<Title>Troubleshooting</Title>
<sect1>
- <title>Client Connections</title>
- <Para>
- If you get the following error message from a
- <ProductName>Postgres</ProductName>
- command (such as <Application>psql</Application> or
- <Application>createdb</Application>):
+ <title>Postmaster Startup Failures</title>
+
+ <para>
+ There are several common reasons for the postmaster to fail to start up.
+ Check the postmaster's log file, or start it by hand (without redirecting
+ standard output or standard error) to see what complaint messages appear.
+ Some of the possible error messages are reasonably self-explanatory,
+ but here are some that are not:
+ </para>
+ <para>
+ <ProgramListing>
+FATAL: StreamServerPort: bind() failed: Address already in use
+ Is another postmaster already running on that port?
+ </ProgramListing>
+ This usually means just what it suggests: you accidentally started a
+ second postmaster on the same port where one is already running.
+ However, if the kernel error
+ message is not "Address already in use" or some variant of that wording,
+ there may be a different problem. For example, trying to start a
+ postmaster on a reserved port number may draw something like
<ProgramListing>
-connectDB() failed: Is the postmaster running at 'localhost' on port '5432'?
+$ postmaster -i -p 666
+FATAL: StreamServerPort: bind() failed: Permission denied
+ Is another postmaster already running on that port?
</ProgramListing>
+ </para>
- it is usually because either the <Application>postmaster</Application> is not running,
- or you are attempting to connect to the wrong server host.
- If you get the following error message:
+ <para>
+ <ProgramListing>
+IpcMemoryCreate: shmget failed (Invalid argument) key=5440001, size=83918612, permission=600
+FATAL 1: ShmemCreate: cannot create region
+ </ProgramListing>
+ A message like this probably means that your kernel's limit on the size
+ of shared memory areas is smaller than the buffer area that Postgres
+ is trying to create. (Or it could mean that you don't have SysV-style
+ shared memory support configured into your kernel at all.) As a temporary
+ workaround, you can try starting the postmaster with a smaller-than-normal
+ number of buffers (-B switch). You will eventually want to reconfigure
+ your kernel to increase the allowed shared memory size, however.
+ You may see this message when trying to start multiple postmasters on
+ the same machine, if their total space requests exceed the kernel limit.
+ </para>
+ <para>
<ProgramListing>
-FATAL 1:Feb 17 23:19:55:process userid (2360) != database owner (268)
+IpcSemaphoreCreate: semget failed (No space left on device) key=5440026, num=16, permission=600
</ProgramListing>
+ A message like this does <emphasis>not</emphasis> mean that you've run out
+ of disk space; it means that your kernel's limit on the number of SysV
+ semaphores is smaller than the number Postgres wants to create. As above,
+ you may be able to work around the problem by starting the postmaster with
+ a reduced number of backend processes (-N switch), but you'll eventually
+ want to increase the kernel limit.
+ </para>
+
+ </sect1>
+
+ <sect1>
+ <title>Client Connection Problems</title>
+
+ <para>
+ Once you have a running postmaster, trying to connect to it with
+ client applications can fail for a variety of reasons. The sample
+ error messages shown here are for clients based on recent versions
+ of libpq --- clients based on other interface libraries may produce
+ other messages with more or less information.
+ </para>
+
+ <para>
+ <ProgramListing>
+connectDB() -- connect() failed: Connection refused
+Is the postmaster running (with -i) at 'server.joe.com' and accepting connections on TCP/IP port '5432'?
+ </ProgramListing>
+ This is the generic "I couldn't find a postmaster to talk to" failure.
+ It looks like the above when TCP/IP communication is attempted, or like
+ this when attempting Unix-socket communication to a local postmaster:
+ <ProgramListing>
+connectDB() -- connect() failed: No such file or directory
+Is the postmaster running at 'localhost' and accepting connections on Unix socket '5432'?
+ </ProgramListing>
+ The last line is useful in verifying that the client is trying to connect
+ where it is supposed to. If there is in fact no postmaster
+ running there, the kernel error message will typically be either
+ "Connection refused" or "No such file or directory", as illustrated.
+ (It is particularly important to realize that "Connection refused" in
+ this context does <emphasis>not</emphasis> mean that the postmaster
+ got your connection request and rejected it --- that case will produce
+ a different message, as shown below.)
+ Other error messages such as "Connection timed out" may indicate more
+ fundamental problems, like lack of network connectivity.
+ </para>
+
+ <para>
+ <ProgramListing>
+No pg_hba.conf entry for host 123.123.123.123, user joeblow, database testdb
+ </ProgramListing>
+ This is what you are most likely to get if you succeed in contacting
+ a postmaster, but it doesn't want to talk to you. As the message
+ suggests, the postmaster refused the connection request because it
+ found no authorizing entry in its pg_hba.conf configuration file.
+ </para>
+
+ <para>
+ <ProgramListing>
+Password authentication failed for user 'joeblow'
+ </ProgramListing>
+ Messages like this indicate that you contacted the postmaster, and it's
+ willing to talk to you, but not until you pass the authorization method
+ specified in the pg_hba.conf file. Check the password you're providing,
+ or check your Kerberos or IDENT software if the complaint mentions
+ one of those authentication types.
+ </para>
+
+ <para>
+ <ProgramListing>
+FATAL 1: SetUserId: user 'joeblow' is not in 'pg_shadow'
+ </ProgramListing>
+ This is another variant of authentication failure: no Postgres create_user
+ command has been executed for the given username.
+ </para>
+
+ <para>
+ <ProgramListing>
+FATAL 1: Database testdb does not exist in pg_database
+ </ProgramListing>
+ There's no database by that name under the control of this postmaster.
+ Note that if you don't specify a database name, it defaults to your
+ Postgres username, which may or may not be the right thing.
+ </para>
- it means that the site administrator started the <Application>postmaster</Application>
- as the wrong user. Tell him to restart it as
- the <ProductName>Postgres</ProductName> superuser.
- </Para>
</sect1>
<sect1>
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