At Thu, 04 Mar 2021 23:40:34 -0500, Tom Lane <t...@sss.pgh.pa.us> wrote in > BTW, I tried simply removing the "allows_streaming" option from > the test, and it failed ten times out of ten tries for me. > So Andres is right that that makes it pretty reproducible in > a stock build.
The difference comes from the difference of shared_buffers. In the "allows_streaming" case, PostgresNode::init() *reduces* the number down to '1MB'(128 blocks) which leads to only 8 XLOGbuffers, which will very soon be wrap-arounded, which leads to XLogWrite. When allows_streaming=0 case, the default size of shared_buffers is 128MB (16384 blocks). WAL buffer (512) doesn't get wrap-arounded during the test and no WAL buffer is written out in that case. regards. -- Kyotaro Horiguchi NTT Open Source Software Center
