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Tweak EXPLAIN for parallel query to show workers launched. 

The previous display was sort of confusing, because it didn't
distinguish between the number of workers that we planned to launch
and the number that actually got launched.  This has already confused
several people, so display both numbers and label them clearly.

Julien Rouhaud, reviewed by me.
This commit is contained in:
Robert Haas 2016-04-15 11:49:41 -04:00
parent 6b85d4ba9b
commit 5702277ca9
3 changed files with 11 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
src/backend/commands/explain.c
View File

@ -1339,8 +1339,16 @@ ExplainNode(PlanState *planstate, List *ancestors,
if (plan->qual) if (plan->qual)
show_instrumentation_count("Rows Removed by Filter", 1, show_instrumentation_count("Rows Removed by Filter", 1,
planstate, es); planstate, es);
ExplainPropertyInteger("Number of Workers", ExplainPropertyInteger("Workers Planned",
gather->num_workers, es); gather->num_workers, es);
if (es->analyze)
{
int nworkers;
nworkers = ((GatherState *) planstate)->nworkers_launched;
ExplainPropertyInteger("Workers Launched",
nworkers, es);
}
if (gather->single_copy) if (gather->single_copy)
ExplainPropertyText("Single Copy", ExplainPropertyText("Single Copy",
gather->single_copy ? "true" : "false", gather->single_copy ? "true" : "false",

1
src/backend/executor/nodeGather.c
View File

@ -166,6 +166,7 @@ ExecGather(GatherState *node)
*/ */
pcxt = node->pei->pcxt; pcxt = node->pei->pcxt;
LaunchParallelWorkers(pcxt); LaunchParallelWorkers(pcxt);
node->nworkers_launched = pcxt->nworkers_launched;
/* Set up tuple queue readers to read the results. */ /* Set up tuple queue readers to read the results. */
if (pcxt->nworkers_launched > 0) if (pcxt->nworkers_launched > 0)

1
src/include/nodes/execnodes.h
View File

@ -1956,6 +1956,7 @@ typedef struct GatherState
struct ParallelExecutorInfo *pei; struct ParallelExecutorInfo *pei;
int nreaders; int nreaders;
int nextreader; int nextreader;
int nworkers_launched;
struct TupleQueueReader **reader; struct TupleQueueReader **reader;
TupleTableSlot *funnel_slot; TupleTableSlot *funnel_slot;
bool need_to_scan_locally; bool need_to_scan_locally;