1PG_RECEIVEWAL(1) PostgreSQL 11.3 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.
26 The write-ahead log is streamed over a regular PostgreSQL connection
28 and uses the replication protocol. The connection must be made with a
29 superuser or a user having REPLICATION permissions (see Section 21.2),
30 and pg_hba.conf must permit the replication connection. The server must
31 also be configured with max_wal_senders set high enough to leave at
32 least one session available for the stream.
33 If the connection is lost, or if it cannot be initially established,
35 with a non-fatal error, pg_receivewal will retry the connection
36 indefinitely, and reestablish streaming as soon as possible. To avoid
37 this behavior, use the -n parameter.
38 In the absence of fatal errors, pg_receivewal will run until terminated
40 by the SIGINT signal (Control+C).
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43 -D directory
44 --directory=directory
45 Directory to write the output to.
46 This parameter is required.
48 -E lsn
50 --endpos=lsn
51 Automatically stop replication and exit with normal exit status 0
52 when receiving reaches the specified LSN.
53 If there is a record with LSN exactly equal to lsn, the record will
55 be processed.
56 --if-not-exists
58 Do not error out when --create-slot is specified and a slot with
59 the specified name already exists.
60 -n
62 --no-loop
63 Don't loop on connection errors. Instead, exit right away with an
64 error.
65 --no-sync
67 This option causes pg_receivewal to not force WAL data to be
68 flushed to disk. This is faster, but means that a subsequent
69 operating system crash can leave the WAL segments corrupt.
70 Generally, this option is useful for testing but should not be used
71 when doing WAL archiving on a production deployment.
72 This option is incompatible with --synchronous.
74 -s interval
76 --status-interval=interval
77 Specifies the number of seconds between status packets sent back to
78 the server. This allows for easier monitoring of the progress from
79 server. A value of zero disables the periodic status updates
80 completely, although an update will still be sent when requested by
81 the server, to avoid timeout disconnect. The default value is 10
82 seconds.
83 -S slotname
85 --slot=slotname
86 Require pg_receivewal to use an existing replication slot (see
87 Section 26.2.6). When this option is used, pg_receivewal will
88 report a flush position to the server, indicating when each segment
89 has been synchronized to disk so that the server can remove that
90 segment if it is not otherwise needed.
91 When the replication client of pg_receivewal is configured on the
93 server as a synchronous standby, then using a replication slot will
94 report the flush position to the server, but only when a WAL file
95 is closed. Therefore, that configuration will cause transactions on
96 the primary to wait for a long time and effectively not work
97 satisfactorily. The option --synchronous (see below) must be
98 specified in addition to make this work correctly.
99 --synchronous
101 Flush the WAL data to disk immediately after it has been received.
102 Also send a status packet back to the server immediately after
103 flushing, regardless of --status-interval.
104 This option should be specified if the replication client of
106 pg_receivewal is configured on the server as a synchronous standby,
107 to ensure that timely feedback is sent to the server.
108 -v
110 --verbose
111 Enables verbose mode.
112 -Z level
114 --compress=level
115 Enables gzip compression of write-ahead logs, and specifies the
116 compression level (0 through 9, 0 being no compression and 9 being
117 best compression). The suffix .gz will automatically be added to
118 all filenames.
119 The following command-line options control the database connection
121 parameters.
122 -d connstr
124 --dbname=connstr
125 Specifies parameters used to connect to the server, as a connection
126 string. See Section 34.1.1 for more information.
127 The option is called --dbname for consistency with other client
129 applications, but because pg_receivewal doesn't connect to any
130 particular database in the cluster, database name in the connection
131 string will be ignored.
132 -h host
134 --host=host
135 Specifies the host name of the machine on which the server is
136 running. If the value begins with a slash, it is used as the
137 directory for the Unix domain socket. The default is taken from the
138 PGHOST environment variable, if set, else a Unix domain socket
139 connection is attempted.
140 -p port
142 --port=port
143 Specifies the TCP port or local Unix domain socket file extension
144 on which the server is listening for connections. Defaults to the
145 PGPORT environment variable, if set, or a compiled-in default.
146 -U username
148 --username=username
149 User name to connect as.
150 -w
152 --no-password
153 Never issue a password prompt. If the server requires password
154 authentication and a password is not available by other means such
155 as a .pgpass file, the connection attempt will fail. This option
156 can be useful in batch jobs and scripts where no user is present to
157 enter a password.
158 -W
160 --password
161 Force pg_receivewal to prompt for a password before connecting to a
162 database.
163 This option is never essential, since pg_receivewal will
165 automatically prompt for a password if the server demands password
166 authentication. However, pg_receivewal will waste a connection
167 attempt finding out that the server wants a password. In some cases
168 it is worth typing -W to avoid the extra connection attempt.
169 pg_receivewal can perform one of the two following actions in order to
171 control physical replication slots:
172 --create-slot
174 Create a new physical replication slot with the name specified in
175 --slot, then exit.
176 --drop-slot
178 Drop the replication slot with the name specified in --slot, then
179 exit.
180 Other options are also available:
182 -V
184 --version
185 Print the pg_receivewal version and exit.
186 -?
188 --help
189 Show help about pg_receivewal command line arguments, and exit.
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192 pg_receivewal will exit with status 0 when terminated by the SIGINT
193 signal. (That is the normal way to end it. Hence it is not an error.)
194 For fatal errors or other signals, the exit status will be nonzero.
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197 This utility, like most other PostgreSQL utilities, uses the
198 environment variables supported by libpq (see Section 34.14).
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201 When using pg_receivewal instead of archive_command as the main WAL
202 backup method, it is strongly recommended to use replication slots.
203 Otherwise, the server is free to recycle or remove write-ahead log
204 files before they are backed up, because it does not have any
205 information, either from archive_command or the replication slots,
206 about how far the WAL stream has been archived. Note, however, that a
207 replication slot will fill up the server's disk space if the receiver
208 does not keep up with fetching the WAL data.
209 pg_receivewal will preserve group permissions on the received WAL files
211 if group permissions are enabled on the source cluster.
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214 To stream the write-ahead log from the server at mydbserver and store
215 it in the local directory /usr/local/pgsql/archive:
216 $ pg_receivewal -h mydbserver -D /usr/local/pgsql/archive
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220 pg_basebackup(1)
221PostgreSQL 11.3 2019 PG_RECEIVEWAL(1)