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Remove FAQ items about IPC errors. We now report the help description
right in the failure. We can always re-add it if required.
This commit is contained in:
Bruce Momjian
72
doc/FAQ
72
doc/FAQ
@ -1,7 +1,7 @@
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Frequently Asked Questions (FAQ) for PostgreSQL
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Last updated: Sat Jan 29 22:51:43 EST 2005
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Last updated: Sat Jan 29 22:59:12 EST 2005
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Current maintainer: Bruce Momjian (pgman@candle.pha.pa.us)
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@ -38,20 +38,14 @@
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3.1) How do I install PostgreSQL somewhere other than
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/usr/local/pgsql?
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3.2) When I start postmaster, I get a Bad System Call or core dumped
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message. Why?
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3.3) When I try to start postmaster, I get IpcMemoryCreate errors.
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Why?
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3.4) When I try to start postmaster, I get IpcSemaphoreCreate errors.
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Why?
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3.5) How do I control connections from other hosts?
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3.6) How do I tune the database engine for better performance?
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3.7) What debugging features are available?
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3.8) Why do I get "Sorry, too many clients" when trying to connect?
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3.9) What is in the pgsql_tmp directory?
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3.10) Why do I need to do a dump and restore to upgrade PostgreSQL
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3.2) How do I control connections from other hosts?
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3.3) How do I tune the database engine for better performance?
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3.4) What debugging features are available?
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3.5) Why do I get "Sorry, too many clients" when trying to connect?
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3.6) What is in the pgsql_tmp directory?
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3.7) Why do I need to do a dump and restore to upgrade PostgreSQL
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releases?
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3.11) What computer hardware should I use?
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3.8) What computer hardware should I use?
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Operational Questions
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@ -419,43 +413,7 @@
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Specify the --prefix option when running configure.
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3.2) When I start postmaster, I get a Bad System Call or core dumped
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message. Why?
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It could be a variety of problems, but first check to see that you
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have System V extensions installed in your kernel. PostgreSQL requires
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kernel support for shared memory and semaphores.
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3.3) When I try to start postmaster, I get IpcMemoryCreate errors. Why?
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You either do not have shared memory configured properly in your
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kernel or you need to enlarge the shared memory available in the
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kernel. The exact amount you need depends on your architecture and how
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many buffers and backend processes you configure for postmaster. For
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most systems, with default numbers of buffers and processes, you need
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a minimum of ~1 MB. See the PostgreSQL Administrator's Guide/Server
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Run-time Environment/Managing Kernel Resources section for more
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detailed information about shared memory and semaphores.
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3.4) When I try to start postmaster, I get IpcSemaphoreCreate errors. Why?
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If the error message is IpcSemaphoreCreate: semget failed (No space
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left on device) then your kernel is not configured with enough
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semaphores. Postgres needs one semaphore per potential backend
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process. A temporary solution is to start postmaster with a smaller
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limit on the number of backend processes. Use -N with a parameter less
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than the default of 32. A more permanent solution is to increase your
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kernel's SEMMNS and SEMMNI parameters.
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Inoperative semaphores can also cause crashes during heavy database
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access.
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If the error message is something else, you might not have semaphore
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support configured in your kernel at all. See the PostgreSQL
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Administrator's Guide for more detailed information about shared
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memory and semaphores.
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3.5) How do I control connections from other hosts?
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3.2) How do I control connections from other hosts?
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By default, PostgreSQL only allows connections from the local machine
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using Unix domain sockets or TCP/IP connections. Other machines will
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@ -463,7 +421,7 @@
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postgresql.conf and enable host-based authentication by modifying the
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file $PGDATA/pg_hba.conf accordingly.
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3.6) How do I tune the database engine for better performance?
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3.3) How do I tune the database engine for better performance?
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Certainly, indexes can speed up queries. The EXPLAIN ANALYZE command
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allows you to see how PostgreSQL is interpreting your query, and which
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@ -495,7 +453,7 @@
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You can also use the CLUSTER command to group data in tables to match
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an index. See the CLUSTER manual page for more details.
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3.7) What debugging features are available?
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3.4) What debugging features are available?
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PostgreSQL has several features that report status information that
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can be valuable for debugging purposes.
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@ -550,7 +508,7 @@ log_*
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in the client's current directory. Linux requires a compile with
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-DLINUX_PROFILE for proper profiling.
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3.8) Why do I get "Sorry, too many clients" when trying to connect?
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3.5) Why do I get "Sorry, too many clients" when trying to connect?
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You need to increase postmaster's limit on how many concurrent backend
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processes it can start.
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@ -570,7 +528,7 @@ log_*
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that PostgreSQL has a limit on the number of allowed backend processes
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is so your system won't run out of resources.
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3.9) What is in the pgsql_tmp directory?
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3.6) What is in the pgsql_tmp directory?
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This directory contains temporary files generated by the query
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executor. For example, if a sort needs to be done to satisfy an ORDER
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@ -581,7 +539,7 @@ log_*
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remain if a backend crashes during a sort. A stop and restart of the
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postmaster will remove files from those directories.
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3.10) Why do I need to do a dump and restore to upgrade between major
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3.7) Why do I need to do a dump and restore to upgrade between major
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PostgreSQL releases?
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The PostgreSQL team makes only small changes between minor releases,
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@ -596,7 +554,7 @@ log_*
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script can be used to upgrade without a dump/restore. The release
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notes mention whether pg_upgrade is available for the release.
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3.11) What computer hardware should I use?
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3.8) What computer hardware should I use?
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Because PC hardware is mostly compatible, people tend to believe that
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all PC hardware is of equal quality. It is not. ECC RAM, SCSI, and
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@ -10,7 +10,7 @@
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alink="#0000ff">
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<H1>Frequently Asked Questions (FAQ) for PostgreSQL</H1>
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<P>Last updated: Sat Jan 29 22:51:43 EST 2005</P>
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<P>Last updated: Sat Jan 29 22:59:12 EST 2005</P>
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<P>Current maintainer: Bruce Momjian (<A href=
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"mailto:pgman@candle.pha.pa.us">pgman@candle.pha.pa.us</A>)<BR>
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@ -56,24 +56,18 @@
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<H2 align="center">Administrative Questions</H2>
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<A href="#3.1">3.1</A>) How do I install PostgreSQL somewhere other
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than <I>/usr/local/pgsql</I>?<BR>
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<A href="#3.2">3.2</A>) When I start <I>postmaster</I>, I get a
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<I>Bad System Call</I> or core dumped message. Why?<BR>
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<A href="#3.3">3.3</A>) When I try to start <I>postmaster</I>, I
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get <I>IpcMemoryCreate</I> errors. Why?<BR>
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<A href="#3.4">3.4</A>) When I try to start <I>postmaster</I>, I
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get <I>IpcSemaphoreCreate</I> errors. Why?<BR>
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<A href="#3.5">3.5</A>) How do I control connections from other
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<A href="#3.2">3.2</A>) How do I control connections from other
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hosts?<BR>
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<A href="#3.6">3.6</A>) How do I tune the database engine for
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<A href="#3.3">3.3</A>) How do I tune the database engine for
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better performance?<BR>
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<A href="#3.7">3.7</A>) What debugging features are available?<BR>
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<A href="#3.8">3.8</A>) Why do I get <I>"Sorry, too many
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<A href="#3.4">3.4</A>) What debugging features are available?<BR>
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<A href="#3.5">3.5</A>) Why do I get <I>"Sorry, too many
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clients"</I> when trying to connect?<BR>
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<A href="#3.9">3.9</A>) What is in the <I>pgsql_tmp</I>
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<A href="#3.6">3.6</A>) What is in the <I>pgsql_tmp</I>
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directory?<BR>
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<A href="#3.10">3.10</A>) Why do I need to do a dump and restore
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<A href="#3.7">3.7</A>) Why do I need to do a dump and restore
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to upgrade PostgreSQL releases?<BR>
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<A href="#3.11">3.11</A>) What computer hardware should I use?<BR>
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<A href="#3.8">3.8</A>) What computer hardware should I use?<BR>
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<H2 align="center">Operational Questions</H2>
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@ -544,47 +538,7 @@
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<P>Specify the <I>--prefix</I> option when running
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<I>configure</I>.</P>
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<H4><A name="3.2">3.2</A>) When I start <I>postmaster</I>, I get a
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<I>Bad System Call</I> or core dumped message. Why?</H4>
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<P>It could be a variety of problems, but first check to see that
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you have System V extensions installed in your kernel. PostgreSQL
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requires kernel support for shared memory and semaphores.</P>
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<H4><A name="3.3">3.3</A>) When I try to start <I>postmaster</I>, I
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get <I>IpcMemoryCreate</I> errors. Why?</H4>
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<P>You either do not have shared memory configured properly in your
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kernel or you need to enlarge the shared memory available in the
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kernel. The exact amount you need depends on your architecture and
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how many buffers and backend processes you configure for
|
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<I>postmaster</I>. For most systems, with default numbers of
|
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buffers and processes, you need a minimum of ~1 MB. See the <A
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href="http://www.postgresql.org/docs/current/static/kernel-resources.html">PostgreSQL
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Administrator's Guide/Server Run-time Environment/Managing Kernel Resources</A>
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section for more detailed information about shared memory and semaphores.</P>
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<H4><A name="3.4">3.4</A>) When I try to start <I>postmaster</I>, I
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get <I>IpcSemaphoreCreate</I> errors. Why?</H4>
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<P>If the error message is <I>IpcSemaphoreCreate: semget failed (No
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space left on device)</I> then your kernel is not configured with
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enough semaphores. Postgres needs one semaphore per potential
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backend process. A temporary solution is to start <I>postmaster</I>
|
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with a smaller limit on the number of backend processes. Use
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<I>-N</I> with a parameter less than the default of 32. A more
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permanent solution is to increase your kernel's
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<SMALL>SEMMNS</SMALL> and <SMALL>SEMMNI</SMALL> parameters.</P>
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<P>Inoperative semaphores can also cause crashes during heavy
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database access.</P>
|
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<P>If the error message is something else, you might not have
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semaphore support configured in your kernel at all. See the
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PostgreSQL Administrator's Guide for more detailed information
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about shared memory and semaphores.</P>
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<H4><A name="3.5">3.5</A>) How do I control connections from other
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<H4><A name="3.2">3.2</A>) How do I control connections from other
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hosts?</H4>
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<P>By default, PostgreSQL only allows connections from the local
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@ -594,7 +548,7 @@
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host-based authentication by modifying the file
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<I>$PGDATA/pg_hba.conf</I> accordingly.</P>
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<H4><A name="3.6">3.6</A>) How do I tune the database engine for
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<H4><A name="3.3">3.3</A>) How do I tune the database engine for
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better performance?</H4>
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<P>Certainly, indexes can speed up queries. The
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@ -633,7 +587,7 @@
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data in tables to match an index. See the <SMALL>CLUSTER</SMALL>
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manual page for more details.</P>
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<H4><A name="3.7">3.7</A>) What debugging features are
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<H4><A name="3.4">3.4</A>) What debugging features are
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available?</H4>
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<P>PostgreSQL has several features that report status information
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@ -691,7 +645,7 @@
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file will be put in the client's current directory. Linux requires
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a compile with <I>-DLINUX_PROFILE</I> for proper profiling.</P>
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<H4><A name="3.8">3.8</A>) Why do I get <I>"Sorry, too many
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<H4><A name="3.5">3.5</A>) Why do I get <I>"Sorry, too many
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clients"</I> when trying to connect?</H4>
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|
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<P>You need to increase <I>postmaster</I>'s limit on how many
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@ -716,7 +670,7 @@
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the number of allowed backend processes is so your system won't run
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out of resources.</P>
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<H4><A name="3.9">3.9</A>) What is in the <I>pgsql_tmp</I> directory?</H4>
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<H4><A name="3.6">3.6</A>) What is in the <I>pgsql_tmp</I> directory?</H4>
|
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<P>This directory contains temporary files generated by the query
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executor. For example, if a sort needs to be done to satisfy an
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@ -728,7 +682,7 @@
|
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remain if a backend crashes during a sort. A stop and restart of the
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<I>postmaster</I> will remove files from those directories.</P>
|
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|
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<H4><A name="3.10">3.10</A>) Why do I need to do a dump and restore
|
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<H4><A name="3.7">3.7</A>) Why do I need to do a dump and restore
|
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to upgrade between major PostgreSQL releases?</H4>
|
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|
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<P>The PostgreSQL team makes only small changes between minor releases,
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@ -744,7 +698,7 @@
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The release notes mention whether <I>pg_upgrade</I> is available for the
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release.</P>
|
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|
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<H4><A name="3.11">3.11</A>) What computer hardware should I use?</H4>
|
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<H4><A name="3.8">3.8</A>) What computer hardware should I use?</H4>
|
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|
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<P>Because PC hardware is mostly compatible, people tend to believe that
|
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all PC hardware is of equal quality. It is not. ECC RAM, SCSI, and
|
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|
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Reference in New Issue
Block a user