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Parameter toast_tuple_target controls TOAST for new rows
Specifies the point at which we try to move long column values into TOAST tables. No effect on existing rows. Discussion: https://postgr.es/m/CANP8+jKsVmw6CX6YP9z7zqkTzcKV1+Uzr3XjKcZW=2Ya00OyQQ@mail.gmail.com Author: Simon Riggs <simon@2ndQudrant.com> Reviewed-by: Andrew Dunstan <andrew.dunstan@2ndQuadrant.com>
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lines changed

7 files changed

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lines changed

‎doc/src/sgml/ref/alter_table.sgml

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -629,7 +629,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
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<para>
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<literal>SHARE UPDATE EXCLUSIVE</literal> lock will be taken for
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fillfactor and autovacuum storage parameters, as well as the
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fillfactor, toast and autovacuum storage parameters, as well as the
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following planner related parameters:
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<varname>effective_io_concurrency</varname>, <varname>parallel_workers</varname>, <varname>seq_page_cost</varname>,
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<varname>random_page_cost</varname>, <varname>n_distinct</varname> and <varname>n_distinct_inherited</varname>.

‎doc/src/sgml/ref/create_table.sgml

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@@ -1200,6 +1200,27 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><literal>toast_tuple_target</> (<type>integer</>)</term>
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<listitem>
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<para>
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The toast_tuple_target specifies the minimum tuple length required before
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we try to move long column values into TOAST tables, and is also the
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target length we try to reduce the length below once toasting begins.
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This only affects columns marked as either External or Extended
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and applies only to new tuples - there is no effect on existing rows.
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By default this parameter is set to allow at least 4 tuples per block,
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which with the default blocksize will be 2040 bytes. Valid values are
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between 128 bytes and the (blocksize - header), by default 8160 bytes.
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Changing this value may not be useful for very short or very long rows.
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Note that the default setting is often close to optimal, and
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it is possible that setting this parameter could have negative
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effects in some cases.
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This parameter cannot be set for TOAST tables.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><literal>parallel_workers</literal> (<type>integer</type>)</term>
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<listitem>

‎src/backend/access/common/reloptions.c

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Original file line numberDiff line numberDiff line change
@@ -23,6 +23,7 @@
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#include "access/nbtree.h"
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#include "access/reloptions.h"
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#include "access/spgist.h"
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#include "access/tuptoaster.h"
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#include "catalog/pg_type.h"
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#include "commands/defrem.h"
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#include "commands/tablespace.h"
@@ -290,6 +291,15 @@ static relopt_int intRelOpts[] =
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},
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-1, -1, INT_MAX
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},
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{
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{
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"toast_tuple_target",
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"Sets the target tuple length at which external columns will be toasted",
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RELOPT_KIND_HEAP,
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ShareUpdateExclusiveLock
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},
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TOAST_TUPLE_TARGET, 128, TOAST_TUPLE_TARGET_MAIN
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},
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{
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{
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"pages_per_range",
@@ -1344,6 +1354,8 @@ default_reloptions(Datum reloptions, bool validate, relopt_kind kind)
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offsetof(StdRdOptions, autovacuum) + offsetof(AutoVacOpts, multixact_freeze_table_age)},
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{"log_autovacuum_min_duration", RELOPT_TYPE_INT,
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offsetof(StdRdOptions, autovacuum) + offsetof(AutoVacOpts, log_min_duration)},
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{"toast_tuple_target", RELOPT_TYPE_INT,
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offsetof(StdRdOptions, toast_tuple_target)},
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{"autovacuum_vacuum_scale_factor", RELOPT_TYPE_REAL,
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offsetof(StdRdOptions, autovacuum) + offsetof(AutoVacOpts, vacuum_scale_factor)},
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{"autovacuum_analyze_scale_factor", RELOPT_TYPE_REAL,

‎src/backend/access/heap/tuptoaster.c

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Original file line numberDiff line numberDiff line change
@@ -727,7 +727,7 @@ toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
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hoff += sizeof(Oid);
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hoff = MAXALIGN(hoff);
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/* now convert to a limit on the tuple data size */
730-
maxDataLen = TOAST_TUPLE_TARGET - hoff;
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maxDataLen = RelationGetToastTupleTarget(rel, TOAST_TUPLE_TARGET) - hoff;
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/*
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* Look for attributes with attstorage 'x' to compress. Also find large

‎src/include/utils/rel.h

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@@ -277,6 +277,7 @@ typedef struct StdRdOptions
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{
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int32 vl_len_; /* varlena header (do not touch directly!) */
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int fillfactor; /* page fill factor in percent (0..100) */
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int toast_tuple_target; /* target for tuple toasting */
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AutoVacOpts autovacuum; /* autovacuum-related options */
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bool user_catalog_table; /* use as an additional catalog relation */
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int parallel_workers; /* max number of parallel workers */
@@ -285,6 +286,14 @@ typedef struct StdRdOptions
285286
#define HEAP_MIN_FILLFACTOR 10
286287
#define HEAP_DEFAULT_FILLFACTOR 100
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289+
/*
290+
* RelationGetToastTupleTarget
291+
* Returns the relation's toast_tuple_target. Note multiple eval of argument!
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*/
293+
#define RelationGetToastTupleTarget(relation, defaulttarg) \
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((relation)->rd_options ? \
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((StdRdOptions *) (relation)->rd_options)->toast_tuple_target : (defaulttarg))
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/*
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* RelationGetFillFactor
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* Returns the relation's fillfactor. Note multiple eval of argument!

‎src/test/regress/expected/strings.out

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Original file line numberDiff line numberDiff line change
@@ -1166,6 +1166,53 @@ SELECT substr(f1, 99995, 10) from toasttest;
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567890
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(4 rows)
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TRUNCATE TABLE toasttest;
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INSERT INTO toasttest values (repeat('1234567890',400));
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INSERT INTO toasttest values (repeat('1234567890',400));
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INSERT INTO toasttest values (repeat('1234567890',400));
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INSERT INTO toasttest values (repeat('1234567890',400));
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SELECT pg_relation_size('toasttest')/current_setting('block_size')::integer as blocks;
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blocks
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--------
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1
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(1 row)
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select pg_relation_size('pg_toast.pg_toast_'||(select oid from pg_class where relname = 'toasttest'))/current_setting('block_size')::integer as blocks;
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blocks
1182+
--------
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3
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(1 row)
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SELECT pg_total_relation_size('toasttest')/current_setting('block_size')::integer as blocks;
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blocks
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--------
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9
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(1 row)
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TRUNCATE TABLE toasttest;
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ALTER TABLE toasttest set (toast_tuple_target = 4080);
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INSERT INTO toasttest values (repeat('1234567890',400));
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INSERT INTO toasttest values (repeat('1234567890',400));
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INSERT INTO toasttest values (repeat('1234567890',400));
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INSERT INTO toasttest values (repeat('1234567890',400));
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SELECT pg_relation_size('toasttest')/current_setting('block_size')::integer as blocks;
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blocks
1200+
--------
1201+
2
1202+
(1 row)
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1204+
select pg_relation_size('pg_toast.pg_toast_'||(select oid from pg_class where relname = 'toasttest'))/current_setting('block_size')::integer as blocks;
1205+
blocks
1206+
--------
1207+
0
1208+
(1 row)
1209+
1210+
SELECT pg_total_relation_size('toasttest')/current_setting('block_size')::integer as blocks;
1211+
blocks
1212+
--------
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6
1214+
(1 row)
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DROP TABLE toasttest;
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--
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-- test substr with toasted bytea values

‎src/test/regress/sql/strings.sql

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Original file line numberDiff line numberDiff line change
@@ -366,6 +366,25 @@ SELECT substr(f1, 99995) from toasttest;
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-- string length
367367
SELECT substr(f1, 99995, 10) from toasttest;
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369+
TRUNCATE TABLE toasttest;
370+
INSERT INTO toasttest values (repeat('1234567890',400));
371+
INSERT INTO toasttest values (repeat('1234567890',400));
372+
INSERT INTO toasttest values (repeat('1234567890',400));
373+
INSERT INTO toasttest values (repeat('1234567890',400));
374+
SELECT pg_relation_size('toasttest')/current_setting('block_size')::integer as blocks;
375+
select pg_relation_size('pg_toast.pg_toast_'||(select oid from pg_class where relname = 'toasttest'))/current_setting('block_size')::integer as blocks;
376+
SELECT pg_total_relation_size('toasttest')/current_setting('block_size')::integer as blocks;
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378+
TRUNCATE TABLE toasttest;
379+
ALTER TABLE toasttest set (toast_tuple_target = 4080);
380+
INSERT INTO toasttest values (repeat('1234567890',400));
381+
INSERT INTO toasttest values (repeat('1234567890',400));
382+
INSERT INTO toasttest values (repeat('1234567890',400));
383+
INSERT INTO toasttest values (repeat('1234567890',400));
384+
SELECT pg_relation_size('toasttest')/current_setting('block_size')::integer as blocks;
385+
select pg_relation_size('pg_toast.pg_toast_'||(select oid from pg_class where relname = 'toasttest'))/current_setting('block_size')::integer as blocks;
386+
SELECT pg_total_relation_size('toasttest')/current_setting('block_size')::integer as blocks;
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DROP TABLE toasttest;
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--

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