Re: Usage of epoch in txid_current

Andres Freund <andres@anarazel.de> writes:
> On 2018-07-10 11:35:59 +1200, Thomas Munro wrote:
>> I think it's probably a good idea to make it very explicit when moving
>> between big and small transaction IDs, hence the including of the word
>> 'big' in variable and function names and the use of a function-like
>> macro (rather than implicit conversion, which C doesn't give me a good
>> way to prevent).  Otherwise there is a class of bug that is hidden for
>> the first 2^32 transactions.

> You could have BigTransactionId (maybe renamed to FullTransactionId?) be
> a struct type. That'd prevent such issues. Most compilers these days
> should be more than good enough to optimize passing around an 8byte
> struct by value...

Or, perhaps, use a struct in assert builds and int64 otherwise?
You could hide the ensuing notational differences in macros.

            regards, tom lane