postgres

Author SHA1 Message Date

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	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
Robert Haas	d1b7c1ffe7	Parallel executor support. This code provides infrastructure for a parallel leader to start up parallel workers to execute subtrees of the plan tree being executed in the master. User-supplied parameters from ParamListInfo are passed down, but PARAM_EXEC parameters are not. Various other constructs, such as initplans, subplans, and CTEs, are also not currently shared. Nevertheless, there's enough here to support a basic implementation of parallel query, and we can lift some of the current restrictions as needed. Amit Kapila and Robert Haas	10 years ago

Robert Haas

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

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

Robert Haas

d1b7c1ffe7

Parallel executor support.

This code provides infrastructure for a parallel leader to start up
parallel workers to execute subtrees of the plan tree being executed
in the master.  User-supplied parameters from ParamListInfo are passed
down, but PARAM_EXEC parameters are not.  Various other constructs,
such as initplans, subplans, and CTEs, are also not currently shared.
Nevertheless, there's enough here to support a basic implementation of
parallel query, and we can lift some of the current restrictions as
needed.

Amit Kapila and Robert Haas

10 years ago

3 Commits (adeee974866085db84b860c1f397dd7c6b136a0a)