1PG_RECEIVEWAL(1) PostgreSQL 13.4 Documentation PG_RECEIVEWAL(1)
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6 pg_receivewal - stream write-ahead logs from a PostgreSQL server
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9 pg_receivewal [option...]
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12 pg_receivewal is used to stream the write-ahead log from a running
13 PostgreSQL cluster. The write-ahead log is streamed using the streaming
14 replication protocol, and is written to a local directory of files.
15 This directory can be used as the archive location for doing a restore
16 using point-in-time recovery (see Section 25.3).
17 pg_receivewal streams the write-ahead log in real time as it's being
19 generated on the server, and does not wait for segments to complete
20 like archive_command does. For this reason, it is not necessary to set
21 archive_timeout when using pg_receivewal.
22 Unlike the WAL receiver of a PostgreSQL standby server, pg_receivewal
24 by default flushes WAL data only when a WAL file is closed. The option
25 --synchronous must be specified to flush WAL data in real time. Since
26 pg_receivewal does not apply WAL, you should not allow it to become a
27 synchronous standby when synchronous_commit equals remote_apply. If it
28 does, it will appear to be a standby that never catches up, and will
29 cause transaction commits to block. To avoid this, you should either
30 configure an appropriate value for synchronous_standby_names, or
31 specify application_name for pg_receivewal that does not match it, or
32 change the value of synchronous_commit to something other than
33 remote_apply.
34 The write-ahead log is streamed over a regular PostgreSQL connection
36 and uses the replication protocol. The connection must be made with a
37 user having REPLICATION permissions (see Section 21.2) or a superuser,
38 and pg_hba.conf must permit the replication connection. The server must
39 also be configured with max_wal_senders set high enough to leave at
40 least one session available for the stream.
41 If the connection is lost, or if it cannot be initially established,
43 with a non-fatal error, pg_receivewal will retry the connection
44 indefinitely, and reestablish streaming as soon as possible. To avoid
45 this behavior, use the -n parameter.
46 In the absence of fatal errors, pg_receivewal will run until terminated
48 by the SIGINT signal (Control+C).
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51 -D directory
52 --directory=directory
53 Directory to write the output to.
54 This parameter is required.
56 -E lsn
58 --endpos=lsn
59 Automatically stop replication and exit with normal exit status 0
60 when receiving reaches the specified LSN.
61 If there is a record with LSN exactly equal to lsn, the record will
63 be processed.
64 --if-not-exists
66 Do not error out when --create-slot is specified and a slot with
67 the specified name already exists.
68 -n
70 --no-loop
71 Don't loop on connection errors. Instead, exit right away with an
72 error.
73 --no-sync
75 This option causes pg_receivewal to not force WAL data to be
76 flushed to disk. This is faster, but means that a subsequent
77 operating system crash can leave the WAL segments corrupt.
78 Generally, this option is useful for testing but should not be used
79 when doing WAL archiving on a production deployment.
80 This option is incompatible with --synchronous.
82 -s interval
84 --status-interval=interval
85 Specifies the number of seconds between status packets sent back to
86 the server. This allows for easier monitoring of the progress from
87 server. A value of zero disables the periodic status updates
88 completely, although an update will still be sent when requested by
89 the server, to avoid timeout disconnect. The default value is 10
90 seconds.
91 -S slotname
93 --slot=slotname
94 Require pg_receivewal to use an existing replication slot (see
95 Section 26.2.6). When this option is used, pg_receivewal will
96 report a flush position to the server, indicating when each segment
97 has been synchronized to disk so that the server can remove that
98 segment if it is not otherwise needed.
99 When the replication client of pg_receivewal is configured on the
101 server as a synchronous standby, then using a replication slot will
102 report the flush position to the server, but only when a WAL file
103 is closed. Therefore, that configuration will cause transactions on
104 the primary to wait for a long time and effectively not work
105 satisfactorily. The option --synchronous (see below) must be
106 specified in addition to make this work correctly.
107 --synchronous
109 Flush the WAL data to disk immediately after it has been received.
110 Also send a status packet back to the server immediately after
111 flushing, regardless of --status-interval.
112 This option should be specified if the replication client of
114 pg_receivewal is configured on the server as a synchronous standby,
115 to ensure that timely feedback is sent to the server.
116 -v
118 --verbose
119 Enables verbose mode.
120 -Z level
122 --compress=level
123 Enables gzip compression of write-ahead logs, and specifies the
124 compression level (0 through 9, 0 being no compression and 9 being
125 best compression). The suffix .gz will automatically be added to
126 all filenames.
127 The following command-line options control the database connection
129 parameters.
130 -d connstr
132 --dbname=connstr
133 Specifies parameters used to connect to the server, as a connection
134 string; these will override any conflicting command line options.
135 The option is called --dbname for consistency with other client
137 applications, but because pg_receivewal doesn't connect to any
138 particular database in the cluster, database name in the connection
139 string will be ignored.
140 -h host
142 --host=host
143 Specifies the host name of the machine on which the server is
144 running. If the value begins with a slash, it is used as the
145 directory for the Unix domain socket. The default is taken from the
146 PGHOST environment variable, if set, else a Unix domain socket
147 connection is attempted.
148 -p port
150 --port=port
151 Specifies the TCP port or local Unix domain socket file extension
152 on which the server is listening for connections. Defaults to the
153 PGPORT environment variable, if set, or a compiled-in default.
154 -U username
156 --username=username
157 User name to connect as.
158 -w
160 --no-password
161 Never issue a password prompt. If the server requires password
162 authentication and a password is not available by other means such
163 as a .pgpass file, the connection attempt will fail. This option
164 can be useful in batch jobs and scripts where no user is present to
165 enter a password.
166 -W
168 --password
169 Force pg_receivewal to prompt for a password before connecting to a
170 database.
171 This option is never essential, since pg_receivewal will
173 automatically prompt for a password if the server demands password
174 authentication. However, pg_receivewal will waste a connection
175 attempt finding out that the server wants a password. In some cases
176 it is worth typing -W to avoid the extra connection attempt.
177 pg_receivewal can perform one of the two following actions in order to
179 control physical replication slots:
180 --create-slot
182 Create a new physical replication slot with the name specified in
183 --slot, then exit.
184 --drop-slot
186 Drop the replication slot with the name specified in --slot, then
187 exit.
188 Other options are also available:
190 -V
192 --version
193 Print the pg_receivewal version and exit.
194 -?
196 --help
197 Show help about pg_receivewal command line arguments, and exit.
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200 pg_receivewal will exit with status 0 when terminated by the SIGINT
201 signal. (That is the normal way to end it. Hence it is not an error.)
202 For fatal errors or other signals, the exit status will be nonzero.
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205 This utility, like most other PostgreSQL utilities, uses the
206 environment variables supported by libpq (see Section 33.14).
207 The environment variable PG_COLOR specifies whether to use color in
209 diagnostic messages. Possible values are always, auto and never.
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212 When using pg_receivewal instead of archive_command as the main WAL
213 backup method, it is strongly recommended to use replication slots.
214 Otherwise, the server is free to recycle or remove write-ahead log
215 files before they are backed up, because it does not have any
216 information, either from archive_command or the replication slots,
217 about how far the WAL stream has been archived. Note, however, that a
218 replication slot will fill up the server's disk space if the receiver
219 does not keep up with fetching the WAL data.
220 pg_receivewal will preserve group permissions on the received WAL files
222 if group permissions are enabled on the source cluster.
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225 To stream the write-ahead log from the server at mydbserver and store
226 it in the local directory /usr/local/pgsql/archive:
227 $ pg_receivewal -h mydbserver -D /usr/local/pgsql/archive
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231 pg_basebackup(1)
232PostgreSQL 13.4 2021 PG_RECEIVEWAL(1)