The general syntax of a variable declaration is:
-name CONSTANT type NOT NULL { DEFAULT | := } expression ;
+name CONSTANT type COLLATE collation_name NOT NULL { DEFAULT | := } expression ;
The DEFAULT clause, if given, specifies the initial value assigned
to the variable when the block is entered. If the DEFAULT clause
is not given then the variable is initialized to the
The CONSTANT option prevents the variable from being
- assigned to, so that its value will remain constant for the duration of
- the block.
+ assigned to after initialization, so that its value will remain constant
+ for the duration of the block.
+ The COLLATE option specifies a collation to use for the
+ variable (see ).
If NOT NULL
is specified, an assignment of a null value results in a run-time
error. All variables declared as NOT NULL
- Explicit COLLATE clauses can be written inside a function
- if it is desired to force a particular collation to be used regardless
- of what the function is called with. For example,
+ A local variable of a collatable data type can have a different collation
+ associated with it by including the COLLATE option in its
+ declaration, for example
+
+DECLARE
+ local_a text COLLATE "en_US";
+
+
+ This option overrides the collation that would otherwise be
+ given to the variable according to the rules above.
+
+
+ Also, of course explicit COLLATE clauses can be written inside
+ a function if it is desired to force a particular collation to be used in
+ a particular operation. For example,
CREATE FUNCTION less_than_c(a text, b text) RETURNS boolean AS $$
END;
$$ LANGUAGE plpgsql;
+
+ This overrides the collations associated with the table columns,
+ parameters, or local variables used in the expression, just as would
+ happen in a plain SQL command.
#include "parser/parse_type.h"
#include "parser/scanner.h"
#include "parser/scansup.h"
+#include "utils/builtins.h"
/* Location tracking support --- simpler than bison's default */
PLcword cword;
PLwdatum wdatum;
bool boolean;
+ Oid oid;
struct
{
char *name;
%type decl_const decl_notnull exit_type
%type decl_defval decl_cursor_query
%type decl_datatype
+%type decl_collate
%type decl_cursor_args
%type decl_cursor_arglist
%type decl_aliasitem
%token K_BY
%token K_CASE
%token K_CLOSE
+%token K_COLLATE
%token K_CONSTANT
%token K_CONTINUE
%token K_CURSOR
}
;
-decl_statement : decl_varname decl_const decl_datatype decl_notnull decl_defval
+decl_statement : decl_varname decl_const decl_datatype decl_collate decl_notnull decl_defval
{
PLpgSQL_variable *var;
+ /*
+ * If a collation is supplied, insert it into the
+ * datatype. We assume decl_datatype always returns
+ * a freshly built struct not shared with other
+ * variables.
+ */
+ if (OidIsValid($4))
+ {
+ if (!OidIsValid($3->collation))
+ ereport(ERROR,
+ (errcode(ERRCODE_DATATYPE_MISMATCH),
+ errmsg("collations are not supported by type %s",
+ format_type_be($3->typoid)),
+ parser_errposition(@4)));
+ $3->collation = $4;
+ }
+
var = plpgsql_build_variable($1.name, $1.lineno,
$3, true);
if ($2)
errmsg("row or record variable cannot be CONSTANT"),
parser_errposition(@2)));
}
- if ($4)
+ if ($5)
{
if (var->dtype == PLPGSQL_DTYPE_VAR)
- ((PLpgSQL_var *) var)->notnull = $4;
+ ((PLpgSQL_var *) var)->notnull = $5;
else
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
parser_errposition(@4)));
}
- if ($5 != NULL)
+ if ($6 != NULL)
{
if (var->dtype == PLPGSQL_DTYPE_VAR)
- ((PLpgSQL_var *) var)->default_val = $5;
+ ((PLpgSQL_var *) var)->default_val = $6;
else
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
}
;
+decl_collate :
+ { $$ = InvalidOid; }
+ | K_COLLATE T_WORD
+ {
+ $$ = get_collation_oid(list_make1(makeString($2.ident)),
+ false);
+ }
+ | K_COLLATE T_CWORD
+ {
+ $$ = get_collation_oid($2.idents, false);
+ }
+ ;
+
decl_notnull :
{ $$ = false; }
| K_NOT K_NULL
yyerror("incomplete data type declaration");
}
/* Possible followers for datatype in a declaration */
- if (tok == K_NOT || tok == '=' || tok == COLON_EQUALS || tok == K_DEFAULT)
+ if (tok == K_COLLATE || tok == K_NOT ||
+ tok == '=' || tok == COLON_EQUALS || tok == K_DEFAULT)
break;
/* Possible followers for datatype in a cursor_arg list */
if ((tok == ',' || tok == ')') && parenlevel == 0)
PG_KEYWORD("by", K_BY, RESERVED_KEYWORD)
PG_KEYWORD("case", K_CASE, RESERVED_KEYWORD)
PG_KEYWORD("close", K_CLOSE, RESERVED_KEYWORD)
+ PG_KEYWORD("collate", K_COLLATE, RESERVED_KEYWORD)
PG_KEYWORD("continue", K_CONTINUE, RESERVED_KEYWORD)
PG_KEYWORD("declare", K_DECLARE, RESERVED_KEYWORD)
PG_KEYWORD("default", K_DEFAULT, RESERVED_KEYWORD)
bbc | bbc | f | f | f | f
(16 rows)
+-- collation override in plpgsql
+CREATE FUNCTION mylt2 (x text, y text) RETURNS boolean LANGUAGE plpgsql AS $$
+declare
+ xx text := x;
+ yy text := y;
+begin
+ return xx < yy;
+end
+$$;
+SELECT mylt2('a', 'B' collate "en_US") as t, mylt2('a', 'B' collate "C") as f;
+ t | f
+---+---
+ t | f
+(1 row)
+
+CREATE OR REPLACE FUNCTION
+ mylt2 (x text, y text) RETURNS boolean LANGUAGE plpgsql AS $$
+declare
+ xx text COLLATE "POSIX" := x;
+ yy text := y;
+begin
+ return xx < yy;
+end
+$$;
+SELECT mylt2('a', 'B') as f;
+ f
+---
+ f
+(1 row)
+
+SELECT mylt2('a', 'B' collate "C") as fail; -- conflicting collations
+ERROR: could not determine which collation to use for string comparison
+HINT: Use the COLLATE clause to set the collation explicitly.
+CONTEXT: PL/pgSQL function "mylt2" line 6 at RETURN
+SELECT mylt2('a', 'B' collate "POSIX") as f;
+ f
+---
+ f
+(1 row)
+
-- polymorphism
SELECT * FROM unnest((SELECT array_agg(b ORDER BY b) FROM collate_test1)) ORDER BY 1;
unnest
ORDER BY a.b, b.b;
+-- collation override in plpgsql
+
+CREATE FUNCTION mylt2 (x text, y text) RETURNS boolean LANGUAGE plpgsql AS $$
+declare
+ xx text := x;
+ yy text := y;
+begin
+ return xx < yy;
+end
+$$;
+
+SELECT mylt2('a', 'B' collate "en_US") as t, mylt2('a', 'B' collate "C") as f;
+
+CREATE OR REPLACE FUNCTION
+ mylt2 (x text, y text) RETURNS boolean LANGUAGE plpgsql AS $$
+declare
+ xx text COLLATE "POSIX" := x;
+ yy text := y;
+begin
+ return xx < yy;
+end
+$$;
+
+SELECT mylt2('a', 'B') as f;
+SELECT mylt2('a', 'B' collate "C") as fail; -- conflicting collations
+SELECT mylt2('a', 'B' collate "POSIX") as f;
+
+
-- polymorphism
SELECT * FROM unnest((SELECT array_agg(b ORDER BY b) FROM collate_test1)) ORDER BY 1;
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