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luyangco First stab to export gap detection. (#5713)
* First stab to export gap detection.

Change-Id: Ibe2f7f87cd0858ff58e47d9897a10bc3be4a5754

* ENG-13760, fix bugs that introduced by rebasing.

Change-Id: Iecb635c9733a567bc6dd94c42c82077aa542415b

* ENG-13760, address review comments.

Change-Id: I18daf57905395fe7463d769df273b06ba24bff27

* ENG-13760, fix junit failures.

Change-Id: I276c5edd39b630215cb01b578d27d7d798c8ecd6

* ENG-13760, fix junit failures.

Change-Id: I52562ff3d1ba453668bea90fdf4907052c962141

* ENG-13760, address more review comments.

Change-Id: Iea018c8439aabb0e2d5aad971aa7c527b3f89a0f

* ENG-13760, fix junit failures in recover test.

Change-Id: I1f060dcf0fbb7c5c770a31671f245457a0fc4db4

* ENG-13760, fix wrong truncation offset computation.

Change-Id: I3b9c7c922df6db990cb43c2f6f61003db5f51bd0

* ENG-13760, remove gap count from export stat.

Change-Id: I42252b7512680b6929d8d2e458c53766e3248394

* ENG-13760, improve gap searching algorithm to find best node to bail out.

Change-Id: I31c77d40aa9fe80316be75dd0f1af6d9969d3565

* ENG-13760, fix the double polling of export buffer.

Change-Id: I1ccf76bae434ff8d4bb58d18e4a6c19293f95421

* ENG-13760, update debug logging.

Change-Id: I93848be22f231fe04aeeb278efcd776a4be28b66

* ENG-13760, fix an error in truncating export gap tracker.

Change-Id: I6fbc5cde19c1ab20a5f4e5a06305d8672a050048

* ENG-13760, correct a wrong sequence number calculation in rollback path.

Change-Id: I2d2e6d6031ff280d42b42d3c32dcdb5b74b2666b
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voltcore.iml Eng 13698 jet brains metadata (#5273) May 4, 2018


What is VoltDB?

Thank you for your interest in VoltDB!

VoltDB is a horizontally-scalable, in-memory SQL RDBMS designed for applications that benefit from strong consistency, high throughput and low, predictable latency.

VoltDB and Open Source

VoltDB offers the fully open source, AGPL3-licensed Community Edition of VoltDB through GitHub here:


Binary downloads of this edition and 30-day trials of the commercial editions of VoltDB can be downloaded from the VoltDB website at the following URL:


The Community Edition has full application compatibility and provides everything needed to run a real-time, in-memory SQL database with datacenter-local redundancy and snapshot-based disk persistence.

The commercial editions add operational features to support industrial strength durability and availability, including per-transaction disk-based persistence, multi-datacenter replication, elastic online expansion, live online upgrade, etc..

For more information, please see our "Editions" page:


VoltDB Branches and Tags

The latest development branch is master. We develop features on branches and merge to master when stable. While master is usually stable, it should not be considered production-ready and may also have partially implemented features.

Code that corresponds to released versions of VoltDB are tagged "voltdb-X.X" or "voltdb-X.X.X". To build corresponding OSS VoltDB versions, use these tags.

Building VoltDB

Information on building VoltDB from this source repository is maintained in a GitHub wiki page available here:


First Steps

From the directory where you installed VoltDB, you can either use bin/{command} or add the bin folder to your path so you can use the VoltDB commands anywhere. For example:

voltdb --version

Then, initialize a root directory and start a single-server database. By default the root directory is created in your current working directory. Or you can use the --dir option to specify a location:

voltdb init [--dir ~/mydb]
voltdb start [--dir ~/mydb] [--background]

To start a SQL console to enter SQL DDL, DML or DQL:


To launch the web-based VoltDB Management Console (VMC), open a web browser and connect to localhost on port 8080 (unless there is a port conflict): http://localhost:8080.

To stop the running VoltDB cluster, use the shutdown command. For commercial customers, the database contents are saved automatically by default. For open-source users, add the --save argument to manually save the contents of your database:

voltadmin shutdown [--save]

Then you can simply use the start comment to restart the database:

voltdb start [--dir ~/mydb] [--background]

Further guidance can be found in the tutorial: https://docs.voltdb.com/tutorial/. For more on the CLI, see the documentation: https://docs.voltdb.com/UsingVoltDB/clivoltdb.php.

Next Steps


You can find application examples in the “examples” directory inside this VoltDB kit.

The Voter app (“examples/voter”) is a great example to start with. See the README to learn what it does and how to get it running, or watch this 5 minute video demonstration of the Voter app: https://voltdb.com/resources/video/voltdb-how-tour-voter-example

The App Gallery has more information on additional examples, some in the kit and some on GitHub.


The VoltDB Tutorial will walk you through building and running your first VoltDB application.



The VoltDB User Guide and supporting documentation is comprehensive and easy to use. It’s a great place for broad understanding or to look up something specific.


Product Overview

The VoltDB Product page contains info at a higher level. This page has in-depth descriptions of features that explain not just what, but why. It also covers use cases and competitive comparisons.


Go Full Cloud

For information on using VoltDB virtualized, containerized or in the Cloud, see the the VoltDB website.


What's Included

If you have installed VoltDB from the distribution kit, you now have a directory containing this README file and several subdirectories, including:

  • bin - Scripts for starting VoltDB, bulk loading data, as well as interacting with and managing the running database. Including:
    • bin/voltdb - Start a VoltDB process.
    • bin/voltadmin - CLI to manage a running cluster.
    • bin/sqlcmd - SQL console.
  • doc - Documentation, tutorials, and java-doc
  • examples - Sample programs demonstrating the use of VoltDB
  • lib - Third party libraries
  • tools - XML schemas, monitoring plugins, and other tools
  • voltdb - the VoltDB binary software itself including:
    • license.xml - An embedded trial license.
    • log4j files - Logging configuration.
    • voltdbclient-version.jar - Java/JVM client for connecting to VoltDB, including native VoltDB client and JDBC driver.
    • voltdb-version.jar - The full VoltDB binary, including platform-specific native libraries embedded within the jar. This is a superset of the client code and can be used as a native client driver or JDBC driver.

Commercial VoltDB Differences

VoltDB offers a pre-built binary distribution of VoltDB under a commercial license. It can be downloaded from the VoltDB website. This download includes a 30 day trial license.


When to use this open-source version:

  • When developing applications (as long as they don't need VoltDB Export).
  • When performance testing in non-redundant configurations.
  • When reading or modifying source code.

When to use the commercial version:

  • When disk persistence is required.
  • When the VoltDB Export feature is required.
  • When high availability features like redundant clustering, live node rejoin, and multi-datacenter replication are required.

Getting Help & Providing Feedback

If you have any questions or comments about VoltDB, we encourage you to reach out to the VoltDB team and community.

  • VoltDB Forums - Create threads, post responses and search existing posts on our community forums at https://forum.voltdb.com.
  • VoltDB Community Slack Channel - Get an invite to chat with community members and the VoltDB team at http://chat.voltdb.com.


This program is free software distributed under the terms of the GNU Affero General Public License Version 3. See the accompanying LICENSE file for details on your rights and responsibilities with regards to the use and redistribution of VoltDB software.