Hi ! On Thu, Jun 18, 2020 at 12:56 PM Fujii Masao <masao.fu...@oss.nttdata.com> wrote: > Agreed. The feature to view how local memory contexts are used in > each process is very useful! +1
> > =# SELECT * FROM pg_stat_get_backend_memory_context(PID); > > I'm afraid that this interface is not convenient when we want to monitor > the usages of local memory contexts for all the processes. For example, > I'd like to monitor how much memory is totally used to store prepared > statements information. For that purpose, I wonder if it's more convenient > to provide the view displaying the memory context usages for > all the processes. How about separating a function that examines memory consumption trends for all processes and a function that examines memory consumption for a particular phase of a particular process? For the former, as Fujii said, the function shows the output limited information for each context type. All processes calculation and output the information at idle status. I think the latter is useful for debugging and other purposes. For example, imagine preparing a function for registration like the following. =# SELECT pg_stat_get_backend_memory_context_regist (pid, context, max_children, calc_point) pid: A target process context: The top level of the context of interest max_children: Maximum number of output for the target context's children (similar to MemoryContextStatsInternal()'s max_children) calc_point: Single or multiple position(s) to calculate and output context information (Existing hooks such as planner_hook, executor_start, etc.. could be used. ) This function informs the target PID to output the information of the specified context at the specified calc_point. When the target PID process reaches the calc_point, it calculates and output the context information one time to a file or DSM. (Currently PostgreSQL has no formal ways of externally modifying the parameters of a particular process, so it may need to be implemented...) Sometimes I want to know the memory usage in the planning phase or others with a query_string and/or plan_tree that before target process move to the idle status. So it would be nice to retrieve memory usage at some arbitrary point in time ! Regards, -- Tatsuhito Kasahara kasahara.tatsuhito _at_ gmail.com
