[erlang-questions] How to speed up mnesia startup?

[Ulf Wiger]

Hmm, the first thing that stands out is the inordinate number of tables.

Out of curiosity, I tried figuring out what is considered a reasonable number of tables for other database management systems:

- Oracle: over 10,000 tables considered insane
  (http://asktom.oracle.com/pls/asktom/f?p=100:11:::::P11_QUESTION_ID:26039880025641)

- Postgres: 10,000 tables works fine; practical limit (on ext3) probably 32k
  (http://blog.endpoint.com/2008/11/10000-databases-on-postgresql-cluster.html)

- MySQL Server: no apparent problems
  (http://stackoverflow.com/questions/610920/maximum-number-of-workable-tables-in-sql-server-and-mysql)

There may be some serialization happening that slows down the table loads. Mnesia is not optimized for this many tables.

BR,
Ulf W

On 12 Apr 2012, at 10:35, Kyungho Yun wrote:

> It usually takes 50 minutes to startup mnesia.
> It is too long.
> 
> Here is my conditions:
>   - DB exists local
>   - more than 60000 tables
>   - sum size is about 28 Giga Bytes.
>   - most tables created options with record_name, attributes(and record_info()) and disc_only_copies.
>   - startup after normal exit (not crash)
>   - R14B04, no_table_loaders 10000
> 
> I've searched many websites, read documents here and other places, changed options.
> but the elapse of mnesia startup wasn't decrease.
> 
> Here is what I controlled:
>   - ulimit -n
>   - no_table_loader, +A, +K, +P, +zdbbl, dc_dump_limit
>   - add option local_content when create table
>   - io schedule type
> 
> finally, I am curious mnesia I/O ability.
> few blocks/s value(about 2000) is shown in iostat during mnesia startup,
> but it's very big blocks/s value (bigger than 100000) is shown during copy something.
> 
> How to speed up mnesia startup?
> Tell me a clue please.
> 
> thanks
> 
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Ulf Wiger, Co-founder & Developer Advocate, Feuerlabs Inc.
http://feuerlabs.com



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