Uncompressed SQLite Archive Files

classic Classic list List threaded Threaded
1 message Options
Reply | Threaded
Open this post in threaded view
|

Uncompressed SQLite Archive Files

Andre deBruin

 
I am a Big fan of the recent support for 'SQLite Archive' files.
Basically I was planning to use  this as a generic version of
an "Application File Format" (sqlite.org/appfileformat.html).
 
As far as I can see the Archive Files functionality does always
compress the blobs if it is found that compression is sensible, other blobs
(as mentioned in the documentation for example in the case of Jpeg data) will
be left uncompressed.
 
That means that the sqlite database files created this way can only be read
if the reader program calls the new sqlar_uncompress code.
 
I am contemplating using this format as alternative for ZIP files for
data which consists mainly of image files (jpeg, tiff) but also contain a large
number of compressible (XML, JSON, etc.) files.
 
It would be really good to have a "do not compress" option in the create function.
 
If there would be an option (just like 'zip -0' ) to DISABLE compression
altogether the advantages could be:
 
- speed of file creation (no compression attempted)the
- speed of extraction (no decompression)
- files can be read with legacy client programs (i.e. programs using basic sqlite API, not the 'sqlar' extensions).
- the compression implementation appears to be experimental (there is mention of supporting new types in
future) so there is a possibility that files written with today's implementation have  to be upgraded when the      
implementation evolves (there is no metadata in the blob to identify compression type).
 
(this last one  point was partly addressed in thread  [sqlite] Issues about SQLite archive files mar 15 2018)
 
_______________________________________________
sqlite-users mailing list
[hidden email]
http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users