[Coral-Trino] Migrate 'CurrentTimestampTransformer' from RelNode to S…

…qlNode layer (#384)
linkedin · Apr 5, 2023 · 825943f · 825943f
1 parent 7d7f962
commit 825943f
Show file tree

Hide file tree

Showing 3 changed files with 41 additions and 16 deletions.
diff --git a/coral-trino/src/main/java/com/linkedin/coral/trino/rel2trino/Calcite2TrinoUDFConverter.java b/coral-trino/src/main/java/com/linkedin/coral/trino/rel2trino/Calcite2TrinoUDFConverter.java
@@ -206,13 +206,6 @@ public RexNode visitCall(RexCall call) {
         }
       }
 
-      if (operatorName.equalsIgnoreCase("current_timestamp")) {
-        Optional<RexNode> modifiedCall = visitCurrentTimestamp(call);
-        if (modifiedCall.isPresent()) {
-          return modifiedCall.get();
-        }
-      }
-
       if (operatorName.equalsIgnoreCase("concat")) {
         Optional<RexNode> modifiedCall = visitConcat(call);
         if (modifiedCall.isPresent()) {
@@ -333,13 +326,6 @@ private Optional<RexNode> visitSubstring(RexCall call) {
       return Optional.empty();
     }
 
-    private Optional<RexNode> visitCurrentTimestamp(RexCall call) {
-      final SqlOperator op = call.getOperator();
-      // We may want to extend this to allow current_timestamp(n) in case of Trino <-> Trino conversion, to make
-      // intermediate representation more complete.
-      return Optional.of(rexBuilder.makeCast(typeFactory.createSqlType(TIMESTAMP, 3), rexBuilder.makeCall(op)));
-    }
-
     private Optional<RexNode> visitCast(RexCall call) {
       final SqlOperator op = call.getOperator();
       if (op.getKind() != SqlKind.CAST) {

diff --git a/...-trino/src/main/java/com/linkedin/coral/trino/rel2trino/CoralToTrinoSqlCallConverter.java b/...-trino/src/main/java/com/linkedin/coral/trino/rel2trino/CoralToTrinoSqlCallConverter.java
@@ -25,6 +25,7 @@
 import com.linkedin.coral.trino.rel2trino.functions.TrinoElementAtFunction;
 import com.linkedin.coral.trino.rel2trino.transformers.CollectListOrSetFunctionTransformer;
 import com.linkedin.coral.trino.rel2trino.transformers.CoralRegistryOperatorRenameSqlCallTransformer;
+import com.linkedin.coral.trino.rel2trino.transformers.CurrentTimestampTransformer;
 import com.linkedin.coral.trino.rel2trino.transformers.GenericCoralRegistryOperatorRenameSqlCallTransformer;
 import com.linkedin.coral.trino.rel2trino.transformers.MapValueConstructorTransformer;
 import com.linkedin.coral.trino.rel2trino.transformers.ToDateOperatorTransformer;
@@ -98,6 +99,7 @@ protected SqlCall transform(SqlCall sqlCall) {
                 + "{\"op\": \"date\", \"operands\":[{\"op\": \"timestamp\", \"operands\":[{\"input\": 1}]}]}]",
             null, null),
         new ToDateOperatorTransformer(configs.getOrDefault(AVOID_TRANSFORM_TO_DATE_UDF, false)),
+        new CurrentTimestampTransformer(),
 
         // LinkedIn specific functions
         new CoralRegistryOperatorRenameSqlCallTransformer(
@@ -124,7 +126,6 @@ private SqlOperator hiveToCoralSqlOperator(String functionName) {
 
   @Override
   public SqlNode visit(SqlCall call) {
-    SqlCall transformedCall = sqlCallTransformers.apply(call);
-    return super.visit(transformedCall);
+    return sqlCallTransformers.apply((SqlCall) super.visit(call));
   }
 }
diff --git a/...ain/java/com/linkedin/coral/trino/rel2trino/transformers/CurrentTimestampTransformer.java b/...ain/java/com/linkedin/coral/trino/rel2trino/transformers/CurrentTimestampTransformer.java
@@ -0,0 +1,38 @@
+/**
+ * Copyright 2023 LinkedIn Corporation. All rights reserved.
+ * Licensed under the BSD-2 Clause license.
+ * See LICENSE in the project root for license information.
+ */
+package com.linkedin.coral.trino.rel2trino.transformers;
+
+import org.apache.calcite.sql.SqlBasicTypeNameSpec;
+import org.apache.calcite.sql.SqlCall;
+import org.apache.calcite.sql.SqlDataTypeSpec;
+import org.apache.calcite.sql.fun.SqlStdOperatorTable;
+import org.apache.calcite.sql.parser.SqlParserPos;
+import org.apache.calcite.sql.type.SqlTypeName;
+
+import com.linkedin.coral.common.transformers.SqlCallTransformer;
+
+
+/**
+ * This class implements the transformation for the CURRENT_TIMESTAMP function.
+ * For example, "SELECT CURRENT_TIMESTAMP" is transformed into "SELECT CAST(CURRENT_TIMESTAMP AS TIMESTAMP(3))".
+ * This transformation ensures compatibility with Trino.
+ */
+public class CurrentTimestampTransformer extends SqlCallTransformer {
+
+  private static final String CURRENT_TIMESTAMP_FUNCTION_NAME = "CURRENT_TIMESTAMP";
+
+  @Override
+  protected boolean condition(SqlCall sqlCall) {
+    return sqlCall.getOperator().getName().equalsIgnoreCase(CURRENT_TIMESTAMP_FUNCTION_NAME);
+  }
+
+  @Override
+  protected SqlCall transform(SqlCall sqlCall) {
+    SqlDataTypeSpec timestampType =
+        new SqlDataTypeSpec(new SqlBasicTypeNameSpec(SqlTypeName.TIMESTAMP, 3, SqlParserPos.ZERO), SqlParserPos.ZERO);
+    return SqlStdOperatorTable.CAST.createCall(SqlParserPos.ZERO, sqlCall, timestampType);
+  }
+}