PDF守护者 开源PDF文档管理 PDFKeeper是免费的开放源代码软件，与兼容的数据库集成在一起，可为PDF​​文档提供集中的存储和管理解决方案。 版本6.1.x中主窗口的屏幕截图。 特征 将PDF文档存储在兼容的关系数据库中，并在其中对其进行索引，并且可以通过网络上安装了PDFKeeper的任何计算机进行管理。 单独或批量上传PDF文档。 此外，可以设置配置的文件夹以允许集成和自动化。 将类别应用于选定的文档记录以及上载PDF文档的时间。 在所选文档记录上设置标记状态，并在PDF文档上载时设置标记状态以进行后续标记。 在选定的文档记录中添加注释，其中可以包括日期，时间和数据库用户帐户名。 所有注释都可以被数据库编辑和索引。 通过文本，选择（作者/主题/类别）或添加日期搜索文档记录。 此外，用户可以列出已标记的文档记录或数据库中的所有文档记录。 使用PDFKeeper，可

Relational database systems have traditionally optimized for I/O performance and organized records sequentially on disk pages using the N-ary Storage Model (NSM) (a.k.a., slotted pages). Recent research, however, indicates that cache utilization and performance is becoming increasingly important on modern platforms. In this paper, we first demonstrate that in-page data placement is the key to high cache performance and that NSM exhibits low cache utilization on modern platforms. Next, we propose a new data organization model called PAX (Partition Attributes Across), that significantly improves cache performance by grouping together all values of each attribute within each page. Because PAX only affects layout inside the pages, it incurs no storage penalty and does not affect I/O behavior. According to our experimental results (which were obtained without using any indices on the participating relations), when compared to NSM (a) PAX exhibits superior cache and memory bandwidth utilization, saving at least 75% of NSM’s stall time due to data cache accesses, (b) range selection queries and updates on memory-resident relations execute 17-25% faster, and (c) TPC-H queries involving I/O execute 11-48% faster. Finally, we show that PAX performs well across different memory system designs.

In this paper we present Ontop, an open-source Ontology Based Data Access (OBDA) system that allows for querying relational data sources through a conceptual representation of the domain of interest, provided in terms of an ontology, to which the data sources are mapped. Key features of Ontop are its solid theoretical foundations, a virtual approach to OBDA that avoids materializing triples and that is implemented through query rewriting techniques, extensive optimizations exploiting all elements of the OBDA architecture, its compliance to all relevant W3C recommendations (including SPARQL queries, R2RML mappings, and OWL 2 QL and RDFS ontologies), and its support for all major relational databases

司法概念基金会。 整个实体，请先进行描述，然后再进行“现代概念组织”（ ）的描述。 排序，生产子图关联， 与子模式关联（ ）， ， ， 等。 Ci-dessous，没有 。 L'appel du program se fait enpremièreligne，un texte d'entréedonnélignes suivantes。 %%mocodo --mld --colors brewer+1 --shapes copperplate --relations diagram markdown_data_dict DF, 11 Élève, 1N Classe Class