postgres on a PDA 
Author Message
 postgres on a PDA

Hi,

I use a linux based PDA (the Zaurus from Sharp).  There are no good, open
source  databases for this device so I'm thinking of cross-compiling
postgresql for the ARM processor and getting it to run on the Zaurus.  I
need to do this because I have a 150MB Access database that I would like to
take with me (I'll figure out some way to port the data once I get postgres
up and running).

My PDA has 32MB of RAM (well more like 16 with the way Sharp allocates it)
and I use a 256MB FLASH memory card which sort of looks like a hard drive on
the PDA. I know postgresql will run in about 8MB of RAM so I think I should
be ok on this front but I'm wondering about the data residing in FLASH.  
Sure I'm prepared for a huge performance hit but aside from that what else
should I expect?

Any thoughts you guys might have are appreciated!

-Al

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Sun, 03 Jul 2005 07:59:18 GMT
 postgres on a PDA

Quote:

> Hi,

> I use a linux based PDA (the Zaurus from Sharp).  There are no good,
> open source  databases for this device so I'm thinking of
> cross-compiling postgresql for the ARM processor and getting it to run
> on the Zaurus.  I need to do this because I have a 150MB Access database
> that I would like to take with me (I'll figure out some way to port the
> data once I get postgres up and running).

> My PDA has 32MB of RAM (well more like 16 with the way Sharp allocates
> it) and I use a 256MB FLASH memory card which sort of looks like a hard
> drive on the PDA. I know postgresql will run in about 8MB of RAM so I
> think I should be ok on this front but I'm wondering about the data
> residing in FLASH.  Sure I'm prepared for a huge performance hit but
> aside from that what else should I expect?

No idea, but the idea of trying it sounds interesting.  It's probably
also worthwhile sending your email to the PostgreSQL "Hackers" mailing
list with a subject line of something like "PostgreSQL on ARM cpu?".

:-)

Regards and best wishes,

Justin Clift

Quote:
> Any thoughts you guys might have are appreciated!

> -Al

> _________________________________________________________________
> The new MSN 8 is here: Try it free* for 2 months
> http://join.msn.com/?page=dept/dialup

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Sun, 03 Jul 2005 08:25:14 GMT
 postgres on a PDA

Quote:

> My PDA has 32MB of RAM (well more like 16 with the way Sharp allocates it)
> and I use a 256MB FLASH memory card which sort of looks like a hard drive on
> the PDA. I know postgresql will run in about 8MB of RAM so I think I should
> be ok on this front but I'm wondering about the data residing in
> FLASH.  

Postgres has kind of gotten away from the notion of a small disk
footprint :-(.  Some things to look at:

* Definitely reduce the size of WAL segments (see XLogSegSize).  You
can't afford the default 16MB.

* You probably don't want to have multiple databases.  I'd suggest doing
all your work in template1.  Consider also dropping template0 --- its
only value would be to reinit template1, and if you need to do that you
might as well re-initdb.

But I fear the real problem is going to be that FLASH memory has a
limited lifetime (measured in write cycles).  Postgres is going to spend
that lifetime with abandon, because it has absolutely no motivation to
avoid disk writes.  Are you prepared to replace the FLASH every so
often?

                        regards, tom lane

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Sun, 03 Jul 2005 12:44:50 GMT
 postgres on a PDA

Quote:
> But I fear the real problem is going to be that FLASH memory has a
> limited lifetime (measured in write cycles).  Postgres is going to
> spend that lifetime with abandon, because it has absolutely no
> motivation to avoid disk writes.  Are you prepared to replace the
> FLASH every so often?

What, roughly, is the limit?
--
Dan Langille : http://www.langille.org/

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Sun, 03 Jul 2005 12:47:30 GMT
 postgres on a PDA

Quote:


>> But I fear the real problem is going to be that FLASH memory has a
>> limited lifetime (measured in write cycles).
> What, roughly, is the limit?

I am probably a decade out of date on this, but when I last paid
attention I think it was on the order of magnitude of 10000 write
cycles --- which Postgres could blow through in no time.  I hope
it's better now, but I dunno by how much.  Anyone have more
up-to-date info?

                        regards, tom lane

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Sun, 03 Jul 2005 13:02:00 GMT
 postgres on a PDA
Quote:

> But I fear the real problem is going to be that FLASH memory has a
> limited lifetime (measured in write cycles).  Postgres is going to spend
> that lifetime with abandon, because it has absolutely no motivation to
> avoid disk writes.  Are you prepared to replace the FLASH every so
> often?

The IBM MicroDrive might be a solution for this kind of problem.

Greetings,
-tb
--

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Sun, 03 Jul 2005 19:51:01 GMT
 postgres on a PDA

Quote:


> >> But I fear the real problem is going to be that FLASH memory has a
> >> limited lifetime (measured in write cycles).

> > What, roughly, is the limit?

> I am probably a decade out of date on this, but when I last paid
> attention I think it was on the order of magnitude of 10000 write
> cycles --- which Postgres could blow through in no time.  I hope
> it's better now, but I dunno by how much.  Anyone have more
> up-to-date info?

We just bought a compact flash from viking and I believe it was 100,000.
It might have been 1mil, but now I don't remember.  I'll ask my co-worker
when he gets in and if it's different let you know.

seems like it would still go through it pretty fast though.

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Mon, 04 Jul 2005 02:31:39 GMT
 postgres on a PDA

Quote:

> To be honest, would BerkeleyDB be better?

Very possibly, if it gets the job done for you.  But last I heard, there
is no SQL engine in BerkeleyDB --- you have to write code against their
access API.  Depending on your taste and the nature of your application,
that might or might not be nicer than writing SQL ...

                        regards, tom lane

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Mon, 04 Jul 2005 05:04:40 GMT
 postgres on a PDA
Yes... The (now Hitachi) Microdrive is a 3600 RPM hard drive with a CF form
factor, and stores up to 1Gb...

The other solution is to build a web application and use the Z's web browser
with a Wireless CF Modem...

Garo


Quote:

>> But I fear the real problem is going to be that FLASH memory has a
>> limited lifetime (measured in write cycles).  Postgres is going to spend
>> that lifetime with abandon, because it has absolutely no motivation to
>> avoid disk writes.  Are you prepared to replace the FLASH every so
>> often?
> The IBM MicroDrive might be a solution for this kind of problem.

> Greetings,
> -tb

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Mon, 04 Jul 2005 05:38:13 GMT
 postgres on a PDA


Quote:
>> To be honest, would BerkeleyDB be better?

TL> Very possibly, if it gets the job done for you.  But last I heard, there
TL> is no SQL engine in BerkeleyDB --- you have to write code against their
TL> access API.  Depending on your taste and the nature of your application,
TL> that might or might not be nicer than writing SQL ...

See http://www.hwaci.com/sw/sqlite/index.html for an embedded SQL
engine.  It used to be based on GDBM, but I'm not sure what the
backing store is now.

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AIM: vivekkhera Y!: vivek_khera   http://www.khera.org/~vivek/



Mon, 04 Jul 2005 05:52:41 GMT
 postgres on a PDA

Quote:

>> the PDA. I know postgresql will run in about 8MB of RAM so I think I should
>> be ok on this front but I'm wondering about the data residing in
>> FLASH.  
> But I fear the real problem is going to be that FLASH memory has a
> limited lifetime (measured in write cycles).  Postgres is going to spend
> that lifetime with abandon, because it has absolutely no motivation to
> avoid disk writes.

If you just want to take the DB with you and not update it, you could
mount it all read-only...

Michael Will
--
https://www.zapatec.com - IT contract jobs on our (no-fee) marketplace.



Mon, 04 Jul 2005 07:05:14 GMT
 postgres on a PDA

Quote:


>>To be honest, would BerkeleyDB be better?

> Very possibly, if it gets the job done for you.  But last I heard, there
> is no SQL engine in BerkeleyDB --- you have to write code against their
> access API.  Depending on your taste and the nature of your application,
> that might or might not be nicer than writing SQL ...

>                    regards, tom lane

> ---------------------------(end of broadcast)---------------------------

> .

Hi,

There's also Sqlite and Metakit; one with and one without an sql front
end...

regards,
nicolas boretos

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Mon, 04 Jul 2005 16:48:43 GMT
 
 [ 12 post ] 

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