The following FAQs are no longer current. They remain here for archival purposes. For the latest information on JavaDB/Derby please visit The Apache DB Project.
This collection of FAQs provides brief answers to the most common questions about Java DB. It also links to more detailed information available from this web site and others.
A: No, Java DB is a relational database management system (RDBMS). Data is stored and queried via SQL or JDBC. Like other RDBMSs, Java DB can also be accessed through a persistence layer such as JPA, Hibernate, or JDO. Java objects can be stored in the columns of Java DB tables.
A: No, Java DB is Oracle's supported version of Apache Derby and contains the same binaries as Apache Derby.
A: Yes, support is available from Oracle via a JDK support contract. You can also contact the Apache Derby user community with questions and bug reports.
A: Absolutely. Java DB is a multi-user database engine and supports concurrent users.
A: Java DB is bundled in the db subdirectory of the Java 7 JDK.
A: See the Getting Started Guide here.
A: Java DB provides data types corresponding to all of the Java primitive types (except for byte), plus Strings, byte arrays, date and time stamps, and user-defined objects.
A: Yes, Java DB supports almost all SQL92 features as well as features from SQL99, SQL2003, and SQL2008. For more information, see SQL-99 and SQL-2003 features mapped to Derby.
A: Yes. For more information on how to implement and invoke procedures and functions, see Derby SQL Routines. Note that procedures and functions are written in Java just like application code.
A: Java DB supports subqueries in WHERE clauses, FROM clauses, IN predicates, and quantified comparison predicates, but does not currently support updatable queries with subqueries. Subqueries can contain OFFSET/FETCH windows and return ORDER BY results.
A: Yes, Java DB supports upper, lower, concat, substring, like, length, and trim.
A: Yes, Java DB provides special functions that allow you to extract the year, month, day, hour, minute, and second from a DATE, TIME, or TIMESTAMP value. The returned values are large integers, so you can perform arithmetic operations on them.
A: Yes, Java DB supports date/time arithmetic through use of the functions TIMESTAMPADD and TIMESTAMPDIFF on a TIMESTAMP value.
A: Java DB supports the SQL standard COUNT, MIN, MAX, AVG, and SUM aggregates, which may be grouped using GROUP BY and ROLLUP clauses.
A: Yes, Java DB supports SQL standard FETCH/OFFSET syntax. Scrollable JDBC ResultSets can also be used for pagination and positioned updates.
A: Java DB supports JDBC 4.1
A: Yes, Java DB supports these features.
A: Yes, Java DB provides a full JDBC metadata API implementation (
A: Yes, Java DB has XA support.
A: Yes, Java DB supports allows this.
A: Java DB stores each base table and each index in a single file, so the data size limit is the file size limit of the JVM and OS on which it runs. Derby is coded against the Java 64 bit interfaces to access these files, so internally the maximum table size is approximately 2**64. The number of tables is only limited by the 64 bit length of table identifiers, for an approximate limit of 2**64 total tables. In practice, system resources such as disk space are a more likely source of size limitations. Java DB is tested on a database using over 350 GB of raw disk space with tables containing over 500 million tuples.
A: The maximum size of a CLOB or BLOB stored in Java DB is 2 GB.
A: Java DB runs on CDC/FP 1.1, Java 5, Java 6, and Java 7.
A: Java DB/Derby provides system procedures for backup and administration tasks. Various open source and commercial GUI tools support Derby administration, such as SQuirreL SQL Client. These work well for most users, given Derby's commitment to ease of use.
A: On many platforms, including Windows and Linux, the disk write cache is enabled by default. This improves disk performance, but can result in data loss or corruption in case of power outage or equipment failure. For more information, see Configuring Apache Derby for Performance and Durablity.
A: Yes. For help, see this JPOX help, this JPA blog, and this Hibernate page.
A: Java DB can be run with the following Java ME technologies: CDC 1.1, Foundation Profile 1.1, JDBC Optional Package for CDC/Foundation Profile (JSR169). See Using Derby on Java ME Platforms.
A: Java DB supports asynchronous replication to an offline slave database.
A: SQL identifiers containing special characters or identifiers that you wish to be case-sensitive must be enclosed in double quotes. Unquoted identifiers will be case insensitive. For more information, see the "Capitalization and special characters" section in the Derby Reference Manual here.
A: For an overview of how to configure Java DB to achieve optimal performance while being able to handle failure scenarios without losing data, see Configuring Apache Derby for Performance and Durability. For tips on investigating performance issues that might occur between Derby releases, see Performance and Diagnosis Tips.