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1 perry 1 POSTMASTER
2 !!!POSTMASTER
3 NAME
4 SYNOPSIS
5 DESCRIPTION
6 NOTES
7 USAGE
8 ----
9 !!NAME
10
11
12 postmaster - PostgreSQL multiuser database server
13 !!SYNOPSIS
14
15
16 __postmaster__ [[ __-A 0__ | __1__ ] [[ __-B__
17 ''nbuffers'' ] [[ __-c__
18 ''name''__=__''value'' ] [[ __-d__
19 ''debug-level'' ] [[ __-D__ ''datadir'' ] [[
20 __-F__ ] [[ __-h__ ''hostname'' ] [[ __-i__ ] [[
21 __-k__ ''directory'' ] [[ __-l__ ] [[ __-N__
22 ''max-connections'' ] [[ __-o__ ''extra-options'' ]
23 [[ __-p__ ''port'' ] [[ __-S__ ] [[
24 __--__''name''__=__''value'' ] [[ __-n__ |
25 __-s__ ]
26 !!DESCRIPTION
27
28
29 __postmaster__ is the PostgreSQL multiuser database
30 server. In order for a client application to access a
31 database it connects (over a network or locally) to a
32 running __postmaster__. The __postmaster__ then starts
33 a separate server process (``postgres(1)'') to handle
34 the connection. The __postmaster__ also manages the
35 communication among server processes.
36
37
38 By default the __postmaster__ starts in the foreground
39 and prints log messages to the standard output. In practical
40 applications the __postmaster__ should be started as a
41 background process, perhaps at boot time.
42
43
44 One __postmaster__ always manages the data from exactly
45 one database cluster. A database cluster is a collection of
46 databases that is stored at a common file system location.
47 When the postmaster starts it needs to know the location of
48 the database cluster files (``data area''). This is done
49 with the __-D__ invocation option or the __PGDATA__
50 environment variable; there is no default. More than one
51 postmaster process can run on a system at one time, as long
52 as they use different data areas and different communication
53 ports (see below). A data area is created with
54 initdb(1).
55
56
57 __OPTIONS__
58
59
60 __postmaster__ accepts the following command line
61 arguments. For a detailed discussion of the options consult
62 the ''Administrator's Guide''. You can also save typing
63 most of these options by setting up a configuration
64 file.
65
66
67 __-A 0|1__
68
69
70 Enables run-time assert checks, which is a debugging aid to
71 detect programming mistakes. This is only available if it
72 was enabled during compilation. If so, the default is
73 on.
74
75
76 __-B__ ''nbuffers''
77
78
79 Sets the number of shared buffers for use by the server
80 processes. This value defaults to 64 buffers, where each
81 buffer is 8 kB.
82
83
84 __-c__ ''name''__=__''value''
85
86
87 Sets a named run-time parameter. Consult the
88 ''Administrator's Guide'' for a list and descriptions.
89 Most of the other command line options are in fact short
90 forms of such a parameter assignment. __-c__ can appear
91 multiple times to set multiple parameters.
92
93
94 __-d__ ''debug-level''
95
96
97 Sets the debug level. The higher this value is set, the more
98 debugging output is written to the server log. The default
99 is 0, which means no debugging. Values up to 4 are useful;
100 higher numbers produce no additional output.
101
102
103 __-D__ ''datadir''
104
105
106 Specifies the file system location of the data directory.
107 See discussion above.
108
109
110 __-F__
111
112
113 Disables __fsync__ calls for performance improvement, at
114 the risk of data corruption in event of a system crash. Read
115 the detailed documentation before using this!
116
117
118 __-h__ ''hostname''
119
120
121 Specifies the TCP/IP host name or address on which the
122 __postmaster__ is to listen for connections from client
123 applications. Defaults to listening on all configured
124 addresses (including __localhost__).
125
126
127 __-i__
128
129
130 Allows clients to connect via TCP/IP (Internet domain)
131 connections. Without this option, only local Unix domain
132 socket connections are accepted.
133
134
135 __-k__ ''directory''
136
137
138 Specifies the directory of the Unix-domain socket on which
139 the __postmaster__ is to listen for connections from
140 client applications. The default is normally ''/tmp'',
141 but can be changed at build time.
142
143
144 __-l__
145
146
147 Enables secure connections using SSL. The __-i__ option
148 is also required. You must have compiled with SSL enabled to
149 use this option.
150
151
152 __-N__ ''max-connections''
153
154
155 Sets the maximum number of client connections that this
156 __postmaster__ will accept. By default, this value is 32,
157 but it can be set as high as your system will support. (Note
158 that __-B__ is required to be at least twice __-N__.
159 See the ''Administrator's Guide'' for a discussion of
160 system resource requirements for large numbers of client
161 connections.)
162
163
164 __-o__ ''extra-options''
165
166
167 The command line-style options specified in
168 ''extra-options'' are passed to all backend server
169 processes started by this __postmaster__. See
170 postgres(1) for possibilities. If the option string
171 contains any spaces, the entire string must be
172 quoted.
173
174
175 __-p__ ''port''
176
177
178 Specifies the TCP/IP port or local Unix domain socket file
179 extension on which the __postmaster__ is to listen for
180 connections from client applications. Defaults to the value
181 of the __PGPORT__ environment variable, or if
182 __PGPORT__ is not set, then defaults to the value
183 established during compilation (normally 5432). If you
184 specify a port other than the default port, then all client
185 applications must specify the same port using either
186 command-line options or __PGPORT__.
187
188
189 __-S__
190
191
192 Specifies that the __postmaster__ process should start up
193 in silent mode. That is, it will disassociate from the
194 user's (controlling) terminal, start its own process group,
195 and redirect its standard output and standard error to
196 ''/dev/null''.
197
198
199 Using this switch discards all logging output, which is
200 probably not what you want, since it makes it very difficult
201 to troubleshoot problems. See below for a better way to
202 start the __postmaster__ in the background.
203
204
205 __--__''name''__=__''value''
206
207
208 Sets a named run-time parameter; a shorter form of
209 __-c__.
210
211
212 Two additional command line options are available for
213 debugging problems that cause a backend to die abnormally.
214 These options control the behavior of the __postmaster__
215 in this situation, and __neither option is intended for use
216 in ordinary operation__.
217
218
219 The ordinary strategy for this situation is to notify all
220 other backends that they must terminate and then
221 reinitialize the shared memory and semaphores. This is
222 because an errant backend could have corrupted some shared
223 state before terminating.
224
225
226 These special-case options are:
227
228
229 __-n__
230
231
232 __postmaster__ will not reinitialize shared data
233 structures. A knowledgeable system programmer can then use a
234 debugger to examine shared memory and semaphore
235 state.
236
237
238 __-s__
239
240
241 __postmaster__ will stop all other backend processes by
242 sending the signal SIGSTOP, but will not cause them to
243 terminate. This permits system programmers to collect core
244 dumps from all backend processes by hand.
245
246
247 __OUTPUTS__
248
249
250 __semget: No space left on device__
251
252
253 If you see this message, you should run the __ipcclean__
254 command. After doing so, try starting __postmaster__
255 again. If this still doesn't work, you probably need to
256 configure your kernel for shared memory and semaphores as
257 described in the installation notes. If you run multiple
258 instances of __postmaster__ on a single host, or have a
259 kernel with particularly small shared memory and/or
260 semaphore limits, you may have to reconfigure your kernel to
261 increase its shared memory or semaphore
262 parameters.
263
264
265 __Tip:__ You may be able to postpone reconfiguring your
266 kernel by decreasing __-B__ to reduce the shared memory
267 consumption of PostgreSQL, and/or by reducing __-N__ to
268 reduce the semaphore consumption.
269
270
3 perry 271 __!StreamServerPort: cannot bind to port__
1 perry 272
273
274 If you see this message, you should make certain that there
275 is no other __postmaster__ process already running on the
276 same port number. The easiest way to determine this is by
277 using the command
278
279
280 $ __ps ax | grep postmaster
281 __or
282
283
284 $ __ps -e | grep postmaster
285 __depending on your system.
286
287
288 If you are sure that no other __postmaster__ processes
289 are running and you still get this error, try specifying a
290 different port using the -p option. You may also get this
291 error if you terminate the __postmaster__ and immediately
292 restart it using the same port; in this case, you must
293 simply wait a few seconds until the operating system closes
294 the port before trying again. Finally, you may get this
295 error if you specify a port number that your operating
296 system considers to be reserved. For example, many versions
297 of Unix consider port numbers under 1024 to be
298 ''trusted'' and only permit the Unix superuser to access
299 them.
300 !!NOTES
301
302
303 If at all possible, __do not__ use SIGKILL to kill the
304 __postmaster__. This will prevent __postmaster__ from
305 freeing the system resources (e.g., shared memory and
306 semaphores) that it holds before terminating.
307
308
309 To terminate the __postmaster__ normally, the signals
310 SIGTERM, SIGINT, or SIGQUIT can be used. The first will wait
311 for all clients to terminate before quitting, the second
312 will forcefully disconnect all clients, and the third will
313 quit immediately without proper shutdown, resulting in a
314 recovery run during restart.
315
316
4 perry 317 The utility command pg_ctl(1) can be used to start
1 perry 318 and shut down the __postmaster__ safely and
319 comfortably.
320
321
322 The __--__ options will not work on FreeBSD or OpenBSD.
323 Use __-c__ instead. This is a bug in the affected
324 operating systems; a future release of PostgreSQL will
325 provide a workaround if this is not fixed.
326 !!USAGE
327
328
329 To start __postmaster__ in the background using default
330 values, type:
331
332
333 $ __nohup postmaster
334 __To start __postmaster__ with a specific port:
335
336
337 $ __postmaster -p 1234
338 __This command will start up __postmaster__ communicating through the port 1234. In order to connect to this __postmaster__ using psql, you would need to run it as
339
340
341 $ __psql -p 1234
342 __or set the environment variable __PGPORT__:
343
344
345 $ __export PGPORT=1234
346 __$ __psql
347 __Named runtime parameters can be set in either of these styles:
348
349
350 $ __postmaster -c sort_mem=1234
351 __$ __postmaster --sort-mem=1234
352 __Either form overrides whatever setting might exist for sort_mem in ''postgresql.conf''. Notice that underscores in parameter names can be written as either underscore or dash on the command line.
353
354
355 __Tip:__ Except for short-term experiments, it's probably
356 better practice to edit the setting in
357 ''postgresql.conf'' than to rely on a command-line switch
358 to set a parameter.
359 ----
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