From b02c18896e4590eff6b396cd0faedac62b29bf68 Mon Sep 17 00:00:00 2001
From: Will Mortensen <will@extrahop.com>
Date: Fri, 26 Aug 2022 23:08:44 -0700
Subject: [PATCH 5/6] doc: add brief summary of Read Committed

---
 doc/src/sgml/mvcc.sgml | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/doc/src/sgml/mvcc.sgml b/doc/src/sgml/mvcc.sgml
index 029c25232c..96bcc8c3ac 100644
--- a/doc/src/sgml/mvcc.sgml
+++ b/doc/src/sgml/mvcc.sgml
@@ -316,8 +316,18 @@
 
    <para>
     <firstterm>Read Committed</firstterm> is the default isolation
-    level in <productname>PostgreSQL</productname>.  When a transaction
-    uses this isolation level, a <command>SELECT</command> query
+    level in <productname>PostgreSQL</productname>. Within a transaction at this
+    isolation level, each command starts with a new snapshot that includes the
+    effects of all transactions committed up to that instant, as well as the
+    effects of the previous commands in the current transaction. As described in
+    more detail below, commands that only read from the database simply see its
+    state at the time of this snapshot, but commands that modify or lock
+    rows may inconsistently observe the effects of any transactions that
+    commit while the command is executing.
+   </para>
+
+   <para>
+    A <command>SELECT</command> query
     (without a <literal>FOR UPDATE/SHARE</literal> clause) sees only data
     committed before the query began; it never sees either uncommitted
     data or changes committed during query execution by concurrent
-- 
2.25.1