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Commit3499df0

Browse files
Support disabling index bypassing by VACUUM.
Generalize the INDEX_CLEANUP VACUUM parameter (and the correspondingreloption): make it into a ternary style boolean parameter. It nowexposes a third option, "auto". The "auto" option (which is now thedefault) enables the "bypass index vacuuming" optimization added bycommit1e55e7d."VACUUM (INDEX_CLEANUP TRUE)" is redefined to once again make VACUUMsimply do any required index vacuuming, regardless of how few deadtuples are encountered during the first scan of the target heap relation(unless there are exactly zero). This gives users a way of opting outof the "bypass index vacuuming" optimization, if for whatever reasonthat proves necessary. It is also expected to be used by PostgreSQLdevelopers as a testing option from time to time."VACUUM (INDEX_CLEANUP FALSE)" does the same thing as it always has: itforcibly disables both index vacuuming and index cleanup. It's notexpected to be used much in PostgreSQL 14. The failsafe mechanism addedby commit1e55e7d addresses the same problem in a simpler way.INDEX_CLEANUP can now be thought of as a testing and compatibilityoption.Author: Peter Geoghegan <pg@bowt.ie>Reviewed-By: Masahiko Sawada <sawada.mshk@gmail.com>Reviewed-By: Justin Pryzby <pryzby@telsasoft.com>Discussion:https://postgr.es/m/CAH2-WznrBoCST4_Gxh_G9hA8NzGUbeBGnOUC8FcXcrhqsv6OHQ@mail.gmail.com
1 parent0912698 commit3499df0

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13 files changed

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-127
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13 files changed

+313
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‎doc/src/sgml/ref/create_table.sgml

Lines changed: 15 additions & 8 deletions
Original file line numberDiff line numberDiff line change
@@ -1473,20 +1473,27 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
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</varlistentry>
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<varlistentry id="reloption-vacuum-index-cleanup" xreflabel="vacuum_index_cleanup">
1476-
<term><literal>vacuum_index_cleanup</literal>, <literal>toast.vacuum_index_cleanup</literal> (<type>boolean</type>)
1476+
<term><literal>vacuum_index_cleanup</literal>, <literal>toast.vacuum_index_cleanup</literal> (<type>enum</type>)
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<indexterm>
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<primary><varname>vacuum_index_cleanup</varname> storage parameter</primary>
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</indexterm>
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</term>
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<listitem>
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<para>
1483-
Enables or disables index cleanup when <command>VACUUM</command> is
1484-
run on this table. The default value is <literal>true</literal>.
1485-
Disabling index cleanup can speed up <command>VACUUM</command> very
1486-
significantly, but may also lead to severely bloated indexes if table
1487-
modifications are frequent. The <literal>INDEX_CLEANUP</literal>
1488-
parameter of <link linkend="sql-vacuum"><command>VACUUM</command></link>, if specified, overrides
1489-
the value of this option.
1483+
Forces or disables index cleanup when <command>VACUUM</command>
1484+
is run on this table. The default value is
1485+
<literal>AUTO</literal>. With <literal>OFF</literal>, index
1486+
cleanup is disabled, with <literal>ON</literal> it is enabled,
1487+
and with <literal>AUTO</literal> a decision is made dynamically,
1488+
each time <command>VACUUM</command> runs. The dynamic behavior
1489+
allows <command>VACUUM</command> to avoid needlessly scanning
1490+
indexes to remove very few dead tuples. Forcibly disabling all
1491+
index cleanup can speed up <command>VACUUM</command> very
1492+
significantly, but may also lead to severely bloated indexes if
1493+
table modifications are frequent. The
1494+
<literal>INDEX_CLEANUP</literal> parameter of <link
1495+
linkend="sql-vacuum"><command>VACUUM</command></link>, if
1496+
specified, overrides the value of this option.
14901497
</para>
14911498
</listitem>
14921499
</varlistentry>

‎doc/src/sgml/ref/vacuum.sgml

Lines changed: 41 additions & 16 deletions
Original file line numberDiff line numberDiff line change
@@ -32,7 +32,7 @@ VACUUM [ FULL ] [ FREEZE ] [ VERBOSE ] [ ANALYZE ] [ <replaceable class="paramet
3232
ANALYZE [ <replaceable class="parameter">boolean</replaceable> ]
3333
DISABLE_PAGE_SKIPPING [ <replaceable class="parameter">boolean</replaceable> ]
3434
SKIP_LOCKED [ <replaceable class="parameter">boolean</replaceable> ]
35-
INDEX_CLEANUP[ <replaceable class="parameter">boolean</replaceable> ]
35+
INDEX_CLEANUP{ AUTO | ON | OFF }
3636
PROCESS_TOAST [ <replaceable class="parameter">boolean</replaceable> ]
3737
TRUNCATE [ <replaceable class="parameter">boolean</replaceable> ]
3838
PARALLEL <replaceable class="parameter">integer</replaceable>
@@ -193,20 +193,45 @@ VACUUM [ FULL ] [ FREEZE ] [ VERBOSE ] [ ANALYZE ] [ <replaceable class="paramet
193193
<term><literal>INDEX_CLEANUP</literal></term>
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<listitem>
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<para>
196-
Specifies that <command>VACUUM</command> should attempt to remove
197-
index entries pointing to dead tuples. This is normally the desired
198-
behavior and is the default unless the
199-
<literal>vacuum_index_cleanup</literal> option has been set to false
200-
for the table to be vacuumed. Setting this option to false may be
201-
useful when it is necessary to make vacuum run as quickly as possible,
202-
for example to avoid imminent transaction ID wraparound
203-
(see <xref linkend="vacuum-for-wraparound"/>). However, if index
204-
cleanup is not performed regularly, performance may suffer, because
205-
as the table is modified, indexes will accumulate dead tuples
206-
and the table itself will accumulate dead line pointers that cannot be
207-
removed until index cleanup is completed. This option has no effect
208-
for tables that do not have an index and is ignored if the
209-
<literal>FULL</literal> option is used.
196+
Normally, <command>VACUUM</command> will skip index vacuuming
197+
when there are very few dead tuples in the table. The cost of
198+
processing all of the table's indexes is expected to greatly
199+
exceed the benefit of removing dead index tuples when this
200+
happens. This option can be used to force
201+
<command>VACUUM</command> to process indexes when there are more
202+
than zero dead tuples. The default is <literal>AUTO</literal>,
203+
which allows <command>VACUUM</command> to skip index vacuuming
204+
when appropriate. If <literal>INDEX_CLEANUP</literal> is set to
205+
<literal>ON</literal>, <command>VACUUM</command> will
206+
conservatively remove all dead tuples from indexes. This may be
207+
useful for backwards compatibility with earlier releases of
208+
<productname>PostgreSQL</productname> where this was the
209+
standard behavior.
210+
</para>
211+
<para>
212+
<literal>INDEX_CLEANUP</literal> can also be set to
213+
<literal>OFF</literal> to force <command>VACUUM</command> to
214+
<emphasis>always</emphasis> skip index vacuuming, even when
215+
there are many dead tuples in the table. This may be useful
216+
when it is necessary to make <command>VACUUM</command> run as
217+
quickly as possible to avoid imminent transaction ID wraparound
218+
(see <xref linkend="vacuum-for-wraparound"/>). However, the
219+
wraparound failsafe mechanism controlled by <xref
220+
linkend="guc-vacuum-failsafe-age"/> will generally trigger
221+
automatically to avoid transaction ID wraparound failure, and
222+
should be preferred. If index cleanup is not performed
223+
regularly, performance may suffer, because as the table is
224+
modified indexes will accumulate dead tuples and the table
225+
itself will accumulate dead line pointers that cannot be removed
226+
until index cleanup is completed.
227+
</para>
228+
<para>
229+
This option has no effect for tables that have no index and is
230+
ignored if the <literal>FULL</literal> option is used. It also
231+
has no effect on the transaction ID wraparound failsafe
232+
mechanism. When triggered it will skip index vacuuming, even
233+
when <literal>INDEX_CLEANUP</literal> is set to
234+
<literal>ON</literal>.
210235
</para>
211236
</listitem>
212237
</varlistentry>
@@ -217,7 +242,7 @@ VACUUM [ FULL ] [ FREEZE ] [ VERBOSE ] [ ANALYZE ] [ <replaceable class="paramet
217242
<para>
218243
Specifies that <command>VACUUM</command> should attempt to process the
219244
corresponding <literal>TOAST</literal> table for each relation, if one
220-
exists. This isnormally the desired behavior and is the default.
245+
exists. This isusually the desired behavior and is the default.
221246
Setting this option to false may be useful when it is only necessary to
222247
vacuum the main relation. This option is required when the
223248
<literal>FULL</literal> option is used.

‎doc/src/sgml/ref/vacuumdb.sgml

Lines changed: 15 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -244,6 +244,21 @@ PostgreSQL documentation
244244
</listitem>
245245
</varlistentry>
246246

247+
<varlistentry>
248+
<term><option>--force-index-cleanup</option></term>
249+
<listitem>
250+
<para>
251+
Always remove index entries pointing to dead tuples.
252+
</para>
253+
<note>
254+
<para>
255+
This option is only available for servers running
256+
<productname>PostgreSQL</productname> 12 and later.
257+
</para>
258+
</note>
259+
</listitem>
260+
</varlistentry>
261+
247262
<varlistentry>
248263
<term><option>--no-process-toast</option></term>
249264
<listitem>

‎src/backend/access/common/reloptions.c

Lines changed: 26 additions & 9 deletions
Original file line numberDiff line numberDiff line change
@@ -140,15 +140,6 @@ static relopt_bool boolRelOpts[] =
140140
},
141141
false
142142
},
143-
{
144-
{
145-
"vacuum_index_cleanup",
146-
"Enables index vacuuming and index cleanup",
147-
RELOPT_KIND_HEAP |RELOPT_KIND_TOAST,
148-
ShareUpdateExclusiveLock
149-
},
150-
true
151-
},
152143
{
153144
{
154145
"vacuum_truncate",
@@ -474,6 +465,21 @@ static relopt_real realRelOpts[] =
474465
{{NULL}}
475466
};
476467

468+
/* values from StdRdOptIndexCleanup */
469+
relopt_enum_elt_defStdRdOptIndexCleanupValues[]=
470+
{
471+
{"auto",STDRD_OPTION_VACUUM_INDEX_CLEANUP_AUTO},
472+
{"on",STDRD_OPTION_VACUUM_INDEX_CLEANUP_ON},
473+
{"off",STDRD_OPTION_VACUUM_INDEX_CLEANUP_OFF},
474+
{"true",STDRD_OPTION_VACUUM_INDEX_CLEANUP_ON},
475+
{"false",STDRD_OPTION_VACUUM_INDEX_CLEANUP_OFF},
476+
{"yes",STDRD_OPTION_VACUUM_INDEX_CLEANUP_ON},
477+
{"no",STDRD_OPTION_VACUUM_INDEX_CLEANUP_OFF},
478+
{"1",STDRD_OPTION_VACUUM_INDEX_CLEANUP_ON},
479+
{"0",STDRD_OPTION_VACUUM_INDEX_CLEANUP_OFF},
480+
{(constchar*)NULL}/* list terminator */
481+
};
482+
477483
/* values from GistOptBufferingMode */
478484
relopt_enum_elt_defgistBufferingOptValues[]=
479485
{
@@ -494,6 +500,17 @@ relopt_enum_elt_def viewCheckOptValues[] =
494500

495501
staticrelopt_enumenumRelOpts[]=
496502
{
503+
{
504+
{
505+
"vacuum_index_cleanup",
506+
"Controls index vacuuming and index cleanup",
507+
RELOPT_KIND_HEAP |RELOPT_KIND_TOAST,
508+
ShareUpdateExclusiveLock
509+
},
510+
StdRdOptIndexCleanupValues,
511+
STDRD_OPTION_VACUUM_INDEX_CLEANUP_AUTO,
512+
gettext_noop("Valid values are \"on\", \"off\", and \"auto\".")
513+
},
497514
{
498515
{
499516
"buffering",

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