Gstore System(also called gStore) is a graph database engine for managing large graph-structured data, which is open-source and targets at Linux operation systems. The whole project is written in C , with the help of some libraries such as readline, antlr, and so on. Only source tarballs are provided currently, which means you have to compile the source code if you want to use our system.

The formal help document is in English(EN) and 中文(ZH).

We have built an IRC channel named #gStore on freenode, and you can visit the homepage of gStore(ZH) or the homepage of gStore(EN).

1.0（stable）：2022-10-01

New features in gStore 1.0 are listed as follows:

• Support of user-defined graph analysis functions: users can manage their own graph analysis functions through the API interfaces or the visual management platform gStore-workbench. Users can obtain the number of nodes and edges of the graph and neighbors of any given node, etc. through interface functions and use them as basic units to implement their own graph analysis functions. Dynamic compilation and execution of user-defined graph analysis functions are supported.

• The gRPC network interface service: gRPC is a high-performance network interface service based on HTTP protocol implemented based on the open source library workflow, which further improves the efficiency and stability of the interface service. Experiments show that gRPC achieves a great improvement in concurrent access performance compared with ghttp, the previous network interface; for example, in the case of 2000/QPS, the rate of denied access is 0%.

• gConsole module: in gStore 1.0, we launched the gConsole module, which enables the long-session operation of gStore with contextual information.

• Decoupling of the optimizer and executor: gStore 1.0 decouples the optimizer and executor, converting from the original deeply coupled greedy strategy to a query optimizer based on dynamic programming and a query executor based on breadth-first traversal.

• Optimization of Top-K queries: We implemented a Top-K SPARQL processing framework based on the DP-B algorithm in gStore, including query segmentation and sub-result aggregation.

• Support of ACID transactions: by introducing the multi-version management mechanism, gStore 1.0 can start ACID transactions for insert and delete operations, which users can open, commit, and roll back. Currently gStore 1.0 supports four isolation levels: read-uncommitted, read-committed, repeatable read and serializable.

• Reconstruction of database kernel and optimization of the plan tree generation logic: in gStore 1.0, two types of join operations (worst-case-optimal joins and binary joins) are introduced to optimize query execution and further improve query efficiency.

• Optimized logging module: based on the log4cplus library, the system logs can be output in a unified format. Users can configure the log output mode (console output or file output), output format, and output level.

• New built-in advanced functions: gStore 1.0 supports four new advanced functions, namely triangleCounting, closenessCentrality, bfsCount and kHopEnumeratePath.

• Extended support for BIND statements: gStore 1.0 supports assigning values to variables using algebraic or logical expressions in BIND statements.

• Optimization of some local commands and API interfaces (e.g., the shutdown command), and fixing a series of bugs (e.g., more accurate gmonitor statistics).

0.9.1：2021-11-25

New features in gStore 0.9.1 are listed as follows:

• Decoupling the parsing and execution of queries in kernel, and further improvements on the query performance through optimized join ordering and other techniques. On complex queries, the performance is improved by over 40%.
• Rewriting of the HTTP service component, ghttp, with improved robustness and the addition of functions such as user permission, heartbeat detection, batch import, and batch deletion; API documents are added.
• Implementation of the Personalized PageRank (PPR) extension function, which can be invoked in the SELECT clause to calculate the correlation between entities.
• Support for arithmetic operations (e.g., ?x ?y = 5) in the FILTER clause.
• Support for transactional operations, such as begin, tquery (transactional query), commit, and rollback;
• A new executive component, gserver, is added to provide another pathway for remote access of gStore aside from the ghttp component, which implements two-way communication via the socket API.
• Unification of the format of command line arguments of executive components. The --help option is uniformly introduced (e.g., $ bin/gbuild --help or $ bin/gbuild -h), by which users can view the command manual including the meaning of each option.
• A number of bug fixes.

0.9：2021-02-10

New features in version 0.9 include:

• Upgrade of the SPARQL parser generator from ANTLR v3 to the newest, well-documented and well-maintained v4;
• Support for writing numeric literals without datatype suffixes in SPARQL queries;
• Support for arithmetic and logical operators in SELECT clause;
• Support for the aggregates SUM, AVG, MIN and MAX in SELECT clause;
• Additional support for built-in functions functions in FILTERs, including datatype, contains, ucase, lcase, strstarts, now, year, month, day, and abs;
• Support for path-related functions as an extension of SPARQL 1.1, including cycle detection, shortest paths and K-hop reachability;
• Support for full & incremental backup and recovery of databases, and automatic full backup can be enabled upon admin configuration;
• Support for log-based rollback opertions;
• Support for transactions with three levels of isolation: read committed, snapshot isolation and serializable;
• Expanding data structures to hold large-scale graphs of up to five billion triples.

The version is a beta version, you can get it by :

git clone https://github.com/pkumod/gStore.git

0.8

The version is a stable version ,you can get it by

 git clone -b 0.8 https://github.com/pkumod/gStore.git

This system is really user-friendly and you can pick it up in several minutes. Remember to check your platform where you want to run this system by viewing System Requirements. After all are verified, please get this project's source code. There are several ways to do this:

• (suggested)type git clone https://github.com/pkumod/gStore.git in your terminal or use git GUI to acquire it

• download the zip from this repository and extract it

• fork this repository in your github account

Then you need to compile the project, for the first time you need to type make pre to prepare the ANTLR library and some Lexer/Parser programs. Later you do not need to type this command again, just use the make command in the home directory of gStore, then all executables will be generated. (For faster compiling speed, use make -j4 instead, using how many threads is up to your machine) To check the correctness of the program, please type make test command.

The first strategy is suggested to get the source code because you can easily acquire the updates of the code by typing git pull in the home directory of gStore repository. In addition, you can directly check the version of the code by typing git log to see the commit logs. If you want to use code from other branches instead of master branch, like 'dev' branch, then:

• clone the master branch and type git checkout dev in your terminal

• clone the dev branch directly by typing git clone -b dev

You can easily deploy gStore via Docker. We provide both of Dockerfile and docker image. Please see our Docker Deployment Doc(EN) or Docker部署文档(中文) for details.

To run gStore, please type bin/gbuild -db database_name -f dataset_path to build a database named by yourself. And you can use bin/gquery -db database_name command to query an existing database. What is more, bin/ghttp is a wonderful tool designed for you, as a database server which can be accessed via HTTP protocol. Notice that all commands should be typed in the root directory of gStore, and your database name should not end with ".db".

If you want to understand the details of the gStore system, or you want to try some advanced operations(for example, using the API, server/client), please see the chapters below.

• Basic Introduction: introduce the theory and features of gStore

• Install Guide: instructions on how to install this system

• How To Use: detailed information about using the gStore system

• API Explanation: guide you to develop applications based on our API

• Project Structure: show the whole structure and process of this project

• Related Essays: contain essays and publications related with gStore

• Update Logs: keep the logs of the system updates

• Test Results: present the test results of a series of experiments

Bugs are recorded in BUG REPORT. You are welcomed to submit the bugs you discover if they do not exist in this file.

We have written a series of short essays addressing recurring challenges in using gStore to realize applications, which are placed in Recipe Book.

You are welcome to report any advice or errors in the github Issues part of this repository, if not requiring in-time reply. However, if you want to urgent on us to deal with your reports, please email to [email protected] to submit your suggestions and report bugs. A full list of our whole team is in Mailing List.

There are some restrictions when you use the current gStore project, you can see them on Limit Description.

Sometimes you may find some strange phenomena(but not wrong case), or something hard to understand/solve(don't know how to do next), then do not hesitate to visit the Frequently Asked Questions page.

Graph database engine is a new area and we are still trying to go further. Things we plan to do next is in Future Plan chapter, and we hope more and more people will support or even join us. You can support in many ways:

• watch/star our project

• fork this repository and submit pull requests to us

• download and use this system, report bugs or suggestions

• ...

People who inspire us or contribute to this project will be listed in the Thanks List chapter.