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Cozo 数据库

🎉🎉🎉 新版本发布 🎉🎉🎉

CozoDB v0.6 已发布!本版本在 Datalog 内引入了带有 HNSW 索引的向量搜索,可以与即席连接、递归 Datalog 和经典的整个图算法等强大功能无缝集成。这显著扩展了 CozoDB 的可能性。 详情见此

简介

[ 中文文档 | English ]

Cozo是一个事务型关系型数据库:

  • 一个 可嵌入 的数据库;
  • 一个使用 Datalog 作为查询语句的数据库;
  • 一个专注于 图数据、图算法 的数据库;
  • 一个可进行 历史穿梭 查询的数据库;
  • 一个支持 高性能、高并发 的数据库。

“可嵌入”是什么意思?

如果某个数据库能在不联网的手机上使用,那它大概就是嵌入式的。举例来说,SQLite 是嵌入式的,而 MySQL、Postgres、Oracle 等不是(它们是客户端—服务器(CS)架构的数据库)。

如果数据库与你的主程序在同一进程中运行,那么它就是 嵌入式 数据库。与此相对,在使用 客户端—服务器 架构的数据库时,主程序需要通过特定的接口(通常是网络接口)访问数据库,而数据库也可能运行在另一台机器或独立的集群上。嵌入式数据库使用简单,资源占用少,并可以在更广泛的环境中使用。

Cozo 同时也支持以客户端—服务器模式运行。因此,Cozo 是一个 可嵌入 而不是仅仅是 嵌入式 的数据库。在客户端—服务器模式下,Cozo 可以更充分地发挥服务器的性能。

“图数据”有什么用?

从本质上来说,数据一定是相互关联、自关联的,而这种关联的数学表达便是 (也叫 网络)。只有考虑这些关联,才能更深入地洞察数据背后的逻辑。

大多数现有的 图数据库 强制要求按照属性图(property graph)的范式存储数据。与此相对,Cozo 使用传统的关系数据模型。关系数据模型有存储逻辑简单、功能强劲等优点,并且处理图数据也毫无问题。更重要的是,数据的洞察常常需要挖掘隐含的关联,而关系数据模型作为关系 代数(relational algebra)可以很好地处理此类问题。比较而言,因为其不构成一个代数,属性图模型仅仅能够将显性的图关系作为图数据处理,可组合性很弱。

“Datalog”好在哪儿?

Datalog 1977 年便出现了,它可表达所有的 关系型查询,而它与 SQL 比起来的优势在于其对 递归 的表达。由于执行逻辑不同,Datalog 对于递归的运行,通常比相应的 SQL 查询更快。Datalog 的可组合性、模块性都很优秀,使用它,你可以逐层、清晰地表达所需的查询。

递归对于图查询尤其重要。Cozo 使用的 Datalog 方言 叫做 CozoScript,其允许在一定条件下混合使用聚合查询与递归,从而进一步增强了 Datalog 的表达能力。同时,Cozo内置了图分析中常用的一些算法(如 PageRank 等),调用简单。

对 Datalog 有进一步了解以后,你会发现 Datalog 的 规则 类似于编程语言中的函数。规则的一大特点是其可组合性:将一个查询分解为多个渐进的规则可使查询更清晰、易维护,且不会有效率上的损失。与此相对的,复杂的 SQL 查询语句通常表达为多层嵌套的“select-from-where”,可读性、可维护性都不高。

历史穿梭?

在数据库中,“历史穿梭”的意思是记录数据的一切变化,以允许针对某一时刻的数据进行执行查询,用来窥探历史。

在某种意义上,这使数据库成为 不可变 数据库,因为没有数据会被真正删除。

每一项额外的功能都有其代价。如果不使用某个功能,理想的状态是不必为这个功能的代价埋单。在 Cozo 中,不是所有数据表都自动支持历史穿梭,这就把是否需要此功能、是否愿意支付代价的选择权交到了用户手里。

这个关于历史穿梭的小故事可能启发出一些历史穿梭的应用场景。

“高性能、高并发”,有多高?

我们在一台 2020 年的 Mac Mini 上,使用 RocksDB 持久性存储引擎(Cozo 支持多种存储引擎)做了性能测试:

  • 对一个有 160 万行的表进行查询:读、写、改的混合事务性查询可达到每秒 10 万次,而只读查询可达到每秒 25 万次。在此过程中,数据库使用的内存峰值仅为50MB。
  • 备份数据的速度为每秒约 100 万行,恢复速度为每秒约 40 万行。备份、恢复的速度不随表单数据增长而变慢。
  • 分析查询:扫描一个有 160 万行的表大约需要 1 秒(根据具体查询语句大约有上下 2 倍以内的差异)。查询所需时间与查询所涉及的行数大致成比例,而内存使用主要决定于返回集合的大小。
  • 对于一个有 160 万个顶点,3100 万条边的图数据表,“两跳”图查询(如查询某人的朋友的朋友都有谁)可在 1 毫秒内完成。
  • Pagerank 算法速度:1 万个顶点,12 万条边:50 毫秒以内;10 个万顶点,170 万条边:1 秒以内;160 万个顶点,3100 万条边:30秒以内。

更多的细节参见此文

学习 Cozo

你得先安装一个数据库才能开始学,对吧?不一定:Cozo 是“嵌入式”的,所以我们直接把它通过 WASM 嵌入到浏览器里了!打开这个页面,然后:

当然也可以一步到位:先翻到后面了解如何在熟悉的环境里安装原生 Cozo 数据库,再开始学习。

一些示例

通过以下示例,可在正式开始学习之前对 Cozo 的查询先有个感性认识。

假设有个表,名为 *route,含有两列,名为 frto,其中数据为机场代码(如 FRA 是法兰克福机场的代码),且每行数据表示一个飞行航线。

FRA 可以不转机到达多少个机场:

?[count_unique(to)] := *route{fr: 'FRA', to}
count_unique(to)
310

FRA 出发,转机一次,可以到达多少个机场:

?[count_unique(to)] := *route{fr: 'FRA', to: stop},
                       *route{fr: stop, to}
count_unique(to)
2222

FRA 出发,转机任意次,可以到达多少个机场:

reachable[to] := *route{fr: 'FRA', to}
reachable[to] := reachable[stop], *route{fr: stop, to}
?[count_unique(to)] := reachable[to]
count_unique(to)
3462

FRA 出发,按所需的最少转机次数排序,到达哪两个机场需要最多的转机次数:

shortest_paths[to, shortest(path)] := *route{fr: 'FRA', to},
                                      path = ['FRA', to]
shortest_paths[to, shortest(path)] := shortest_paths[stop, prev_path],
                                      *route{fr: stop, to},
                                      path = append(prev_path, to)
?[to, path, p_len] := shortest_paths[to, path], p_len = length(path)

:order -p_len
:limit 2
to path p_len
YPO ["FRA","YYZ","YTS","YMO","YFA","ZKE","YAT","YPO"] 8
BVI ["FRA","AUH","BNE","ISA","BQL","BEU","BVI"] 7

FRAYPO 这两个机场之间最短的路径以及其实际飞行里程是多少:

start[] <- [['FRA']]
end[] <- [['YPO]]
?[src, dst, distance, path] <~ ShortestPathDijkstra(*route[], start[], end[])
src dst distance path
FRA YPO 4544.0 ["FRA","YUL","YVO","YKQ","YMO","YFA","ZKE","YAT","YPO"]

当查询语句有错时,Cozo 会提供明确有用的错误信息:

?[x, Y] := x = 1, y = x + 1
eval::unbound_symb_in_head

  × Symbol 'Y' in rule head is unbound
   ╭────
 1 │ ?[x, Y] := x = 1, y = x + 1
   · 
   ╰────
  help: Note that symbols occurring only in negated positions are not considered bound

安装 Cozo

建议先学习,再安装。当然反过来我们也不反对。

Cozo 可以安装在一大堆不同的语言与环境中:

语言/环境 官方支持的平台 存储引擎
Python国内镜像 Linux (x86_64), Mac (ARM64, x86_64), Windows (x86_64) MQR
NodeJS Linux (x86_64, ARM64), Mac (ARM64, x86_64), Windows (x86_64) MQR
浏览器 支持WASM的浏览器(较新的浏览器全都支持) M
Java (JVM)国内镜像 Linux (x86_64, ARM64), Mac (ARM64, x86_64), Windows (x86_64) MQR
Clojure (JVM)国内镜像 Linux (x86_64, ARM64), Mac (ARM64, x86_64), Windows (x86_64) MQR
安卓国内镜像 Android (ARM64, ARMv7, x86_64, x86) MQ
iOS/macOS (Swift) iOS (ARM64, 模拟器), Mac (ARM64, x86_64) MQ
Rust 任何支持std平台(源代码编译) MQRST
Go国内镜像 Linux (x86_64, ARM64), Mac (ARM64, x86_64), Windows (x86_64) MQR
C/C++/支持 C FFI 的语言 Linux (x86_64, ARM64), Mac (ARM64, x86_64), Windows (x86_64) MQR
独立的 HTTP 服务 Linux (x86_64, ARM64), Mac (ARM64, x86_64), Windows (x86_64) MQRST

“存储引擎”列中各个字母的含义:

  • M: 基于内存的非持久性存储引擎
  • Q: 基于 SQLite 的存储引擎
  • R: 基于 RocksDB 的存储引擎
  • S: 基于 Sled 的存储引擎
  • T: 基于 TiKV 的分布式存储引擎

Cozo 的 Rust API 文档(英文)中有一些额外的关于存储选择的建议。

你也可以尝试为其它平台、语言、引擎自行编译 Cozo。可能需要调整一些代码,但总体来说不难。

优化基于 RocksDB 的存储引擎

RocksDB 有五花八门的选项以供用户进行性能调优。但是调优这个问题太复杂了,就连 RocksDB 他们自己也搞不定,所以实际生产中他们用的是强化学习来自动调优。对于 95% 的用户来说,费这个劲根本不值得,尤其是 Cozo “开箱”的设置就已经相当快、足够快了。

如果你坚信你是剩下那 5% 里面的:当你用 RocksDB 引擎创建 CozoDB 实例时,你提供过一个存储数据的目录路径。如果在这个目录里创建一个名为options的文件,RocksDB 引擎便会将其解读为 RocksDB 选项文件 并应用其中的设置。如果使用的是独立的 cozo 程序,激活此功能时会有一条提示日志。

每次 RocksDB 引擎启动时,存储目录下的 data/OPTIONS-XXXXXX 文件会记录当前应用设置。你可以把这个文件拷贝出来,在其基础上修改。如果你不是 RocksDB 的专家,建议只改动那些你大概知道什么意思的数字型选项。设置不当可能会搞乱、搞坏数据库。

Cozo 的架构

Cozo 数据库有三个上下游部分组成,其中每部分只调用下游部分的接口。

(用户代码)
语言/环境包装
查询引擎
存储引擎
(操作系统)

存储引擎

在存储引擎这一部分里,Cozo 定义了一个存储接口(Rust 中的 trait),这个接口的功能是对二进制数据的键值进行存储及范围扫描。目前这个接口有以下官方实现:

  • 基于内存的非持久性存储引擎
  • 基于 SQLite 的存储引擎
  • 基于 RocksDB 的存储引擎
  • 基于 Sled 的存储引擎
  • 基于 TiKV 的分布式存储引擎

不是所有的二进制包都包含以上所有引擎。这些引擎中,SQLite 引擎具有特殊地位:Cozo 使用它的文件作为备份文件,用以在不同引擎的 Cozo 之间交换数据。Rust 使用者可以轻松实现自己的引擎(不是说写一个引擎很轻松,这里意思是把现有的引擎接入到 Cozo 里很轻松)。

Cozo 使用 面向行 而非 面向列 的二进制存储格式。在这个格式中,对键的存储通过 memcomparable 的方法将复合键存储为一个字节数组,而直接对这些字节数组按照字节顺序排序就能得到正确的语义排序。这也意味着直接用 SQL 查询在 SQLite 引擎中存储的数据得到的结果看起来像是乱码。实现存储引擎本身的接口并不需要了解这个格式。

查询引擎

查询引擎部分实现了以下功能:

  • 各种函数、聚合算子、算法的实现
  • 表单数据结构的定义(schema)
  • 数据库查询事务(transaction)
  • 查询语句的编译
  • 查询的执行

这部分包含 Cozo 项目的大部分代码。关于查询的执行,文档中有一整章来详细介绍。

Cozo 的 Rust API 实际上就是查询引擎的公共接口。

语言、环境封装

Cozo 的 Rust 以外的所有语言、环境都只是对 Rust API 的进一步封装。例如,在独立服务器(cozo)中,Rust API 被封装为了 HTTP 端点,而在 Cozo-Node 中,同步的Rust API 被封装为基于 JavaScript 运行时的异步 API。

封装 Rust API 不难,如果你想让 Cozo 在其它语言上跑起来可以试试。Rust 有一些现成的库用来与其它语言交互。如果你想用某个语言而没有现成的交互库,我们建议你直接封装 Cozo 的 C 语言 API。官方支持的 Go 库就是这么实现的(通过 cgo)。

项目进程

Cozo 一开始预想的功能已经实现得不少了,但是项目仍然年轻得很。欢迎各界朋友使用并提出宝贵意见。

Cozo 1.0 之前的版本不承诺语法、API 的稳定性或存储兼容性。

许可证和贡献

Cozo 以 MPL-2.0 或其更高版本授权。如果你有兴趣为该项目贡献代码,请看这里

Mozilla Public License Version 2.0 ================================== 1. Definitions -------------- 1.1. "Contributor" means each individual or legal entity that creates, contributes to the creation of, or owns Covered Software. 1.2. "Contributor Version" means the combination of the Contributions of others (if any) used by a Contributor and that particular Contributor's Contribution. 1.3. "Contribution" means Covered Software of a particular Contributor. 1.4. "Covered Software" means Source Code Form to which the initial Contributor has attached the notice in Exhibit A, the Executable Form of such Source Code Form, and Modifications of such Source Code Form, in each case including portions thereof. 1.5. "Incompatible With Secondary Licenses" means (a) that the initial Contributor has attached the notice described in Exhibit B to the Covered Software; or (b) that the Covered Software was made available under the terms of version 1.1 or earlier of the License, but not also under the terms of a Secondary License. 1.6. "Executable Form" means any form of the work other than Source Code Form. 1.7. "Larger Work" means a work that combines Covered Software with other material, in a separate file or files, that is not Covered Software. 1.8. "License" means this document. 1.9. "Licensable" means having the right to grant, to the maximum extent possible, whether at the time of the initial grant or subsequently, any and all of the rights conveyed by this License. 1.10. "Modifications" means any of the following: (a) any file in Source Code Form that results from an addition to, deletion from, or modification of the contents of Covered Software; or (b) any new file in Source Code Form that contains any Covered Software. 1.11. "Patent Claims" of a Contributor means any patent claim(s), including without limitation, method, process, and apparatus claims, in any patent Licensable by such Contributor that would be infringed, but for the grant of the License, by the making, using, selling, offering for sale, having made, import, or transfer of either its Contributions or its Contributor Version. 1.12. "Secondary License" means either the GNU General Public License, Version 2.0, the GNU Lesser General Public License, Version 2.1, the GNU Affero General Public License, Version 3.0, or any later versions of those licenses. 1.13. "Source Code Form" means the form of the work preferred for making modifications. 1.14. "You" (or "Your") means an individual or a legal entity exercising rights under this License. For legal entities, "You" includes any entity that controls, is controlled by, or is under common control with You. For purposes of this definition, "control" means (a) the power, direct or indirect, to cause the direction or management of such entity, whether by contract or otherwise, or (b) ownership of more than fifty percent (50%) of the outstanding shares or beneficial ownership of such entity. 2. License Grants and Conditions -------------------------------- 2.1. Grants Each Contributor hereby grants You a world-wide, royalty-free, non-exclusive license: (a) under intellectual property rights (other than patent or trademark) Licensable by such Contributor to use, reproduce, make available, modify, display, perform, distribute, and otherwise exploit its Contributions, either on an unmodified basis, with Modifications, or as part of a Larger Work; and (b) under Patent Claims of such Contributor to make, use, sell, offer for sale, have made, import, and otherwise transfer either its Contributions or its Contributor Version. 2.2. Effective Date The licenses granted in Section 2.1 with respect to any Contribution become effective for each Contribution on the date the Contributor first distributes such Contribution. 2.3. Limitations on Grant Scope The licenses granted in this Section 2 are the only rights granted under this License. No additional rights or licenses will be implied from the distribution or licensing of Covered Software under this License. Notwithstanding Section 2.1(b) above, no patent license is granted by a Contributor: (a) for any code that a Contributor has removed from Covered Software; or (b) for infringements caused by: (i) Your and any other third party's modifications of Covered Software, or (ii) the combination of its Contributions with other software (except as part of its Contributor Version); or (c) under Patent Claims infringed by Covered Software in the absence of its Contributions. This License does not grant any rights in the trademarks, service marks, or logos of any Contributor (except as may be necessary to comply with the notice requirements in Section 3.4). 2.4. Subsequent Licenses No Contributor makes additional grants as a result of Your choice to distribute the Covered Software under a subsequent version of this License (see Section 10.2) or under the terms of a Secondary License (if permitted under the terms of Section 3.3). 2.5. Representation Each Contributor represents that the Contributor believes its Contributions are its original creation(s) or it has sufficient rights to grant the rights to its Contributions conveyed by this License. 2.6. Fair Use This License is not intended to limit any rights You have under applicable copyright doctrines of fair use, fair dealing, or other equivalents. 2.7. Conditions Sections 3.1, 3.2, 3.3, and 3.4 are conditions of the licenses granted in Section 2.1. 3. Responsibilities ------------------- 3.1. Distribution of Source Form All distribution of Covered Software in Source Code Form, including any Modifications that You create or to which You contribute, must be under the terms of this License. You must inform recipients that the Source Code Form of the Covered Software is governed by the terms of this License, and how they can obtain a copy of this License. You may not attempt to alter or restrict the recipients' rights in the Source Code Form. 3.2. Distribution of Executable Form If You distribute Covered Software in Executable Form then: (a) such Covered Software must also be made available in Source Code Form, as described in Section 3.1, and You must inform recipients of the Executable Form how they can obtain a copy of such Source Code Form by reasonable means in a timely manner, at a charge no more than the cost of distribution to the recipient; and (b) You may distribute such Executable Form under the terms of this License, or sublicense it under different terms, provided that the license for the Executable Form does not attempt to limit or alter the recipients' rights in the Source Code Form under this License. 3.3. Distribution of a Larger Work You may create and distribute a Larger Work under terms of Your choice, provided that You also comply with the requirements of this License for the Covered Software. If the Larger Work is a combination of Covered Software with a work governed by one or more Secondary Licenses, and the Covered Software is not Incompatible With Secondary Licenses, this License permits You to additionally distribute such Covered Software under the terms of such Secondary License(s), so that the recipient of the Larger Work may, at their option, further distribute the Covered Software under the terms of either this License or such Secondary License(s). 3.4. Notices You may not remove or alter the substance of any license notices (including copyright notices, patent notices, disclaimers of warranty, or limitations of liability) contained within the Source Code Form of the Covered Software, except that You may alter any license notices to the extent required to remedy known factual inaccuracies. 3.5. Application of Additional Terms You may choose to offer, and to charge a fee for, warranty, support, indemnity or liability obligations to one or more recipients of Covered Software. However, You may do so only on Your own behalf, and not on behalf of any Contributor. You must make it absolutely clear that any such warranty, support, indemnity, or liability obligation is offered by You alone, and You hereby agree to indemnify every Contributor for any liability incurred by such Contributor as a result of warranty, support, indemnity or liability terms You offer. You may include additional disclaimers of warranty and limitations of liability specific to any jurisdiction. 4. Inability to Comply Due to Statute or Regulation --------------------------------------------------- If it is impossible for You to comply with any of the terms of this License with respect to some or all of the Covered Software due to statute, judicial order, or regulation then You must: (a) comply with the terms of this License to the maximum extent possible; and (b) describe the limitations and the code they affect. Such description must be placed in a text file included with all distributions of the Covered Software under this License. Except to the extent prohibited by statute or regulation, such description must be sufficiently detailed for a recipient of ordinary skill to be able to understand it. 5. Termination -------------- 5.1. The rights granted under this License will terminate automatically if You fail to comply with any of its terms. However, if You become compliant, then the rights granted under this License from a particular Contributor are reinstated (a) provisionally, unless and until such Contributor explicitly and finally terminates Your grants, and (b) on an ongoing basis, if such Contributor fails to notify You of the non-compliance by some reasonable means prior to 60 days after You have come back into compliance. Moreover, Your grants from a particular Contributor are reinstated on an ongoing basis if such Contributor notifies You of the non-compliance by some reasonable means, this is the first time You have received notice of non-compliance with this License from such Contributor, and You become compliant prior to 30 days after Your receipt of the notice. 5.2. If You initiate litigation against any entity by asserting a patent infringement claim (excluding declaratory judgment actions, counter-claims, and cross-claims) alleging that a Contributor Version directly or indirectly infringes any patent, then the rights granted to You by any and all Contributors for the Covered Software under Section 2.1 of this License shall terminate. 5.3. In the event of termination under Sections 5.1 or 5.2 above, all end user license agreements (excluding distributors and resellers) which have been validly granted by You or Your distributors under this License prior to termination shall survive termination. ************************************************************************ * * * 6. Disclaimer of Warranty * * ------------------------- * * * * Covered Software is provided under this License on an "as is" * * basis, without warranty of any kind, either expressed, implied, or * * statutory, including, without limitation, warranties that the * * Covered Software is free of defects, merchantable, fit for a * * particular purpose or non-infringing. The entire risk as to the * * quality and performance of the Covered Software is with You. * * Should any Covered Software prove defective in any respect, You * * (not any Contributor) assume the cost of any necessary servicing, * * repair, or correction. This disclaimer of warranty constitutes an * * essential part of this License. No use of any Covered Software is * * authorized under this License except under this disclaimer. * * * ************************************************************************ ************************************************************************ * * * 7. Limitation of Liability * * -------------------------- * * * * Under no circumstances and under no legal theory, whether tort * * (including negligence), contract, or otherwise, shall any * * Contributor, or anyone who distributes Covered Software as * * permitted above, be liable to You for any direct, indirect, * * special, incidental, or consequential damages of any character * * including, without limitation, damages for lost profits, loss of * * goodwill, work stoppage, computer failure or malfunction, or any * * and all other commercial damages or losses, even if such party * * shall have been informed of the possibility of such damages. This * * limitation of liability shall not apply to liability for death or * * personal injury resulting from such party's negligence to the * * extent applicable law prohibits such limitation. Some * * jurisdictions do not allow the exclusion or limitation of * * incidental or consequential damages, so this exclusion and * * limitation may not apply to You. * * * ************************************************************************ 8. Litigation ------------- Any litigation relating to this License may be brought only in the courts of a jurisdiction where the defendant maintains its principal place of business and such litigation shall be governed by laws of that jurisdiction, without reference to its conflict-of-law provisions. Nothing in this Section shall prevent a party's ability to bring cross-claims or counter-claims. 9. Miscellaneous ---------------- This License represents the complete agreement concerning the subject matter hereof. If any provision of this License is held to be unenforceable, such provision shall be reformed only to the extent necessary to make it enforceable. Any law or regulation which provides that the language of a contract shall be construed against the drafter shall not be used to construe this License against a Contributor. 10. Versions of the License --------------------------- 10.1. New Versions Mozilla Foundation is the license steward. Except as provided in Section 10.3, no one other than the license steward has the right to modify or publish new versions of this License. Each version will be given a distinguishing version number. 10.2. Effect of New Versions You may distribute the Covered Software under the terms of the version of the License under which You originally received the Covered Software, or under the terms of any subsequent version published by the license steward. 10.3. Modified Versions If you create software not governed by this License, and you want to create a new license for such software, you may create and use a modified version of this License if you rename the license and remove any references to the name of the license steward (except to note that such modified license differs from this License). 10.4. Distributing Source Code Form that is Incompatible With Secondary Licenses If You choose to distribute Source Code Form that is Incompatible With Secondary Licenses under the terms of this version of the License, the notice described in Exhibit B of this License must be attached. Exhibit A - Source Code Form License Notice ------------------------------------------- This Source Code Form is subject to the terms of the Mozilla Public License, v. 2.0. If a copy of the MPL was not distributed with this file, You can obtain one at http://mozilla.org/MPL/2.0/. If it is not possible or desirable to put the notice in a particular file, then You may include the notice in a location (such as a LICENSE file in a relevant directory) where a recipient would be likely to look for such a notice. You may add additional accurate notices of copyright ownership. Exhibit B - "Incompatible With Secondary Licenses" Notice --------------------------------------------------------- This Source Code Form is "Incompatible With Secondary Licenses", as defined by the Mozilla Public License, v. 2.0.

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使用 Datalog 作为查询语言的高性能·关系型·可嵌入式·图数据库,还可进行历史穿梭查询 展开 收起
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