On Thu, Dec 6, 2018 at 12:30 PM Pavel Stehule <pavel.stehule@gmail.com> wrote: > > čt 6. 12. 2018 v 7:55 odesílatel Mithun Cy <mithun.cy@enterprisedb.com> napsal: >> >> On Thu, Dec 6, 2018 at 11:13 AM Amit Kapila <amit.kapila16@gmail.com> wrote: >> > >> > On Thu, Dec 6, 2018 at 10:03 AM Pavel Stehule <pavel.stehule@gmail.com> wrote: >> > > >> > > čt 6. 12. 2018 v 5:02 odesílatel Mithun Cy <mithun.cy@enterprisedb.com> napsal: >> > >> >> > >> COPY command seems to have improved very slightly with zheap in both with size of wal and execution time. I also did some tests with insert statement where I could see some regression in zheap when compared to heap with respect to execution time. With further more investigation I will reply here. >> > >> >> > > >> > > 20% of size reduction looks like effect of fill factor. >> > > >> > >> > I think it is because of smaller zheap tuple sizes. Mithun can tell >> > more about setup whether he has used different fillfactor or anything >> > else which could lead to such a big difference. >> >> Yes default fillfactor is unaltered, zheap tuples sizes are less and >> alinged each at 2 Bytes >> > > I am sorry, I know zero about zheap - does zheap use fill factor? if yes, why? >
Good question. It is required because tuples can expand (Update tuple to bigger length). In such cases, we try to perform in-place update if there is a space in the page. So, having fillfactor can help.
