HHH-14435 Improve table information extraction (especially for Oracle with enableSynonyms)

Previously Oracle with enableSynonyms ran into a timeout on CI because the JDBC driver issues a rather expensive query. The new implementation issues a dummy query and uses the result set metadata as suggested in various online articles about schema introspection

Author: beikov

hibernate-core/src/main/java/org/hibernate/boot/model/relational/QualifiedTableName.java

@@ -23,4 +23,20 @@ public QualifiedTableName(Namespace.Name schemaName, Identifier tableName) {
 	public Identifier getTableName() {
 		return getObjectName();
 	}
+
+	public QualifiedTableName quote() {
+		Identifier catalogName = getCatalogName();
+		if ( catalogName != null ) {
+			catalogName = new Identifier( catalogName.getText(), true );
+		}
+		Identifier schemaName = getSchemaName();
+		if ( schemaName != null ) {
+			schemaName = new Identifier( schemaName.getText(), true );
+		}
+		Identifier tableName = getTableName();
+		if ( tableName != null ) {
+			tableName = new Identifier( tableName.getText(), true );
+		}
+		return new QualifiedTableName( catalogName, schemaName, tableName );
+	}
 }

hibernate-core/src/main/java/org/hibernate/tool/schema/extract/internal/InformationExtractorJdbcDatabaseMetaDataImpl.java

@@ -8,7 +8,9 @@
 
 import java.sql.DatabaseMetaData;
 import java.sql.ResultSet;
+import java.sql.ResultSetMetaData;
 import java.sql.SQLException;
+import java.sql.Statement;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.HashMap;
@@ -540,62 +542,53 @@ protected boolean isPhysicalTableType(String tableType) {
 	}
 
 	private void addColumns(TableInformation tableInformation) {
-		final QualifiedTableName tableName = tableInformation.getName();
-		final Identifier catalog = tableName.getCatalogName();
-		final Identifier schema = tableName.getSchemaName();
-
-		final String catalogFilter;
-		final String schemaFilter;
-
-		if ( catalog == null ) {
-			catalogFilter = "";
-		}
-		else {
-			catalogFilter = catalog.getText();
-		}
-
-		if ( schema == null ) {
-			schemaFilter = "";
-		}
-		else {
-			schemaFilter = schema.getText();
-		}
-
-		try {
-			ResultSet resultSet = extractionContext.getJdbcDatabaseMetaData().getColumns(
-					catalogFilter,
-					schemaFilter,
-					tableName.getTableName().getText(),
-					"%"
-			);
-
-			try {
-				while ( resultSet.next() ) {
-					final String columnName = resultSet.getString( "COLUMN_NAME" );
-					final ColumnInformationImpl columnInformation = new ColumnInformationImpl(
-							tableInformation,
-							DatabaseIdentifier.toIdentifier( columnName ),
-							resultSet.getInt( "DATA_TYPE" ),
-							new StringTokenizer( resultSet.getString( "TYPE_NAME" ), "() " ).nextToken(),
-							resultSet.getInt( "COLUMN_SIZE" ),
-							resultSet.getInt( "DECIMAL_DIGITS" ),
-							interpretTruthValue( resultSet.getString( "IS_NULLABLE" ) )
-					);
-					tableInformation.addColumn( columnInformation );
-				}
-			}
-			finally {
-				resultSet.close();
+		// We use this dummy query to retrieve the table information through the ResultSetMetaData
+		// This is significantly better than to use the DatabaseMetaData especially on Oracle with synonyms enabled
+		final String tableName = extractionContext.getJdbcEnvironment().getQualifiedObjectNameFormatter().format(
+				// The name comes from the database, so the case is correct
+				// But we quote here to avoid issues with reserved words
+				tableInformation.getName().quote(),
+				extractionContext.getJdbcEnvironment().getDialect()
+		);
+		final String query = "select * from " + tableName + " where 1=0";
+		try (Statement statement = extractionContext.getJdbcConnection()
+				.createStatement(); ResultSet resultSet = statement.executeQuery( query )) {
+			final ResultSetMetaData metaData = resultSet.getMetaData();
+			final int columnCount = metaData.getColumnCount();
+
+			for ( int i = 1; i <= columnCount; i++ ) {
+				final String columnName = metaData.getColumnName( i );
+				final ColumnInformationImpl columnInformation = new ColumnInformationImpl(
+						tableInformation,
+						DatabaseIdentifier.toIdentifier( columnName ),
+						metaData.getColumnType( i ),
+						new StringTokenizer( metaData.getColumnTypeName( i ), "() " ).nextToken(),
+						metaData.getPrecision( i ),
+						metaData.getScale( i ),
+						interpretNullable( metaData.isNullable( i ) )
+				);
+				tableInformation.addColumn( columnInformation );
 			}
 		}
 		catch (SQLException e) {
 			throw convertSQLException(
 					e,
-					"Error accessing column metadata: " + tableName.toString()
+					"Error accessing column metadata: " + tableInformation.getName().toString()
 			);
 		}
 	}
 
+	private TruthValue interpretNullable(int nullable) {
+		switch ( nullable ) {
+			case ResultSetMetaData.columnNullable:
+				return TruthValue.TRUE;
+			case ResultSetMetaData.columnNoNulls:
+				return TruthValue.FALSE;
+			default:
+				return TruthValue.UNKNOWN;
+		}
+	}
+
 	private TruthValue interpretTruthValue(String nullable) {
 		if ( "yes".equalsIgnoreCase( nullable ) ) {
 			return TruthValue.TRUE;