From 473d0d2b000b2cd1f685f20f5b9b9baea4b3b161 Mon Sep 17 00:00:00 2001 From: Amit Kapila Date: Wed, 21 Oct 2020 09:05:01 +0530 Subject: [PATCH v3] Update description of spilled counters in pg_stat_replication_slots view. Author: Amit Kapila Reviewed-by: Sawada Masahiko Discussion: https://postgr.es/m/CA+fd4k5_pPAYRTDrO2PbtTOe0eHQpBvuqmCr8ic39uTNmR49Eg@mail.gmail.com --- doc/src/sgml/monitoring.sgml | 14 +++++++++----- 1 file changed, 9 insertions(+), 5 deletions(-) diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml index f5cf163..aeb694d 100644 --- a/doc/src/sgml/monitoring.sgml +++ b/doc/src/sgml/monitoring.sgml @@ -2603,9 +2603,9 @@ SELECT pid, wait_event_type, wait_event FROM pg_stat_activity WHERE wait_event i Number of transactions spilled to disk after the memory used by - logical decoding exceeds logical_decoding_work_mem. The - counter gets incremented both for toplevel transactions and - subtransactions. + logical decoding of changes from WAL for this slot exceeds + logical_decoding_work_mem. The counter gets + incremented both for toplevel transactions and subtransactions. @@ -2614,7 +2614,8 @@ SELECT pid, wait_event_type, wait_event FROM pg_stat_activity WHERE wait_event i spill_count bigint - Number of times transactions were spilled to disk. Transactions + Number of times transactions were spilled to disk while performing + decoding of changes from WAL for this slot. Transactions may get spilled repeatedly, and this counter gets incremented on every such invocation. @@ -2625,7 +2626,10 @@ SELECT pid, wait_event_type, wait_event FROM pg_stat_activity WHERE wait_event i spill_bytes bigint - Amount of decoded transaction data spilled to disk. + Amount of decoded transaction data spilled to disk while performing + decoding of changes from WAL for this slot. This and other spill + counters can be used to gauge the I/O occurred during logical decoding + and accordingly can tune logical_decoding_work_mem. -- 1.8.3.1