From 117469006bf525c6e8dc84cb9fcbdc4c1a050878 Mon Sep 17 00:00:00 2001
From: Simon Riggs
Date: Mon, 27 Nov 2017 09:51:51 +0000
Subject: Additional docs for toast_tuple_target changes
---
doc/src/sgml/storage.sgml | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
(limited to 'doc/src/sgml/storage.sgml')
diff --git a/doc/src/sgml/storage.sgml b/doc/src/sgml/storage.sgml
index 128b19cbc98..c0e548fa5bc 100644
--- a/doc/src/sgml/storage.sgml
+++ b/doc/src/sgml/storage.sgml
@@ -429,7 +429,7 @@ when a row value to be stored in a table is wider than
TOAST_TUPLE_THRESHOLD bytes (normally 2 kB).
The TOAST code will compress and/or move
field values out-of-line until the row value is shorter than
-TOAST_TUPLE_TARGET bytes (also normally 2 kB)
+TOAST_TUPLE_TARGET bytes (also normally 2 kB, adjustable)
or no more gains can be had. During an UPDATE
operation, values of unchanged fields are normally preserved as-is; so an
UPDATE of a row with out-of-line values incurs no TOAST costs if
@@ -483,6 +483,11 @@ of that data type, but the strategy for a given table column can be altered
with ALTER TABLE ... SET STORAGE.
+
+TOAST_TUPLE_TARGET can be adjusted for each table using
+ALTER TABLE ... SET (toast_tuple_target = N)
+
+
This scheme has a number of advantages compared to a more straightforward
approach such as allowing row values to span pages. Assuming that queries are
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