Hi, On 2016-06-28 10:01:28 +0000, Rajeev rastogi wrote: > >3) Our 1-by-1 tuple flow in the executor has two major issues: > > Agreed, In order to tackle this IMHO, we should > 1. Makes the processing data-centric instead of operator centric. > 2. Instead of pulling each tuple from immediate operator, operator can push the tuple to its parent. It can be allowed to push until it sees any operator, which cannot be processed without result from other operator. > More details from another thread: > https://www.postgresql.org/message-id/BF2827DCCE55594C8D7A8F7FFD3AB77159A9B904@szxeml521-mbs.china.huawei.com
I doubt that that's going to be ok in the generic case (memory usage, materializing too much, "bushy plans", merge joins)
Yeah. You'd likely start landing up with Haskell-esque predictability of memory use. Given how limited and flawed work_mem handling etc already is, that doesn't sound like an appealing direction to go in. Not without a bunch of infrastructure to manage queue sizes and force work into batches to limit memory use, anyway.