On Tue, Apr 28, 2020 at 12:56:19PM +0900, Fujii Masao wrote: > Yes. Attached is the updated version of the patch, which introduces > +(pg_lsn, numeric) and -(pg_lsn, numeric) operators. > To implement them, I added also numeric_pg_lsn() function that converts > numeric to pg_lsn.
- those write-ahead log locations.
+ those write-ahead log locations. Also the number of bytes can be added
+ into and substracted from LSN using the <literal>+</literal> and
+ <literal>-</literal> operators, respectively.
That's short. Should this mention the restriction with numeric (or
just recommend its use) because we don't have a 64b unsigned type
internally, basically Robert's point?
+ /* XXX would it be better to return NULL? */
+ if (NUMERIC_IS_NAN(num))
+ ereport(ERROR,
+ (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+ errmsg("cannot convert NaN to pg_lsn")));
That would be good to test, and an error sounds fine to me.
--
Michael
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