/org/apache/spark/sql/catalyst/expressions/StringExpressionsSuite.scala b/...yst/src/test/scala/org/apache/spark/sql/catalyst/expressions/StringExpressionsSuite.scala
@@ -428,6 +428,30 @@ class StringExpressionsSuite extends SparkFunSuite with ExpressionEvalHelper {
     // scalastyle:on
   }
 
+  test("overlay") {
+    checkEvaluation(new Overlay(Literal("Spark SQL"), Literal("_"),
+      Literal.create(6, IntegerType)), "Spark_SQL")
+    checkEvaluation(new Overlay(Literal("Spark SQL"), Literal("CORE"),
+      Literal.create(7, IntegerType)), "Spark CORE")
+    checkEvaluation(Overlay(Literal("Spark SQL"), Literal("ANSI "),
+      Literal.create(7, IntegerType), Literal.create(0, IntegerType)), "Spark ANSI SQL")
+    checkEvaluation(Overlay(Literal("Spark SQL"), Literal("tructured"),
+      Literal.create(2, IntegerType), Literal.create(4, IntegerType)), "Structured SQL")
+    checkEvaluation(new Overlay(Literal.create(null, StringType), Literal("_"),
+      Literal.create(6, IntegerType)), null)
+    checkEvaluation(new Overlay(Literal.create(null, StringType), Literal("CORE"),
+      Literal.create(7, IntegerType)), null)
+    checkEvaluation(Overlay(Literal.create(null, StringType), Literal("ANSI "),
+      Literal.create(7, IntegerType), Literal.create(0, IntegerType)), null)
+    checkEvaluation(Overlay(Literal.create(null, StringType), Literal("tructured"),
+      Literal.create(2, IntegerType), Literal.create(4, IntegerType)), null)
+    // scalastyle:off
+    // non ascii characters are not allowed in the source code, so we disable the scalastyle.
+    checkEvaluation(new Overlay(Literal("Spark的SQL"), Literal("_"),
+      Literal.create(6, IntegerType)), "Spark_SQL")
+    // scalastyle:on
+  }
+
   test("translate") {
     checkEvaluation(
       StringTranslate(Literal("translate"), Literal("rnlt"), Literal("123")), "1a2s3ae")

diff --git a/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/parser/PlanParserSuite.scala b/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/parser/PlanParserSuite.scala
@@ -744,6 +744,35 @@ class PlanParserSuite extends AnalysisTest {
     )
   }
 
+  test("OVERLAY function") {
+    def assertOverlayPlans(inputSQL: String, expectedExpression: Expression): Unit = {
+      comparePlans(
+        parsePlan(inputSQL),
+        Project(Seq(UnresolvedAlias(expectedExpression)), OneRowRelation())
+      )
+    }
+
+    assertOverlayPlans(
+      "SELECT OVERLAY('Spark SQL' PLACING '_' FROM 6)",
+      new Overlay(Literal("Spark SQL"), Literal("_"), Literal(6))
+    )
+
+    assertOverlayPlans(
+      "SELECT OVERLAY('Spark SQL' PLACING 'CORE' FROM 7)",
+      new Overlay(Literal("Spark SQL"), Literal("CORE"), Literal(7))
+    )
+
+    assertOverlayPlans(
+      "SELECT OVERLAY('Spark SQL' PLACING 'ANSI ' FROM 7 FOR 0)",
+      Overlay(Literal("Spark SQL"), Literal("ANSI "), Literal(7), Literal(0))
+    )
+
+    assertOverlayPlans(
+      "SELECT OVERLAY('Spark SQL' PLACING 'tructured' FROM 2 FOR 4)",
+      Overlay(Literal("Spark SQL"), Literal("tructured"), Literal(2), Literal(4))
+    )
+  }
+
   test("precedence of set operations") {
     val a = table("a").select(star())
     val b = table("b").select(star())

diff --git a/sql/core/src/main/scala/org/apache/spark/sql/functions.scala b/sql/core/src/main/scala/org/apache/spark/sql/functions.scala
@@ -2516,6 +2516,28 @@ object functions {
     SubstringIndex(str.expr, lit(delim).expr, lit(count).expr)
   }
 
+  /**
+   * Overlay the specified portion of `src` with `replaceString`,
+   *  starting from byte position `pos` of `inputString` and proceeding for `len` bytes.
+   *
+   * @group string_funcs
+   * @since 3.0.0
+   */
+  def overlay(src: Column, replaceString: String, pos: Int, len: Int): Column = withExpr {
+    Overlay(src.expr, lit(replaceString).expr, lit(pos).expr, lit(len).expr)
+  }
+
+  /**
+   * Overlay the specified portion of `src` with `replaceString`,
+   *  starting from byte position `pos` of `inputString`.
+   *
+   * @group string_funcs
+   * @since 3.0.0
+   */
+  def overlay(src: Column, replaceString: String, pos: Int): Column = withExpr {
+    new Overlay(src.expr, lit(replaceString).expr, lit(pos).expr)
+  }
+
   /**
    * Translate any character in the src by a character in replaceString.
    * The characters in replaceString correspond to the characters in matchingString.