I am a bit confused about how to perform a minor PostgreSQL version update on AWS RDS.
I read multiple articles from AWS documentation:
https://aws.amazon.com/about-aws/whats-new/2018/12/amazon-rds-enhances-auto-minor-version-upgrades/
https://docs.aws.amazon.com/AmazonRDS/latest/AuroraUserGuide/USER_UpgradeDBInstance.Upgrading.html
https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/USER_UpgradeDBInstance.Upgrading.html
None of them pointed me to the exact command or set of instructions necessary to perform the minor update released in early August 2019.
I fully understand that major updates can be performed from the AWS Console -> Modify section of the RDS DB Instance or from the AWS CLI.
I even did a search on the available engine versions for Postgres:
aws rds describe-db-engine-versions --engine postgres
And this command only outputs major engine versions, and the latest one is "PostgreSQL 11.4-R1", the one I use.
I am aware that minor updates can be enabled during the maintenance period, but I did not see any minor updates applied.
The lastest August release is crucial four our DB instance because it solves a couple of bugs we have reported regarding PG 11 Partitioning.
Is there a way to perform a manual version update on RDS for Postgres? Locally I updated the PG engine and all works fine.
Thank you and have a great day!
In the RDS console, when you go to the database details and view the "Maintenance & backups" tab, there is a section that displays if there are pending maintenance tasks. Here's a screenshot of a database that has a pending maintenance task:
If there are no pending maintenance tasks that will say "none" instead of "available". If there are no pending maintenance tasks then your database should be running the latest version. If there are pending maintenance tasks, then you can manually initiate the maintenance tasks anytime you want, which should update your database to the latest minor version if it isn't already updated.
I don't have a PostgreSQL RDS instance to test this on, but you could try running SELECT version(); on the database to get the current version, which might indicate the minor release version.
I don't see any other way to get to the minor version unfortunately, so you may have to open an AWS support ticket to get them to tell you what version the DB instance is running.
You will need to change the maintenance window to the earliest time.
AWS doesn't allow us to manually trigger the minor update process.
Related
The current version is 9.4.20 and I want to upgrade to 9.5.X. I am wondering the right procedure to do this since my Postgres has read replica so it is a bit more than just Modify. Downtime is acceptable. The seamless upgrade is NOT required. The docs on the AWS side are not clear. https://i.stack.imgur.com/WlCqV.png
amz docs
Here are the purposed steps, yet I can't figure out how to perform the second step:
take a snapshot of the primary instance,
stop replication,
upgrade a primary instance,
upgrade read replica,
promote read replica and start replication again
I will just post what I did as an answer.
snapshot primary,
delete old read replica,
upgrade primary,
create new read replica, done.
The RDS for PostgreSQL doc https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/USER_UpgradeDBInstance.PostgreSQL.html states:
"A read replica can't undergo a major version upgrade but the read replica's source instance can. If a read replica's source instance undergoes a major version upgrade, all read replicas for that source instance remain with the previous engine version. In this case, the read replicas can no longer replicate changes performed on the source instance.
We recommend that you either promote your read replicas, or delete and recreate them after the source instance has upgraded to a different major version."
When you initiate a major version upgrade for an RDS for PostgreSQL instance with one or more read replicas, the replication will be automatically stopped, and it won't be restarted after the primary (source) is finished upgrading. You will need to create new read replicas after upgrading the source database instance.
I have created a replicated Postgresql database (Master - Slave). I did this with an already existing Ansible Playbook (Role) , which I don't fully understand yet. The cluster currently consists of only 2 databases on different VMs.
So I want to test this replication now.
Unfortunately I have little experience with Postgresql.
How can I control whether they connect stable?
If the slave really takes over the task if the master should fail?
Many thanks for any information, tips & tricks.
Postgresql v. 9.6
Official PostgreSQL does not yet support automatic failover (Although there are multiple third-party projects which support this feature). Therefore if the deployment you have mentioned is only official PostgreSQL, after master failure, none of replicas take over the write task. But they can answer read queries if they are configured as hot_standby.
If you want to check the state of replication, in master you can check out pg_stat_replication in master.
Also these official docs would help you understand Postgres streaming replication & failover better:
https://www.postgresql.org/docs/9.6/warm-standby.html#STREAMING-REPLICATION
https://www.postgresql.org/docs/9.6/warm-standby-failover.html
I have an web application that executes query against a RDS Postgres Database. For this application, we use a Trunk based development and our developers can and should deploy anything on master branch directly to production. During the day, when we are operating in a low workload we can't see any performance degradation on database, but at night ( we operate a courier service), when we experiment huge workload we can have some performance degradation...
My question is: How should I monitor this kind of behaviour?
I don't want to impose to run a stress test before deploy to production.
I would like to have a tool that can monitor our database and inform like: "Take care! You have a new query (or a slow query) on your database caused by Pull Request 1234".
If you are on RDS for PostgreSQL 10, or can upgrade to that version, then you can use Performance Insights to monitor your running instance, to see which queries are generating load on your instance, and what wait states those queries are in. You can find more info here: https://aws.amazon.com/rds/performance-insights/
Full disclosure: I am the Product Manager for Amazon Aurora PostgreSQL, which was the first db engine to support Performance Insights.
The simple solution is to use the pg_stat_statements. extension. It can show you the queries that consumed the most run time altogethet ar one glance.
I have been using PG Backups add-on recently and everything has worked fine, however this morning the backup process triggered at 10:00 A.M. in the morning generating some blocks and timeouts in my application.
Is there a way to specify the schedule of the backups made with this add-on? I've been searching and haven't found anything specific.
Use Cron for Manual Backup Scheduling
Heroku gives you two types of backups: automated and user-initiated. Each plan has a different number of daily, weekly, and manual backups that are retained. You can't control when the automated backups occur with PG Backups Auto, but you can use cron to trigger a "manual" backup at any time.
For example:
# Trigger a "manual" backup every four hours.
0 */4 * * * source $HOME/database_credentials; heroku pgbackups:capture
See Creating a Backup for more information about using the pgbackups command.
No, there is no way to do it currently, aside from using an external process to fire the calls.
An email to support might reveal more.
While the original question is old, Heroku does have a schedule option for PGBackups now:
https://devcenter.heroku.com/articles/heroku-postgres-backups#scheduling-backups
I need to replicate a PostgreSQL database server as follows:
Two servers are adjacent to each-other - one is the master and the other standby. If the master fails, the standby takes over. Replication from master to slave needs to be failsafe, hence, synchronous. The standby will not be used for any querying unless it has become a master. So, no high-availability/load-balancing is required.
There is another backup server at a remote location. Data from the master server mentioned above will be replicated to this remote server asynchronously and in batches. Time is not a factor at all in this replication - a couple of hours is just fine. This server would be used just for backup.
I've studied the currently available replication solutions from the PostgreSQL docs as well as from Google, but can't decide which combination of synchronous-asynchronous solutions would I need.
The closest I came up with is using pgpool-II for scenario 1 and Mammoth for scenario 2. However, as pgpool is statement-based, what would happen to queries containing rand() and now()?
Please note that I'd rather use free and open-source replication tools.
Also, just a side question - according to scenario 1 above, when the master fails, the standby will take over. Would the master-slave role be reversed after that, or would after the recovery of the master server the slave would go back to its standby state?
Any suggestion would be highly appreciated. Thanks.
I suggest using DRBD for scenario 1 and either 9.0 built-in replication or Slony for scenario 2.
Before PostgreSQL 9.1 (not yet released), there is no other synchronous replication solution available, and DRBD is widely established for this purpose. Together with Pacemaker or Heartbeat, which come with all the scripts needed for PostgreSQL monitoring and switchover, you have a very robust and fairly easy to manage solution. (In fact, I'd consider continuing to use DRBD even after 9.1 comes out; it's just a lot easier and has a longer track record.)
For the cross-site asynchronous, you could try the built-in replication of PostgreSQL 9.0, perhaps in conjunction with repmgr for monitoring and management. Alternatively, you could try the (now a bit) old-school Slony, but I'd guess it will more complicated for your needs.
You didn't mention if the server in question was on a specific version or if this was a new project with the freedom to choose the version. The answers vary based on that information.
If you are starting with a clean slate, I would recommend designing based on the PostgreSQL 9.1 beta. The final version will be released long before you would be ready to go into a production environment and it has binary synchronous replication built-in.
I've been using the built-in asynchronous replication in PostgreSQL for years in almost the exact same scenario you describe and it has always been rock-solid for me. It's become even better with 9.0 with Hot standby and it's become much easier to configure and maintain. 9.1 provides the only missing piece you require.
However, if you are trying to replicate an existing server, built-in asynchronous replication with aggressive settings for "checkpoint_timeout" a very frequent backup of unarchived WAL files could be sufficient until you can upgrade to 9.1.
The bottom line here is that you can get exactly what you want is with stock PostgreSQL 9.1--no third-party products required.
As for failover, it is not an automatic process, you'll need to handle that yourself. I would recommend that after a failover, switching the roles of the two machines until either the next failover event or until a controlled manual failover during a scheduled outage during a slow period of use. Again, this is not automatic and much be managed by the administrator (via shell scripts, presumably).