In terms of databases, what does 'roach motel' mean?

Question

Recently Larry used it in one of the OpenWorld keynotes.

Wikipedia says

In computers, sometimes as slang use:

• Sometimes used to refer to a proprietary file standard -- "you can check your data in, but you can't check it out".

I fail to understand the meaning here. In what situations will one not be able to check out the data?

Answer 1

Generally, I understand (could be wrong of course) it to be either

• opaque vendor lock-in
• difficulty in re-using data how you want

The second point is seen every day

You buy an app that runs on a mainstream RDBMS: you can report on data, extract it, mine it whatever. Or you buy an app that locks the data into some internal, opaque, proprietary format (not a well known one like PDF or DOC or XLS) where you are forced to use the vendor's (perhaps limited) API.

A couple of other examples

• Larry Ellison on Salesforce
• Facebook vs Twitter