From ed9ec3abb601bbe6a22363ca5ac80959de8c14ef Mon Sep 17 00:00:00 2001 From: Tomas Vondra Date: Fri, 26 Jun 2026 17:57:26 +0200 Subject: [PATCH] Improve docs for EXPLAIN (IO) Commit 681daed931 introduced a new EXPLAIN option "IO", but the docs did not explain what information was added to the output. Expand the description a little bit, similarly to the other EXPLAIN options. While at it, fix a typo in the first sentence. Author: Tomas Vondra --- doc/src/sgml/ref/explain.sgml | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/doc/src/sgml/ref/explain.sgml b/doc/src/sgml/ref/explain.sgml index e95e19081e1..f38d31e106a 100644 --- a/doc/src/sgml/ref/explain.sgml +++ b/doc/src/sgml/ref/explain.sgml @@ -303,7 +303,14 @@ ROLLBACK; IO - Include information on I/O performed by scan nodes proving such information. + Include information on I/O performed by scan nodes providing such + information. + Specifically, include information about the prefetch queue (the average + and the maximum distance, and the queue capacity), and information about + issued I/O requests (the total number of requests, the average request + size, the number of I/O waits, and the average number of concurrent I/O + requests). The request size is reported in blocks. + In text format, only non-zero values are printed. This parameter may only be used when ANALYZE is also enabled. It defaults to FALSE.