Coerce varchar(0) to varchar(1) for Hive table

trinodb · Sep 15, 2023 · 735770f · 735770f
1 parent 7d36ed5
commit 735770f
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diff --git a/plugin/trino-hive/src/main/java/io/trino/plugin/hive/HiveMetadata.java b/plugin/trino-hive/src/main/java/io/trino/plugin/hive/HiveMetadata.java
@@ -124,6 +124,7 @@
 import io.trino.spi.type.TimestampType;
 import io.trino.spi.type.Type;
 import io.trino.spi.type.TypeManager;
+import io.trino.spi.type.VarcharType;
 import org.apache.avro.Schema;
 import org.apache.avro.SchemaParseException;
 import org.apache.hadoop.fs.Path;
@@ -3414,6 +3415,15 @@ public Optional<ConnectorTableLayout> getNewTableLayout(ConnectorSession session
                 multipleWritersPerPartitionSupported));
     }
 
+    @Override
+    public Optional<Type> getSupportedType(ConnectorSession session, Type type)
+    {
+        if (type instanceof VarcharType varcharType && !varcharType.isUnbounded() && varcharType.getBoundedLength() == 0) {
+            return Optional.of(VarcharType.createVarcharType(1));
+        }
+        return Optional.empty();
+    }
+
     @Override
     public Optional<ConnectorTableLayout> getLayoutForTableExecute(ConnectorSession session, ConnectorTableExecuteHandle executeHandle)
     {

diff --git a/plugin/trino-hive/src/test/java/io/trino/plugin/hive/BaseHiveConnectorTest.java b/plugin/trino-hive/src/test/java/io/trino/plugin/hive/BaseHiveConnectorTest.java
@@ -7987,6 +7987,41 @@ public void testWriteInvalidPrecisionTimestamp()
                 "\\QIncorrect timestamp precision for timestamp(3); the configured precision is " + HiveTimestampPrecision.MICROSECONDS + "; column name: ts");
     }
 
+    @Test
+    public void testCoercingVarchar0ToVarchar1()
+    {
+        try (TestTable testTable = new TestTable(
+                getQueryRunner()::execute,
+                "test_coercion_create_table_varchar",
+                "(var_column_0 varchar(0), var_column_1 varchar(1), var_column_10 varchar(10))")) {
+            assertEquals(getColumnType(testTable.getName(), "var_column_0"), "varchar(1)");
+            assertEquals(getColumnType(testTable.getName(), "var_column_1"), "varchar(1)");
+            assertEquals(getColumnType(testTable.getName(), "var_column_10"), "varchar(10)");
+        }
+    }
+
+    @Test
+    public void testCoercingVarchar0ToVarchar1WithCTAS()
+    {
+        try (TestTable testTable = new TestTable(
+                getQueryRunner()::execute,
+                "test_coercion_ctas_varchar",
+                "AS SELECT '' AS var_column")) {
+            assertEquals(getColumnType(testTable.getName(), "var_column"), "varchar(1)");
+        }
+    }
+
+    @Test
+    public void testCoercingVarchar0ToVarchar1WithCTASNoData()
+    {
+        try (TestTable testTable = new TestTable(
+                getQueryRunner()::execute,
+                "test_coercion_ctas_nd_varchar",
+                "AS SELECT '' AS var_column WITH NO DATA")) {
+            assertEquals(getColumnType(testTable.getName(), "var_column"), "varchar(1)");
+        }
+    }
+
     @Test
     public void testOptimize()
     {