[Zope-dev] SQLite as a Light DB component for Zope and Python

[William Trenker]

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At 10:45 AM 4/2/02 -0600, "Ross J. Reedstrom" <reedstrm@rice.edu> wrote:
>Scale, as in multiuser? Hardly at all: it's an SQL library that accesses a 
>single, textbased, flatfile for the entire database.

>As a lightweight replacement for gadfly, it looks like it might be pretty 
>good.

Exactly.  I'm proposing this as a lightweight component, just as you say, 
not as a replacement for something like MySQL or PostgreSQL.  What I have 
in mind is a small, simple, built-in SQL engine that could be used as a 
step up from something like TinyTablePlus in Zope and be compact enough to 
even be considered as a module candidate for the standard Python library.

>Note that the scripting language of choice of the author seems to be Tcl, 
>rather than Python. This probably explains the 'everything is a string' 
>approach :-)

If you look into the C interface you will find it is almost trivial to 
build a Python extension module and "bring" SQLite into the realm of Python 
scripting.  SQLite also has it's own C interface for adding expression 
functions and aggregates to the SQL syntax.  I expect this could be hooked 
into Python through the Python extension interface as a callback.

Again, the "everything is a string" approach fits in with the idea of 
"simple, lightweight".  Mind you, SQLite supports SQL expressions so it can 
do things like "SELECT * FROM my_table WHERE my_field / 2 > 23.8", or 
"INSERT INTO my_table VALUES (100 / 30.0)".  SQLite does implicit 
conversions, as required.

>The speed comparisions with PostgreSQL are very much an apples vs. fish 
>sort of thing: the pgsql server was not tuned _at all_, and does a whole 
>lot more that was never tested, such as multi-user writer access.

You could be right.  I'm not an expert with PostgreSQL so I can't 
comment.  But, at the risk of being repetitious, I'm thinking 
"lightweight".  My intent is to propose a small relational tool  that 
doesn't impose a significant overhead on the host system and might be 
simple enough that the Zope and Python developers would consider SQLite, 
together with a Python DB API and Zope DA, for their standard libraries.

Thanks for commenting,
Bill



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