[Dbix-class] ANN - SQLite 3.6.8 adds nested transactions

[Darren Duncan]

Good news everyone!

The SQLite DBMS, as of the new version 3.6.8, now has nested transaction support.

See http://www.sqlite.org/releaselog/3_6_8.html for the release announcement, 
and http://www.sqlite.org/lang_savepoint.html for documentation of the feature.

As far as I was concerned, and AFAIK had argued in the past, that was the single 
most important piece of missing functionality.  Something whose presence can 
make reliable database development an order of magnitude easier.  Unlike some 
add-on features which could be done in wrappers, nested transactions was 
definitely something that was only appropriate to be implemented in the same low 
level as normal transactions in the DBMS.  Its about code being able to declare 
and have enforced at any level of granularity that a set of operations is 
atomic, as a transaction, without worrying about what calling code is doing with 
transactions, and making it easier to do error handling and retry/abort etc.

I'm letting you know about this update today as encouragement to make use of the 
feature in any of your applications or DBMS toolkits that do or want to support 
SQLite.  It is now also easier to implement TTM's concept of a "D" language 
(which cares about reliability and ease of use) over SQLite.

Note that I'm promoting this under the assumption the new feature works as 
advertised and is efficient; if not, presumably any deficiencies will be soon 
fixed; I will be testing it myself before too long.

Similarly, you should exploit any native nested transaction support of any other 
DBMS you are using.

-- Darren Duncan