[hotfix][table-common] Provide Schema.derived() for convenience

ruslandanilin · Aug 25, 2021 · 3510e26 · 3510e26
1 parent a3f6821
commit 3510e26
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diff --git a/...ink-table-api-java/src/test/java/org/apache/flink/table/catalog/SchemaTranslatorTest.java b/...ink-table-api-java/src/test/java/org/apache/flink/table/catalog/SchemaTranslatorTest.java
@@ -311,6 +311,30 @@ public void testOutputToNoSchema() {
         assertEquals(Optional.empty(), result.getPhysicalDataType());
     }
 
+    @Test
+    public void testOutputToEmptySchema() {
+        final ResolvedSchema tableSchema =
+                ResolvedSchema.of(
+                        Column.physical("id", DataTypes.BIGINT()),
+                        Column.metadata("rowtime", DataTypes.TIMESTAMP_LTZ(3), null, false),
+                        Column.physical("name", DataTypes.STRING()));
+
+        final ProducingResult result =
+                SchemaTranslator.createProducingResult(tableSchema, Schema.derived());
+
+        assertEquals(Optional.empty(), result.getProjections());
+
+        assertEquals(
+                Schema.newBuilder()
+                        .column("id", DataTypes.BIGINT())
+                        .column("rowtime", DataTypes.TIMESTAMP_LTZ(3)) // becomes physical
+                        .column("name", DataTypes.STRING())
+                        .build(),
+                result.getSchema());
+
+        assertEquals(Optional.empty(), result.getPhysicalDataType());
+    }
+
     @Test
     public void testOutputToMetadataSchema() {
         final ResolvedSchema tableSchema =

diff --git a/flink-table/flink-table-common/src/main/java/org/apache/flink/table/api/Schema.java b/flink-table/flink-table-common/src/main/java/org/apache/flink/table/api/Schema.java
@@ -71,6 +71,8 @@
 @PublicEvolving
 public final class Schema {
 
+    private static final Schema EMPTY = Schema.newBuilder().build();
+
     private final List<UnresolvedColumn> columns;
 
     private final List<UnresolvedWatermarkSpec> watermarkSpecs;
@@ -91,6 +93,19 @@ public static Schema.Builder newBuilder() {
         return new Builder();
     }
 
+    /**
+     * Convenience method for stating explicitly that a schema is empty and should be fully derived
+     * by the framework.
+     *
+     * <p>The semantics are equivalent to calling {@code Schema.newBuilder().build()}.
+     *
+     * <p>Note that derivation depends on the context. Usually, the method that accepts a {@link
+     * Schema} instance will mention whether schema derivation is supported or not.
+     */
+    public static Schema derived() {
+        return EMPTY;
+    }
+
     public List<UnresolvedColumn> getColumns() {
         return columns;
     }