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Thread: How to reduce a database

How to reduce a database

From
Mario Behring
Date:
Hi list,

I have an openNMS server that uses a Postgres database. For those who are not familiar, openNMS is an open source network management product.

Anyway, the openNMS database is very large now, more than 25GB (considering all tables) and I am starting to have disk space issues. The openNMS product has a vacuumdb procedure that runs every 24 hours and reads a vacuumd-configuration.xml file for parameters on what to do.

The problem is that this process is not reducing the database size. What I need to do is to delete some records based on timestamp fileds or something like that. I don't know how to do it though.

Can you guys help me with some command line examples?

There is this table, called EVENTS, that have the following structure:

 eventid                 | integer                     | not null
 eventuei                | character varying(256)      | not null
 nodeid                  | integer                     |
 eventtime               | timestamp without time zone | not null
 eventhost               | character varying(256)      |
 eventsource             | character varying(128)      | not null
 ipaddr                  | character varying(16)       |
 eventdpname             | character varying(12)       | not null
 eventsnmphost           | character varying(256)      |
 serviceid               | integer                     |
 eventsnmp               | character varying(256)      |
 eventparms              | text                        |
 eventcreatetime         | timestamp without time zone | not null
 eventdescr              | character varying(4000)     |
 eventloggroup           | character varying(32)       |
 eventlogmsg             | character varying(256)      |
 eventseverity           | integer                     | not null
 eventpathoutage         | character varying(1024)     |
 eventcorrelation        | character varying(1024)     |
 eventsuppressedcount    | integer                     |
 eventoperinstruct       | character varying(1024)     |
 eventautoaction         | character varying(256)      |
 eventoperaction         | character varying(256)      |
 eventoperactionmenutext | character varying(64)       |
 eventnotification       | character varying(128)      |
 eventtticket            | character varying(128)      |
 eventtticketstate       | integer                     |
 eventforward            | character varying(256)      |
 eventmouseovertext      | character varying(64)       |
 eventlog                | character(1)                | not null
 eventdisplay            | character(1)                | not null
 eventackuser            | character varying(256)      |
 eventacktime            | timestamp without time zone |

I was thinking about using a DELETE FROM EVENTS WHERE  eventtime = <some point in time>......but I am kind of worried on what this could cause on other tables, if there is some relations between them or something.....

Here is the vacuumd-configuration.xml file:

<VacuumdConfiguration period="86400000" >
    <statement><!-- this deletes all the nodes that have been marked as deleted - it relies on cascading deletes --> DELETE FROM node       WHERE node.nodeType = 'D'; </statement>
    <statement><!-- this deletes all the interfaces that have been marked as deleted - it relies on cascading deletes --> DELETE FROM       ipInterface WHERE ipInterface.isManaged = 'D'; </statement>
    <statement><!-- this deletes all the services that have been marked as deleted - it relies on cascading deletes --> DELETE FROM if      Services WHERE ifServices.status = 'D'; </statement>
    <statement><!-- this deletes any events that are not associated with outages - Thanks to Chris Fedde for this --> DELETE FROM even      ts WHERE NOT EXISTS (SELECT svclosteventid FROM outages WHERE svclosteventid = events.eventid UNION SELECT svcregainedeventid FROM out      ages WHERE svcregainedeventid = events.eventid UNION SELECT eventid FROM notifications WHERE eventid = events.eventid) AND eventtime &      lt; now() - interval '6 weeks'; </statement>
</VacuumdConfiguration>

Any help is appreciated.

Thank you.

Mario

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Re: How to reduce a database

From
Ragnar
Date:
On fös, 2006-12-29 at 07:09 -0800, Mario Behring wrote:

> Anyway, the openNMS database is very large now, more than 25GB
> (considering all tables) and I am starting to have disk space issues.
> The openNMS product has a vacuumdb procedure that runs every 24 hours
> and reads a vacuumd-configuration.xml file for parameters on what to
> do. 

> The problem is that this process is not reducing the database size.
> What I need to do is to delete some records based on timestamp fileds
> or something like that. I don't know how to do it though.

before you start deleting random rows in a database you are not
too familiar with, let us start by trying to determine your
actual problem.

you should issue a manual VACUUM VERBOSE, and look at the
output of that first. possibly you will find that the database 
is suffering from bloat due to too small fsm settings.

if that is the case, a VACUUM FULL might be indicated, but
note that it will take exclusive locks, so you should
schedule that for some time where you can afford downtime.

if this is not enough, then you can take a look at deleting
rows, but you would probably get better advice on that
from the OpenNMS community. I assume they have
mailinglists or forums. 


> <VacuumdConfiguration period="86400000" >
>     <statement><!-- this deletes all the nodes that have been marked
> as deleted - it relies on cascading deletes --> DELETE FROM node
> WHERE node.nodeType = 'D'; </statement>
>     <statement><!-- this deletes all the interfaces that have been
> marked as deleted - it relies on cascading deletes --> DELETE FROM
> ipInterface WHERE ipInterface.isManaged = 'D'; </statement>
>     <statement><!-- this deletes all the services that have been
> marked as deleted - it relies on cascading deletes --> DELETE FROM if
> Services WHERE ifServices.status = 'D'; </statement>
>     <statement><!-- this deletes any events that are not associated
> with outages - Thanks to Chris Fedde for this --> DELETE FROM even
> ts WHERE NOT EXISTS (SELECT svclosteventid FROM outages WHERE
> svclosteventid = events.eventid UNION SELECT svcregainedeventid FROM
> out      ages WHERE svcregainedeventid = events.eventid UNION SELECT
> eventid FROM notifications WHERE eventid = events.eventid) AND
> eventtime &      lt; now() - interval '6 weeks'; </statement>
> </VacuumdConfiguration>

these all seem to be deletes (no VACUUMs), so you might want
to check if vacuumd is actually running to be 100% sure.

also, what version postgres is this ?

gnari

>

Re: How to reduce a database

From
"Travis Whitton"
Date:
I don't remember where I read it, but I saw something online a while back comparing vacuum stragies vs dumping with pg_dump and then reloading. The pg_dump and restore ended up compacting the database significantly more. I don't know if that still applies with 8.2, but it might be worth a try. I can find the article if you're interested.

Travis

On 12/29/06, Mario Behring < mariobehring@yahoo.com> wrote:
Hi list,

I have an openNMS server that uses a Postgres database. For those who are not familiar, openNMS is an open source network management product.

Anyway, the openNMS database is very large now, more than 25GB (considering all tables) and I am starting to have disk space issues. The openNMS product has a vacuumdb procedure that runs every 24 hours and reads a vacuumd-configuration.xml file for parameters on what to do.

The problem is that this process is not reducing the database size. What I need to do is to delete some records based on timestamp fileds or something like that. I don't know how to do it though.

Can you guys help me with some command line examples?

There is this table, called EVENTS, that have the following structure:

 eventid                 | integer                     | not null
 eventuei                | character varying(256)      | not null
 nodeid                  | integer                     |
 eventtime               | timestamp without time zone | not null
 eventhost               | character varying(256)      |
 eventsource             | character varying(128)      | not null
 ipaddr                  | character varying(16)       |
 eventdpname             | character varying(12)       | not null
 eventsnmphost           | character varying(256)      |
 serviceid               | integer                     |
 eventsnmp               | character varying(256)      |
 eventparms              | text                        |
 eventcreatetime         | timestamp without time zone | not null
 eventdescr              | character varying(4000)     |
 eventloggroup           | character varying(32)       |
 eventlogmsg             | character varying(256)      |
 eventseverity           | integer                     | not null
 eventpathoutage         | character varying(1024)     |
 eventcorrelation        | character varying(1024)     |
 eventsuppressedcount    | integer                     |
 eventoperinstruct       | character varying(1024)     |
 eventautoaction         | character varying(256)      |
 eventoperaction         | character varying(256)      |
 eventoperactionmenutext | character varying(64)       |
 eventnotification       | character varying(128)      |
 eventtticket            | character varying(128)      |
 eventtticketstate       | integer                     |
 eventforward            | character varying(256)      |
 eventmouseovertext      | character varying(64)       |
 eventlog                | character(1)                | not null
 eventdisplay            | character(1)                | not null
 eventackuser            | character varying(256)      |
 eventacktime            | timestamp without time zone |

I was thinking about using a DELETE FROM EVENTS WHERE  eventtime = <some point in time>.... ..but I am kind of worried on what this could cause on other tables, if there is some relations between them or something.....

Here is the vacuumd-configuration.xml file:

<VacuumdConfiguration period="86400000" >
    <statement><!-- this deletes all the nodes that have been marked as deleted - it relies on cascading deletes --> DELETE FROM node       WHERE node.nodeType = 'D'; </statement>
    <statement><!-- this deletes all the interfaces that have been marked as deleted - it relies on cascading deletes --> DELETE FROM       ipInterface WHERE ipInterface.isManaged = 'D'; </statement>
    <statement><!-- this deletes all the services that have been marked as deleted - it relies on cascading deletes --> DELETE FROM if      Services WHERE ifServices.status = 'D'; </statement>
    <statement><!-- this deletes any events that are not associated with outages - Thanks to Chris Fedde for this --> DELETE FROM even      ts WHERE NOT EXISTS (SELECT svclosteventid FROM outages WHERE svclosteventid = events.eventid UNION SELECT svcregainedeventid FROM out      ages WHERE svcregainedeventid = events.eventid UNION SELECT eventid FROM notifications WHERE eventid = events.eventid) AND eventtime &      lt; now() - interval '6 weeks'; </statement>
</VacuumdConfiguration>

Any help is appreciated.

Thank you.

Mario

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