Run-time Configuration
Sets the planner's assumption about the effective size of the
disk cache that is available to a single index scan. This is
- factored into estimates of the cost of using an index; a higher
- value makes it more likely index scans will be used, a lower
- value makes it more likely sequential scans will be used. When
- setting this parameter you should consider both
+ factored into estimates of the cost of using an index; a
+ higher value makes it more likely index scans will be used, a
+ lower value makes it more likely sequential scans will be
+ used. When setting this parameter you should consider both
PostgreSQL's shared buffers and the
portion of the kernel's disk cache that will be used for
-
PostgreSQL data files. Also, take
into
- account the expected number of concurrent queries using different
- indexes, since they will have to share the available space.
- This parameter has no effect on the size of shared memory
- allocated by PostgreSQL, nor does it reserve kernel disk cache;
- it is used only for estimation purposes.
- The value is measured in disk pages, which are
- normally 8192 bytes each. The default is 1000.
+
PostgreSQL data files. Also, take
+ into account the expected number of concurrent queries using
+ different indexes, since they will have to share the available
+ space. This parameter has no effect on the size of shared
+ memory allocated by
PostgreSQL, nor
+ does it reserve kernel disk cache; it is used only for
+ estimation purposes. The value is measured in disk pages,
+ which are normally 8192 bytes each. The default is 1000.
determines whether OIDs will be included in tables created by
SELECT INTO. In
PostgreSQL>
8.1 default_with_oids> is disabled by default; in
- prior versions of PostgreSQL, it was on by default.
+ prior versions of
PostgreSQL, it
+ was on by default.
literals be explicitly typed:
TIMESTAMP WITH TIME ZONE '2004-10-19 10:23:54+02'
If a literal is not explicitly indicated as being of timestamp with time zone,
- PostgreSQL will silently ignore any time zone indication in the literal.
+
PostgreSQL will silently ignore any time zone indication in the literal.
That is, the resulting date/time value is derived from the date/time
fields in the input value, and is not adjusted for time zone.
- CYCLE
+ CYCLE
The optional CYCLE key word may be used to enable
- NO CYCLE
+ NO CYCLE
If the optional NO CYCLE key word is
ALTER SEQUENCE will not immediately affect
- <literal>nextval> results in backends,
+ <function>nextval> results in backends,
other than the current one, that have preallocated (cached) sequence
values. They will use up all cached values prior to noticing the changed
sequence parameters. The current backend will be affected immediately.