C# Insert data in file without rewriting it

Question

I have a file with some data in it. Now i want to add some content but not by appending it. More like "adding this block of 4 bytes between the current 10th and 11th byte in this file". Currently I'm using FileStream to to read and write from files.
So my question: is there a way to insert this data without rewriting the entire file?
Thank you,
Nils.

Answer 1

Edit 2 - the rewrite

After a lot of comments, I figured out the real issue is that you have a database that mostly works like a file System. The biggest difference is propably that the clusters know the file they belong to, rather then the other way around. I am going to use Filesystem terminology for the DDL/Shema. Sorry I can not get proper SQL Syntax highlighting to work.

CREATE TABLE Files(
  ID INTEGER PRIMARY KEY
  /* a bunch of other columns that do not really mater for this */
);

CREATE TABLE Clusters(
  ID INTEGER PRIMARY KEY,
  FK_FileID INTEGER FOREIGN KEY (Files.ID), -- Special, see text
  ClusterNumber INTEGER, --Special, see text
  Contents --whatver type you need
);

Clusters is a odd table in many regardes:

• the pirmary key is most irrelevant. Indeed you can propably remove indexing for it. The only reasons I have it are a) habit, b) becaue you might regret lacking it and c) it might be usefull for management work
• ClusterNumber is the "N-th Cluster for FK_FileID"
• ClusterNumber and FK_FileID should have a shared unique constraint (the combination of both must be unique) and should propably be on a index covering both. Think of them as if they were a Composite Primary key or multirow surrogate key (wich does sound like a oxymoron). You will use those way more often then the official PK.

You would get all the clusters for a File like this:

SELECT Content FROM Clusters 
ORDER BY ClusterNumber 
WHERE FK_FileID = /*The file whose whole data you want*/

Wich would be nice covered by that extra Index.

If you want to shove in a segment anywhere in this you would:

1. Move all the following segments ClusterNumber 1 up
2. Just add a Cluster entry with that newly freed-up ClusterNumber for this file
3. You can be somewhat wastefull with that last step, like only adding a 4 letter cluster.

Asuming you store this on a HDD/Rotating Disk Storage you will propably not get around defragmenting this regulary anyway, so you might as well consolidate the clusters to cut the waste then while doing so. Unless you can somehow teach the DBMS to properly read this (you need to ask DB experts for this), you want to have all clusters of a file in sequence in the DB as much as possible, so it will be together on the disk as well. Of course is the physical medium is a proper SSD, you can skip the defragmentation and only consolidate.

Advanced options include stuff like reserving expansion room for a file (that no other file will be using) ahead of time. So the clusters can be kept together (even if not in order) and the need for defragmentation is less.