On tor, 2012-01-12 at 21:25 -0800, probabble wrote:
> Compiling on Ubuntu 10.04 LTS AMD64 on a GoGrid virtual machine from
> 2012-01-12 checkout.
>
> Bison upgraded to v2.5, and downgraded to v2.4.1
>
> Make process for both versions resulted in the following errors:
>
> make[3]: Leaving directory `/usr/local/src/pgbuild/src/backend/catalog'
> make -C parser gram.h
> make[3]: Entering directory `/usr/local/src/pgbuild/src/backend/parser'
> /usr/local/bin/bison -d -o gram.c gram.y
> gram.y: conflicts: 370 reduce/reduce
> gram.y: expected 0 reduce/reduce conflicts
> gram.y:10482.27-10494.33: warning: rule useless in parser due to conflicts:
> func_expr: COLLATION FOR '(' a_expr ')'
> make[3]: *** [gram.c] Error 1
I can't reproduce that.
In the meantime, attached is a re-merged version of the patch; the old
version doesn't apply cleanly anymore.
diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml
index ff9b8b0..4d77024 100644
--- a/doc/src/sgml/func.sgml
+++ b/doc/src/sgml/func.sgml
@@ -13637,6 +13637,10 @@ SELECT pg_type_is_visible('myschema.widget'::regtype);
<primary>pg_typeof</primary>
</indexterm>
+ <indexterm>
+ <primary>collation for</primary>
+ </indexterm>
+
<para>
<xref linkend="functions-info-catalog-table"> lists functions that
extract information from the system catalogs.
@@ -13790,6 +13794,11 @@ SELECT pg_type_is_visible('myschema.widget'::regtype);
<entry><type>regtype</type></entry>
<entry>get the data type of any value</entry>
</row>
+ <row>
+ <entry><literal><function>collation for (<parameter>any</parameter>)</function></literal></entry>
+ <entry><type>text</type></entry>
+ <entry>get the collation of the argument</entry>
+ </row>
</tbody>
</tgroup>
</table>
@@ -13916,6 +13925,27 @@ SELECT typlen FROM pg_type WHERE oid = pg_typeof(33);
</programlisting>
</para>
+ <para>
+ The expression <literal>collation for</literal> returns the collation of the
+ value that is passed to it. Example:
+<programlisting>
+SELECT collation for (description) FROM pg_description LIMIT 1;
+ pg_collation_for
+------------------
+ "default"
+(1 row)
+
+SELECT collation for ('foo' COLLATE "de_DE");
+ pg_collation_for
+------------------
+ "de_DE"
+(1 row)
+</programlisting>
+ The value might be quoted and schema-qualified. If no collation is derived
+ for the argument expression, then a null value is returned. If the argument
+ is not of a collatable data type, then an error is raised.
+ </para>
+
<indexterm>
<primary>col_description</primary>
</indexterm>
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 0ec039b..dd0e2e8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -10466,6 +10466,19 @@ func_expr: func_name '(' ')' over_clause
n->location = @1;
$$ = (Node *)n;
}
+ | COLLATION FOR '(' a_expr ')'
+ {
+ FuncCall *n = makeNode(FuncCall);
+ n->funcname = SystemFuncName("pg_collation_for");
+ n->args = list_make1($4);
+ n->agg_order = NIL;
+ n->agg_star = FALSE;
+ n->agg_distinct = FALSE;
+ n->func_variadic = FALSE;
+ n->over = NULL;
+ n->location = @1;
+ $$ = (Node *)n;
+ }
| CURRENT_DATE
{
/*
@@ -11917,7 +11930,6 @@ unreserved_keyword:
| CLASS
| CLOSE
| CLUSTER
- | COLLATION
| COMMENT
| COMMENTS
| COMMIT
@@ -12253,6 +12265,7 @@ reserved_keyword:
| CAST
| CHECK
| COLLATE
+ | COLLATION
| COLUMN
| CONSTRAINT
| CREATE
diff --git a/src/backend/utils/adt/misc.c b/src/backend/utils/adt/misc.c
index 3de6a5c..84dad33 100644
--- a/src/backend/utils/adt/misc.c
+++ b/src/backend/utils/adt/misc.c
@@ -26,12 +26,14 @@
#include "commands/dbcommands.h"
#include "funcapi.h"
#include "miscadmin.h"
+#include "nodes/nodeFuncs.h"
#include "parser/keywords.h"
#include "postmaster/syslogger.h"
#include "storage/fd.h"
#include "storage/pmsignal.h"
#include "storage/proc.h"
#include "storage/procarray.h"
+#include "utils/lsyscache.h"
#include "tcop/tcopprot.h"
#include "utils/builtins.h"
#include "utils/timestamp.h"
@@ -492,3 +494,29 @@ pg_typeof(PG_FUNCTION_ARGS)
{
PG_RETURN_OID(get_fn_expr_argtype(fcinfo->flinfo, 0));
}
+
+
+/*
+ * Implementation of the COLLATE FOR expression; returns the collation
+ * of the argument.
+ */
+Datum
+pg_collation_for(PG_FUNCTION_ARGS)
+{
+ Oid typeid;
+ Oid collid;
+
+ typeid = get_fn_expr_argtype(fcinfo->flinfo, 0);
+ if (!typeid)
+ PG_RETURN_NULL();
+ if (!type_is_collatable(typeid) && typeid != UNKNOWNOID)
+ ereport(ERROR,
+ (errcode(ERRCODE_DATATYPE_MISMATCH),
+ errmsg("collations are not supported by type %s",
+ format_type_be(typeid))));
+
+ collid = PG_GET_COLLATION();
+ if (!collid)
+ PG_RETURN_NULL();
+ PG_RETURN_TEXT_P(cstring_to_text(generate_collation_name(collid)));
+}
diff --git a/src/include/catalog/pg_proc.h b/src/include/catalog/pg_proc.h
index 9994468..e4ea0d5 100644
--- a/src/include/catalog/pg_proc.h
+++ b/src/include/catalog/pg_proc.h
@@ -1945,6 +1945,8 @@ DESCR("convert generic options array to name/value table");
DATA(insert OID = 1619 ( pg_typeof PGNSP PGUID 12 1 0 0 0 f f f f f s 1 0 2206 "2276" _null_ _null_ _null_ _null_ pg_typeof _null_ _null_ _null_ ));
DESCR("type of the argument");
+DATA(insert OID = 3163 ( pg_collation_for PGNSP PGUID 12 1 0 0 0 f f f f f s 1 0 25 "2276" _null_ _null_ _null_ _null_ pg_collation_for _null_ _null_ _null_ ));
+DESCR("collation of the argument; implementation of the COLLATION FOR expression");
/* Deferrable unique constraint trigger */
DATA(insert OID = 1250 ( unique_key_recheck PGNSP PGUID 12 1 0 0 0 f f f t f v 0 0 2279 "" _null_ _null_ _null_ _null_ unique_key_recheck _null_ _null_ _null_ ));
diff --git a/src/include/parser/kwlist.h b/src/include/parser/kwlist.h
index 3d7de06..43933e9 100644
--- a/src/include/parser/kwlist.h
+++ b/src/include/parser/kwlist.h
@@ -79,7 +79,7 @@ PG_KEYWORD("close", CLOSE, UNRESERVED_KEYWORD)
PG_KEYWORD("cluster", CLUSTER, UNRESERVED_KEYWORD)
PG_KEYWORD("coalesce", COALESCE, COL_NAME_KEYWORD)
PG_KEYWORD("collate", COLLATE, RESERVED_KEYWORD)
-PG_KEYWORD("collation", COLLATION, UNRESERVED_KEYWORD)
+PG_KEYWORD("collation", COLLATION, RESERVED_KEYWORD)
PG_KEYWORD("column", COLUMN, RESERVED_KEYWORD)
PG_KEYWORD("comment", COMMENT, UNRESERVED_KEYWORD)
PG_KEYWORD("comments", COMMENTS, UNRESERVED_KEYWORD)
diff --git a/src/include/utils/builtins.h b/src/include/utils/builtins.h
index 46b2f3b..25b5e72 100644
--- a/src/include/utils/builtins.h
+++ b/src/include/utils/builtins.h
@@ -480,6 +480,7 @@ extern Datum pg_rotate_logfile(PG_FUNCTION_ARGS);
extern Datum pg_sleep(PG_FUNCTION_ARGS);
extern Datum pg_get_keywords(PG_FUNCTION_ARGS);
extern Datum pg_typeof(PG_FUNCTION_ARGS);
+extern Datum pg_collation_for(PG_FUNCTION_ARGS);
/* oid.c */
extern Datum oidin(PG_FUNCTION_ARGS);
diff --git a/src/test/regress/expected/collate.out b/src/test/regress/expected/collate.out
index a15e691..81ac6de 100644
--- a/src/test/regress/expected/collate.out
+++ b/src/test/regress/expected/collate.out
@@ -577,6 +577,26 @@ RESET enable_nestloop;
-- 9.1 bug with useless COLLATE in an expression subject to length coercion
CREATE TEMP TABLE vctable (f1 varchar(25));
INSERT INTO vctable VALUES ('foo' COLLATE "C");
+SELECT collation for ('foo'); -- unknown type - null
+ pg_collation_for
+------------------
+
+(1 row)
+
+SELECT collation for ('foo'::text);
+ pg_collation_for
+------------------
+ "default"
+(1 row)
+
+SELECT collation for ((SELECT a FROM collate_test1 LIMIT 1)); -- non-collatable type - error
+ERROR: collations are not supported by type integer
+SELECT collation for ((SELECT b FROM collate_test1 LIMIT 1));
+ pg_collation_for
+------------------
+ "C"
+(1 row)
+
--
-- Clean up. Many of these table names will be re-used if the user is
-- trying to run any platform-specific collation tests later, so we
diff --git a/src/test/regress/sql/collate.sql b/src/test/regress/sql/collate.sql
index f72f3ed..3c960e7 100644
--- a/src/test/regress/sql/collate.sql
+++ b/src/test/regress/sql/collate.sql
@@ -219,6 +219,13 @@ RESET enable_nestloop;
CREATE TEMP TABLE vctable (f1 varchar(25));
INSERT INTO vctable VALUES ('foo' COLLATE "C");
+
+SELECT collation for ('foo'); -- unknown type - null
+SELECT collation for ('foo'::text);
+SELECT collation for ((SELECT a FROM collate_test1 LIMIT 1)); -- non-collatable type - error
+SELECT collation for ((SELECT b FROM collate_test1 LIMIT 1));
+
+
--
-- Clean up. Many of these table names will be re-used if the user is
-- trying to run any platform-specific collation tests later, so we
--
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