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The database produced by gStore contains several indexes, whose structures may have been changed in the new gStore version. So, please rebuild your dataset just in case.
You need to add these phrases at the beginning of your main program, otherwise gStore will not run correctly:
//NOTICE:this is needed to set several debug files
Util util;
You need to adjust the parameters of jvm, see url1 and url2 for details.
In ArchLinux, you only need to use -lreadline to link the readline library. Please remove the -ltermcap in the makefle which is located in the root of the gStore project if you would like to use ArchLinux.
gStore does not support all RDF formats currently. However, it is quite easy for you to convey your RDF data format to the N3 file format that is used in gStore.
Codes, markdowns or other text files, and pictures can be read directly on GitHub. However, if you are using some light weight browsers like midori, for files in pdf type, please download them and read on your computer or other devices.
There are some documents’s names are in Chinese, and you don’t need to worry about it.
In centos7, if the watdiv.db(a generated database after gbuild) is copied or compressed/uncompressed, the size of watdiv.db will be different(generally increasing) if using du -h command to check?
A: It’s the change of B+-trees’ size in watdiv/kv_store/ that causes the change of the whole database’s size. The reason is that in storage/Storage.cpp, many operations use fseek to move file pointer. As everyone knows, file is organized in blocks, and if we request for new block, file pointer may be moved beyond the end of this file(file operations are all achieved by C in gStore, no errors are reported), then contents will be written in the new position!
In Advanced Programming In The Unix Environment, “file hole” is used to describe this phenomenon. “file hole” will be flled with 0, and it’s also one part of the file. You can use ls -l to see the size of file(computing the size of holes), while du -h command shows the size of blocks that directory/file occupies in system. Generally, the output of du -h is large than that of ls -l, but if “file hole” exists, the opposite is the case because the size of holes are neglected.
The actual size of files containing holes are fixed, while in some operation systems, holes will be transformed to contents(also 0) when copied. Operation mv will not affect the size if not across different devices.(only need to adjust
the file tree index) However, cp and all kinds of compress methods need to scan the file and transfer data.(there are two ways to achieve cp command, neglect holes or not, while the output size of ls -l not varies)
It is valid to use “file hole” in C, and this is not an error, which means you can go on using gStore. We achieve a small program to describe the “file holes”, you can download and try it yourself.
In gclient console, a database is built, queried, and then I quit the console. Next time I enter the console, load the originally imported database, but no output for any queries(originally the output is not empty)?
You need to unload the using database before quiting the gclient console, otherwise errors come.
If query results contain null value, how can I use the full_test utility? Tab separated method will cause problem here because null value cannot be checked!
You may use other programming language(for example, Python) to deal with the null value cases. For example, you can change null value in output to special character like ‘,’, later you can use the full_test utility.
Please use ./gserver command to start up a gStore server first, and notice that the server ip and port must be matched.
Please ensure that you include the position of your own program in class path of java. The whole command should be something like java -cp /home/bookug/project/devGstore/api/java/lib/GstoreJavaAPI.jar:.JavaAPIExample, and the “:.” in this command cannot be neglected.