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Remove FAQ items about IPC errors. We now report the help description

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right in the failure.  We can always re-add it if required.
This commit is contained in:
Bruce Momjian
2005-01-30 04:00:19 +00:00
parent 93e1795404
commit e136a49c5d
2 changed files with 30 additions and 118 deletions
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doc/FAQ
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Frequently Asked Questions (FAQ) for PostgreSQL
Last updated: Sat Jan 29 22:51:43 EST 2005
Last updated: Sat Jan 29 22:59:12 EST 2005
Current maintainer: Bruce Momjian (pgman@candle.pha.pa.us)
@ -38,20 +38,14 @@
3.1) How do I install PostgreSQL somewhere other than
/usr/local/pgsql?
3.2) When I start postmaster, I get a Bad System Call or core dumped
message. Why?
3.3) When I try to start postmaster, I get IpcMemoryCreate errors.
Why?
3.4) When I try to start postmaster, I get IpcSemaphoreCreate errors.
Why?
3.5) How do I control connections from other hosts?
3.6) How do I tune the database engine for better performance?
3.7) What debugging features are available?
3.8) Why do I get "Sorry, too many clients" when trying to connect?
3.9) What is in the pgsql_tmp directory?
3.10) Why do I need to do a dump and restore to upgrade PostgreSQL
3.2) How do I control connections from other hosts?
3.3) How do I tune the database engine for better performance?
3.4) What debugging features are available?
3.5) Why do I get "Sorry, too many clients" when trying to connect?
3.6) What is in the pgsql_tmp directory?
3.7) Why do I need to do a dump and restore to upgrade PostgreSQL
releases?
3.11) What computer hardware should I use?
3.8) What computer hardware should I use?
Operational Questions
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Specify the --prefix option when running configure.
3.2) When I start postmaster, I get a Bad System Call or core dumped
message. Why?
It could be a variety of problems, but first check to see that you
have System V extensions installed in your kernel. PostgreSQL requires
kernel support for shared memory and semaphores.
3.3) When I try to start postmaster, I get IpcMemoryCreate errors. Why?
You either do not have shared memory configured properly in your
kernel or you need to enlarge the shared memory available in the
kernel. The exact amount you need depends on your architecture and how
many buffers and backend processes you configure for postmaster. For
most systems, with default numbers of buffers and processes, you need
a minimum of ~1 MB. See the PostgreSQL Administrator's Guide/Server
Run-time Environment/Managing Kernel Resources section for more
detailed information about shared memory and semaphores.
3.4) When I try to start postmaster, I get IpcSemaphoreCreate errors. Why?
If the error message is IpcSemaphoreCreate: semget failed (No space
left on device) then your kernel is not configured with enough
semaphores. Postgres needs one semaphore per potential backend
process. A temporary solution is to start postmaster with a smaller
limit on the number of backend processes. Use -N with a parameter less
than the default of 32. A more permanent solution is to increase your
kernel's SEMMNS and SEMMNI parameters.
Inoperative semaphores can also cause crashes during heavy database
access.
If the error message is something else, you might not have semaphore
support configured in your kernel at all. See the PostgreSQL
Administrator's Guide for more detailed information about shared
memory and semaphores.
3.5) How do I control connections from other hosts?
3.2) How do I control connections from other hosts?
By default, PostgreSQL only allows connections from the local machine
using Unix domain sockets or TCP/IP connections. Other machines will
@ -463,7 +421,7 @@
postgresql.conf and enable host-based authentication by modifying the
file $PGDATA/pg_hba.conf accordingly.
3.6) How do I tune the database engine for better performance?
3.3) How do I tune the database engine for better performance?
Certainly, indexes can speed up queries. The EXPLAIN ANALYZE command
allows you to see how PostgreSQL is interpreting your query, and which
@ -495,7 +453,7 @@
You can also use the CLUSTER command to group data in tables to match
an index. See the CLUSTER manual page for more details.
3.7) What debugging features are available?
3.4) What debugging features are available?
PostgreSQL has several features that report status information that
can be valuable for debugging purposes.
@ -550,7 +508,7 @@ log_*
in the client's current directory. Linux requires a compile with
-DLINUX_PROFILE for proper profiling.
3.8) Why do I get "Sorry, too many clients" when trying to connect?
3.5) Why do I get "Sorry, too many clients" when trying to connect?
You need to increase postmaster's limit on how many concurrent backend
processes it can start.
@ -570,7 +528,7 @@ log_*
that PostgreSQL has a limit on the number of allowed backend processes
is so your system won't run out of resources.
3.9) What is in the pgsql_tmp directory?
3.6) What is in the pgsql_tmp directory?
This directory contains temporary files generated by the query
executor. For example, if a sort needs to be done to satisfy an ORDER
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remain if a backend crashes during a sort. A stop and restart of the
postmaster will remove files from those directories.
3.10) Why do I need to do a dump and restore to upgrade between major
3.7) Why do I need to do a dump and restore to upgrade between major
PostgreSQL releases?
The PostgreSQL team makes only small changes between minor releases,
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script can be used to upgrade without a dump/restore. The release
notes mention whether pg_upgrade is available for the release.
3.11) What computer hardware should I use?
3.8) What computer hardware should I use?
Because PC hardware is mostly compatible, people tend to believe that
all PC hardware is of equal quality. It is not. ECC RAM, SCSI, and