examinable by non-superusers, and use it to protect the recently-added
GUC variables for data directory and config files. For now I have only
flagged those variables that could be used to deduce something about
the server's filesystem layout, but possibly we should also mark vars
related to logging settings and other admin-only information?
Refactor code into something reasonably understandable, cause
use of the feature to not fail in standalone backends or in
EXEC_BACKEND case, fix sloppy guc.c table entries, make the
documentation minimally usable.
performance front, but with feature freeze upon us I think it's time to
drive a stake in the ground and say that this will be in 7.5.
Alvaro Herrera, with some help from Tom Lane.
extend the GUC variable set".
Plugin modules like the pl<lang> modules needs a way to declare
configuration parameters. The postmaster has no knowledge of such
modules when it reads the postgresql.conf file. Rather than allowing
totally unknown configuration parameters, the concept of a variable
"class" is introduced. Variables that belongs to a declared classes will
create a placeholder value of string type and will not generate an
error. When a module is loaded, it will declare variables for such a
class and make those variables "consume" any placeholders that has been
defined. Finally, the module will generate warnings for unrecognized
placeholders defined for its class.
More detail:
The design is outlined after the suggestions made by Tom Lane and Joe
Conway in this thread:
http://archives.postgresql.org/pgsql-hackers/2004-02/msg00229.php
A new string variable 'custom_variable_classes' is introduced. This
variable is a comma separated string of identifiers. Each identifier
denots a 'class' that will allow its members to be added without error.
This variable must be defined in postmaster.conf.
The lexer (guc_file.l) is changed so that it can accept a qualified name
in the form <ID>.<ID> as the name of a variable. I also changed so that
the 'custom_variable_classes', if found, is added first of all variables
in order to remove the order of declaration issue.
The guc_variables table is made more dynamic. It is originally created
with 20% slack and can grow dynamically. A capacity is introduced to
avoid resizing every time a new variable is added. guc_variables and
num_guc_variables becomes static (hidden).
The GucInfoMain now uses the new function get_guc_variables() and
GetNumConfigOptions instead or using the guc_variables directly.
The find_option() function, when passed a missing name, will check if
the name is qualified. If the name is qualified and if the qualifier
denotes a class included in the 'custom_variable_classes', a placeholder
variable will be created. Such a placeholder will not participate in a
list operation but will otherwise function as a normal string variable.
Define<type>GucVariable() functions will be added, one for each variable
type. They are inteded to be used by add-on modules like the pl<lang>
mappings. Example:
extern void DefineCustomBoolVariable(
const char* name,
const char* short_desc,
const char* long_desc,
bool* valueAddr,
GucContext context,
GucBoolAssignHook assign_hook,
GucShowHook show_hook);
(I created typedefs for the assign-hook and show-hook functions). A call
to these functions will define a new GUC-variable. If a placeholder
exists it will be replaced but it's value will be used in place of the
default value. The valueAddr is assumed ot point at a default value when
the define function is called. The only constraint that is imposed on a
Custom variable is that its name is qualified.
Finally, a function:
void EmittWarningsOnPlacholders(const char* className)
was added. This function should be called when a module has completed
its variable definitions. At that time, no placeholders should remain
for the class that the module uses. If they do, elog(INFO, ...) messages
will be issued to inform the user that unrecognized variables are
present.
Thomas Hallgren
should not be too eager to reject paths involving unknown schemas, since
it can't really tell whether the schemas exist in the target database.
(Also, when reading pg_dumpall output, it could be that the schemas
don't exist yet, but eventually will.) ALTER USER SET has a similar issue.
So, reduce the normal ERROR to a NOTICE when checking search_path values
for these commands. Supporting this requires changing the API for GUC
assign_hook functions, which causes the patch to touch a lot of places,
but the changes are conceptually trivial.
to certain compile-time options (FUNC_MAX_ARGS, INDEX_MAX_KEYS,
NAMEDATALEN, BLCKSZ, HAVE_INT64_TIMESTAMP). Also added "category",
"short_desc", and "extra_desc" to the pg_settings view. Per recent
discussion here:
http://archives.postgresql.org/pgsql-patches/2003-11/msg00363.php
materialized.
New items have been added to GucContext and GucSource enums, but of
course they were not added to the corresponding GucContextName[] and
GucSourceName[] arrays in the patch. Here's a new patch to fix the
resulting bugs.
Joe Conway
>>ISTM that "source" is worth knowing.
>
> Hm, possibly. Any other opinions?
This version has the seven fields I proposed, including "source". Here's
an example that shows why I think it's valuable:
regression=# \x
Expanded display is on.
regression=# select * from pg_settings where name = 'enable_seqscan';
-[ RECORD 1 ]-----------
name | enable_seqscan
setting | on
context | user
vartype | bool
source | default
min_val |
max_val |
regression=# update pg_settings set setting = 'off' where name =
'enable_seqscan';
-[ RECORD 1 ]---
set_config | off
regression=# select * from pg_settings where name = 'enable_seqscan';
-[ RECORD 1 ]-----------
name | enable_seqscan
setting | off
context | user
vartype | bool
source | session
min_val |
max_val |
regression=# alter user postgres set enable_seqscan to 'off';
ALTER USER
(log out and then back in again)
regression=# \x
Expanded display is on.
regression=# select * from pg_settings where name = 'enable_seqscan';
-[ RECORD 1 ]-----------
name | enable_seqscan
setting | off
context | user
vartype | bool
source | user
min_val |
max_val |
In the first case, enable_seqscan is set to its default value. After
setting it to off, it is obvious that the value has been changed for the
session only. In the third case, you can see that the value has been set
specifically for the user.
Joe Conway
without needing a running backend. Reorder postgresql.conf.sample
to match new layout of runtime.sgml. This commit re-adds work lost
in Wednesday's crash.