Re: Add LSN along with offset to error messages reported for WAL file read/write/validate header failures

On 2022-Sep-19, Bharath Rupireddy wrote:

> We have a bunch of messages [1] that have an offset, but not LSN in
> the error message. Firstly, is there an easiest way to figure out LSN
> from offset reported in the error messages? If not, is adding LSN to
> these messages along with offset a good idea? Of course, we can't just
> convert offset to LSN using XLogSegNoOffsetToRecPtr() and report, but
> something meaningful like reporting the LSN of the page that we are
> reading-in or writing-out etc.

Maybe add errcontext() somewhere that reports the LSN would be
appropriate.  For example, the page_read() callbacks have the LSN
readily available, so the ones in backend could install the errcontext
callback; or perhaps ReadPageInternal can do it #ifndef FRONTEND.  Not
sure what is best of those options, but either of those sounds better
than sticking the LSN in a lower-level routine that doesn't necessarily
have the info already.

-- 
Álvaro Herrera        Breisgau, Deutschland  —  https://www.EnterpriseDB.com/