Hide support for PostgreSQL arrays behind a config switch

As we want to replace existing mapping with something more suitable, the
first step is to provide a config toggle that will help during
transition period.

presto-postgresql/pom.xml

@@ -67,6 +67,11 @@
             <artifactId>joda-time</artifactId>
         </dependency>
 
+        <dependency>
+            <groupId>javax.validation</groupId>
+            <artifactId>validation-api</artifactId>
+        </dependency>
+
         <!-- Presto SPI -->
         <dependency>
             <groupId>io.prestosql</groupId>

presto-postgresql/src/main/java/io/prestosql/plugin/postgresql/PostgreSqlClient.java

@@ -17,6 +17,7 @@
 import com.fasterxml.jackson.core.JsonParser;
 import com.fasterxml.jackson.databind.ObjectMapper;
 import com.google.common.collect.ImmutableList;
+import com.google.common.collect.ImmutableMap;
 import io.airlift.json.ObjectMapperProvider;
 import io.airlift.slice.DynamicSliceOutput;
 import io.airlift.slice.Slice;
@@ -97,12 +98,24 @@ public class PostgreSqlClient
     private static final String DUPLICATE_TABLE_SQLSTATE = "42P07";
 
     private final Type jsonType;
+    private final boolean supportArrays;
 
     @Inject
-    public PostgreSqlClient(BaseJdbcConfig config, TypeManager typeManager)
+    public PostgreSqlClient(BaseJdbcConfig config, PostgreSqlConfig postgreSqlConfig, TypeManager typeManager)
     {
         super(config, "\"", new DriverConnectionFactory(new Driver(), config));
         this.jsonType = typeManager.getType(new TypeSignature(StandardTypes.JSON));
+
+        switch (postgreSqlConfig.getArrayMapping()) {
+            case DISABLED:
+                supportArrays = false;
+                break;
+            case AS_ARRAY:
+                supportArrays = true;
+                break;
+            default:
+                throw new IllegalArgumentException("Unsupported ArrayMapping: " + postgreSqlConfig.getArrayMapping());
+        }
     }
 
     @Override
@@ -197,6 +210,9 @@ public List<JdbcColumnHandle> getColumns(ConnectorSession session, JdbcTableHand
     private Map<String, Integer> getArrayColumnDimensions(Connection connection, JdbcTableHandle tableHandle)
             throws SQLException
     {
+        if (!supportArrays) {
+            return ImmutableMap.of();
+        }
         String sql = "" +
                 "SELECT att.attname, att.attndims " +
                 "FROM pg_attribute att " +
@@ -237,7 +253,7 @@ public Optional<ColumnMapping> toPrestoType(ConnectorSession session, JdbcTypeHa
         if (typeHandle.getJdbcType() == Types.TIMESTAMP) {
             return Optional.of(timestampColumnMapping(session));
         }
-        if (typeHandle.getJdbcType() == Types.ARRAY) {
+        if (typeHandle.getJdbcType() == Types.ARRAY && supportArrays) {
             if (!typeHandle.getArrayDimensions().isPresent()) {
                 return Optional.empty();
             }
@@ -278,7 +294,7 @@ public WriteMapping toWriteMapping(ConnectorSession session, Type type)
         if (type.getTypeSignature().getBase().equals(StandardTypes.JSON)) {
             return WriteMapping.sliceMapping("jsonb", typedVarcharWriteFunction("json"));
         }
-        if (type instanceof ArrayType) {
+        if (type instanceof ArrayType && supportArrays) {
             Type elementType = ((ArrayType) type).getElementType();
             String elementDataType = toWriteMapping(session, elementType).getDataType();
             return WriteMapping.blockMapping(elementDataType + "[]", arrayWriteFunction(session, elementType, getArrayElementPgTypeName(session, this, elementType)));

presto-postgresql/src/main/java/io/prestosql/plugin/postgresql/PostgreSqlClientModule.java

@@ -29,5 +29,6 @@ public void configure(Binder binder)
     {
         binder.bind(JdbcClient.class).to(PostgreSqlClient.class).in(Scopes.SINGLETON);
         configBinder(binder).bindConfig(BaseJdbcConfig.class);
+        configBinder(binder).bindConfig(PostgreSqlConfig.class);
     }
 }

presto-postgresql/src/main/java/io/prestosql/plugin/postgresql/PostgreSqlConfig.java

@@ -0,0 +1,42 @@
+/*
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package io.prestosql.plugin.postgresql;
+
+import io.airlift.configuration.Config;
+
+import javax.validation.constraints.NotNull;
+
+public class PostgreSqlConfig
+{
+    private ArrayMapping arrayMapping = ArrayMapping.DISABLED;
+
+    public enum ArrayMapping {
+        DISABLED,
+        @Deprecated // TODO https://github.com/prestosql/presto/issues/682
+        AS_ARRAY,
+    }
+
+    @NotNull
+    public ArrayMapping getArrayMapping()
+    {
+        return arrayMapping;
+    }
+
+    @Config("postgresql.experimental.array-mapping")
+    public PostgreSqlConfig setArrayMapping(ArrayMapping arrayMapping)
+    {
+        this.arrayMapping = arrayMapping;
+        return this;
+    }
+}

presto-postgresql/src/test/java/io/prestosql/plugin/postgresql/TestPostgreSqlConfig.java

@@ -0,0 +1,43 @@
+/*
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package io.prestosql.plugin.postgresql;
+
+import com.google.common.collect.ImmutableMap;
+import io.airlift.configuration.testing.ConfigAssertions;
+import org.testng.annotations.Test;
+
+import java.util.Map;
+
+public class TestPostgreSqlConfig
+{
+    @Test
+    public void testDefaults()
+    {
+        ConfigAssertions.assertRecordedDefaults(ConfigAssertions.recordDefaults(PostgreSqlConfig.class)
+                .setArrayMapping(PostgreSqlConfig.ArrayMapping.DISABLED));
+    }
+
+    @Test
+    public void testExplicitPropertyMappings()
+    {
+        Map<String, String> properties = new ImmutableMap.Builder<String, String>()
+                .put("postgresql.experimental.array-mapping", "AS_ARRAY")
+                .build();
+
+        PostgreSqlConfig expected = new PostgreSqlConfig()
+                .setArrayMapping(PostgreSqlConfig.ArrayMapping.AS_ARRAY);
+
+        ConfigAssertions.assertFullMapping(properties, expected);
+    }
+}

presto-postgresql/src/test/java/io/prestosql/plugin/postgresql/TestPostgreSqlDistributedQueries.java

@@ -55,6 +55,13 @@ protected boolean supportsViews()
         return false;
     }
 
+    @Override
+    protected boolean supportsArrays()
+    {
+        // Arrays are supported conditionally. Check the defaults.
+        return new PostgreSqlConfig().getArrayMapping() != PostgreSqlConfig.ArrayMapping.DISABLED;
+    }
+
     @Override
     public void testCommentTable()
     {

presto-postgresql/src/test/java/io/prestosql/plugin/postgresql/TestPostgreSqlTypeMapping.java

@@ -85,7 +85,7 @@ public TestPostgreSqlTypeMapping()
 
     private TestPostgreSqlTypeMapping(TestingPostgreSqlServer postgreSqlServer)
     {
-        super(() -> createPostgreSqlQueryRunner(postgreSqlServer, ImmutableMap.of(), ImmutableList.of()));
+        super(() -> createPostgreSqlQueryRunner(postgreSqlServer, ImmutableMap.of("postgresql.experimental.array-mapping", "AS_ARRAY"), ImmutableList.of()));
         this.postgreSqlServer = postgreSqlServer;
     }