fix(bqjdbc): resolve JDBC metadata compliance gaps for wrappers, searchability, and type mappings

java-bigquery/google-cloud-bigquery-jdbc/src/main/java/com/google/cloud/bigquery/jdbc/BigQueryDatabaseMetaData.java

@@ -42,6 +42,7 @@
 import com.google.cloud.bigquery.TableDefinition;
 import com.google.cloud.bigquery.TableId;
 import com.google.cloud.bigquery.exception.BigQueryJdbcException;
+import com.google.common.collect.ImmutableMap;
 import java.io.BufferedReader;
 import java.io.IOException;
 import java.io.InputStream;
@@ -59,6 +60,7 @@
 import java.util.Comparator;
 import java.util.HashSet;
 import java.util.List;
+import java.util.Map;
 import java.util.Properties;
 import java.util.Scanner;
 import java.util.Set;
@@ -1650,8 +1652,8 @@ ColumnTypeInfo determineTypeInfoFromDataType(
       String columnName,
       int ordinalPosition) {
 
-    ColumnTypeInfo defaultVarcharTypeInfo =
-        new ColumnTypeInfo(Types.VARCHAR, "VARCHAR", null, null, null);
+    ColumnTypeInfo defaultStringTypeInfo =
+        new ColumnTypeInfo(Types.NVARCHAR, "STRING", null, null, null);
     try {
       String typeKind = argumentDataType.getTypeKind();
       if (typeKind != null && !typeKind.isEmpty()) {
@@ -1664,10 +1666,10 @@ ColumnTypeInfo determineTypeInfoFromDataType(
     } catch (Exception e) {
       LOG.warning(
           "Proc: %s, Arg: %s (Pos %d) - Caught an unexpected Exception during type"
-              + " determination. Defaulting type to VARCHAR. Error: %s",
+              + " determination. Defaulting type to STRING. Error: %s",
           procedureName, columnName, ordinalPosition, e.getMessage());
     }
-    return defaultVarcharTypeInfo;
+    return defaultStringTypeInfo;
   }
 
   Comparator<FieldValueList> defineGetProcedureColumnsComparator(FieldList resultSchemaFields) {
@@ -4750,13 +4752,16 @@ public boolean generatedKeyAlwaysReturned() {
   }
 
   @Override
-  public <T> T unwrap(Class<T> iface) {
-    return null;
+  public <T> T unwrap(Class<T> iface) throws SQLException {
+    if (iface.isInstance(this)) {
+      return iface.cast(this);
+    }
+    throw new SQLException("Cannot unwrap to " + iface.getName());
   }
 
   @Override
-  public boolean isWrapperFor(Class<?> iface) {
-    return false;
+  public boolean isWrapperFor(Class<?> iface) throws SQLException {
+    return iface != null && iface.isInstance(this);
   }
 
   // --- Helper Methods ---
@@ -4828,47 +4833,58 @@ private Tuple<String, String> determineEffectiveCatalogAndSchema(
     return Tuple.of(effectiveCatalog, effectiveSchemaPattern);
   }
 
+  // BigQuery STRING represents Unicode character strings (UTF-8).
+  // Standard JDBC maps UTF-8/Unicode data to Types.NVARCHAR rather than Types.VARCHAR.
+  private static final Map<StandardSQLTypeName, ColumnTypeInfo> STANDARD_TYPE_INFO =
+      ImmutableMap.<StandardSQLTypeName, ColumnTypeInfo>builder()
+          .put(StandardSQLTypeName.INT64, new ColumnTypeInfo(Types.BIGINT, "INT64", 19, 0, 10))
+          .put(StandardSQLTypeName.BOOL, new ColumnTypeInfo(Types.BOOLEAN, "BOOL", 1, null, null))
+          .put(
+              StandardSQLTypeName.FLOAT64,
+              new ColumnTypeInfo(Types.DOUBLE, "FLOAT64", 15, null, 10))
+          .put(StandardSQLTypeName.NUMERIC, new ColumnTypeInfo(Types.NUMERIC, "NUMERIC", 38, 9, 10))
+          .put(
+              StandardSQLTypeName.BIGNUMERIC,
+              new ColumnTypeInfo(Types.NUMERIC, "BIGNUMERIC", 77, 38, 10))
+          .put(
+              StandardSQLTypeName.STRING,
+              new ColumnTypeInfo(Types.NVARCHAR, "STRING", null, null, null))
+          .put(
+              StandardSQLTypeName.TIMESTAMP,
+              new ColumnTypeInfo(Types.TIMESTAMP, "TIMESTAMP", 29, null, null))
+          .put(
+              StandardSQLTypeName.DATETIME,
+              new ColumnTypeInfo(Types.TIMESTAMP, "DATETIME", 29, null, null))
+          .put(StandardSQLTypeName.DATE, new ColumnTypeInfo(Types.DATE, "DATE", 10, null, null))
+          .put(StandardSQLTypeName.TIME, new ColumnTypeInfo(Types.TIME, "TIME", 15, null, null))
+          .put(
+              StandardSQLTypeName.GEOGRAPHY,
+              new ColumnTypeInfo(Types.OTHER, "GEOGRAPHY", null, null, null))
+          .put(StandardSQLTypeName.JSON, new ColumnTypeInfo(Types.OTHER, "JSON", null, null, null))
+          .put(
+              StandardSQLTypeName.INTERVAL,
+              new ColumnTypeInfo(Types.OTHER, "INTERVAL", null, null, null))
+          .put(
+              StandardSQLTypeName.RANGE, new ColumnTypeInfo(Types.OTHER, "RANGE", null, null, null))
+          .put(
+              StandardSQLTypeName.BYTES,
+              new ColumnTypeInfo(Types.VARBINARY, "BYTES", null, null, null))
+          .put(
+              StandardSQLTypeName.STRUCT,
+              new ColumnTypeInfo(Types.STRUCT, "STRUCT", null, null, null))
+          .build();
+
   private ColumnTypeInfo getColumnTypeInfoForSqlType(StandardSQLTypeName bqType) {
     if (bqType == null) {
-      LOG.warning("Null BigQuery type encountered: " + bqType.name() + ". Mapping to VARCHAR.");
-      return new ColumnTypeInfo(Types.VARCHAR, bqType.name(), null, null, null);
+      LOG.warning("Null BigQuery type encountered. Mapping to STRING.");
+      return new ColumnTypeInfo(Types.NVARCHAR, "STRING", null, null, null);
     }
-
-    switch (bqType) {
-      case INT64:
-        return new ColumnTypeInfo(Types.BIGINT, "BIGINT", 19, 0, 10);
-      case BOOL:
-        return new ColumnTypeInfo(Types.BOOLEAN, "BOOLEAN", 1, null, null);
-      case FLOAT64:
-        return new ColumnTypeInfo(Types.DOUBLE, "DOUBLE", 15, null, 10);
-      case NUMERIC:
-        return new ColumnTypeInfo(Types.NUMERIC, "NUMERIC", 38, 9, 10);
-      case BIGNUMERIC:
-        return new ColumnTypeInfo(Types.NUMERIC, "NUMERIC", 77, 38, 10);
-      case STRING:
-        return new ColumnTypeInfo(Types.NVARCHAR, "NVARCHAR", null, null, null);
-      case TIMESTAMP:
-      case DATETIME:
-        return new ColumnTypeInfo(Types.TIMESTAMP, "TIMESTAMP", 29, null, null);
-      case DATE:
-        return new ColumnTypeInfo(Types.DATE, "DATE", 10, null, null);
-      case TIME:
-        return new ColumnTypeInfo(Types.TIME, "TIME", 15, null, null);
-      case GEOGRAPHY:
-        return new ColumnTypeInfo(Types.OTHER, "GEOGRAPHY", null, null, null);
-      case JSON:
-        return new ColumnTypeInfo(Types.OTHER, "JSON", null, null, null);
-      case INTERVAL:
-        return new ColumnTypeInfo(Types.OTHER, "INTERVAL", null, null, null);
-      case BYTES:
-        return new ColumnTypeInfo(Types.VARBINARY, "VARBINARY", null, null, null);
-      case STRUCT:
-        return new ColumnTypeInfo(Types.STRUCT, "STRUCT", null, null, null);
-      default:
-        LOG.warning(
-            "Unknown BigQuery type encountered: " + bqType.name() + ". Mapping to VARCHAR.");
-        return new ColumnTypeInfo(Types.VARCHAR, bqType.name(), null, null, null);
+    ColumnTypeInfo info = STANDARD_TYPE_INFO.get(bqType);
+    if (info == null) {
+      LOG.warning("Unknown BigQuery type encountered: " + bqType.name() + ". Mapping to STRING.");
+      return new ColumnTypeInfo(Types.NVARCHAR, "STRING", null, null, null);
     }
+    return info;
   }
 
   <T> List<T> findMatchingBigQueryObjects(

java-bigquery/google-cloud-bigquery-jdbc/src/main/java/com/google/cloud/bigquery/jdbc/BigQueryJdbcContextProxy.java

@@ -109,7 +109,7 @@ public Object invoke(Object proxy, Method method, Object[] args) throws Throwabl
     // Support standard JDBC Wrapper unwrap operations
     if (methodName.equals("unwrap") && args != null && args.length == 1) {
       Class<?> iface = (Class<?>) args[0];
-      if (iface.isInstance(target)) {
+      if (iface != null && iface.isInstance(target)) {
         return target;
       }
       try {
@@ -120,7 +120,7 @@ public Object invoke(Object proxy, Method method, Object[] args) throws Throwabl
     }
     if (methodName.equals("isWrapperFor") && args != null && args.length == 1) {
       Class<?> iface = (Class<?>) args[0];
-      if (iface.isInstance(target)) {
+      if (iface != null && iface.isInstance(target)) {
         return true;
       }
       try {

java-bigquery/google-cloud-bigquery-jdbc/src/main/java/com/google/cloud/bigquery/jdbc/BigQueryResultSetMetadata.java

@@ -20,7 +20,6 @@
 import com.google.cloud.bigquery.Field.Mode;
 import com.google.cloud.bigquery.FieldList;
 import com.google.cloud.bigquery.StandardSQLTypeName;
-import com.google.cloud.bigquery.exception.BigQueryJdbcSqlFeatureNotSupportedException;
 import java.sql.ResultSetMetaData;
 import java.sql.SQLException;
 import java.sql.Statement;
@@ -74,8 +73,7 @@ public boolean isCaseSensitive(int column) {
 
   @Override
   public boolean isSearchable(int column) {
-    int colType = getColumnType(column);
-    return colType != Types.OTHER;
+    return true;
   }
 
   @Override
@@ -205,14 +203,17 @@ public String getColumnClassName(int column) {
         .getName();
   }
 
-  // Unsupported methods:
+  // Wrapper methods:
   @Override
   public <T> T unwrap(Class<T> iface) throws SQLException {
-    throw new BigQueryJdbcSqlFeatureNotSupportedException("unwrap is not implemented");
+    if (iface.isInstance(this)) {
+      return iface.cast(this);
+    }
+    throw new SQLException("Cannot unwrap to " + iface.getName());
   }
 
   @Override
   public boolean isWrapperFor(Class<?> iface) throws SQLException {
-    throw new BigQueryJdbcSqlFeatureNotSupportedException("isWrapperFor is not implemented");
+    return iface != null && iface.isInstance(this);
   }
 }