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
+
3.10) Why do I need to do a dump and restore
to upgrade PostgreSQL releases?
-
+
Operational Questions
4.1) What is the difference between binary
Features section above. We are built for reliability and
features, though we continue to improve performance in every
release. There is an interesting Web page comparing PostgreSQL to
-
- http://openacs.org/why-not-mysql.html
+ http://openacs.org/philosophy/why-not-mysql.html
If you are doing many INSERTs, consider doing
them in a large batch using the COPY command. This
- is much faster than individual INSERTS. Second,
+ is much faster than individual INSERTS. Second,
statements not in a BEGIN WORK/COMMIT transaction
block are considered to be in their own transaction. Consider
performing several statements in a single transaction block. This
If postmaster is running, start psql in one
window, then find the PID of the postgres
process used by psql. Use a debugger to attach to the
- postgres PID. You can set breakpoints in the
+ postgres PID. You can set breakpoints in the
debugger and issue queries from psql. If you are debugging
postgres startup, you can set PGOPTIONS="-W n", then start
psql. This will cause startup to delay for n seconds
maximum number of processes, NPROC; the maximum
number of processes per user, MAXUPRC; and the
maximum number of open files, NFILE and
- NINODE. The reason that PostgreSQL has a limit on
+ NINODE. The reason that PostgreSQL has a limit on
the number of allowed backend processes is so your system won't run
out of resources.
the MaxBackendId constant in
include/storage/sinvaladt.h.
-
3.9) What are the pgsql_tmp
- directory?
+
3.9) What is in the pgsql_tmp directory?
-
They are temporary files generated by the query executor. For
- example, if a sort needs to be done to satisfy an ORDER
- BY, and the sort requires more space than the backend's
- -S parameter allows, then temporary files are created to
- hold the extra data.
+
This directory contains temporary files generated by the query
+ executor. For example, if a sort needs to be done to satisfy an
+ ORDER BY and the sort requires more space than the
+ backend's -S parameter allows, then temporary files are created
+ here to hold the extra data.
The temporary files are usually deleted automatically, but might
remain if a backend crashes during a sort. A stop and restart of the
The entire query may have to be evaluated, even if you only want
the first few rows. Consider using a query that has an ORDER
- BY. If there is an index that matches the ORDER
+ BY. If there is an index that matches the ORDER
BY, PostgreSQL may be able to evaluate only the first few
records requested, or the entire query may have to be evaluated
until the desired rows have been generated.
When using wild-card operators such as LIKE or
- ~, indexes can only be used in certain circumstances:
+ ~, indexes can only be used in certain circumstances:
The beginning of the search string must be anchored to the start
- of the string, i.e.:
+ of the string, i.e.
-
LIKE patterns must not start with %.
+
LIKE patterns must not start with %.
~ (regular expression) patterns must start with
- ^.
-
+ ^.
+
The search string can not start with a character class,
e.g. [a-e].
Case-insensitive searches such as ILIKE and
~* do not utilise indexes. Instead, use functional
indexes, which are described in section
4.12.
The default C locale must be used during
- initdb.
+ initdb.
Because PostgreSQL loads database-specific system catalogs, it is
uncertain how a cross-database query should even behave.
-
/contrib/dblink allows cross-database queries using
+
contrib/dblink allows cross-database queries using
function calls. Of course, a client can make simultaneous
connections to different databases and merge the results on the
client side.
4.28) What encryption options are available?
-
/contrib/pgcrypto contains many encryption functions for
+
contrib/pgcrypto contains many encryption functions for
use in SQL queries.
The only way to encrypt transmission from the client to the
server is by using hostssl in pg_hba.conf.
Database user passwords are automatically encrypted when stored
in version 7.3. In previous versions, you must enable the option
- <i>PASSWORD_ENCRYPTION in postgresql.conf>.
+ <I>PASSWORD_ENCRYPTION in postgresql.conf>.
The server can run using an encrypted file system.
functions are fully supported in C, PL/PgSQL, and SQL. See the
Programmer's Guide for more information. An example of a
table-returning function defined in C can be found in
- contrib/tablefunc.
+ contrib/tablefunc.
5.4) I have changed a source file. Why does
the recompile not see the change?