[erlang-questions] 64-bit fragmented mnesia table benefits?

Valentin Micic valentin@REDACTED
Tue Mar 25 22:54:36 CET 2008

We used to run quite a substantial fragmented database ( about 250 milion 
entries spread around 512 fragments) on DETS (disc-only copy), and do not 
remember that memory was ever an issue (but then again, we had about 8GB of 
RAM). However, when a particular fragment get populated beyond, say, 
250,000 entries, insert and/or update of a particular table fragment (file) 
suffers  a considerable performance degradation.

As for recovery, well it could take quite some time, depending on size of 
the database.

----- Original Message ----- 
From: "Christian S" <chsu79@REDACTED>
To: "Philip Robinson" <chlorophil@REDACTED>
Cc: "Erlang Questions" <erlang-questions@REDACTED>
Sent: Tuesday, March 25, 2008 4:49 PM
Subject: Re: [erlang-questions] 64-bit fragmented mnesia table benefits?

> On Tue, Mar 25, 2008 at 3:22 PM, Philip Robinson <chlorophil@REDACTED> 
> wrote:
>> Hello all.
>>  It is my understanding that using a 64-bit operating system pretty
>>  much removes any of the size limitations for mnesia tables.
> The dets files still have their 32bit limitation.
> I've heard it rumoured here that dets have the following issues
> * when fragmented, the freelist is all in memory and occupies too much 
> memory
> * recovery time for large files are unresonable long
> Are they true, as in, has it been a problem for anyone?
> How do solutions that perform better do?
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