On Mon, Dec 9, 2019 at 11:54 PM Alvaro Herrera <alvhe...@2ndquadrant.com> wrote:
> On 2019-Dec-09, Ibrar Ahmed wrote: > > > Hi, > > > > The memory consumption of VACUUM has some issues and could be improved. > > Some of its limitations are recorded in the comments of the > “vacuumlazy.c” > > file. The current design of VACUUM memory usage is that it stores the TID > > in a fixed-size array which is allocated at the start, based upon > > maintenance_work_mem. There are three problems with that design > > Did you see this thread? > > https://postgr.es/m/CAGTBQpbDCaR6vv9=scXzuT8fSbckf=a3ngzdwfwzbdvugvh...@mail.gmail.com > > Yes, and somehow did what is explained. Robert: "What I think we need to do is make some provision to initially allocate only a small amount of memory and then grow the allocation later if needed. For example, instead of having vacrelstats->dead_tuples be declared as ItemPointer, declare it as ItemPointer * and allocate the array progressively in segments. I'd actually argue that the segment size should be substantially smaller than 1 GB, like say 64MB; there are still some people running systems which are small enough that allocating 1 GB when we may need only 6 bytes can drive the system into OOM." I change vacrelstats->dead_tuples to ItemPointer * and allocate small memory and added more when needed. What I did new is divide maintenance_work_mem in fixed-size chunks. > -- > Álvaro Herrera https://www.2ndQuadrant.com/ > PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services > -- Ibrar Ahmed
