in Ram database?

**Ganesan R** · Jul 18 '05, 02:17 AM

Re: in Ram database?

>>>>> "John" == John D <lists@webcrunc hers.com> writes:
[color=blue]
> I kinda like the idea of being able to define smaller tables as
> "in-memory" types, and the really large massive ones in other forms
> managed by mySQL, PostGres, or bsddb3 databases.[/color]

Use PySQLite (http://pysqlite.sf.net). Make sure that you have at least
version 2.8.1 of SQLite and give the database name as :memory: (this is not
obvious from the documentation). Since SQLite can handle databases upto 2
terabytes, you use it to store "really massive ones" on disk too :-).

Ganesan

--
Ganesan R

**John J. Lee** · Jul 18 '05, 02:17 AM

Re: in Ram database?

"John D." <lists@webcrunc hers.com> writes:
[...][color=blue]
> Is such a database available? If so, who is working on it,
> or where is it?[/color]

Gadfly, PySQLite.

[color=blue]
> I've heard that Python supports a stand-alone database. I looked
> for it in the Docs, and see the "dbm" module. I haven't found
> any examples of code, so don't know how to use them. I'm one
> of those guys that learn through examples, and have very little
> luck in figuring out how to use anything unless I can see examples
> of their use.[/color]

These sorts of dbs aren't in-memory. Still, if you want to find some
simple examples, I'm sure a few queries like 'group:comp.lan g.python
bsddb example' in Google Groups will find something.

[color=blue]
> My idea is that ALL datums would be Python Dictionary objects, so
> not only can you store data, but python objects as well.[/color]

Sounds like you might want ZODB (again, not in-memory). It's more of
an object persistence system + BTrees than it is a DBMS, since there's
no query system. IndexedCatalog is a query system built on top of
ZODB, but it's quite feasible to roll your own simple
application-specific queries with BTrees (and the other data
structures it provides). BTrees are rather like dictionaries, but
they support on-demand loading of data, so not everything has to be in
memory at once.

[color=blue]
> I kinda like the idea of being able to define smaller tables as
> "in-memory" types, and the really large massive ones in other forms
> managed by mySQL, PostGres, or bsddb3 databases.[/color]

That sounds like a recipe for extra work to me. If you need a big
DBMS, use that for everything.

John

**John Roth** · Jul 18 '05, 02:18 AM

Re: in Ram database?

"John D." <lists@webcrunc hers.com> wrote in message
news:mailman.10 62728122.8678.p ython-list@python.org ...[color=blue]
> Does anyone know if there is an "in-ram" dictionary based database
> for Python.
>
> I can see some applications where this can really be powerful in
> applications requiring 10,000 records or less.
>
> Is such a database available? If so, who is working on it,
> or where is it?
>
> I've heard that Python supports a stand-alone database. I looked
> for it in the Docs, and see the "dbm" module. I haven't found
> any examples of code, so don't know how to use them. I'm one
> of those guys that learn through examples, and have very little
> luck in figuring out how to use anything unless I can see examples
> of their use.
>
> My idea is that ALL datums would be Python Dictionary objects, so
> not only can you store data, but python objects as well.
>
> Storage to disk would be through pickled files, or through CSV
> format, allowing easy import and export from other databases.
>
> I'm sure something like this exists, I just haven't found it yet,
> and if not, then I'm well on my way of implementing one myself.
>
> I kinda like the idea of being able to define smaller tables as
> "in-memory" types, and the really large massive ones in other forms
> managed by mySQL, PostGres, or bsddb3 databases.
>
> Any leads you guys???[/color]

Look at Prevalyar. While it's a Java project, it might give
you some ideas about what's possible if you forget "data base"
and simply think "persistanc e."

John Roth[color=blue]
>
> JD
>
>
>[/color]

**Romuald Texier** · Jul 18 '05, 02:18 AM

Re: in Ram database?

John D. wrote:
[color=blue]
> Does anyone know if there is an "in-ram" dictionary based database
> for Python.
>
> I can see some applications where this can really be powerful in
> applications requiring 10,000 records or less.
>
> Is such a database available? If so, who is working on it,
> or where is it?
>
> I've heard that Python supports a stand-alone database. I looked
> for it in the Docs, and see the "dbm" module. I haven't found
> any examples of code, so don't know how to use them. I'm one
> of those guys that learn through examples, and have very little
> luck in figuring out how to use anything unless I can see examples
> of their use.
>
> My idea is that ALL datums would be Python Dictionary objects, so
> not only can you store data, but python objects as well.
>
> Storage to disk would be through pickled files, or through CSV
> format, allowing easy import and export from other databases.
>
> I'm sure something like this exists, I just haven't found it yet,
> and if not, then I'm well on my way of implementing one myself.
>
> I kinda like the idea of being able to define smaller tables as
> "in-memory" types, and the really large massive ones in other forms
> managed by mySQL, PostGres, or bsddb3 databases.
>
> Any leads you guys???
>[/color]

Why not just use Dictionaries, or an object tree? Why do you want tables or
SQL abstraction if it is "in-memory"? Nothing else but your app will be
able to access the "live" data, anyway.

**John Roth** · Jul 18 '05, 02:18 AM

Re: in Ram database?

"Andy Todd" <andy47@halfcoo ked.com> wrote in message
news:mailman.10 62776296.7505.p ython-list@python.org ...[color=blue]
> John Roth wrote:
>[color=green]
> > "John D." <lists@webcrunc hers.com> wrote in message
> > news:mailman.10 62728122.8678.p ython-list@python.org ...
> >[color=darkred]
> >>Does anyone know if there is an "in-ram" dictionary based database
> >>for Python.
> >>
> >>I can see some applications where this can really be powerful in
> >>application s requiring 10,000 records or less.
> >>
> >>Is such a database available? If so, who is working on it,
> >>or where is it?
> >>
> >>I've heard that Python supports a stand-alone database. I looked
> >>for it in the Docs, and see the "dbm" module. I haven't found
> >>any examples of code, so don't know how to use them. I'm one
> >>of those guys that learn through examples, and have very little
> >>luck in figuring out how to use anything unless I can see examples
> >>of their use.
> >>
> >>My idea is that ALL datums would be Python Dictionary objects, so
> >>not only can you store data, but python objects as well.
> >>
> >>Storage to disk would be through pickled files, or through CSV
> >>format, allowing easy import and export from other databases.
> >>
> >>I'm sure something like this exists, I just haven't found it yet,
> >>and if not, then I'm well on my way of implementing one myself.
> >>
> >>I kinda like the idea of being able to define smaller tables as
> >>"in-memory" types, and the really large massive ones in other forms
> >>managed by mySQL, PostGres, or bsddb3 databases.
> >>
> >>Any leads you guys???[/color]
> >
> >
> > Look at Prevalyar. While it's a Java project, it might give
> > you some ideas about what's possible if you forget "data base"
> > and simply think "persistanc e."
> >
> > John Roth
> >[color=darkred]
> >>JD
> >>[/color][/color]
>
> Or you could look at the Python port of Prevayler (well, thats how it
> started out);
>
> http://www.orbtech.com/wiki/PyPerSyst[/color]

Thanks for the reference.

John Roth[color=blue]
>
> Regards,
> Andy
> --
> --------------------------------------------------------------------------[/color]
------[color=blue]
> From the desk of Andrew J Todd esq - http://www.halfcooked.com/
>
>
>[/color]

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