Add transforms feature

This provides a mechanism for specifying conversions between SQL data
types and procedural languages.  As examples, there are transforms
for hstore and ltree for PL/Perl and PL/Python.

reviews by Pavel Stěhule and Andres Freund

contrib/Makefile

@@ -71,6 +71,18 @@ else
 ALWAYS_SUBDIRS += sepgsql
 endif
 
+ifeq ($(with_perl),yes)
+SUBDIRS += hstore_plperl
+else
+ALWAYS_SUBDIRS += hstore_plperl
+endif
+
+ifeq ($(with_python),yes)
+SUBDIRS += hstore_plpython ltree_plpython
+else
+ALWAYS_SUBDIRS += hstore_plpython ltree_plpython
+endif
+
 # Missing:
 #		start-scripts	\ (does not have a makefile)
 

contrib/hstore_plperl/.gitignore

+# Generated subdirectories
+/log/
+/results/
+/tmp_check/

contrib/hstore_plperl/Makefile

+# contrib/hstore_plperl/Makefile
+
+MODULE_big = hstore_plperl
+OBJS = hstore_plperl.o
+
+PG_CPPFLAGS = -I$(top_srcdir)/src/pl/plperl -I$(perl_archlibexp)/CORE -I$(top_srcdir)/contrib/hstore
+
+EXTENSION = hstore_plperl hstore_plperlu
+DATA = hstore_plperl--1.0.sql hstore_plperlu--1.0.sql
+
+REGRESS = hstore_plperl create_transform
+REGRESS_OPTS = --load-extension=hstore --load-extension=plperl --load-extension=plperlu
+EXTRA_INSTALL = contrib/hstore
+
+ifdef USE_PGXS
+PG_CONFIG = pg_config
+PGXS := $(shell $(PG_CONFIG) --pgxs)
+include $(PGXS)
+else
+subdir = contrib/hstore_plperl
+top_builddir = ../..
+include $(top_builddir)/src/Makefile.global
+include $(top_srcdir)/contrib/contrib-global.mk
+endif

contrib/hstore_plperl/expected/create_transform.out

+-- general regression test for transforms
+DROP EXTENSION IF EXISTS hstore CASCADE;
+NOTICE:  extension "hstore" does not exist, skipping
+DROP EXTENSION IF EXISTS plperl CASCADE;
+NOTICE:  extension "plperl" does not exist, skipping
+DROP EXTENSION IF EXISTS hstore_plperl CASCADE;
+NOTICE:  extension "hstore_plperl" does not exist, skipping
+CREATE EXTENSION hstore;
+CREATE EXTENSION plperl;
+CREATE FUNCTION hstore_to_plperl(val internal) RETURNS internal
+LANGUAGE C STRICT IMMUTABLE
+AS '$libdir/hstore_plperl';
+CREATE FUNCTION plperl_to_hstore(val internal) RETURNS hstore
+LANGUAGE C STRICT IMMUTABLE
+AS '$libdir/hstore_plperl';
+CREATE TRANSFORM FOR foo LANGUAGE plperl (FROM SQL WITH FUNCTION hstore_to_plperl(internal), TO SQL WITH FUNCTION plperl_to_hstore(internal));  -- fail
+ERROR:  type "foo" does not exist
+CREATE TRANSFORM FOR hstore LANGUAGE foo (FROM SQL WITH FUNCTION hstore_to_plperl(internal), TO SQL WITH FUNCTION plperl_to_hstore(internal));  -- fail
+ERROR:  language "foo" does not exist
+CREATE TRANSFORM FOR hstore LANGUAGE plperl (FROM SQL WITH FUNCTION hstore_out(hstore), TO SQL WITH FUNCTION plperl_to_hstore(internal));  -- fail
+ERROR:  return data type of FROM SQL function must be "internal"
+CREATE TRANSFORM FOR hstore LANGUAGE plperl (FROM SQL WITH FUNCTION internal_in(cstring), TO SQL WITH FUNCTION plperl_to_hstore(internal));  -- fail
+ERROR:  first argument of transform function must be type "internal"
+CREATE TRANSFORM FOR hstore LANGUAGE plperl (FROM SQL WITH FUNCTION hstore_to_plperl(internal), TO SQL WITH FUNCTION plperl_to_hstore(internal));  -- ok
+CREATE TRANSFORM FOR hstore LANGUAGE plperl (FROM SQL WITH FUNCTION hstore_to_plperl(internal), TO SQL WITH FUNCTION plperl_to_hstore(internal));  -- fail
+ERROR:  transform for type hstore language plperl already exists
+CREATE OR REPLACE TRANSFORM FOR hstore LANGUAGE plperl (FROM SQL WITH FUNCTION hstore_to_plperl(internal), TO SQL WITH FUNCTION plperl_to_hstore(internal));  -- ok
+CREATE OR REPLACE TRANSFORM FOR hstore LANGUAGE plperl (FROM SQL WITH FUNCTION hstore_to_plperl(internal));  -- ok
+CREATE OR REPLACE TRANSFORM FOR hstore LANGUAGE plperl (TO SQL WITH FUNCTION plperl_to_hstore(internal));  -- ok
+DROP TRANSFORM IF EXISTS FOR fake_type LANGUAGE plperl;
+NOTICE:  type "fake_type" does not exist, skipping
+DROP TRANSFORM IF EXISTS FOR hstore LANGUAGE fake_lang;
+NOTICE:  transform for type hstore language fake_lang does not exist, skipping
+DROP TRANSFORM FOR foo LANGUAGE plperl;
+ERROR:  type "foo" does not exist
+DROP TRANSFORM FOR hstore LANGUAGE foo;
+ERROR:  language "foo" does not exist
+DROP TRANSFORM FOR hstore LANGUAGE plperl;
+DROP TRANSFORM IF EXISTS FOR hstore LANGUAGE plperl;
+NOTICE:  transform for type hstore language plperl does not exist, skipping
+DROP FUNCTION hstore_to_plperl(val internal);
+DROP FUNCTION plperl_to_hstore(val internal);
+CREATE EXTENSION hstore_plperl;
+\dx+ hstore_plperl
+ Objects in extension "hstore_plperl"
+          Object Description          
+--------------------------------------
+ function hstore_to_plperl(internal)
+ function plperl_to_hstore(internal)
+ transform for hstore language plperl
+(3 rows)
+
+ALTER EXTENSION hstore_plperl DROP TRANSFORM FOR hstore LANGUAGE plperl;
+\dx+ hstore_plperl
+Objects in extension "hstore_plperl"
+         Object Description          
+-------------------------------------
+ function hstore_to_plperl(internal)
+ function plperl_to_hstore(internal)
+(2 rows)
+
+ALTER EXTENSION hstore_plperl ADD TRANSFORM FOR hstore LANGUAGE plperl;
+\dx+ hstore_plperl
+ Objects in extension "hstore_plperl"
+          Object Description          
+--------------------------------------
+ function hstore_to_plperl(internal)
+ function plperl_to_hstore(internal)
+ transform for hstore language plperl
+(3 rows)
+
+DROP EXTENSION hstore CASCADE;
+NOTICE:  drop cascades to extension hstore_plperl
+DROP EXTENSION plperl CASCADE;

contrib/hstore_plperl/expected/hstore_plperl.out

+CREATE EXTENSION hstore_plperl;
+CREATE EXTENSION hstore_plperlu;
+SELECT transforms.udt_schema, transforms.udt_name,
+       routine_schema, routine_name,
+       group_name, transform_type
+FROM information_schema.transforms JOIN information_schema.routines
+     USING (specific_catalog, specific_schema, specific_name)
+ORDER BY 1, 2, 5, 6;
+ udt_schema | udt_name | routine_schema |   routine_name    | group_name | transform_type 
+------------+----------+----------------+-------------------+------------+----------------
+ public     | hstore   | public         | hstore_to_plperl  | plperl     | FROM SQL
+ public     | hstore   | public         | plperl_to_hstore  | plperl     | TO SQL
+ public     | hstore   | public         | hstore_to_plperlu | plperlu    | FROM SQL
+ public     | hstore   | public         | plperlu_to_hstore | plperlu    | TO SQL
+(4 rows)
+
+-- test hstore -> perl
+CREATE FUNCTION test1(val hstore) RETURNS int
+LANGUAGE plperlu
+TRANSFORM FOR TYPE hstore
+AS $$
+use Data::Dumper;
+$Data::Dumper::Sortkeys = 1;
+elog(INFO, Dumper($_[0]));
+return scalar(keys %{$_[0]});
+$$;
+SELECT test1('aa=>bb, cc=>NULL'::hstore);
+INFO:  $VAR1 = {
+          'aa' => 'bb',
+          'cc' => undef
+        };
+
+CONTEXT:  PL/Perl function "test1"
+ test1 
+-------
+     2
+(1 row)
+
+CREATE FUNCTION test1none(val hstore) RETURNS int
+LANGUAGE plperlu
+AS $$
+use Data::Dumper;
+$Data::Dumper::Sortkeys = 1;
+elog(INFO, Dumper($_[0]));
+return scalar(keys %{$_[0]});
+$$;
+SELECT test1none('aa=>bb, cc=>NULL'::hstore);
+INFO:  $VAR1 = '"aa"=>"bb", "cc"=>NULL';
+
+CONTEXT:  PL/Perl function "test1none"
+ test1none 
+-----------
+         0
+(1 row)
+
+CREATE FUNCTION test1list(val hstore) RETURNS int
+LANGUAGE plperlu
+TRANSFORM FOR TYPE hstore
+AS $$
+use Data::Dumper;
+$Data::Dumper::Sortkeys = 1;
+elog(INFO, Dumper($_[0]));
+return scalar(keys %{$_[0]});
+$$;
+SELECT test1list('aa=>bb, cc=>NULL'::hstore);
+INFO:  $VAR1 = {
+          'aa' => 'bb',
+          'cc' => undef
+        };
+
+CONTEXT:  PL/Perl function "test1list"
+ test1list 
+-----------
+         2
+(1 row)
+
+-- test hstore[] -> perl
+CREATE FUNCTION test1arr(val hstore[]) RETURNS int
+LANGUAGE plperlu
+TRANSFORM FOR TYPE hstore
+AS $$
+use Data::Dumper;
+$Data::Dumper::Sortkeys = 1;
+elog(INFO, Dumper($_[0]->[0], $_[0]->[1]));
+return scalar(keys %{$_[0]});
+$$;
+SELECT test1arr(array['aa=>bb, cc=>NULL'::hstore, 'dd=>ee']);
+INFO:  $VAR1 = {
+          'aa' => 'bb',
+          'cc' => undef
+        };
+$VAR2 = {
+          'dd' => 'ee'
+        };
+
+CONTEXT:  PL/Perl function "test1arr"
+ test1arr 
+----------
+        2
+(1 row)
+
+-- test perl -> hstore
+CREATE FUNCTION test2() RETURNS hstore
+LANGUAGE plperl
+TRANSFORM FOR TYPE hstore
+AS $$
+$val = {a => 1, b => 'boo', c => undef};
+return $val;
+$$;
+SELECT test2();
+              test2              
+---------------------------------
+ "a"=>"1", "b"=>"boo", "c"=>NULL
+(1 row)
+
+-- test perl -> hstore[]
+CREATE FUNCTION test2arr() RETURNS hstore[]
+LANGUAGE plperl
+TRANSFORM FOR TYPE hstore
+AS $$
+$val = [{a => 1, b => 'boo', c => undef}, {d => 2}];
+return $val;
+$$;
+SELECT test2arr();
+                           test2arr                           
+--------------------------------------------------------------
+ {"\"a\"=>\"1\", \"b\"=>\"boo\", \"c\"=>NULL","\"d\"=>\"2\""}
+(1 row)
+
+-- test as part of prepare/execute
+CREATE FUNCTION test3() RETURNS void
+LANGUAGE plperlu
+TRANSFORM FOR TYPE hstore
+AS $$
+use Data::Dumper;
+$Data::Dumper::Sortkeys = 1;
+
+$rv = spi_exec_query(q{SELECT 'aa=>bb, cc=>NULL'::hstore AS col1});
+elog(INFO, Dumper($rv->{rows}[0]->{col1}));
+
+$val = {a => 1, b => 'boo', c => undef};
+$plan = spi_prepare(q{SELECT $1::text AS col1}, "hstore");
+$rv = spi_exec_prepared($plan, {}, $val);
+elog(INFO, Dumper($rv->{rows}[0]->{col1}));
+$$;
+SELECT test3();
+INFO:  $VAR1 = {
+          'aa' => 'bb',
+          'cc' => undef
+        };
+
+CONTEXT:  PL/Perl function "test3"
+INFO:  $VAR1 = '"a"=>"1", "b"=>"boo", "c"=>NULL';
+
+CONTEXT:  PL/Perl function "test3"
+ test3 
+-------
+ 
+(1 row)
+
+-- test trigger
+CREATE TABLE test1 (a int, b hstore);
+INSERT INTO test1 VALUES (1, 'aa=>bb, cc=>NULL');
+SELECT * FROM test1;
+ a |           b            
+---+------------------------
+ 1 | "aa"=>"bb", "cc"=>NULL
+(1 row)
+
+CREATE FUNCTION test4() RETURNS trigger
+LANGUAGE plperlu
+TRANSFORM FOR TYPE hstore
+AS $$
+use Data::Dumper;
+$Data::Dumper::Sortkeys = 1;
+elog(INFO, Dumper($_TD->{new}));
+if ($_TD->{new}{a} == 1) {
+    $_TD->{new}{b} = {a => 1, b => 'boo', c => undef};
+}
+
+return "MODIFY";
+$$;
+CREATE TRIGGER test4 BEFORE UPDATE ON test1 FOR EACH ROW EXECUTE PROCEDURE test4();
+UPDATE test1 SET a = a;
+INFO:  $VAR1 = {
+          'a' => '1',
+          'b' => {
+                 'aa' => 'bb',
+                 'cc' => undef
+               }
+        };
+
+CONTEXT:  PL/Perl function "test4"
+SELECT * FROM test1;
+ a |                b                
+---+---------------------------------
+ 1 | "a"=>"1", "b"=>"boo", "c"=>NULL
+(1 row)
+
+DROP TABLE test1;
+DROP FUNCTION test1(hstore);
+DROP FUNCTION test1none(hstore);
+DROP FUNCTION test1list(hstore);
+DROP FUNCTION test1arr(hstore[]);
+DROP FUNCTION test2();
+DROP FUNCTION test2arr();
+DROP FUNCTION test3();
+DROP FUNCTION test4();
+DROP EXTENSION hstore_plperl;
+DROP EXTENSION hstore_plperlu;
+DROP EXTENSION hstore;
+DROP EXTENSION plperl;
+DROP EXTENSION plperlu;

contrib/hstore_plperl/hstore_plperl--1.0.sql

+-- make sure the prerequisite libraries are loaded
+DO '' LANGUAGE plperl;
+SELECT NULL::hstore;
+
+
+CREATE FUNCTION hstore_to_plperl(val internal) RETURNS internal
+LANGUAGE C STRICT IMMUTABLE
+AS 'MODULE_PATHNAME';
+
+CREATE FUNCTION plperl_to_hstore(val internal) RETURNS hstore
+LANGUAGE C STRICT IMMUTABLE
+AS 'MODULE_PATHNAME';
+
+CREATE TRANSFORM FOR hstore LANGUAGE plperl (
+    FROM SQL WITH FUNCTION hstore_to_plperl(internal),
+    TO SQL WITH FUNCTION plperl_to_hstore(internal)
+);

contrib/hstore_plperl/hstore_plperl.c

+#include "postgres.h"
+#undef _
+#include "fmgr.h"
+#include "plperl.h"
+#include "plperl_helpers.h"
+#include "hstore.h"
+
+PG_MODULE_MAGIC;
+
+
+PG_FUNCTION_INFO_V1(hstore_to_plperl);
+Datum hstore_to_plperl(PG_FUNCTION_ARGS);
+
+Datum
+hstore_to_plperl(PG_FUNCTION_ARGS)
+{
+	HStore	   *in = PG_GETARG_HS(0);
+	int			i;
+	int			count = HS_COUNT(in);
+	char	   *base = STRPTR(in);
+	HEntry	   *entries = ARRPTR(in);
+	HV		   *hv;
+
+	hv = newHV();
+
+	for (i = 0; i < count; i++)
+	{
+		const char *key;
+		SV	   *value;
+
+		key = pnstrdup(HS_KEY(entries, base, i), HS_KEYLEN(entries, i));
+		value = HS_VALISNULL(entries, i) ? newSV(0) : cstr2sv(pnstrdup(HS_VAL(entries, base,i), HS_VALLEN(entries, i)));
+
+		(void) hv_store(hv, key, strlen(key), value, 0);
+	}
+
+	return PointerGetDatum(newRV((SV *) hv));
+}
+
+
+PG_FUNCTION_INFO_V1(plperl_to_hstore);
+Datum plperl_to_hstore(PG_FUNCTION_ARGS);
+
+Datum
+plperl_to_hstore(PG_FUNCTION_ARGS)
+{
+	HV		   *hv;
+	HE		   *he;
+	int32		buflen;
+	int32		i;
+	int32		pcount;
+	HStore	   *out;
+	Pairs	   *pairs;
+
+	hv = (HV *) SvRV((SV *) PG_GETARG_POINTER(0));
+
+	pcount = hv_iterinit(hv);
+
+	pairs = palloc(pcount * sizeof(Pairs));
+
+	i = 0;
+	while ((he = hv_iternext(hv)))
+	{
+		char	 *key = sv2cstr(HeSVKEY_force(he));
+		SV		 *value = HeVAL(he);
+
+		pairs[i].key = pstrdup(key);
+		pairs[i].keylen = hstoreCheckKeyLen(strlen(pairs[i].key));
+		pairs[i].needfree = true;
+
+		if (!SvOK(value))
+		{
+			pairs[i].val = NULL;
+			pairs[i].vallen = 0;
+			pairs[i].isnull = true;
+		}
+		else
+		{
+			pairs[i].val = pstrdup(sv2cstr(value));
+			pairs[i].vallen = hstoreCheckValLen(strlen(pairs[i].val));
+			pairs[i].isnull = false;
+		}
+
+		i++;
+	}
+
+	pcount = hstoreUniquePairs(pairs, pcount, &buflen);
+	out = hstorePairs(pairs, pcount, buflen);
+	PG_RETURN_POINTER(out);
+}

contrib/hstore_plperl/hstore_plperl.control

+# hstore_plperl extension
+comment = 'transform between hstore and plperl'
+default_version = '1.0'
+module_pathname = '$libdir/hstore_plperl'
+relocatable = true
+requires = 'hstore,plperl'

contrib/hstore_plperl/hstore_plperlu--1.0.sql

+-- make sure the prerequisite libraries are loaded
+DO '' LANGUAGE plperlu;
+SELECT NULL::hstore;
+
+
+CREATE FUNCTION hstore_to_plperlu(val internal) RETURNS internal
+LANGUAGE C STRICT IMMUTABLE
+AS 'MODULE_PATHNAME', 'hstore_to_plperl';
+
+CREATE FUNCTION plperlu_to_hstore(val internal) RETURNS hstore
+LANGUAGE C STRICT IMMUTABLE
+AS 'MODULE_PATHNAME', 'plperl_to_hstore';
+
+CREATE TRANSFORM FOR hstore LANGUAGE plperlu (
+    FROM SQL WITH FUNCTION hstore_to_plperlu(internal),
+    TO SQL WITH FUNCTION plperlu_to_hstore(internal)
+);

contrib/hstore_plperl/hstore_plperlu.control

+# hstore_plperlu extension
+comment = 'transform between hstore and plperlu'
+default_version = '1.0'
+module_pathname = '$libdir/hstore_plperl'
+relocatable = true
+requires = 'hstore,plperlu'

contrib/hstore_plperl/sql/create_transform.sql

+-- general regression test for transforms
+
+DROP EXTENSION IF EXISTS hstore CASCADE;
+DROP EXTENSION IF EXISTS plperl CASCADE;
+DROP EXTENSION IF EXISTS hstore_plperl CASCADE;
+
+CREATE EXTENSION hstore;
+CREATE EXTENSION plperl;
+
+CREATE FUNCTION hstore_to_plperl(val internal) RETURNS internal
+LANGUAGE C STRICT IMMUTABLE
+AS '$libdir/hstore_plperl';
+
+CREATE FUNCTION plperl_to_hstore(val internal) RETURNS hstore
+LANGUAGE C STRICT IMMUTABLE
+AS '$libdir/hstore_plperl';
+
+CREATE TRANSFORM FOR foo LANGUAGE plperl (FROM SQL WITH FUNCTION hstore_to_plperl(internal), TO SQL WITH FUNCTION plperl_to_hstore(internal));  -- fail
+CREATE TRANSFORM FOR hstore LANGUAGE foo (FROM SQL WITH FUNCTION hstore_to_plperl(internal), TO SQL WITH FUNCTION plperl_to_hstore(internal));  -- fail
+CREATE TRANSFORM FOR hstore LANGUAGE plperl (FROM SQL WITH FUNCTION hstore_out(hstore), TO SQL WITH FUNCTION plperl_to_hstore(internal));  -- fail
+CREATE TRANSFORM FOR hstore LANGUAGE plperl (FROM SQL WITH FUNCTION internal_in(cstring), TO SQL WITH FUNCTION plperl_to_hstore(internal));  -- fail
+
+CREATE TRANSFORM FOR hstore LANGUAGE plperl (FROM SQL WITH FUNCTION hstore_to_plperl(internal), TO SQL WITH FUNCTION plperl_to_hstore(internal));  -- ok
+CREATE TRANSFORM FOR hstore LANGUAGE plperl (FROM SQL WITH FUNCTION hstore_to_plperl(internal), TO SQL WITH FUNCTION plperl_to_hstore(internal));  -- fail
+CREATE OR REPLACE TRANSFORM FOR hstore LANGUAGE plperl (FROM SQL WITH FUNCTION hstore_to_plperl(internal), TO SQL WITH FUNCTION plperl_to_hstore(internal));  -- ok
+CREATE OR REPLACE TRANSFORM FOR hstore LANGUAGE plperl (FROM SQL WITH FUNCTION hstore_to_plperl(internal));  -- ok
+CREATE OR REPLACE TRANSFORM FOR hstore LANGUAGE plperl (TO SQL WITH FUNCTION plperl_to_hstore(internal));  -- ok
+
+DROP TRANSFORM IF EXISTS FOR fake_type LANGUAGE plperl;
+DROP TRANSFORM IF EXISTS FOR hstore LANGUAGE fake_lang;
+DROP TRANSFORM FOR foo LANGUAGE plperl;
+DROP TRANSFORM FOR hstore LANGUAGE foo;
+DROP TRANSFORM FOR hstore LANGUAGE plperl;
+DROP TRANSFORM IF EXISTS FOR hstore LANGUAGE plperl;
+
+DROP FUNCTION hstore_to_plperl(val internal);
+DROP FUNCTION plperl_to_hstore(val internal);
+
+CREATE EXTENSION hstore_plperl;
+\dx+ hstore_plperl
+ALTER EXTENSION hstore_plperl DROP TRANSFORM FOR hstore LANGUAGE plperl;
+\dx+ hstore_plperl
+ALTER EXTENSION hstore_plperl ADD TRANSFORM FOR hstore LANGUAGE plperl;
+\dx+ hstore_plperl
+
+DROP EXTENSION hstore CASCADE;
+DROP EXTENSION plperl CASCADE;

contrib/hstore_plperl/sql/hstore_plperl.sql

+CREATE EXTENSION hstore_plperl;
+CREATE EXTENSION hstore_plperlu;
+
+SELECT transforms.udt_schema, transforms.udt_name,
+       routine_schema, routine_name,
+       group_name, transform_type
+FROM information_schema.transforms JOIN information_schema.routines
+     USING (specific_catalog, specific_schema, specific_name)
+ORDER BY 1, 2, 5, 6;
+
+
+-- test hstore -> perl
+CREATE FUNCTION test1(val hstore) RETURNS int
+LANGUAGE plperlu
+TRANSFORM FOR TYPE hstore
+AS $$
+use Data::Dumper;
+$Data::Dumper::Sortkeys = 1;
+elog(INFO, Dumper($_[0]));
+return scalar(keys %{$_[0]});
+$$;
+
+SELECT test1('aa=>bb, cc=>NULL'::hstore);
+
+CREATE FUNCTION test1none(val hstore) RETURNS int
+LANGUAGE plperlu
+AS $$
+use Data::Dumper;
+$Data::Dumper::Sortkeys = 1;
+elog(INFO, Dumper($_[0]));
+return scalar(keys %{$_[0]});
+$$;
+
+SELECT test1none('aa=>bb, cc=>NULL'::hstore);
+
+CREATE FUNCTION test1list(val hstore) RETURNS int
+LANGUAGE plperlu
+TRANSFORM FOR TYPE hstore
+AS $$
+use Data::Dumper;
+$Data::Dumper::Sortkeys = 1;
+elog(INFO, Dumper($_[0]));
+return scalar(keys %{$_[0]});
+$$;
+
+SELECT test1list('aa=>bb, cc=>NULL'::hstore);
+
+
+-- test hstore[] -> perl
+CREATE FUNCTION test1arr(val hstore[]) RETURNS int
+LANGUAGE plperlu
+TRANSFORM FOR TYPE hstore
+AS $$
+use Data::Dumper;
+$Data::Dumper::Sortkeys = 1;
+elog(INFO, Dumper($_[0]->[0], $_[0]->[1]));
+return scalar(keys %{$_[0]});
+$$;
+
+SELECT test1arr(array['aa=>bb, cc=>NULL'::hstore, 'dd=>ee']);
+
+
+-- test perl -> hstore
+CREATE FUNCTION test2() RETURNS hstore
+LANGUAGE plperl
+TRANSFORM FOR TYPE hstore
+AS $$
+$val = {a => 1, b => 'boo', c => undef};
+return $val;
+$$;
+
+SELECT test2();
+
+
+-- test perl -> hstore[]
+CREATE FUNCTION test2arr() RETURNS hstore[]
+LANGUAGE plperl
+TRANSFORM FOR TYPE hstore
+AS $$
+$val = [{a => 1, b => 'boo', c => undef}, {d => 2}];
+return $val;
+$$;
+
+SELECT test2arr();
+
+
+-- test as part of prepare/execute
+CREATE FUNCTION test3() RETURNS void
+LANGUAGE plperlu
+TRANSFORM FOR TYPE hstore
+AS $$
+use Data::Dumper;
+$Data::Dumper::Sortkeys = 1;
+
+$rv = spi_exec_query(q{SELECT 'aa=>bb, cc=>NULL'::hstore AS col1});
+elog(INFO, Dumper($rv->{rows}[0]->{col1}));
+
+$val = {a => 1, b => 'boo', c => undef};
+$plan = spi_prepare(q{SELECT $1::text AS col1}, "hstore");
+$rv = spi_exec_prepared($plan, {}, $val);
+elog(INFO, Dumper($rv->{rows}[0]->{col1}));
+$$;
+
+SELECT test3();
+
+
+-- test trigger
+CREATE TABLE test1 (a int, b hstore);
+INSERT INTO test1 VALUES (1, 'aa=>bb, cc=>NULL');
+SELECT * FROM test1;
+
+CREATE FUNCTION test4() RETURNS trigger
+LANGUAGE plperlu
+TRANSFORM FOR TYPE hstore
+AS $$
+use Data::Dumper;
+$Data::Dumper::Sortkeys = 1;
+elog(INFO, Dumper($_TD->{new}));
+if ($_TD->{new}{a} == 1) {
+    $_TD->{new}{b} = {a => 1, b => 'boo', c => undef};
+}
+
+return "MODIFY";
+$$;
+
+CREATE TRIGGER test4 BEFORE UPDATE ON test1 FOR EACH ROW EXECUTE PROCEDURE test4();
+
+UPDATE test1 SET a = a;
+SELECT * FROM test1;
+
+
+DROP TABLE test1;
+
+DROP FUNCTION test1(hstore);
+DROP FUNCTION test1none(hstore);
+DROP FUNCTION test1list(hstore);
+DROP FUNCTION test1arr(hstore[]);
+DROP FUNCTION test2();
+DROP FUNCTION test2arr();
+DROP FUNCTION test3();
+DROP FUNCTION test4();
+
+
+DROP EXTENSION hstore_plperl;
+DROP EXTENSION hstore_plperlu;
+DROP EXTENSION hstore;
+DROP EXTENSION plperl;
+DROP EXTENSION plperlu;

contrib/hstore_plpython/.gitignore

+# Generated subdirectories
+/expected/python3/
+/log/
+/results/
+/sql/python3/
+/tmp_check/

contrib/hstore_plpython/Makefile

+# contrib/hstore_plpython/Makefile
+
+MODULE_big = hstore_plpython$(python_majorversion)
+OBJS = hstore_plpython.o
+
+PG_CPPFLAGS = -I$(top_srcdir)/src/pl/plpython $(python_includespec) -I$(top_srcdir)/contrib/hstore
+
+EXTENSION = hstore_plpythonu hstore_plpython2u hstore_plpython3u
+DATA = hstore_plpythonu--1.0.sql hstore_plpython2u--1.0.sql hstore_plpython3u--1.0.sql
+
+REGRESS = hstore_plpython
+REGRESS_PLPYTHON3_MANGLE := $(REGRESS)
+
+ifdef USE_PGXS
+PG_CONFIG = pg_config
+PGXS := $(shell $(PG_CONFIG) --pgxs)
+include $(PGXS)
+else
+subdir = contrib/hstore_plpython
+top_builddir = ../..
+include $(top_builddir)/src/Makefile.global
+include $(top_srcdir)/contrib/contrib-global.mk
+endif
+
+REGRESS_OPTS = --load-extension=hstore
+ifeq ($(python_majorversion),2)
+REGRESS_OPTS += --load-extension=plpythonu --load-extension=hstore_plpythonu
+endif
+EXTRA_INSTALL = contrib/hstore
+
+include $(top_srcdir)/src/pl/plpython/regress-python3-mangle.mk

contrib/hstore_plpython/expected/hstore_plpython.out

+CREATE EXTENSION plpython2u;
+CREATE EXTENSION hstore_plpython2u;
+-- test hstore -> python
+CREATE FUNCTION test1(val hstore) RETURNS int
+LANGUAGE plpythonu
+TRANSFORM FOR TYPE hstore
+AS $$
+assert isinstance(val, dict)
+plpy.info(sorted(val.items()))
+return len(val)
+$$;
+SELECT test1('aa=>bb, cc=>NULL'::hstore);
+INFO:  [('aa', 'bb'), ('cc', None)]
+CONTEXT:  PL/Python function "test1"
+ test1 
+-------
+     2
+(1 row)
+
+-- the same with the versioned language name
+CREATE FUNCTION test1n(val hstore) RETURNS int
+LANGUAGE plpython2u
+TRANSFORM FOR TYPE hstore
+AS $$
+assert isinstance(val, dict)
+plpy.info(sorted(val.items()))
+return len(val)
+$$;
+SELECT test1n('aa=>bb, cc=>NULL'::hstore);
+INFO:  [('aa', 'bb'), ('cc', None)]
+CONTEXT:  PL/Python function "test1n"
+ test1n 
+--------
+      2
+(1 row)
+
+-- test hstore[] -> python
+CREATE FUNCTION test1arr(val hstore[]) RETURNS int
+LANGUAGE plpythonu
+TRANSFORM FOR TYPE hstore
+AS $$
+plpy.info(repr(val))
+return len(val)
+$$;
+SELECT test1arr(array['aa=>bb, cc=>NULL'::hstore, 'dd=>ee']);
+INFO:  [{'aa': 'bb', 'cc': None}, {'dd': 'ee'}]
+CONTEXT:  PL/Python function "test1arr"
+ test1arr 
+----------
+        2
+(1 row)
+
+-- test python -> hstore
+CREATE FUNCTION test2() RETURNS hstore
+LANGUAGE plpythonu
+TRANSFORM FOR TYPE hstore
+AS $$
+val = {'a': 1, 'b': 'boo', 'c': None}
+return val
+$$;
+SELECT test2();
+              test2              
+---------------------------------
+ "a"=>"1", "b"=>"boo", "c"=>NULL
+(1 row)
+
+-- test python -> hstore[]
+CREATE FUNCTION test2arr() RETURNS hstore[]
+LANGUAGE plpythonu
+TRANSFORM FOR TYPE hstore
+AS $$
+val = [{'a': 1, 'b': 'boo', 'c': None}, {'d': 2}]
+return val
+$$;
+ SELECT test2arr();
+                           test2arr                           
+--------------------------------------------------------------
+ {"\"a\"=>\"1\", \"b\"=>\"boo\", \"c\"=>NULL","\"d\"=>\"2\""}
+(1 row)
+
+-- test as part of prepare/execute
+CREATE FUNCTION test3() RETURNS void
+LANGUAGE plpythonu
+TRANSFORM FOR TYPE hstore
+AS $$
+rv = plpy.execute("SELECT 'aa=>bb, cc=>NULL'::hstore AS col1")
+plpy.info(repr(rv[0]["col1"]))
+
+val = {'a': 1, 'b': 'boo', 'c': None}
+plan = plpy.prepare("SELECT $1::text AS col1", ["hstore"])
+rv = plpy.execute(plan, [val])
+plpy.info(repr(rv[0]["col1"]))
+$$;
+SELECT test3();
+INFO:  {'aa': 'bb', 'cc': None}
+CONTEXT:  PL/Python function "test3"
+INFO:  '"a"=>"1", "b"=>"boo", "c"=>NULL'
+CONTEXT:  PL/Python function "test3"
+ test3 
+-------
+ 
+(1 row)
+
+-- test trigger
+CREATE TABLE test1 (a int, b hstore);
+INSERT INTO test1 VALUES (1, 'aa=>bb, cc=>NULL');
+SELECT * FROM test1;
+ a |           b            
+---+------------------------
+ 1 | "aa"=>"bb", "cc"=>NULL
+(1 row)
+
+CREATE FUNCTION test4() RETURNS trigger
+LANGUAGE plpythonu
+TRANSFORM FOR TYPE hstore
+AS $$
+plpy.info("Trigger row: {'a': %r, 'b': %r}" % (TD["new"]["a"], TD["new"]["b"]))
+if TD["new"]["a"] == 1:
+    TD["new"]["b"] = {'a': 1, 'b': 'boo', 'c': None}
+
+return "MODIFY"
+$$;
+CREATE TRIGGER test4 BEFORE UPDATE ON test1 FOR EACH ROW EXECUTE PROCEDURE test4();
+UPDATE test1 SET a = a;
+INFO:  Trigger row: {'a': 1, 'b': {'aa': 'bb', 'cc': None}}
+CONTEXT:  PL/Python function "test4"
+SELECT * FROM test1;
+ a |                b                
+---+---------------------------------
+ 1 | "a"=>"1", "b"=>"boo", "c"=>NULL
+(1 row)
+

contrib/hstore_plpython/hstore_plpython.c

+#include "postgres.h"
+#include "fmgr.h"
+#include "plpython.h"
+#include "plpy_typeio.h"
+#include "hstore.h"
+
+PG_MODULE_MAGIC;
+
+
+PG_FUNCTION_INFO_V1(hstore_to_plpython);
+Datum hstore_to_plpython(PG_FUNCTION_ARGS);
+
+Datum
+hstore_to_plpython(PG_FUNCTION_ARGS)
+{
+	HStore	   *in = PG_GETARG_HS(0);
+	int			i;
+	int			count = HS_COUNT(in);
+	char	   *base = STRPTR(in);
+	HEntry	   *entries = ARRPTR(in);
+	PyObject   *dict;
+
+	dict = PyDict_New();
+
+	for (i = 0; i < count; i++)
+	{
+		PyObject   *key;
+
+		key = PyString_FromStringAndSize(HS_KEY(entries, base, i), HS_KEYLEN(entries, i));
+		if (HS_VALISNULL(entries, i))
+			PyDict_SetItem(dict, key, Py_None);
+		else
+		{
+			PyObject *value;
+
+			value = PyString_FromStringAndSize(HS_VAL(entries, base,i), HS_VALLEN(entries, i));
+			PyDict_SetItem(dict, key, value);
+			Py_XDECREF(value);
+		}
+		Py_XDECREF(key);
+	}
+
+	return PointerGetDatum(dict);
+}
+
+
+PG_FUNCTION_INFO_V1(plpython_to_hstore);
+Datum plpython_to_hstore(PG_FUNCTION_ARGS);
+
+Datum
+plpython_to_hstore(PG_FUNCTION_ARGS)
+{
+	PyObject   *dict;
+	volatile PyObject *items_v = NULL;
+	int32		pcount;
+	HStore	   *out;
+
+	dict = (PyObject *) PG_GETARG_POINTER(0);
+	if (!PyMapping_Check(dict))
+		ereport(ERROR,
+				(errcode(ERRCODE_WRONG_OBJECT_TYPE),
+				 errmsg("not a Python mapping")));
+
+	pcount = PyMapping_Size(dict);
+	items_v = PyMapping_Items(dict);
+
+	PG_TRY();
+	{
+		int32		buflen;
+		int32		i;
+		Pairs	   *pairs;
+		PyObject   *items = (PyObject *) items_v;
+
+		pairs = palloc(pcount * sizeof(*pairs));
+
+		for (i = 0; i < pcount; i++)
+		{
+			PyObject *tuple;
+			PyObject *key;
+			PyObject *value;
+
+			tuple = PyList_GetItem(items, i);
+			key = PyTuple_GetItem(tuple, 0);
+			value = PyTuple_GetItem(tuple, 1);
+
+			pairs[i].key = PLyObject_AsString(key);
+			pairs[i].keylen = hstoreCheckKeyLen(strlen(pairs[i].key));
+			pairs[i].needfree = true;
+
+			if (value == Py_None)
+			{
+				pairs[i].val = NULL;
+				pairs[i].vallen = 0;
+				pairs[i].isnull = true;
+			}
+			else
+			{
+				pairs[i].val = PLyObject_AsString(value);
+				pairs[i].vallen = hstoreCheckValLen(strlen(pairs[i].val));
+				pairs[i].isnull = false;
+			}
+		}
+		Py_DECREF(items_v);
+
+		pcount = hstoreUniquePairs(pairs, pcount, &buflen);
+		out = hstorePairs(pairs, pcount, buflen);
+	}
+	PG_CATCH();
+	{
+		Py_DECREF(items_v);
+		PG_RE_THROW();
+	}
+	PG_END_TRY();
+
+	PG_RETURN_POINTER(out);
+}

contrib/hstore_plpython/hstore_plpython2u--1.0.sql

+-- make sure the prerequisite libraries are loaded
+DO '1' LANGUAGE plpython2u;
+SELECT NULL::hstore;
+
+
+CREATE FUNCTION hstore_to_plpython2(val internal) RETURNS internal
+LANGUAGE C STRICT IMMUTABLE
+AS 'MODULE_PATHNAME', 'hstore_to_plpython';
+
+CREATE FUNCTION plpython2_to_hstore(val internal) RETURNS hstore
+LANGUAGE C STRICT IMMUTABLE
+AS 'MODULE_PATHNAME', 'plpython_to_hstore';
+
+CREATE TRANSFORM FOR hstore LANGUAGE plpython2u (
+    FROM SQL WITH FUNCTION hstore_to_plpython2(internal),
+    TO SQL WITH FUNCTION plpython2_to_hstore(internal)
+);
+
+COMMENT ON TRANSFORM FOR hstore LANGUAGE plpython2u IS 'transform between hstore and Python dict';

contrib/hstore_plpython/hstore_plpython2u.control

+# hstore_plpython2u extension
+comment = 'transform between hstore and plpython2u'
+default_version = '1.0'
+module_pathname = '$libdir/hstore_plpython2'
+relocatable = true
+requires = 'hstore,plpython2u'

contrib/hstore_plpython/hstore_plpython3u--1.0.sql

+-- make sure the prerequisite libraries are loaded
+DO '1' LANGUAGE plpython3u;
+SELECT NULL::hstore;
+
+
+CREATE FUNCTION hstore_to_plpython3(val internal) RETURNS internal
+LANGUAGE C STRICT IMMUTABLE
+AS 'MODULE_PATHNAME', 'hstore_to_plpython';
+
+CREATE FUNCTION plpython3_to_hstore(val internal) RETURNS hstore
+LANGUAGE C STRICT IMMUTABLE
+AS 'MODULE_PATHNAME', 'plpython_to_hstore';
+
+CREATE TRANSFORM FOR hstore LANGUAGE plpython3u (
+    FROM SQL WITH FUNCTION hstore_to_plpython3(internal),
+    TO SQL WITH FUNCTION plpython3_to_hstore(internal)
+);
+
+COMMENT ON TRANSFORM FOR hstore LANGUAGE plpython3u IS 'transform between hstore and Python dict';

contrib/hstore_plpython/hstore_plpython3u.control

+# hstore_plpython3u extension
+comment = 'transform between hstore and plpython3u'
+default_version = '1.0'
+module_pathname = '$libdir/hstore_plpython3'
+relocatable = true
+requires = 'hstore,plpython3u'