# FAQ

This page is a resource to answer commonly asked questions on the dr4 document format.

# Data

# What kind of data can dr4 store?

dr4 is equipped to store any kind of data that can be represented in some form of an object. Text, database tables, CSV files, json files, can all be converted and stored as dr4 documents. The rather larger limit to the size of individual data rows (4294 MB) in dr4 also allows large data types to be stored in dr4 as well.

# Why is dr4 a binary format?

Binary data can be processed more quickly and can hold more information about data while taking up less space. While it's not easily readable by humans, the structure of a dr4 document allows visualizers or debuggers to interpret and print a textual representation of it's data.

Classic data formats such as XML that allow detailed information to be stored about data take up far more space than dr4 does.

# Can different types of data be stored in the same document?

Yes. The sizes and fields of each row within a document can all be different from one another. dr4 is unique in the fact it can store heterogeneous data objects, in binary form.

# What is the max size of a dr4 document?

None. The only limits imposed on the size of an entire document lie with the operating system it is stored on. As explained in the format description, there is no storage of the entire size of the document. This allows new rows to be easily added to a document, without needing to read all of it into memory, or update other portions of it.

The max size of an individual row is 4294 MB.

# What kind of libraries are available to handle dr4 documents?

The projects page contains a directory of open source libraries and projects that provide functionality for dealing with dr4 documents and files. New submissions to the projects directory are always welcomed.

# How can more rows be added to a document?

A dr4 document does not store information related to the total size of the document, nor the number of rows. Thus, additional rows can be appended or added to the end of document by overwriting it's termination cap, writing more rows, and then re-writing the cap after the new last row of the document.

Below is an example of such an operation:

{doc_header} {row_1} {row_2} \x00\x00\x00\x00
                            ^
                            |
                            | overwrite
                            |
                            {row-3} \x00\x00\x00\x00