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doc: Mention that toast_tuple_target affects also column marked as Main.

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Previously it was documented that toast_tuple_target affected column
marked as only External or Extended. But this description is not correct
and toast_tuple_target affects also column marked as Main.

Back-patch to v11 where toast_tuple_target reloption was introduced.

Author: Shinya Okano
Reviewed-by: Tatsuhito Kasahara, Fujii Masao
Discussion: https://postgr.es/m/93f46e311a67422e89e770d236059817@oss.nttdata.com
This commit is contained in:
Fujii Masao 2020-10-15 11:04:07 +09:00
parent cfa4cff30c
commit cc1fc7b862
1 changed files with 5 additions and 4 deletions

9
doc/src/sgml/ref/create_table.sgml

@ -1260,10 +1260,11 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
<listitem>
<para>
The toast_tuple_target specifies the minimum tuple length required before
we try to move long column values into TOAST tables, and is also the
target length we try to reduce the length below once toasting begins.
This only affects columns marked as either External or Extended
and applies only to new tuples - there is no effect on existing rows.
we try to compress and/or move long column values into TOAST tables, and
is also the target length we try to reduce the length below once toasting
begins. This affects columns marked as External (for move),
Main (for compression), or Extended (for both) and applies only to new
tuples. There is no effect on existing rows.
By default this parameter is set to allow at least 4 tuples per block,
which with the default blocksize will be 2040 bytes. Valid values are
between 128 bytes and the (blocksize - header), by default 8160 bytes.