+
−RELEASE NOTES
+
−MonetDB JDBC driver version 2.29 (Liberica/MCL-1.18)
+
−Release date: 2020-02-12
+
−
+
−The Java Database Connectivity (JDBC) API provides universal data access from
+
−the Java programming language.
+
−
+
−The MonetDB JDBC driver is designed for use with MonetDB, an Open-Source column-store RDBMS.
+
−For more information see https://www.monetdb.org/
+
−
+
−The latest MonetDB JDBC driver can be downloaded from
+
−https://www.monetdb.org/downloads/Java/
+
−
+
−The MonetDB JDBC connection URL format to use is:
+
−  jdbc:monetdb://<hostname>[:<portnr>]/<databasename>[?<property>=<value>[&<property>=<value>]]
+
−
+
−Note: For a successful connection the database name part must be provided
+
− and be equal to the name of the database served by the mserver5 process running on
+
− the specified host and listening to the specified port number (default port is 50000).
+
−
+
−Supported connection properties are:
+
−	user=<login name>
+
−	password=<secret value>
+
−	so_timeout=<time in milliseconds>  default is: 0 (no timeout)
+
−	treat_clob_as_varchar=false        default is: true
+
−	treat_blob_as_binary=false         default is: true
+
−	language=<sql or mal>              default is: sql
+
−  fetchsize=<nr of rows>             default is: 250
+
−	debug=true                         default is: false
+
−	logfile=<name of logfile>
+
−	hash=<SHA512, SHA384, SHA256 or SHA1>
+
−
+
−The treat_clob_as_varchar property (when set to true) will let the method
+
−ResultSetMetaData.getColumnType(int) to return Types.VARCHAR instead of Types.CLOB
+
−for CLOB ResultSet columns. Generic JDBC applications such as SQuirreL SQL and DBeaver
+
−will than use rs.getString() instead of rs.getClob() to fetch any CLOB column data.
+
−Using rs.getString() avoids creating new objects and multiple copies of the clob
+
−string data resulting in (much) faster response and better user experience.
+
−This property is turned on by default as of release monetdb-jdbc-2.30.jre8.jar.
+
−You can turn it off if you prefer the old behavior.
+
−
+
−The treat_blob_as_binary property (when set to true) will let the method
+
−ResultSetMetaData.getColumnType(int) to return Types.VARBINARY instead of Types.BLOB
+
−for BLOB ResultSet columns. Generic JDBC applications such as SQuirreL SQL and DBeaver
+
−will than use rs.getBytes() instead of rs.getBlob() to fetch any BLOB column data.
+
−Using rs.getBytes() avoids creating new objects and multiple copies of the blob
+
−string data resulting in (much) faster response and better user experience.
+
−This property is turned on by default as of release monetdb-jdbc-2.30.jre8.jar.
+
−You can turn it off if you prefer the old behavior.
+
−
+
−We recommend to set following connection properties:
+
−	so_timeout=20000
+
−
+
−Multiple connection properties are separated by the & character.
+
−For example:
+
−  jdbc:monetdb://localhost:41000/mydb?user=monetdb&password=onlyiknow&so_timeout=20000
+
−
+
−See also: https://www.monetdb.org/Documentation/SQLreference/Programming/JDBC
+
−
+
−
+
−JDBC COMPLIANCE
+
−The MonetDB JDBC driver is a type 4 driver (100% pure Java) and
+
−complies to JDBC 4.2 definition, see
+
− http://docs.oracle.com/javase/8/docs/technotes/guides/jdbc/index.html
+
−and
+
− https://en.wikipedia.org/wiki/Java_Database_Connectivity
+
−
+
−Within the current implementation not all functionalities of the JDBC
+
−interface are available.  It is believed, however, that this
+
−implementation is rich enough to be suitable for a majority of
+
−application settings.
+
−
+
−Below a list of (un)supported features can be found.
+
−Please read this list if you intend to use this JDBC driver.
+
−
+
−If you feel some features are missing or have encountered an issue/bug,
+
−please let us know at our bugtracker:
+
−  https://www.monetdb.org/bugzilla/
+
−
+
−Currently implemented JDBC 4.2 interfaces include:
+
−  * java.sql.Driver
+
−
+
−  * java.sql.Connection
+
−    The next features/methods are NOT useable/supported:
+
−    - createArrayOf, createNClob, createStruct, createSQLXML
+
−    - prepareStatement with array of column indices or column names
+
−    - setHoldability (close/hold cursors over commit is not configurable)
+
−
+
−    NOTE: be sure to check for warnings after setting concurrencies or
+
−          isolation levels; MonetDB currently does not support anything
+
−          else but "fully serializable" transactions.
+
−
+
−  * java.sql.DatabaseMetaData
+
−
+
−  * java.sql.Statement
+
−    The next methods/options are NOT useable/supported:
+
−    - cancel (query execution cannot be terminated, once started)
+
−       see also: https://www.monetdb.org/bugzilla/show_bug.cgi?id=6222
+
−    - execute with column indices or names
+
−    - executeUpdate with column indices or names
+
−    - setMaxFieldSize
+
−    - setCursorName
+
−    - setEscapeProcessing on
+
−
+
−  * java.sql.PreparedStatement
+
−    The next methods are NOT useable/supported:
+
−    - setArray
+
−    - setAsciiStream, setBinaryStream, setUnicodeStream
+
−    - setBlob
+
−    - setNClob
+
−    - setRef, setRowId, setSQLXML
+
−
+
−  * java.sql.ParameterMetaData
+
−
+
−  * java.sql.CallableStatement
+
−    The next methods are NOT useable/supported:
+
−    - all getXyz(parameterIndex/parameterName, ...) methods because
+
−      output parameters in stored procedures are not supported by MonetDB
+
−    - all registerOutParameter(parameterIndex/parameterName, int sqlType, ...) methods
+
−      because output parameters in stored procedures are not supported by MonetDB
+
−    - wasNull() method because output parameters in stored procedures are
+
−      not supported by MonetDB
+
−
+
−  * java.sql.ResultSet
+
−    The next methods are NOT useable/supported:
+
−    - getArray
+
−    - getAsciiStream, getUnicodeStream
+
−    - getNClob
+
−    - getRef, getRowId, getSQLXML
+
−    - All methods related to updateable result sets
+
−
+
−  * java.sql.ResultSetMetaData
+
−
+
−  * java.sql.SavePoint
+
−
+
−  * java.sql.Wrapper
+
−
+
−  * java.sql.Blob
+
−    A simple implementation using a byte[] to store the whole BLOB.
+
−    The next method is NOT useable/supported:
+
−    - setBinaryStream
+
−
+
−  * java.sql.Clob
+
−    A simple implementation using a StringBuilder to store the whole CLOB.
+
−    The next methods are NOT useable/supported:
+
−    - setAsciiStream
+
−    - setCharacterStream
+
−
+
−  * java.sql.SQLData
+
−    implemented by class: org.monetdb.jdbc.types.INET
+
−            and by class: org.monetdb.jdbc.types.URL
+
−
+
−  * javax.sql.DataSource (not tested)
+
−
+
−
+
−The following java.sql.* interfaces are NOT implemented:
+
−  * java.sql.Array
+
−  * java.sql.DriverAction
+
−  * java.sql.NClob
+
−  * java.sql.Ref
+
−  * java.sql.Rowid
+
−  * java.sql.SQLInput
+
−  * java.sql.SQLOutput
+
−  * java.sql.SQLType
+
−  * java.sql.SQLXML
+
−  * java.sql.Struct
+
−
+
−
+
−Notes and Tips for Java Programmers using MonetDB JDBC driver:
+
−- Close JDBC ResultSet, Statement, PreparedStatement, CallableStatement and
+
−  Connection objects immediately (via close()) when they are no longer needed,
+
−  in order to release resources and memory on the server and client side.
+
−  Especially ResultSets can occupy large amounts of memory on the server and
+
−  client side.
+
−
+
−- When you need to execute many SQL queries sequentially reuse the Statement
+
−  object instead of creating a new Statement for each single SQL query.
+
−  Alternatively you can execute the SQL queries as one script (each SQL query
+
−  must be separated by a ; character) string via stmt.execute(script),
+
−  stmt.getResultSet() and stmt.getMoreResults().
+
−  Or you can use the batch execution functionality, see stmt.addBatch() and
+
−  stmt.executeBatch() methods.
+
−
+
−- The fastest way to retrieve data from a MonetDB ResultSet is via the
+
−  getString(int columnIndex) method, because internally all data
+
−  values (of all types) are stored as Strings, so no conversions are needed.
+
−
+
−- Avoid using rs.getObject() as it will need to construct a new Object for
+
−  each value, even for primitive types such as int, long, boolean.
+
−
+
−- Avoid using rs.getClob(). Instead use getString() for all CLOB
+
−  columns, which is much faster and uses much (3 times) less memory.
+
−
+
−- Avoid using rs.getBlob(). Instead use getBytes() to get a byte array
+
−  or use getString() to get a string containing hex pairs, for all BLOB
+
−  columns. These methods are much faster and use much less memory.
+
−  The getString() is the fastest way as no conversions are done at all.
+
−  The getBytes() will need to convert the hex char string into a new bytes[].
+
−
+
−- Try to avoid calling "rs.get...(String columnLabel)" methods inside the
+
−   while(rs.next()) {...} loop. Instead resolve the columnLabels to column
+
−  numbers before the loop via method "int findColumn(String columnLabel)"
+
−  and use the int variables with the rs.get...(int columnIndex) methods.
+
−  This eliminates the call to findColumn(String columnLabel) for
+
−  each value of every column for every row in the ResultSet.
+
−  See also the example Java JDBC program on:
+
−  https://www.monetdb.org/Documentation/SQLreference/Programming/JDBC
+
−
+
−- By default the ResultSets created by methods in DatabaseMetaData
+
−  which return a ResultSet (such as dbmd.getColumns(...)) are
+
−  TYPE_SCROLL_INSENSITIVE, so they cache their ResultSet data to
+
−  allow absolute, relative and random access to data rows and fields.
+
−  To free heap memory and server resoucres, close those ResultSets
+
−  immediately when no longer needed.
+
−
+
−- By default the ResultSets created by stmt.executeQuery(...) or
+
−  stmt.execute(...) are TYPE_FORWARD_ONLY, to reduce the potentially large
+
−  amount of client memory needed to cache the whole ResultSet data.
+
−
+
−Warning:
+
− The current implementation of the MonetDB JDBC driver is *not*
+
− multi-thread safe. If your program uses multiple threads concurrently on
+
− the same Connection (so one MapiSocket), this may lead to incorrect behavior
+
− and results (due to race conditions).
+
− You will need to serialize the processing of the threads in your Java program.
+
− Alternatively you can use a separate JDBC Connection for each thread.
+
−
+
−Note: as of Febr 2020 (monetdb-jdbc-2.29.jre8.jar) we compile all
+
− the java sources to target: Java SE 8 (profile compact2), so
+
− you need a JRE/JDK JVM of version 8 or higher to use it.
+
−