I am just getting started with LoqiQL and LogicBlox. While looking at the different operators, I came across the transaction ID and the unique identifiers. What are use cases for these two operators?
These two operators are not very commonly used. Because the identifiers for both the uid p2p and transaction:id are only unique in the lifetime of a database, you can't use them as UUIDs (we'll add that functionality at some point). If you need to export the data and re-import into a different workspace, then you can will get conflicts eventually.
The transaction identifier can be helpful for debugging issues. For example, in LogiQL you can write a delta rule that records a log of changes to a predicate. Instead of using datetime:now (the resolution might not be sufficient), you can use the transaction id to keep a log of changes per transaction.