7 Commits (cbb82e370da8e80aa9667ffbb395cabb0529ea00)

Author	SHA1	Message	Date
Robert Haas	3a1f8611f2	Update parallel executor support to reuse the same DSM. ... Commit b0b0d84b3d purported to make it possible to relaunch workers using the same parallel context, but it had an unpleasant race condition: we might reinitialize after the workers have sent their last control message but before they have dettached the DSM, leaving to crashes. Repair by introducing a new ParallelContext operation, ReinitializeParallelDSM. Adjust execParallel.c to use this new support, so that we can rescan a Gather node by relaunching workers but without needing to recreate the DSM. Amit Kapila, with some adjustments by me. Extracted from latest parallel sequential scan patch.	10 years ago
Robert Haas	8538a63070	Make Gather node projection-capable. ... The original Gather code failed to mark a Gather node as not able to do projection, but it couldn't, even though it did call initialize its projection info via ExecAssignProjectionInfo. There doesn't seem to be any good reason for this node not to have projection capability, so clean things up so that it does. Without this, plans using Gather nodes might need to carry extra Result nodes to do projection.	10 years ago
Robert Haas	31ba62ce32	Fix typos in comments. ... CharSyam	10 years ago
Robert Haas	1a219fa15b	Add header comments to execParallel.c and nodeGather.c. ... Patch by me, per a note from Simon Riggs. Reviewed by Amit Kapila and Amit Langote.	10 years ago
Robert Haas	bfc78d7196	Rewrite interaction of parallel mode with parallel executor support. ... In the previous coding, before returning from ExecutorRun, we'd shut down all parallel workers. This was dead wrong if ExecutorRun was called with a non-zero tuple count; it had the effect of truncating the query output. To fix, give ExecutePlan control over whether to enter parallel mode, and have it refuse to do so if the tuple count is non-zero. Rewrite the Gather logic so that it can cope with being called outside parallel mode. Commit 7aea8e4f2d is largely to blame for this problem, though this patch modifies some subsequently-committed code which relied on the guarantees it purported to make.	10 years ago
Tom Lane	bf686796a0	Add missing "static" specifier. ... Per buildfarm (pademelon, at least, doesn't like this).	10 years ago
Robert Haas	3bd909b220	Add a Gather executor node. ... A Gather executor node runs any number of copies of a plan in an equal number of workers and merges all of the results into a single tuple stream. It can also run the plan itself, if the workers are unavailable or haven't started up yet. It is intended to work with the Partial Seq Scan node which will be added in future commits. It could also be used to implement parallel query of a different sort by itself, without help from Partial Seq Scan, if the single_copy mode is used. In that mode, a worker executes the plan, and the parallel leader does not, merely collecting the worker's results. So, a Gather node could be inserted into a plan to split the execution of that plan across two processes. Nested Gather nodes aren't currently supported, but we might want to add support for that in the future. There's nothing in the planner to actually generate Gather nodes yet, so it's not quite time to break out the champagne. But we're getting close. Amit Kapila. Some designs suggestions were provided by me, and I also reviewed the patch. Single-copy mode, documentation, and other minor changes also by me.	10 years ago