There is coordinate data which is stored in a BLOB, similar to the arcgis ST_GEOMETRY type of points. The storage contains the byte stream of the point coordinates that define the geometry like this:
How can I get the data from the BLOB in Oracle?
BLOBs are binary data. They could contain literally anything. Oracle has no built-in mechanism for extracting data from a BLOB. Your options are:
Whatever part of your application wrote the binary data should be responsible for unpacking and displaying the data.
Write some PL/SQL to retrieve the data using UTL_RAW functions to work with binary data. Find out more Doing this requires you to understand how the program which wrote the binary structured it.
This is why storing data in binary is usually a bad idea. Sure, you save space but essentially this obfuscates the data and imposes a toll on using it. If storage is that much of an issue consider compression instead.
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I'm new to programming and I'd like to know if files such as BMPs, MP3s, EXEs are considered to be data structures as well.
I'm new to programming and I'd like to know if files such as BMPs, MP3s, EXEs are considered to be data structures as well.
No, they are some form of compressed(or not) data that should be read on any kind of program that can read them.
But they are structured data. That means you have some specific way your program should read them. For example, in bmp you should know how to read its width and height of the image, then start reading its pixels. Then you continue looping it until its over.
There is more complexes structured datas, as exe's, which your operating system reads, or mp3 which you have to execute some algorithms to make the data understandable
Data structures are actually some default way to think about how to store and read your data and use them for specific situations, such as a command history.
The well known command CTRL+Z, CTRL+SHIFT+Z, (undo & redo), they are implemented as stacks, which means each command is piled up one above the other, when undoing you will need to take the command that is topmost in the stack, pop it and execute its undo function.
Not really. Frow Wikipedia, "In computer science, a data structure is a data organization, management, and storage format that enables efficient access and modification. More precisely, a data structure is a collection of data values, the relationships among them, and the functions or operations that can be applied to the data, i.e., it is an algebraic structure about data."
You normally read or write such files as a whole and do not perform local modifications. Anyway, for some formats (such as TIFF images for instance), the individual data fields can be accessed directly rather than sequentially.
I understand how parquet works for tabular data and json data.
I'm struggling to understand if/how parquet manages binary images like png files?
Are there any benefits?
Open to moving this question elsewhere, I just couldn't see another community from stack that made sense
Parquet can store arbitrary byte strings so it can support storing images but it there are no particular benefits for doing so and most bindings aren't necessarily geared to handle very large row sizes, so an image per row could run into some unexpected performance or scalability issues.
What are the reasons to use SequenceFile instead of a text file?
I'm guessing that they are good since input/output comes to serialization, instead of parsing an object, if that object needs to be used multiple times.
Also, I read that it performs compression of the file, so it takes less space and that it is good to aggregate many small files into one large one.
Are this arguments valid and what else?
Binary data (as in SequenceFiles) is usually more compact than text data (TextFiles) even without explicit compression. So less data needs to be read from/written to the hard disks. The space savings depend on the data that is written.
Reading binary data is more CPU efficient than String parsing.
However,
SequenceFiles cannot be read humans and
are bound to a specific object type / class, whereas text data can be interpreted in different ways as needed.
I´ve got a quick question to the Oracle XML DB experts:
I measured the insert performance of several large xml files. In theory XMLType CLOB should have a unrivaled insert performance, because the inserted XML document is directly written in a character large object, no conversion needed. But my measurements suggest that the insert in the XMLType BINARY column is much faster, although it is a preparsed binary format. Can someone tell me how this is possible?
Actually, if the documents are large i'd expect Binary to be better, as with Binary XML you'll find the stored data is smaller, so you're saving on disk IO on writing all that data away. I guess the overall comparison would depend on the time saved on IO vs extra CPU time on converting to binary on your system.
I want to read binary data from disk and store it in a Mercury variable. According to the string library, strings don't allow embedded null bytes and store content with UTF-8 encoding so I don't think that will work. The best I've found so far is a line in the bitmap library that says, "Accessing bitmaps as if they are an array of eight bit bytes is especially efficient"
Are bitmaps a good way to store arbitrary binary data? Is there something better?
Yes, bitmaps are the recommended way to read/write/store binary data.