Hello, At Fri, 19 Jan 2018 11:28:58 +0000, Greg Stark <st...@mit.edu> wrote in <CAM-w4HMU==skhhzs6kdsrniku9vk2r4tg73m4fjza-8yui3...@mail.gmail.com> > On 19 January 2017 at 09:37, Kyotaro HORIGUCHI > <horiguchi.kyot...@lab.ntt.co.jp> wrote: > > > > Though I haven't look closer to how a modification is splitted > > into WAL records. A tuple cannot be so long. As a simple test, I > > observed rechder->xl_tot_len at the end of XLogRecordAssemble > > inserting an about 400KB not-so-compressable string into a text > > column, but I saw a series of many records with shorter than > > several thousand bytes. > > I think the case to check is a commit record with many thousands of > subtransactions. I'm not sure you can fill a whole segment though.
Thanks, potentially it can. 1 subtransaction adds 4 bytes so roughly 4.2M subtransactions will fill a segment but a transaction with 100000 subtrans didn't end returning a pile of many-many commans tags. ... Anyway, current point of the discussion is I think moved to the validity of taking a series of continuation records from different WAL sources, or acceptability of adding record-awareness to wal-receiver side. regards, -- Kyotaro Horiguchi NTT Open Source Software Center
