loading one table from RDS / postgres into Redshift - postgresql

We have a Redshift cluster that needs one table from one of our RDS / postgres databases. I'm not quite sure the best way to export that data and bring it in, what the exact steps should be.
In piecing together various blogs and articles the consensus appears to be using pg_dump to copy the table to a csv file, then copying it to an S3 bucket, and from there use the Redshift COPY command to bring it in to a new table-- that's my high level understanding, but am not sure what the command line switches should be, or the actual details. Is anyone doing this currently and if so, is what I have above the 'recommended' way to do a one-off import into Redshift?

It appears that you want to:
Export from Amazon RDS PostgreSQL
Import into Amazon Redshift
From Exporting data from an RDS for PostgreSQL DB instance to Amazon S3 - Amazon Relational Database Service:
You can query data from an RDS for PostgreSQL DB instance and export it directly into files stored in an Amazon S3 bucket. To do this, you use the aws_s3 PostgreSQL extension that Amazon RDS provides.
This will save a CSV file into Amazon S3.
You can then use the Amazon Redshift COPY command to load this CSV file into an existing Redshift table.
You will need some way to orchestrate these operations, which would involve running a command against the RDS database, waiting for it to finish, then running a command in the Redshift database. This could be done via a Python script that connects to each database (eg via psycopg2) in turn and runs the command.

Related

How to restore exported RDS snapshot from S3 to RDS cluster

I have an AWS RDS Aurora PostgreSQL cluster (compatible with PostgreSQL 13.4).
I successfully followed this tutorial to back up my PostgreSQL RDS aurora cluster snapshot to S3, and it seems that all the data is backed up to s3.
Now I'm trying to restore the exported snapshot from S3 to PostgreSQL RDS cluster, and I couldn't find explanation how to do it.
Any idea how to do it? maybe I need to first restore the exported data from S3 to snapshot, and then connect it to to RDS, or any other way?
The RDS Snapshot to S3 export feature is not intended for additional backups of your data. It is intended to convert your data to Parquet for use in analytics tools like Redshift or Athena. Some data type conversion happens during this export process.
There is currently no method available to import these Parquet files back into RDS. You would have to write some code yourself to read the Parquet files and insert the data back into a running RDS instance if you needed that.
If you are just wanting a secondary backup of your RDS instance in addition to the RDS snapshots, you could either look into cross-region or cross-account copies of your RDS snapshots, or look into using the AWS Backup service.

How to export result set as CSV from Aurora Postgres DB to AWS-S3?

As part of my Flask and Celery application, I'm trying to move data from AWS-Aurora Postgres DB to Redshift.
I'll be running this application in Kubernetes.
My approach is to query the aurora Postgres database and write the result set to a CSV file which is saved on to an attached volume and then upload it to S3 and then import the file into Redshift.
However, I came across another article which lets us directly upload the result set as a CSV file to S3 instead of having an intermediate volume.
https://docs.aws.amazon.com/AmazonRDS/latest/AuroraUserGuide/AuroraMySQL.Integrating.SaveIntoS3.html
They've mentioned the usage of OUTFILE command. But it's mentioned about MySQL. But they haven't mentioned anything about Postgres DB.
Is it even possible to use the command on Aurora Postgres DB and export to S3.
If you can connect to the database with psql, you can use the \copy command to export the output from any select statement to a csv:
https://codeburst.io/two-handy-examples-of-the-psql-copy-meta-command-2feaefd5dd90
https://dba.stackexchange.com/questions/7651/postgres-client-copy-copy-command-doesnt-have-access-to-a-temporary-table
Yes, Aurora runs on MySQL so you can use the outfile command. Did you even try running a query with outfile?

Backing up redshift database

I want to backup entire redshift cluster, such that I can use it in other databases like mysql or hadoop in future.
I was looking up and creating a manual screenshot seems to be an option but I guess that wont work for cross database languages.
So what would be the detailed steps to backup the entire cluster of redshift
Cluster backups can be done via the aws console, however these can only be restored to another redshift cluster.
Because Redshift is not the same as postgres in many ways, it will be inpossible / tricky to use standard tools like pg_dump and pg_restore.
I think that your best option is to :
extract the ddl from the Redshift tables that you wish to create elsewhere, most ide's have a simple way to do this.
modify the ddl to work with your target database (e.g. postgres will
be easy, mysql harder)
copy the contents of the Redshift database, one table at a time to s3 using
the unload command
import the data that you unloaded in step 3 to your target tables

Get big(250Gb) RDS PostgreSQL db dump into my local machine

My problem is to get big(250Gb) postgres dump on my local machine.
Its on AWS RDS. I tried to dump it to local machine, but it takes too long, kinda 3+ days.
Trying to find a way to dump it into S3 and download from there safely. May be you could suggest more effective way to do that. Will appreciate any kind of help.
Thanks!
As of my knowledge, aws does not provide a way to backup db into s3
you can take a look into this question and answers,
Export huge database from amazon RDS to local mysql
here is one answer
If the data is that big I would suggest copying the RDS snapshot on S3, as explained here.
Link to documentation to copy snapshot to s3
This topic is covered in this StackOverflow thread Exporting a AWS Postgres RDS Table to AWS S3
Another solution would be to spin up an EC2 instance and dump the database to a local EBS volume that is large enough for the following steps. Then chose one of the following:
Compress the DB dump into multiple files and copy to S3 for download. I would use a smart S3 download manager given the size of the database dump.
Export the S3 data using Snowball Export S3 Data. If your Internet connection is not fast enough / reliable enough then Snowball will get you the data.

Backup and Restore Single Schema/Table

Is there a way to backup or restore a specific schema or table on a Cloud SQL server? Backing up the entire set of data, but then being able to restore only certain schemas or tables would be very helpful for multi-tenant systems.
Not via backup/restore. You can export a specific schema or table to Google Cloud Storage, but that's probably not what you're looking for.
The Cloud SQL use MySQL database with some limitations. You can check out the unsupported features and functions at the following link:
https://cloud.google.com/sql/faq#supportmysqlfeatures
With this in mind any backup/restore tool that are being used for MySQL should work for Google Cloud SQL as well. Using mysqldump for import/export of Cloud SQL is covered at this document:
https://cloud.google.com/sql/docs/import-export
You can use mysqldump to backup specific table or backup entire database and restore only specific tables using the solutions offered in these links:
Can I restore a single table from a full mysql mysqldump file?
How to take backup of a single table in a MySQL database?
You can restore the backup to a different instance and then replace the data on the original instance with the data from the backup instance.