In mongoshell you can connect to several databases and use them at the same time. A plain simple copy would be this one:
var db_A = Mongo("mongodb://user:password@host-A").getDB("data")
var db_B = Mongo("mongodb://user:password@host-B").getDB("data")
var docs = db_A.getCollection("collection_name").find()....
(Addressing first question)
Toss comment_unseen; instead, use a LEFT JOIN ... WHERE ... IS NULL or WHERE NOT EXISTS ( SELECT 1 FROM comment_seen WHERE ... )
For comment_seen, replace
CONSTRAINT user_id UNIQUE (user_id, comment_id)
with this (Note: a PK includes a uniqueness constraint):
PRIMARY KEY(user_id, comment_id)
If you need to look up which users ...
Yes, It's possible.
You can migrate databases from older versions like SQL Server 2008 R2 to SQL Server 2019.
Check answer from here. Migrate to SQL Server 2019
Log shipping: Log shipping is supported if primary is running SQL
Server 2008 SP3 or later, or SQL Server 2008 R2 SP2 or later, and
secondary is running SQL Server 2019.
Warning: If an automatic or ...
Too risky! You are doing 3 things at the same time:
Change from Failover Cluster to Availability Group
Upgrade from SQL Server 2014 to SQL Server 2019
Plus you said that you have 100 databases with 50+ different application hitting them. I don't want to be a psychologist but you are telling to me "What could possibly go wrong? I will ...
To avoid this, I usually prefer to set up a fresh installation of an instance in the new domain. Then I restore the databases. Then I script proper instance configurations/agents/other things, adapting them to the new domain.
As suggested by @Ronaldo, you can enter in this emergency situation using:
2 Massive questions
You haven't said anything about what is connecting to your databases.
For swapping over the databases log shipping will give you a much shorter cutover time than backup & restore.
If you can add a AOAG Listener with the name of the old server you will simplify updating all of the client connection strings (means the old server has to ...
Azure Synapse Pathway is a new tool currently in preview which can look at existing Netezza code for you, attempt to convert it and flag up errors.
Download the tool and run it against your Netezza installation. Start here:
As a wizard, it's ...