My site runs on MongoDB and I'm using MongoLab as a host for the database. I have 10-15 people using the site at any given time and would rather not 'switch them off' if at all possible.
If I have a MongoDB dump that I'd like to restore, it takes a very long time (the file size is around 360mb and this takes a good while to upload on my connection speed). What's more, it appears that MongoDB wants me to delete my collection before doing a restore, so the user would have no data to look through while it's updating.
Is there any way around this, besides, say, having two mongoLab accounts, one 'active' and one for uploading backups and I switch between the two when I need to do a restore?
Is there a general recommended strategy for this sort of thing?
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I'm looking to deploy moodle in the cloud however I have some 50 odd sites which require access to this moodle possibly even temporarily offline. So I'm looking into replicating moodle down onto each site. From what I understand there are 2 data stores that require replication, moodledata and the database, postgresql in our case. moodledata if I'm not mistaken contains the multimedia data and the database among other things all the user records. Luckily the multimedia data will be centralized and is thus synched only one way down to the nodes, that seems doable. Where I'm stuck is how do I handle the Postgres database where the sync will need to be bidirectional?
What I mean by witable is that you can CRUD on each database, and it automatically syncs with the other so that all of them are synced all the time (as much as possible).
I want to start a project for a company with some tricks.
The company is present in many locations (at least 5) and wants the app to run locally (with local database), but when there's a change(Create Update or Delete), the change is propagated to the other databases.
The goal is to have them all synced at every moment, but with the possibility that if internet connection is lost on one site, they continue to use the app properly since they are actually connected to the local database. That's why they don't one a totally online database.
They use MongoDB.
I saw the replica sets technology, but since it's with a unique master, it seems complicated.
Please can you share solutions to such a situation?
I'm trying to set up an architecture with 2 databases, say preview and live, that have the exact same schemas. The use case is that edits can be made to the preview database and then pushed to the live database after they are vetted and approved. The production application would read from the live database.
What would be the most appropriate way to push all data from the preview database to the live database without bringing the live database down? Ideally the copy from preview to live would be an atomic transaction.
I've worked with this type of setup in MSSQL, but I'm fairly new to Postgres. So I'm open to hearing other ways to architect this (with Schemas perhaps?).
EDIT: The main reason to use separate databases is that I may need more than 1 target database (not just a single "live" database). I also may need to switch target databases on the fly without altering the source database schema.
I think what you're looking for is a "hot standby". This would be a separate instance of Postgresql, possibly on the same server but usually not, which is a near-real-time replica of the primary server.
In broad strokes, this is done by shipping the binary transaction logs from the primary server to the backup server, and then "replaying" them there. The exact mechanism for transmitting the logs may vary depending on your requirements.
Fortunately, the docs on this are excellent:
https://www.postgresql.org/docs/9.3/static/warm-standby.html
https://www.postgresql.org/docs/9.0/static/hot-standby.html
I'm going to develop a multi-tenant application, where each tenant lives in its own database or schema (I've not decided this yet).
In this scenario, if I wanted to use point in time recovery (PITR), I also want to have it per-tenant. If a tenant has a problem, I want to be able to roll back only his database or schema and not the whole server.
While I found information how to do backup/restore in such situations with pg_dump and pg_restore, I haven't found any information for PITR.
Is this even possible? If yes, only per database or even per schema?
I can imagine that postgres maybe stores the log of the whole server in a single file, which may be the reason why it could not be possible. But I may be wrong..
This question has been asked multiple times, here and here, and the answer to get this working is fairly straight forward: add an environmental variable to your bash_profile and all Meteor instances on your localhost will share that MONGO_URL.
What I've noticed however is that while this may be the case, there's quite a bit of latency in the "reactivity" of Meteor. I've tested this with two very lean Meteor apps, with empty collections. Inserting a document to a collection from one Meteor app, where my second app is querying that same collection and printing out a field from the documents does work, but there's a noticeable lag before it updates. I've ruled out the possibility of the collection insertion being the source of the lag (simple console.log callback on the client of the first app, logging the id of the newly inserted document).
My purpose for having multiple apps (two to be precise) sharing the same MongoDB is to separate an admin panel from a mobile app without going crazy regarding name-spacing and bloat. This configuration works, but I'm not sure it's the "proper" way of accomplishing the task, and it certainly seems to be causing a performance hit.
Any insight into this matter would be appreciated. Thank you!
EDIT: To clarify, the db URL I'm using is on my localhost, and isn't something hosted online.
When you use an external database, by default meteor will use periodic polling (every few seconds) in order to observe any changes. The delay you are experiencing is a result of this polling process. You can remove the delay and reduce your app's CPU usage by taking advantage of meteor's oplog tailing feature. In order to use it you will:
Get access to a mongodb instance with the oplog turned on.
Set the environment variable MONGO_OPLOG_URL so your app(s) can read the oplog.
Personally, I'd recommend compose.io for this. They provide exactly this as part of their basic elastic deployment. See this post for detailed instructions.
For users who wish to connect to the oplog created locally for you, you can obtain the URL via:
MongoInternals.defaultRemoteCollectionDriver().mongo._oplogHandle._oplogUrl
It should end up looking something like mongodb://127.0.0.1:3001/local