Please don't build your own SQLite without reading this (was: Re: Sqlite Version???)

FROM : Alastair Houghton
DATE : Thu Jul 20 12:08:15 2006

On Jun 21, 2006, at 3:57 AM, Jerry Krinock wrote:

> on 06/06/20 18:43, Rick Langschultz at <email_removed> wrote:
>

>> If i create a program that uses a SQLite datastore to save files
>> which version of SQLite will my app use to save files? Is it the
>> latest up to date version of sqlite on the system or another version?

>
> The SQLite that ships in Tiger is version 3.1.3, March 2005, and I 
> found it
> was quite painful to have things not work per current SQLite 
> documentation,
> and then have to dig through the version history to find out the 
> bad news.
>
> So, you'll either want to use CoreData, or else if you need to support
> Panther, build an SQLite static library yourself from the latest 
> SQLite
> source code.  Regarding the latter, search the archives of
> <email_removed> for a message I wrote about a month ago, which
> explains how to build it using Xcode in 5 minutes.


I know this is nearly a month old now (I only periodically scan the 
list at present), but please don't just go building the official 
SQLite sources because they don't work right for files on e.g. AFP or 
SMB shares, because the locking code won't work there.  (That's not 
to say that AFP or SMB don't support locking, because they do, it's 
just that it doesn't work through the fcntl() function.)

Apple's version includes extra code to fix this problem, so if you're 
going to build your own version of SQLite, you need to port that code 
(or fix the issue yourself) otherwise it won't work for any users 
whose home or data storage is on such a filesystem, which is quite a 
few of us (me included).  Either that, or you could turn locking off, 
but only if you're sure that your application will never need it (and 
again, please remember those of us with networked home areas... I can 
run your app on two machines against the same file if it lets me, so 
if you have no locking whatsoever you might lose my data :-().

I ported Apple's locking code to the latest SQLite (3.3.6):

  <http://www.alastairs-place.net/archives/000085.html>

I'll also add that you may not actually want to rely on SQLite's 
locking; for instance, if you store your app's data in a bundle, you 
might want to create a lock file inside the bundle to indicate that 
the data is in use... then you could detect the lock file and prevent 
people from opening the data on two machines at the same time (for 
instance).

Kind regards,

Alastair.

--
http://www.alastairs-place.net