Why are fixed-width file formats still in use?

xml fixed-width
Josh M. picture Josh M. · Oct 5, 2011 · Viewed 12.1k times · Source

Are there any advantages to a fixed-width file format over something like XML? I realize XML would likely take up more disk space to store the same amount of data but the file could also be compressed. I guess you could also, in theory, read a specific piece of data based on where it is in the file (just grab those bytes). But other than that, what else?

Answer

Tommy picture Tommy · Jan 27, 2012

When the data is large (Giga/Terra-bytes), fixed width format files can be MUCH more efficient.

Since each record and field has fixed sizes, you can simply seek to the (for example) n-millionth row and read a couple of records from there. You can also memory map the whole file into memory and get rather efficient and easy random access to everything.

XML files aren't a good fit in these cases.

Related questions

XML to Fixed width text file with xsl style sheet

I need help formatting this xml to a fixed width text file using a xsl style sheet. I know very little about xsl and have found very little information online on how this can be done. Basically I need this …

Read More
How do I comment out a block of tags in XML?

How do I comment out a block of tags in XML? I.e. How can I comment out <staticText> and everything inside it, in the code below? <detail> <band height="20"> <staticText> <…

Read More
Text editor to open big (giant, huge, large) text files

I mean 100+ MB big; such text files can push the envelope of editors. I need to look through a large XML file, but cannot if the editor is buggy. Any suggestions?

Read More