Propagate sort instrumentation from workers back to leader.

Up until now, when parallel query was used, no details about the
sort method or space used by the workers were available; details
were shown only for any sorting done by the leader.  Fix that.

Commit 1177ab1dabf72bafee8f19d904cee3a299f25892 forced the test case
added by commit 1f6d515a67ec98194c23a5db25660856c9aab944 to run
without parallelism; now that we have this infrastructure, allow
that again, with a little tweaking to make it pass with and without
force_parallel_mode.

Robert Haas and Tom Lane

Discussion: http://postgr.es/m/CA+Tgmoa2VBZW6S8AAXfhpHczb=Rf6RqQ2br+zJvEgwJ0uoD_tQ@mail.gmail.com

3 files changed, 50 insertions, 3 deletions

diff --git a/src/include/executor/nodeSort.h b/src/include/executor/nodeSort.h
index ed0e9dbb53..77ac06597f 100644
--- a/src/include/executor/nodeSort.h
+++ b/src/include/executor/nodeSort.h
@@ -14,6 +14,7 @@
 #ifndef NODESORT_H
 #define NODESORT_H
 
+#include "access/parallel.h"
 #include "nodes/execnodes.h"
 
 extern SortState *ExecInitSort(Sort *node, EState *estate, int eflags);
@@ -22,4 +23,10 @@ extern void ExecSortMarkPos(SortState *node);
 extern void ExecSortRestrPos(SortState *node);
 extern void ExecReScanSort(SortState *node);
 
+/* parallel instrumentation support */
+extern void ExecSortEstimate(SortState *node, ParallelContext *pcxt);
+extern void ExecSortInitializeDSM(SortState *node, ParallelContext *pcxt);
+extern void ExecSortInitializeWorker(SortState *node, shm_toc *toc);
+extern void ExecSortRetrieveInstrumentation(SortState *node);
+
 #endif							/* NODESORT_H */
diff --git a/src/include/nodes/execnodes.h b/src/include/nodes/execnodes.h
index 15a84269ec..d1565e7496 100644
--- a/src/include/nodes/execnodes.h
+++ b/src/include/nodes/execnodes.h
@@ -1731,6 +1731,16 @@ typedef struct MaterialState
 } MaterialState;
 
 /* ----------------
+ *	 Shared memory container for per-worker sort information
+ * ----------------
+ */
+typedef struct SharedSortInfo
+{
+	int			num_workers;
+	TuplesortInstrumentation sinstrument[FLEXIBLE_ARRAY_MEMBER];
+} SharedSortInfo;
+
+/* ----------------
  *	 SortState information
  * ----------------
  */
@@ -1744,6 +1754,8 @@ typedef struct SortState
 	bool		bounded_Done;	/* value of bounded we did the sort with */
 	int64		bound_Done;		/* value of bound we did the sort with */
 	void	   *tuplesortstate; /* private state of tuplesort.c */
+	bool		am_worker;		/* are we a worker? */
+	SharedSortInfo *shared_info;	/* one entry per worker */
 } SortState;
 
 /* ---------------------
diff --git a/src/include/utils/tuplesort.h b/src/include/utils/tuplesort.h
index 28c168a801..b6b8c8ef8c 100644
--- a/src/include/utils/tuplesort.h
+++ b/src/include/utils/tuplesort.h
@@ -32,6 +32,34 @@
 typedef struct Tuplesortstate Tuplesortstate;
 
 /*
+ * Data structures for reporting sort statistics.  Note that
+ * TuplesortInstrumentation can't contain any pointers because we
+ * sometimes put it in shared memory.
+ */
+typedef enum
+{
+	SORT_TYPE_STILL_IN_PROGRESS = 0,
+	SORT_TYPE_TOP_N_HEAPSORT,
+	SORT_TYPE_QUICKSORT,
+	SORT_TYPE_EXTERNAL_SORT,
+	SORT_TYPE_EXTERNAL_MERGE
+} TuplesortMethod;
+
+typedef enum
+{
+	SORT_SPACE_TYPE_DISK,
+	SORT_SPACE_TYPE_MEMORY
+} TuplesortSpaceType;
+
+typedef struct TuplesortInstrumentation
+{
+	TuplesortMethod sortMethod; /* sort algorithm used */
+	TuplesortSpaceType spaceType;	/* type of space spaceUsed represents */
+	long		spaceUsed;		/* space consumption, in kB */
+} TuplesortInstrumentation;
+
+
+/*
  * We provide multiple interfaces to what is essentially the same code,
  * since different callers have different data to be sorted and want to
  * specify the sort key information differently.  There are two APIs for
@@ -107,9 +135,9 @@ extern bool tuplesort_skiptuples(Tuplesortstate *state, int64 ntuples,
 extern void tuplesort_end(Tuplesortstate *state);
 
 extern void tuplesort_get_stats(Tuplesortstate *state,
-					const char **sortMethod,
-					const char **spaceType,
-					long *spaceUsed);
+					TuplesortInstrumentation *stats);
+extern const char *tuplesort_method_name(TuplesortMethod m);
+extern const char *tuplesort_space_type_name(TuplesortSpaceType t);
 
 extern int	tuplesort_merge_order(int64 allowedMem);