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commit    88d7fdcc9aaa065daf10ff3b777f607fe65bdc02
Author:   Amit Kapila <akapila@postgresql.org>
Date:     Mon Apr 20 04:47:47 2026 +0000
First released in: 16.14, 17.10, 18.4

    Flush statistics during idle periods in parallel apply worker.
    
    Parallel apply workers previously failed to report statistics while
    waiting for new work in the main loop. This resulted in the stats from the
    most recent transaction remaining unbuffered, leading to arbitrary
    reporting delays—particularly when streamed transactions were infrequent.
    
    This commit ensures that statistics are explicitly flushed when the worker
    is idle, providing timely visibility into accumulated worker activity.
    
    Author: Zhijie Hou <houzj.fnst@fujitsu.com>
    Reviewed-by: Chao Li <li.evan.chao@gmail.com>
    Reviewed-by: Amit Kapila <amit.kapila16@gmail.com>
    Backpatch-through: 16, where it was introduced
    Discussion: https://postgr.es/m/TYRPR01MB1419579F217CC4332B615589594202@TYRPR01MB14195.jpnprd01.prod.outlook.com


 src/backend/replication/logical/applyparallelworker.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/src/backend/replication/logical/applyparallelworker.c b/src/backend/replication/logical/applyparallelworker.c
index cfaa625356e..cb43962d010 100644
--- a/src/backend/replication/logical/applyparallelworker.c
+++ b/src/backend/replication/logical/applyparallelworker.c
@@ -811,6 +811,15 @@ LogicalParallelApplyLoop(shm_mq_handle *mqh)
 
 				if (rc & WL_LATCH_SET)
 					ResetLatch(MyLatch);
+
+				/*
+				 * Force stats reporting to avoid long delays. There can be long
+				 * idle gaps before the leader assigns the next transaction, and
+				 * the only opportunity to report stats during such gaps is
+				 * here.
+				 */
+				if ((rc & WL_TIMEOUT) && !IsTransactionState())
+					pgstat_report_stat(true);
 			}
 		}
 		else


[parent: 0d09492a745b]