All i'm building is In-Memory Index as an extension over Postgres.
Postgres Indexes will get Insert calls and Read calls from various processes(typically client/connection process - forked processes to postmaster process). Hence i have to maintain my In-Memory index in shared memory.
If i create DynamicSharedArea (DSA) in postmaster/main process, all these Client/Connection processes(In-Memory Index Processes) need not attach to that DSA using area handle. Because these are forked processes to postmaster/Main process and hence they automatically gets attached.
Hence i'm trying to create DSA in _PG_init function as it is called by postmaster/main process.
On Tue, May 23, 2017 at 6:42 AM, Mahi Gurram <teckymahi@gmail.com> wrote: > I'm building In-Memory index extension for Postgres, for which i'm trying to > use DSA. But ended with some issues, as it is not allowing me to create > DSA(Dynamic Shared Area) in _PG_init function. > > Please refer my_PG_init code below: >> >> void >> _PG_init(void) >> { >> area = dsa_create(LWLockNewTrancheId(), "CustomIndex_DSA"); >> area_handle = dsa_get_handle(area); >> } > > > Because of this code, Postgres is not starting. Not even giving any error > messages in pg logs. Hence, i'm totally clue less :(
It seems to me that you are creating those too early. For example, for a background worker process, DSA segments would likely be created in the main process routine. Without understanding what you are trying to achieve, it is hard to make a good answer. You could always use a ramdisk, but that would be likely be a waste of memory as Postgres has its own buffer pool, killing the performance gains of OS caching. -- Michael
