Mnesia tables: load times and sizes after deletion

Bruce Fitzsimons <>
Thu Aug 14 14:07:24 CEST 2003


Gentlemen,

I've just been playing with my little jukebox I wrote for broadcasting
background music in Erlang. It logs the songs played into an mnesia table
'playlog' (set, disc_copies).

I managed to get 71,000 entries into the table, at which point it took a
number of minutes to open on my little Duron 1300 w/ ATA100 hd

I used a (inefficient) mnemosyne query to get all the entries older than 1
day and delete them, and this worked. Surprisingly fast, to mnemosynes
credit.

What did surprise me is that the on-disk size, and the size reported by
mnesia:table_info(playlog, size) continued to increased (it was still
playing).

Is this normal? The docs say size = total number of records, is it actually
max size? Even after the delete and normal shutdown the table did not shrink
in either sense. It still took a number of minutes to open too.

I guess I'm just curious to know if this is normal?

I attempted to directly open the mnesia files under dets to query them...but
that is apparently not allowed. A good thing probably.

Thanks for any info. I've deleted and recreated the table now. This is all
under R9C (nice work guys, great docs), although the DB was created using
R9B-1.

/Bruce





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