1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
|
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<HTML
><HEAD
><TITLE
>Automatic Vacuuming</TITLE
><META
NAME="GENERATOR"
CONTENT="Modular DocBook HTML Stylesheet Version 1.79"><LINK
REV="MADE"
HREF="mailto:pgsql-docs@postgresql.org"><LINK
REL="HOME"
TITLE="PostgreSQL 9.3.13 Documentation"
HREF="index.html"><LINK
REL="UP"
TITLE="Server Configuration"
HREF="runtime-config.html"><LINK
REL="PREVIOUS"
TITLE="Run-time Statistics"
HREF="runtime-config-statistics.html"><LINK
REL="NEXT"
TITLE="Client Connection Defaults"
HREF="runtime-config-client.html"><LINK
REL="STYLESHEET"
TYPE="text/css"
HREF="stylesheet.css"><META
HTTP-EQUIV="Content-Type"
CONTENT="text/html; charset=ISO-8859-1"><META
NAME="creation"
CONTENT="2016-05-09T21:13:26"></HEAD
><BODY
CLASS="SECT1"
><DIV
CLASS="NAVHEADER"
><TABLE
SUMMARY="Header navigation table"
WIDTH="100%"
BORDER="0"
CELLPADDING="0"
CELLSPACING="0"
><TR
><TH
COLSPAN="5"
ALIGN="center"
VALIGN="bottom"
><A
HREF="index.html"
>PostgreSQL 9.3.13 Documentation</A
></TH
></TR
><TR
><TD
WIDTH="10%"
ALIGN="left"
VALIGN="top"
><A
TITLE="Run-time Statistics"
HREF="runtime-config-statistics.html"
ACCESSKEY="P"
>Prev</A
></TD
><TD
WIDTH="10%"
ALIGN="left"
VALIGN="top"
><A
HREF="runtime-config.html"
ACCESSKEY="U"
>Up</A
></TD
><TD
WIDTH="60%"
ALIGN="center"
VALIGN="bottom"
>Chapter 18. Server Configuration</TD
><TD
WIDTH="20%"
ALIGN="right"
VALIGN="top"
><A
TITLE="Client Connection Defaults"
HREF="runtime-config-client.html"
ACCESSKEY="N"
>Next</A
></TD
></TR
></TABLE
><HR
ALIGN="LEFT"
WIDTH="100%"></DIV
><DIV
CLASS="SECT1"
><H1
CLASS="SECT1"
><A
NAME="RUNTIME-CONFIG-AUTOVACUUM"
>18.10. Automatic Vacuuming</A
></H1
><P
> These settings control the behavior of the <I
CLASS="FIRSTTERM"
>autovacuum</I
>
feature. Refer to <A
HREF="routine-vacuuming.html#AUTOVACUUM"
>Section 23.1.6</A
> for
more information.
</P
><P
></P
><DIV
CLASS="VARIABLELIST"
><DL
><DT
><A
NAME="GUC-AUTOVACUUM"
></A
><TT
CLASS="VARNAME"
>autovacuum</TT
> (<TT
CLASS="TYPE"
>boolean</TT
>)</DT
><DD
><P
> Controls whether the server should run the
autovacuum launcher daemon. This is on by default; however,
<A
HREF="runtime-config-statistics.html#GUC-TRACK-COUNTS"
>track_counts</A
> must also be enabled for
autovacuum to work.
This parameter can only be set in the <TT
CLASS="FILENAME"
>postgresql.conf</TT
>
file or on the server command line.
</P
><P
> Note that even when this parameter is disabled, the system
will launch autovacuum processes if necessary to
prevent transaction ID wraparound. See <A
HREF="routine-vacuuming.html#VACUUM-FOR-WRAPAROUND"
>Section 23.1.5</A
> for more information.
</P
></DD
><DT
><A
NAME="GUC-LOG-AUTOVACUUM-MIN-DURATION"
></A
><TT
CLASS="VARNAME"
>log_autovacuum_min_duration</TT
> (<TT
CLASS="TYPE"
>integer</TT
>)</DT
><DD
><P
> Causes each action executed by autovacuum to be logged if it ran for at
least the specified number of milliseconds. Setting this to zero logs
all autovacuum actions. Minus-one (the default) disables logging
autovacuum actions. For example, if you set this to
<TT
CLASS="LITERAL"
>250ms</TT
> then all automatic vacuums and analyzes that run
250ms or longer will be logged. In addition, when this parameter is
set to any value other than <TT
CLASS="LITERAL"
>-1</TT
>, a message will be
logged if an autovacuum action is skipped due to the existence of a
conflicting lock. Enabling this parameter can be helpful
in tracking autovacuum activity. This setting can only be set in
the <TT
CLASS="FILENAME"
>postgresql.conf</TT
> file or on the server command line.
</P
></DD
><DT
><A
NAME="GUC-AUTOVACUUM-MAX-WORKERS"
></A
><TT
CLASS="VARNAME"
>autovacuum_max_workers</TT
> (<TT
CLASS="TYPE"
>integer</TT
>)</DT
><DD
><P
> Specifies the maximum number of autovacuum processes (other than the
autovacuum launcher) which may be running at any one time. The default
is three. This parameter can only be set at server start.
</P
></DD
><DT
><A
NAME="GUC-AUTOVACUUM-NAPTIME"
></A
><TT
CLASS="VARNAME"
>autovacuum_naptime</TT
> (<TT
CLASS="TYPE"
>integer</TT
>)</DT
><DD
><P
> Specifies the minimum delay between autovacuum runs on any given
database. In each round the daemon examines the
database and issues <TT
CLASS="COMMAND"
>VACUUM</TT
> and <TT
CLASS="COMMAND"
>ANALYZE</TT
> commands
as needed for tables in that database. The delay is measured
in seconds, and the default is one minute (<TT
CLASS="LITERAL"
>1min</TT
>).
This parameter can only be set in the <TT
CLASS="FILENAME"
>postgresql.conf</TT
>
file or on the server command line.
</P
></DD
><DT
><A
NAME="GUC-AUTOVACUUM-VACUUM-THRESHOLD"
></A
><TT
CLASS="VARNAME"
>autovacuum_vacuum_threshold</TT
> (<TT
CLASS="TYPE"
>integer</TT
>)</DT
><DD
><P
> Specifies the minimum number of updated or deleted tuples needed
to trigger a <TT
CLASS="COMMAND"
>VACUUM</TT
> in any one table.
The default is 50 tuples.
This parameter can only be set in the <TT
CLASS="FILENAME"
>postgresql.conf</TT
>
file or on the server command line.
This setting can be overridden for individual tables by
changing storage parameters.
</P
></DD
><DT
><A
NAME="GUC-AUTOVACUUM-ANALYZE-THRESHOLD"
></A
><TT
CLASS="VARNAME"
>autovacuum_analyze_threshold</TT
> (<TT
CLASS="TYPE"
>integer</TT
>)</DT
><DD
><P
> Specifies the minimum number of inserted, updated or deleted tuples
needed to trigger an <TT
CLASS="COMMAND"
>ANALYZE</TT
> in any one table.
The default is 50 tuples.
This parameter can only be set in the <TT
CLASS="FILENAME"
>postgresql.conf</TT
>
file or on the server command line.
This setting can be overridden for individual tables by
changing storage parameters.
</P
></DD
><DT
><A
NAME="GUC-AUTOVACUUM-VACUUM-SCALE-FACTOR"
></A
><TT
CLASS="VARNAME"
>autovacuum_vacuum_scale_factor</TT
> (<TT
CLASS="TYPE"
>floating point</TT
>)</DT
><DD
><P
> Specifies a fraction of the table size to add to
<TT
CLASS="VARNAME"
>autovacuum_vacuum_threshold</TT
>
when deciding whether to trigger a <TT
CLASS="COMMAND"
>VACUUM</TT
>.
The default is 0.2 (20% of table size).
This parameter can only be set in the <TT
CLASS="FILENAME"
>postgresql.conf</TT
>
file or on the server command line.
This setting can be overridden for individual tables by
changing storage parameters.
</P
></DD
><DT
><A
NAME="GUC-AUTOVACUUM-ANALYZE-SCALE-FACTOR"
></A
><TT
CLASS="VARNAME"
>autovacuum_analyze_scale_factor</TT
> (<TT
CLASS="TYPE"
>floating point</TT
>)</DT
><DD
><P
> Specifies a fraction of the table size to add to
<TT
CLASS="VARNAME"
>autovacuum_analyze_threshold</TT
>
when deciding whether to trigger an <TT
CLASS="COMMAND"
>ANALYZE</TT
>.
The default is 0.1 (10% of table size).
This parameter can only be set in the <TT
CLASS="FILENAME"
>postgresql.conf</TT
>
file or on the server command line.
This setting can be overridden for individual tables by
changing storage parameters.
</P
></DD
><DT
><A
NAME="GUC-AUTOVACUUM-FREEZE-MAX-AGE"
></A
><TT
CLASS="VARNAME"
>autovacuum_freeze_max_age</TT
> (<TT
CLASS="TYPE"
>integer</TT
>)</DT
><DD
><P
> Specifies the maximum age (in transactions) that a table's
<TT
CLASS="STRUCTNAME"
>pg_class</TT
>.<TT
CLASS="STRUCTFIELD"
>relfrozenxid</TT
> field can
attain before a <TT
CLASS="COMMAND"
>VACUUM</TT
> operation is forced
to prevent transaction ID wraparound within the table.
Note that the system will launch autovacuum processes to
prevent wraparound even when autovacuum is otherwise disabled.
</P
><P
> Vacuum also allows removal of old files from the
<TT
CLASS="FILENAME"
>pg_clog</TT
> subdirectory, which is why the default
is a relatively low 200 million transactions.
This parameter can only be set at server start, but the setting
can be reduced for individual tables by
changing storage parameters.
For more information see <A
HREF="routine-vacuuming.html#VACUUM-FOR-WRAPAROUND"
>Section 23.1.5</A
>.
</P
></DD
><DT
><A
NAME="GUC-AUTOVACUUM-MULTIXACT-FREEZE-MAX-AGE"
></A
><TT
CLASS="VARNAME"
>autovacuum_multixact_freeze_max_age</TT
> (<TT
CLASS="TYPE"
>integer</TT
>)</DT
><DD
><P
> Specifies the maximum age (in multixacts) that a table's
<TT
CLASS="STRUCTNAME"
>pg_class</TT
>.<TT
CLASS="STRUCTFIELD"
>relminmxid</TT
> field can
attain before a <TT
CLASS="COMMAND"
>VACUUM</TT
> operation is forced to
prevent multixact ID wraparound within the table.
Note that the system will launch autovacuum processes to
prevent wraparound even when autovacuum is otherwise disabled.
</P
><P
> Vacuuming multixacts also allows removal of old files from the
<TT
CLASS="FILENAME"
>pg_multixact/members</TT
> and <TT
CLASS="FILENAME"
>pg_multixact/offsets</TT
>
subdirectories, which is why the default is a relatively low
400 million multixacts.
This parameter can only be set at server start, but the setting
can be reduced for individual tables by changing storage parameters.
For more information see <A
HREF="routine-vacuuming.html#VACUUM-FOR-MULTIXACT-WRAPAROUND"
>Section 23.1.5.1</A
>.
</P
></DD
><DT
><A
NAME="GUC-AUTOVACUUM-VACUUM-COST-DELAY"
></A
><TT
CLASS="VARNAME"
>autovacuum_vacuum_cost_delay</TT
> (<TT
CLASS="TYPE"
>integer</TT
>)</DT
><DD
><P
> Specifies the cost delay value that will be used in automatic
<TT
CLASS="COMMAND"
>VACUUM</TT
> operations. If -1 is specified, the regular
<A
HREF="runtime-config-resource.html#GUC-VACUUM-COST-DELAY"
>vacuum_cost_delay</A
> value will be used.
The default value is 20 milliseconds.
This parameter can only be set in the <TT
CLASS="FILENAME"
>postgresql.conf</TT
>
file or on the server command line.
This setting can be overridden for individual tables by
changing storage parameters.
</P
></DD
><DT
><A
NAME="GUC-AUTOVACUUM-VACUUM-COST-LIMIT"
></A
><TT
CLASS="VARNAME"
>autovacuum_vacuum_cost_limit</TT
> (<TT
CLASS="TYPE"
>integer</TT
>)</DT
><DD
><P
> Specifies the cost limit value that will be used in automatic
<TT
CLASS="COMMAND"
>VACUUM</TT
> operations. If -1 is specified (which is the
default), the regular
<A
HREF="runtime-config-resource.html#GUC-VACUUM-COST-LIMIT"
>vacuum_cost_limit</A
> value will be used. Note that
the value is distributed proportionally among the running autovacuum
workers, if there is more than one, so that the sum of the limits of
each worker never exceeds the limit on this variable.
This parameter can only be set in the <TT
CLASS="FILENAME"
>postgresql.conf</TT
>
file or on the server command line.
This setting can be overridden for individual tables by
changing storage parameters.
</P
></DD
></DL
></DIV
></DIV
><DIV
CLASS="NAVFOOTER"
><HR
ALIGN="LEFT"
WIDTH="100%"><TABLE
SUMMARY="Footer navigation table"
WIDTH="100%"
BORDER="0"
CELLPADDING="0"
CELLSPACING="0"
><TR
><TD
WIDTH="33%"
ALIGN="left"
VALIGN="top"
><A
HREF="runtime-config-statistics.html"
ACCESSKEY="P"
>Prev</A
></TD
><TD
WIDTH="34%"
ALIGN="center"
VALIGN="top"
><A
HREF="index.html"
ACCESSKEY="H"
>Home</A
></TD
><TD
WIDTH="33%"
ALIGN="right"
VALIGN="top"
><A
HREF="runtime-config-client.html"
ACCESSKEY="N"
>Next</A
></TD
></TR
><TR
><TD
WIDTH="33%"
ALIGN="left"
VALIGN="top"
>Run-time Statistics</TD
><TD
WIDTH="34%"
ALIGN="center"
VALIGN="top"
><A
HREF="runtime-config.html"
ACCESSKEY="U"
>Up</A
></TD
><TD
WIDTH="33%"
ALIGN="right"
VALIGN="top"
>Client Connection Defaults</TD
></TR
></TABLE
></DIV
></BODY
></HTML
>
|