Fix EXPLAIN ANALYZE for parallel HashAgg plans

Since 1f39bce02, HashAgg nodes have had the ability to spill to disk when
memory consumption exceeds work_mem. That commit added new properties to
EXPLAIN ANALYZE to show the maximum memory usage and disk usage, however,
it didn't quite go as far as showing that information for parallel
workers.  Since workers may have experienced something very different from
the main process, we should show this information per worker, as is done
in Sort.

Reviewed-by: Justin Pryzby
Reviewed-by: Jeff Davis
Discussion: https://postgr.es/m/CAApHDvpEKbfZa18mM1TD7qV6PG+w97pwCWq5tVD0dX7e11gRJw@mail.gmail.com
Backpatch-through: 13, where the hashagg spilling code was added.

1 files changed, 22 insertions, 0 deletions

diff --git a/src/include/nodes/execnodes.h b/src/include/nodes/execnodes.h
index 98e0072b8ad..f5dfa32d55c 100644
--- a/src/include/nodes/execnodes.h
+++ b/src/include/nodes/execnodes.h
@@ -2102,6 +2102,27 @@ typedef struct GroupState
 } GroupState;
 
 /* ---------------------
+ *	per-worker aggregate information
+ * ---------------------
+ */
+typedef struct AggregateInstrumentation
+{
+	Size		hash_mem_peak;	/* peak hash table memory usage */
+	uint64		hash_disk_used; /* kB of disk space used */
+	int			hash_batches_used;	/* batches used during entire execution */
+} AggregateInstrumentation;
+
+/* ----------------
+ *	 Shared memory container for per-worker aggregate information
+ * ----------------
+ */
+typedef struct SharedAggInfo
+{
+	int			num_workers;
+	AggregateInstrumentation sinstrument[FLEXIBLE_ARRAY_MEMBER];
+} SharedAggInfo;
+
+/* ---------------------
  *	AggState information
  *
  *	ss.ss_ScanTupleSlot refers to output of underlying plan.
@@ -2190,6 +2211,7 @@ typedef struct AggState
 	AggStatePerGroup *all_pergroups;	/* array of first ->pergroups, than
 										 * ->hash_pergroup */
 	ProjectionInfo *combinedproj;	/* projection machinery */
+	SharedAggInfo *shared_info; /* one entry per worker */
 } AggState;
 
 /* ----------------