Initial background job rebalance details

src/backend/distributed/metadata/metadata_cache.c

@@ -161,6 +161,7 @@ typedef struct MetadataCacheData
 	Oid citusTaskStatusErrorId;
 	Oid citusTaskStatusSnscheduledId;
 	Oid distRebalanceStrategyRelationId;
+	Oid distRebalanceTaskDetailsRelationId;
 	Oid distNodeRelationId;
 	Oid distNodeNodeIdIndexId;
 	Oid distLocalGroupRelationId;
@@ -2474,6 +2475,16 @@ DistRebalanceStrategyRelationId(void)
 }
 
 
+Oid
+DistRebalanceTaskDetailsRelationId(void)
+{
+	CachedRelationLookup("pg_dist_rebalance_task_details",
+						 &MetadataCache.distRebalanceTaskDetailsRelationId);
+
+	return MetadataCache.distRebalanceTaskDetailsRelationId;
+}
+
+
 /* return the oid of citus namespace */
 Oid
 CitusCatalogNamespaceId(void)

src/backend/distributed/operations/shard_rebalancer.c

@@ -41,6 +41,7 @@
 #include "distributed/multi_progress.h"
 #include "distributed/multi_server_executor.h"
 #include "distributed/pg_dist_rebalance_strategy.h"
+#include "distributed/pg_dist_rebalance_task_details.h"
 #include "distributed/reference_table_utils.h"
 #include "distributed/remote_commands.h"
 #include "distributed/repair_shards.h"
@@ -1521,6 +1522,45 @@ NonColocatedDistRelationIdList(void)
 }
 
 
+static void
+CreateRebalanceTaskDetails(int64 jobId,
+						   int64 taskId,
+						   WorkerNode *sourceNode,
+						   WorkerNode *targetNode,
+						   uint64 shardId)
+{
+	Relation pgDistRebalanceTaskDetails =
+		table_open(DistRebalanceTaskDetailsRelationId(), RowExclusiveLock);
+
+	/* insert new job */
+	Datum values[Natts_pg_dist_rebalance_task_details] = { 0 };
+	bool nulls[Natts_pg_dist_rebalance_task_details] = { 0 };
+
+	memset(nulls, true, sizeof(nulls));
+
+	values[Anum_pg_dist_rebalance_task_details_job_id - 1] = Int64GetDatum(jobId);
+	nulls[Anum_pg_dist_rebalance_task_details_job_id - 1] = false;
+	values[Anum_pg_dist_rebalance_task_details_task_id - 1] = Int64GetDatum(taskId);
+	nulls[Anum_pg_dist_rebalance_task_details_task_id - 1] = false;
+	values[Anum_pg_dist_rebalance_task_details_source_node - 1] = Int64GetDatum(
+		sourceNode->nodeId);
+	nulls[Anum_pg_dist_rebalance_task_details_source_node - 1] = false;
+	values[Anum_pg_dist_rebalance_task_details_target_node - 1] = Int64GetDatum(
+		targetNode->nodeId);
+	nulls[Anum_pg_dist_rebalance_task_details_target_node - 1] = false;
+	values[Anum_pg_dist_rebalance_task_details_shard_id - 1] = Int64GetDatum(shardId);
+	nulls[Anum_pg_dist_rebalance_task_details_shard_id - 1] = false;
+	values[Anum_pg_dist_rebalance_task_details_details - 1] = DirectFunctionCall1(
+		jsonb_in, CStringGetDatum("{}"));
+	nulls[Anum_pg_dist_rebalance_task_details_details - 1] = false;
+	HeapTuple newTuple = heap_form_tuple(RelationGetDescr(pgDistRebalanceTaskDetails),
+										 values, nulls);
+	CatalogTupleInsert(pgDistRebalanceTaskDetails, newTuple);
+
+	table_close(pgDistRebalanceTaskDetails, NoLock);
+}
+
+
 /*
  * RebalanceTableShards rebalances the shards for the relations inside the
  * relationIdList across the different workers.
@@ -1588,6 +1628,8 @@ RebalanceTableShards(RebalanceOptions *options, Oid shardReplicationModeOid)
 
 		BackgroundTask *task = ScheduleBackgroundTask(jobId, buf.data, first ? 0 : 1,
 													  &prevJobId);
+		CreateRebalanceTaskDetails(jobId, task->taskid, move->sourceNode,
+								   move->targetNode, move->shardId);
 		prevJobId = task->taskid;
 		first = false;
 	}

src/backend/distributed/sql/citus--11.0-4--11.1-1.sql

@@ -121,4 +121,17 @@ ALTER TABLE citus.pg_dist_background_tasks_depend SET SCHEMA pg_catalog;
 CREATE INDEX pg_dist_background_tasks_depend_task_id ON pg_catalog.pg_dist_background_tasks_depend  USING btree(job_id, task_id);
 CREATE INDEX pg_dist_background_tasks_depend_depends_on ON pg_catalog.pg_dist_background_tasks_depend USING btree(job_id, depends_on);
 
+CREATE TABLE citus.pg_dist_rebalance_task_details(
+    job_id bigint NOT NULL,
+    task_id bigint NOT NULL,
+    source_node integer NOT NULL,
+    target_node integer NOT NULL,
+    shard_id bigint NOT NULL,
+    details jsonb NOT NULL DEFAULT '{}',
+
+    UNIQUE(job_id, task_id),
+    FOREIGN KEY (job_id, task_id) REFERENCES pg_catalog.pg_dist_background_tasks (job_id, task_id) ON DELETE CASCADE
+);
+ALTER TABLE citus.pg_dist_rebalance_task_details SET SCHEMA pg_catalog;
+
 #include "udfs/citus_job_wait/11.1-1.sql"

src/backend/distributed/utils/background_jobs.c

@@ -217,7 +217,7 @@ CitusBackgroundTaskMonitorMain(Datum arg)
 		/* TODO find the actual database and username */
 		dsm_segment *seg = NULL;
 		BackgroundWorkerHandle *handle =
-			StartCitusBackgroundJobExecuter("postgres", "nilsdijk", task->command,
+			StartCitusBackgroundJobExecuter("postgres", "jelte", task->command,
 											&seg);
 
 		if (handle == NULL)

src/include/distributed/metadata_cache.h

@@ -230,6 +230,7 @@ extern Oid DistNodeRelationId(void);
 extern Oid DistBackgroundJobsRelationId(void);
 extern Oid DistBackgroundTasksRelationId(void);
 extern Oid DistRebalanceStrategyRelationId(void);
+extern Oid DistRebalanceTaskDetailsRelationId(void);
 extern Oid DistLocalGroupIdRelationId(void);
 extern Oid DistObjectRelationId(void);
 extern Oid DistEnabledCustomAggregatesId(void);

src/include/distributed/pg_dist_rebalance_task_details.h

@@ -0,0 +1,17 @@
+
+#ifndef CITUS_PG_DIST_REBALANCE_TASK_DETAILS_H
+#define CITUS_PG_DIST_REBALANCE_TASK_DETAILS_H
+
+/* ----------------
+ *      compiler constants for pg_dist_rebalance_task_details
+ * ----------------
+ */
+#define Natts_pg_dist_rebalance_task_details 6
+#define Anum_pg_dist_rebalance_task_details_job_id 1
+#define Anum_pg_dist_rebalance_task_details_task_id 2
+#define Anum_pg_dist_rebalance_task_details_source_node 3
+#define Anum_pg_dist_rebalance_task_details_target_node 4
+#define Anum_pg_dist_rebalance_task_details_shard_id 5
+#define Anum_pg_dist_rebalance_task_details_details 6
+
+#endif /* CITUS_PG_DIST_REBALANCE_TASK_DETAILS_H */