Ignoring the cost, there's the risk/reward alignment you see in large enterprises.
Imagine you're a new CIO. You know you're probably looking at a 3-5 year tenure at this new company and you want to lead with some big wins to set the tone and show your value.
You're reviewing proposals from your senior leadership. One of the options is an Oracle migration. It could cost a million dollars to migrate, but you'd save a million dollars a year going forward. Oracle runs your mission-critical internal systems, any issues with the migration and the system you migrate to is going to cause significant financial and reputation damage. You'll have to defend this decision if anything goes wrong, i.e. you've absorbed a lot of risk but a lot less upside to you personally.
What do you do? You put the proposal to the side and look for something that has a lot better upside.
lift and shift migrations dont really make sense. It would make sense to do architectural rewrite, from on-prem Oracle monolith to cloud native serverless stack for example. Digital transformation, yeah
I worked in a bank previously and we migrated all our databases from Oracle to MS SQL Server. I think we used like 7-8 years to do it so I can understand people who are hesistant to convert. I think the advantages at the time (this was 10 years ago) was lower price for the db servers but also more people who are familiar with Sql Server compared to Oracle.
I work with a few former-Oracle DBAs in a PostgreSQL-flavored consultancy now and they are aces. All the root-cause analysis and organization skills transfer handily.
Postgres is functionally and conceptually extremely similar to Oracle. There are a few oddities (in particular, oracle's "nulls are never in indexes" is kinda weird) but the redo log is similar to the WAL, etc. In most cases, similar approaches will perform similarly and experience pretty much transfers over with a few months of experience.
Imagine you're a new CIO. You know you're probably looking at a 3-5 year tenure at this new company and you want to lead with some big wins to set the tone and show your value.
You're reviewing proposals from your senior leadership. One of the options is an Oracle migration. It could cost a million dollars to migrate, but you'd save a million dollars a year going forward. Oracle runs your mission-critical internal systems, any issues with the migration and the system you migrate to is going to cause significant financial and reputation damage. You'll have to defend this decision if anything goes wrong, i.e. you've absorbed a lot of risk but a lot less upside to you personally.
What do you do? You put the proposal to the side and look for something that has a lot better upside.