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Add an optional missing_ok argument to SQL function current_setting().
This allows convenient checking for existence of a GUC from SQL, which is particularly useful when dealing with custom variables. David Christensen, reviewed by Jeevan Chalke
1 parent 7261172 commit 10fb48d

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9 files changed

+101
-17
lines changed

9 files changed

+101
-17
lines changed

‎contrib/tsearch2/tsearch2.c

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -363,7 +363,7 @@ tsa_tsearch2(PG_FUNCTION_ARGS)
363363
tgargs[i + 1] = trigger->tgargs[i];
364364

365365
tgargs[1] = pstrdup(GetConfigOptionByName("default_text_search_config",
366-
NULL));
366+
NULL, false));
367367
tgargs_old = trigger->tgargs;
368368
trigger->tgargs = tgargs;
369369
trigger->tgnargs++;

‎doc/src/sgml/func.sgml

Lines changed: 6 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -16444,7 +16444,7 @@ SELECT collation for ('foo' COLLATE "de_DE");
1644416444
<indexterm>
1644516445
<primary>current_setting</primary>
1644616446
</indexterm>
16447-
<literal><function>current_setting(<parameter>setting_name</parameter>)</function></literal>
16447+
<literal><function>current_setting(<parameter>setting_name</parameter> [, <parameter>missing_ok</parameter> ])</function></literal>
1644816448
</entry>
1644916449
<entry><type>text</type></entry>
1645016450
<entry>get current value of setting</entry>
@@ -16492,6 +16492,11 @@ SELECT current_setting('datestyle');
1649216492
ISO, MDY
1649316493
(1 row)
1649416494
</programlisting>
16495+
16496+
If there is no setting named <parameter>setting_name</parameter>,
16497+
<function>current_setting</function> throws an error
16498+
unless <parameter>missing_ok</parameter> is supplied and is
16499+
<literal>true</literal>.
1649516500
</para>
1649616501

1649716502
<para>

‎src/backend/utils/misc/guc.c

Lines changed: 42 additions & 11 deletions
Original file line numberDiff line numberDiff line change
@@ -7131,7 +7131,7 @@ ExtractSetVariableArgs(VariableSetStmt *stmt)
71317131
case VAR_SET_VALUE:
71327132
return flatten_set_variable_args(stmt->name, stmt->args);
71337133
case VAR_SET_CURRENT:
7134-
return GetConfigOptionByName(stmt->name, NULL);
7134+
return GetConfigOptionByName(stmt->name, NULL, false);
71357135
default:
71367136
return NULL;
71377137
}
@@ -7200,7 +7200,7 @@ set_config_by_name(PG_FUNCTION_ARGS)
72007200
true, 0, false);
72017201

72027202
/* get the new current value */
7203-
new_value = GetConfigOptionByName(name, NULL);
7203+
new_value = GetConfigOptionByName(name, NULL, false);
72047204

72057205
/* Convert return string to text */
72067206
PG_RETURN_TEXT_P(cstring_to_text(new_value));
@@ -7627,7 +7627,7 @@ GetPGVariableResultDesc(const char *name)
76277627
const char *varname;
76287628

76297629
/* Get the canonical spelling of name */
7630-
(void) GetConfigOptionByName(name, &varname);
7630+
(void) GetConfigOptionByName(name, &varname, false);
76317631

76327632
/* need a tuple descriptor representing a single TEXT column */
76337633
tupdesc = CreateTemplateTupleDesc(1, false);
@@ -7650,7 +7650,7 @@ ShowGUCConfigOption(const char *name, DestReceiver *dest)
76507650
char *value;
76517651

76527652
/* Get the value and canonical spelling of name */
7653-
value = GetConfigOptionByName(name, &varname);
7653+
value = GetConfigOptionByName(name, &varname, false);
76547654

76557655
/* need a tuple descriptor representing a single TEXT column */
76567656
tupdesc = CreateTemplateTupleDesc(1, false);
@@ -7734,19 +7734,30 @@ ShowAllGUCConfig(DestReceiver *dest)
77347734
}
77357735

77367736
/*
7737-
* Return GUC variable value by name; optionally return canonical
7738-
* form of name. Return value is palloc'd.
7737+
* Return GUC variable value by name; optionally return canonical form of
7738+
* name. If the GUC is unset, then throw an error unless missing_ok is true,
7739+
* in which case return NULL. Return value is palloc'd (but *varname isn't).
77397740
*/
77407741
char *
7741-
GetConfigOptionByName(const char *name, const char **varname)
7742+
GetConfigOptionByName(const char *name, const char **varname, bool missing_ok)
77427743
{
77437744
struct config_generic *record;
77447745

77457746
record = find_option(name, false, ERROR);
77467747
if (record == NULL)
7748+
{
7749+
if (missing_ok)
7750+
{
7751+
if (varname)
7752+
*varname = NULL;
7753+
return NULL;
7754+
}
7755+
77477756
ereport(ERROR,
77487757
(errcode(ERRCODE_UNDEFINED_OBJECT),
77497758
errmsg("unrecognized configuration parameter \"%s\"", name)));
7759+
}
7760+
77507761
if ((record->flags & GUC_SUPERUSER_ONLY) && !superuser())
77517762
ereport(ERROR,
77527763
(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
@@ -8033,14 +8044,34 @@ GetNumConfigOptions(void)
80338044
Datum
80348045
show_config_by_name(PG_FUNCTION_ARGS)
80358046
{
8036-
char *varname;
8047+
char *varname = TextDatumGetCString(PG_GETARG_DATUM(0));
80378048
char *varval;
80388049

8039-
/* Get the GUC variable name */
8040-
varname = TextDatumGetCString(PG_GETARG_DATUM(0));
8050+
/* Get the value */
8051+
varval = GetConfigOptionByName(varname, NULL, false);
8052+
8053+
/* Convert to text */
8054+
PG_RETURN_TEXT_P(cstring_to_text(varval));
8055+
}
8056+
8057+
/*
8058+
* show_config_by_name_missing_ok - equiv to SHOW X command but implemented as
8059+
* a function. If X does not exist, suppress the error and just return NULL
8060+
* if missing_ok is TRUE.
8061+
*/
8062+
Datum
8063+
show_config_by_name_missing_ok(PG_FUNCTION_ARGS)
8064+
{
8065+
char *varname = TextDatumGetCString(PG_GETARG_DATUM(0));
8066+
bool missing_ok = PG_GETARG_BOOL(1);
8067+
char *varval;
80418068

80428069
/* Get the value */
8043-
varval = GetConfigOptionByName(varname, NULL);
8070+
varval = GetConfigOptionByName(varname, NULL, missing_ok);
8071+
8072+
/* return NULL if no such variable */
8073+
if (varval == NULL)
8074+
PG_RETURN_NULL();
80448075

80458076
/* Convert to text */
80468077
PG_RETURN_TEXT_P(cstring_to_text(varval));

‎src/include/catalog/catversion.h

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -53,6 +53,6 @@
5353
*/
5454

5555
/* yyyymmddN */
56-
#define CATALOG_VERSION_NO 201506282
56+
#define CATALOG_VERSION_NO 201507021
5757

5858
#endif

‎src/include/catalog/pg_proc.h

Lines changed: 4 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -3067,6 +3067,8 @@ DESCR("convert bitstring to int8");
30673067

30683068
DATA(insert OID = 2077 ( current_setting PGNSP PGUID 12 1 0 0 0 f f f f t f s 1 0 25 "25" _null_ _null_ _null_ _null_ _null_ show_config_by_name _null_ _null_ _null_ ));
30693069
DESCR("SHOW X as a function");
3070+
DATA(insert OID = 3294 ( current_setting PGNSP PGUID 12 1 0 0 0 f f f f t f s 2 0 25 "25 16" _null_ _null_ _null_ _null_ _null_ show_config_by_name_missing_ok _null_ _null_ _null_ ));
3071+
DESCR("SHOW X as a function, optionally no error for missing variable");
30703072
DATA(insert OID = 2078 ( set_config PGNSP PGUID 12 1 0 0 0 f f f f f f v 3 0 25 "25 25 16" _null_ _null_ _null_ _null_ _null_ set_config_by_name _null_ _null_ _null_ ));
30713073
DESCR("SET X as a function");
30723074
DATA(insert OID = 2084 ( pg_show_all_settings PGNSP PGUID 12 1 1000 0 0 f f f f t t s 0 0 2249 "" "{25,25,25,25,25,25,25,25,25,25,25,1009,25,25,25,23,16}" "{o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}" "{name,setting,unit,category,short_desc,extra_desc,context,vartype,source,min_val,max_val,enumvals,boot_val,reset_val,sourcefile,sourceline,pending_restart}" _null_ _null_ show_all_settings _null_ _null_ _null_ ));
@@ -4866,8 +4868,8 @@ DESCR("GIN support");
48664868
DATA(insert OID = 3301 ( jsonb_concat PGNSP PGUID 12 1 0 0 0 f f f f t f i 2 0 3802 "3802 3802" _null_ _null_ _null_ _null_ _null_ jsonb_concat _null_ _null_ _null_ ));
48674869
DATA(insert OID = 3302 ( jsonb_delete PGNSP PGUID 12 1 0 0 0 f f f f t f i 2 0 3802 "3802 25" _null_ _null_ _null_ _null_ _null_ jsonb_delete _null_ _null_ _null_ ));
48684870
DATA(insert OID = 3303 ( jsonb_delete PGNSP PGUID 12 1 0 0 0 f f f f t f i 2 0 3802 "3802 23" _null_ _null_ _null_ _null_ _null_ jsonb_delete_idx _null_ _null_ _null_ ));
4869-
DATA(insert OID = 3304 ( jsonb_delete_path PGNSP PGUID 12 1 0 0 0 f f f f t f i 2 0 3802 "3802 1009" _null_ _null_ _null_ _null_ _null_ jsonb_delete_path _null_ _null_ _null_ ));
4870-
DATA(insert OID = 3305 ( jsonb_set PGNSP PGUID 12 1 0 0 0 f f f f t f i 4 0 3802 "3802 1009 3802 16" _null_ _null_ _null_ _null_ _null_ jsonb_set _null_ _null_ _null_ ));
4871+
DATA(insert OID = 3304 ( jsonb_delete_path PGNSP PGUID 12 1 0 0 0 f f f f t f i 2 0 3802 "3802 1009" _null_ _null_ _null_ _null_ _null_ jsonb_delete_path _null_ _null_ _null_ ));
4872+
DATA(insert OID = 3305 ( jsonb_set PGNSP PGUID 12 1 0 0 0 f f f f t f i 4 0 3802 "3802 1009 3802 16" _null_ _null_ _null_ _null_ _null_ jsonb_set _null_ _null_ _null_ ));
48714873
DESCR("Set part of a jsonb");
48724874
DATA(insert OID = 3306 ( jsonb_pretty PGNSP PGUID 12 1 0 0 0 f f f f t f i 1 0 25 "3802" _null_ _null_ _null_ _null_ _null_ jsonb_pretty _null_ _null_ _null_ ));
48734875
DESCR("Indented text from jsonb");

‎src/include/utils/builtins.h

Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -1114,6 +1114,7 @@ extern Datum quote_nullable(PG_FUNCTION_ARGS);
11141114

11151115
/* guc.c */
11161116
extern Datum show_config_by_name(PG_FUNCTION_ARGS);
1117+
extern Datum show_config_by_name_missing_ok(PG_FUNCTION_ARGS);
11171118
extern Datum set_config_by_name(PG_FUNCTION_ARGS);
11181119
extern Datum show_all_settings(PG_FUNCTION_ARGS);
11191120
extern Datum show_all_file_settings(PG_FUNCTION_ARGS);

‎src/include/utils/guc.h

Lines changed: 2 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -365,7 +365,8 @@ extern int set_config_option(const char *name, const char *value,
365365
GucAction action, bool changeVal, int elevel,
366366
bool is_reload);
367367
extern void AlterSystemSetConfigFile(AlterSystemStmt *setstmt);
368-
extern char *GetConfigOptionByName(const char *name, const char **varname);
368+
extern char *GetConfigOptionByName(const char *name, const char **varname,
369+
bool missing_ok);
369370
extern void GetConfigOptionByNum(int varnum, const char **values, bool *noshow);
370371
extern int GetNumConfigOptions(void);
371372

‎src/test/regress/expected/guc.out

Lines changed: 31 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -720,6 +720,37 @@ select myfunc(1), current_setting('work_mem');
720720
2MB | 2MB
721721
(1 row)
722722

723+
-- check current_setting()'s behavior with invalid setting name
724+
select current_setting('nosuch.setting'); -- FAIL
725+
ERROR: unrecognized configuration parameter "nosuch.setting"
726+
select current_setting('nosuch.setting', false); -- FAIL
727+
ERROR: unrecognized configuration parameter "nosuch.setting"
728+
select current_setting('nosuch.setting', true) is null;
729+
?column?
730+
----------
731+
t
732+
(1 row)
733+
734+
-- after this, all three cases should yield 'nada'
735+
set nosuch.setting = 'nada';
736+
select current_setting('nosuch.setting');
737+
current_setting
738+
-----------------
739+
nada
740+
(1 row)
741+
742+
select current_setting('nosuch.setting', false);
743+
current_setting
744+
-----------------
745+
nada
746+
(1 row)
747+
748+
select current_setting('nosuch.setting', true);
749+
current_setting
750+
-----------------
751+
nada
752+
(1 row)
753+
723754
-- Normally, CREATE FUNCTION should complain about invalid values in
724755
-- function SET options; but not if check_function_bodies is off,
725756
-- because that creates ordering hazards for pg_dump

‎src/test/regress/sql/guc.sql

Lines changed: 13 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -258,6 +258,19 @@ select myfunc(0);
258258
select current_setting('work_mem');
259259
select myfunc(1), current_setting('work_mem');
260260

261+
-- check current_setting()'s behavior with invalid setting name
262+
263+
select current_setting('nosuch.setting'); -- FAIL
264+
select current_setting('nosuch.setting', false); -- FAIL
265+
select current_setting('nosuch.setting', true) is null;
266+
267+
-- after this, all three cases should yield 'nada'
268+
set nosuch.setting = 'nada';
269+
270+
select current_setting('nosuch.setting');
271+
select current_setting('nosuch.setting', false);
272+
select current_setting('nosuch.setting', true);
273+
261274
-- Normally, CREATE FUNCTION should complain about invalid values in
262275
-- function SET options; but not if check_function_bodies is off,
263276
-- because that creates ordering hazards for pg_dump

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