We want to migrate an external postgresql database into amazon RDS however for some time we need to keep both of them working and in sync. I have found ways of doing it but only with RDS being the master and not the Slave. Is there a good and viable solution which could help us?
There is AWS service Database Migration Service which can be used to migrate external databases to Amazon AWS RDS.
https://docs.aws.amazon.com/dms/latest/userguide/Welcome.html
It supports postgresql 9.4 and higher.
There are different task types and you need to use Ongoing Replication to keep them sync.
https://docs.aws.amazon.com/dms/latest/userguide/CHAP_Task.CDC.html
To setup that task you need to enable Logical Replication for source database
Related
We are migrating data from a couple of Aurora instances to our own single Aurora instance. All of them run Postgres. I realized that some of our tasks are configured to use PostgreSQL while others are configured to use Amazon Aurora PostgreSQL. Now we have not had any visible problems using either of them (with source being an Aurora instance). But I am curious on whether this can create any future problems. Does anyone have an answer on what the differences are, since I couldn't find any documentation on this.
I want to understand AWS Relational Database Service (RDS) and discover benefits from using it.
Why RDS is better than manually installed PostgreSQL database in EC2 instance?
Is it possible to connent existing database in EC2 instance with Amazon RDS?
How it really works?
How I should automation RDS?
When I want create new database in existing EC2 instance I can use Ansible in simply way. How I should connect my application with database which uses RDS ?
Thanks in advance!
I want to understand AWS Relational Database Service (RDS) and discover benefits from using it.
As already commented, read the docs and whitepapers.
Why RDS is better than manually installed PostgreSQL database in EC2 instance?
you can be sure it is well setup, you will get point in time recovery, backups and high availability. As well you can set it up yourself, however using RDS you have it all already configured.
Ifs it possible to connent existing database in EC2 instance with Amazon RDS? How it really works?
you don't have access to any underlying configuration, so nope, you cannot really connect ec2 database w/ rds (e. g. wal for wal streaming).
you still can use database migration tools to migrate all databases and updates to or from rds
How I should automation RDS? When I want create new database in existing EC2 instance I can use Ansible in simply way.
you can use a cloudformation template or cli commands
How I should connect my application with database which uses RDS ?
when you create a rds instance, you will define an admin user and receive a connection url
https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/USER_VPC.Scenarios.html#USER_VPC.Scenario1
I have a requirement of replicate data from AWS RDS Postgres(9.6) Database to On-Premise Postgres(9.5) Database. I have found stuff about replication from On-premise to On-premise. But How can we implement it for AWS RDS to On-premise?
I do this using Bucardo.
Check-out this: https://bucardo.org/Bucardo/
With Bucardo you can replicate RDS postgres instance to a slave postgres present somewhere, only configuring slave, so without the needs to configure RDS stuff.
Also you can do this with zero downtime.
Anyway I am not sure this will work using different versions of Postgresql. You should use same version if possible. I tested it with 9.4.x and it is working.
UPDATE
I can confirm that this is working also using different version of Postgres, for example I was able to replicate with these versions:
AWS RDS postgresql 9.4.x
On-premise postgresql 9.6.x
http://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/CHAP_PostgreSQL.html#PostgreSQL.Concepts.General.FeatureSupport.LogicalReplication
Beginning with PostgreSQL version 9.4, PostgreSQL supports the
streaming of WAL changes using logical replication slots. Amazon RDS
supports logical replication for a PostgreSQL DB instance version
9.4.9 and higher and 9.5.4 and higher. Using logical replication, you can set up logical replication slots on your instance and stream
database changes through these slots to a client like pg_recvlogical.
Logical slots are created at the database level and support
replication connections to a single database.
mind possible problems eg https://dba.stackexchange.com/questions/173267/aws-rds-postgres-logical-replication
can I migrate from AWS RDS to standalone Postgres instance using AWS DMS?
I RTFM, but It does not state anywhere clearly If I can or not. In theory migration should be the same - create supporting scheme in RDS and move on. But have anyone done it?
Well, from AWS DMS manual:
AWS Database Migration Service (AWS DMS) can migrate your data to and from most widely used commercial and open-source databases such as Oracle, PostgreSQL, Microsoft SQL Server, Amazon Redshift, Amazon Aurora, MariaDB, and MySQL. The service supports homogeneous migrations such as Oracle to Oracle, and also heterogeneous migrations between different database platforms, such as Oracle to MySQL or MySQL to Amazon Aurora. The source or target database must be on an AWS service.
In your case the source is on an AWS service, and if by "standalone" you mean a PostgreSQL instance on EC2 machine, then your target is as well. So, based on that, then answer should be "yes".
Yes, that is possible. We have moved data from RDS Postgres to Postgres Installed on EC2 Instance using DMS and works great so far. Make sure to create endpoints for the source/target and create a replication instance and you are good to go
I want to migrate our postgres db from heroku to our own postgres on AWS.
I have tried using pg_dump and pg_restore to do the migration and it works; but it takes a really long time to do this. Our database size is around 20GB.
What's the best way to do the migration with minimal downtime?
If you mean AWS RDS PostgreSQL:
pg_dump and pg_restore
I know you don't like it, but you don't really have other options. With a lot of hoop jumping you might be able to do it with Londiste or Slony-I on a nearby EC2 instance, but it'd be ... interesting. That's not the most friendly way to do an upgrade, to say the least.
What you should be able to do is ship WAL into RDS PostgreSQL, and/or stream replication logs. However Amazon don't support this.
Hopefully Amazon will adopt some part of 9.4's logical replication and logical changeset extraction features, or better yet the BDR project - but I wouldn't hold my breath.
If you mean AWS EC2
If you're running your own EC2 instance with Pg, use replication then promote the standby into the new master.