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Questions tagged [mnesia]

A distributed DataBase Management System used in Erlang applications.

Mnesia is a distributed DataBase Management System (DBMS), appropriate for telecommunications applications and other Erlang applications which require continuous operation and exhibit soft real-time properties.

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RabbitMQ (beam.smp) and high CPU/memory load issue

I have a debian box running tasks with celery and rabbitmq for about a year. Recently I noticed tasks were not being processed so I logged into the system and noticed that celery could not connect to rabbitmq. I restarted rabbitmq-server and even…
marcin_koss
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Remove not_exist_already node from mnesia cluster(scheme)

I have a bad node (it doesn't exist) in the mnesia cluster data when I get: > mnesia:system_info(db_nodes) [bad@node, ...] How do I remove it from the cluster? I tried: > mnesia:del_table_copy(scheme, bad@node). {aborted,{not_active,"All replicas…
vinnitu
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What is the storage capacity of a Mnesia database?

Some places state 2GB period. Some places state it depends up the number of nodes.
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How to add a node to an mnesia cluster?

I'm an erlang and mnesia newbie.. How do I add a new disc_only_copies node to an mnesia database that already has a schema? Thanks
Luca Martinetti
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Very Large Mnesia Tables in Production

We are using Mnesia as a primary Database for a very large system. Mnesia Fragmented Tables have behaved so well over the testing period. System has got about 15 tables, each replicated across 2 sites (nodes), and each table is highly fragmented.…
Muzaaya Joshua
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Online mnesia recovery from network partition

Is it possible to recover from a network partition in an mnesia cluster without restarting any of the nodes involved? If so, how does one go about it? I'm interested specifically in knowing: How this can be done with the standard OTP mnesia…
archaelus
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what is the proper way to backup/restore a mnesia database?

WARNING: the background info is pretty long. Skip to the bottom if you think you need the question before the background info. Appreciate the time this is gonna take! I've been all over the web (read google) and I have not found a good answer. YES,…
Richard
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How to rename the Node running a mnesia Database

I created a Mnesia database / Schema on machine1. The node was named mypl@machine1. I then moved all files to machine2, because machine1 broke down. Everything runs fine as long as the code is running with the name "mypl@machine1". Obviously this is…
max
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How to monitor mnesia load?

I sometimes get mnesia overloaded error message while using primarily async_dirty queries and ram_copies tables. So to understand what is going on I want to get more information about mnesia state such as number of queries per second or the size of…
citxx
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In a mnesia cluster, which node is queried?

Let's say you have a mnesia table replicated on nodes A and B. If on node C, which does not contain a copy of the table, I do mnesia:change_config(extra_db_nodes, [NodeA, NodeB]), and then on node C I do mnesia:dirty_read(user, bob) how does node C…
ryeguy
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how to backup/restore only single table from/to mnesia?

I have some big tables with disc_only_copies type. Now I need change short node name to long but cannot do it with RAM limitation... Can I use backup/restore database partly (table by table)?
vinnitu
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Profiling Mnesia Queries

Our Mnesia DB is running slowly and we think it should be somewhat faster. So we need to profile it and work out what is happening. There are a number of options that suggest themselves: run fprof and see where the time is going run cprof and see…
Gordon Guthrie
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Help me understand mnesia (NoSQL) modeling

In my Quest to understanding Mnesia, I still struggle with thinking in relational terms. So I will put my struggles up here and ask for the best way to solve them. one-to-many-relations Say I have a bunch of people, -record(contact, {name, phone}).…
CONTRACT SAYS I'M RIGHT
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which is more efficent among ets and mnesia

ets:select vs mnesia:select Which is better to use.And also in case of insertion and deletion which one of these two we should use.I am working on ejabberd.Any pointers?
Geek
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how do I remove an extra node

I have a group of erlang nodes that are replicating their data through Mnesia's "extra_db_nodes"... I need to upgrade hardware and software so I have to detach some nodes as I make my way from node to node. How does one remove a node and still…
Richard
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