| From: | Andres Freund <andres(at)anarazel(dot)de> |
|---|---|
| To: | Thomas Munro <thomas(dot)munro(at)enterprisedb(dot)com> |
| Cc: | Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>, Alexander Korotkov <a(dot)korotkov(at)postgrespro(dot)ru>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Usage of epoch in txid_current |
| Date: | 2018-07-09 23:43:16 |
| Message-ID: | 20180709234316.lswzqvow3exqbobt@alap3.anarazel.de |
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| Lists: | pgsql-hackers |
On 2018-07-10 11:35:59 +1200, Thomas Munro wrote:
> I played around with this idea yesterday. Experiment-grade patch
> attached.
Cool!
> 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...
Greetings,
Andres Freund
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