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POWhere are tables in Mnesia located?
 

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  1. POWhere are tables in Mnesia located?
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    <p>I try to compare Mnesia with more traditional databases.</p> <p>As I understand it tables in Mnesia can be located to (see <a href="http://www.erlang.org/~hakan/mnesia_consumption.txt" rel="nofollow noreferrer">Memory consumption in Mnesia</a>):</p> <ul> <li><code>ram_copies</code> - tables are stored in <code>ets</code>, so no durability as in ACID.</li> <li><code>disc_copies</code> - tables are located to <code>ets</code> and <code>dets</code>, so the table can not be bigger than the available memory? And if the table are fragmented, the database can not be bigger than the available memory?</li> <li><code>disc_only_copies</code> - tables are located <code>dets</code>, so no caching in memory and worse performance. And the size of the table are limited to the size of <code>dets</code> or the table has to be fragmented.</li> </ul> <p>So if I want the performance of doing reads from RAM and the durability of writes to disc, then the size of the tables are very limited compared to a traditional RDBMS like MySQL or PostgreSQL.</p> <p>I know that Mnesia aren't meant to replace traditional RDBMS:s, but can it be used as a big RDBMS or do I have to look for another database?</p> <p>The server I will use is a VPS with limited amount of memory, around <b>512MB</b>, but I want good database performance.</p> <p>Are <code>disc_copies</code> and the other types of tables in Mnesia so limited as I have understood? Can´t the database be partially on memory and a full copy on disc?</p>
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