Hackathon!

configure

@@ -6160,3 +6160,4 @@ if test -n "$ac_unrecognized_opts" && test "$enable_option_checking" != no; then
   { $as_echo "$as_me:${as_lineno-$LINENO}: WARNING: unrecognized options: $ac_unrecognized_opts" >&5
 $as_echo "$as_me: WARNING: unrecognized options: $ac_unrecognized_opts" >&2;}
 fi
+

src/backend/distributed/shared_library_init.c

@@ -86,6 +86,7 @@
 #include "distributed/remote_commands.h"
 #include "distributed/shard_rebalancer.h"
 #include "distributed/shared_library_init.h"
+#include "distributed/smart_hint.h"
 #include "distributed/statistics_collection.h"
 #include "distributed/subplan_execution.h"
 #include "distributed/resource_lock.h"
@@ -701,6 +702,8 @@ multi_log_hook(ErrorData *edata)
 								 "involved in a distributed deadlock");
 	}
 
+    ReplaceCitusHintSmart(edata);
+
 	if (original_emit_log_hook)
 	{
 		original_emit_log_hook(edata);

src/backend/distributed/smart_hint.c

@@ -0,0 +1,8 @@
+#include "postgres.h"
+#include "distributed/smart_hint.h"
+
+void
+ReplaceCitusHintSmart(ErrorData *edata)
+{
+    edata->hint = pstrdup("Try to run the query with the smart hint");
+}

src/backend/distributed/sql/citus--11.3-1--12.0-1.sql

@@ -1,3 +1,27 @@
 -- citus--11.3-1--12.0-1
 
 -- bump version to 12.0-1
+
+CREATE OR REPLACE FUNCTION pg_catalog.get_cluster_stats()
+RETURNS text
+AS $$
+DECLARE
+    cluster_stats text;
+BEGIN
+    WITH citus_tables_arr AS (
+        SELECT array_agg(row_to_json(t.*)) d FROM public.citus_tables t
+    ),
+    citus_nodes_arr AS (
+        SELECT array_agg(row_to_json(t.*)) d FROM pg_catalog.pg_dist_node t
+    ),
+    key_values AS (
+    SELECT unnest(ARRAY['citus_tables', 'citus_nodes']) AS key,
+            unnest(ARRAY[to_json(citus_tables_arr.d), to_json(citus_nodes_arr.d)]::json[]) AS value
+    FROM citus_tables_arr, citus_nodes_arr
+    )
+    SELECT json_object_agg(key, value)::text INTO cluster_stats
+    FROM key_values;
+
+    RETURN cluster_stats;
+END;
+$$ LANGUAGE plpgsql;

src/include/distributed/smart_hint.h

@@ -0,0 +1,9 @@
+
+#ifndef DISTRIBUTED_SMART_HINT_H
+#define DISTRIBUTED_SMART_HINT_H
+
+#include "postgres.h"
+
+extern void ReplaceCitusHintSmart(ErrorData *edata);
+
+#endif /* DISTRIBUTED_SMART_HINT_H */