diff --git a/doc/src/sgml/plhandler.sgml b/doc/src/sgml/plhandler.sgml
index e1b0af7a60..40ee59de9f 100644
--- a/doc/src/sgml/plhandler.sgml
+++ b/doc/src/sgml/plhandler.sgml
@@ -96,62 +96,10 @@
- This is a template for a procedural-language handler written in C:
-
-#include "postgres.h"
-#include "executor/spi.h"
-#include "commands/trigger.h"
-#include "fmgr.h"
-#include "access/heapam.h"
-#include "utils/syscache.h"
-#include "catalog/pg_proc.h"
-#include "catalog/pg_type.h"
-
-PG_MODULE_MAGIC;
-
-PG_FUNCTION_INFO_V1(plsample_call_handler);
-
-Datum
-plsample_call_handler(PG_FUNCTION_ARGS)
-{
- Datum retval;
-
- if (CALLED_AS_TRIGGER(fcinfo))
- {
- /*
- * Called as a trigger function
- */
- TriggerData *trigdata = (TriggerData *) fcinfo->context;
-
- retval = ...
- }
- else
- {
- /*
- * Called as a function
- */
-
- retval = ...
- }
-
- return retval;
-}
-
- Only a few thousand lines of code have to be added instead of the
- dots to complete the call handler.
-
-
-
- After having compiled the handler function into a loadable module
- (see ), the following commands then
- register the sample procedural language:
-
-CREATE FUNCTION plsample_call_handler() RETURNS language_handler
- AS 'filename'
- LANGUAGE C;
-CREATE LANGUAGE plsample
- HANDLER plsample_call_handler;
-
+ A template for a procedural-language handler written as a C extension is
+ provided in src/test/modules/plsample. This is a
+ working sample demonstrating one way to create a procedural-language
+ handler, process parameters, and return a value.
diff --git a/src/test/modules/Makefile b/src/test/modules/Makefile
index 1428529b04..a6d2ffbf9e 100644
--- a/src/test/modules/Makefile
+++ b/src/test/modules/Makefile
@@ -10,6 +10,7 @@ SUBDIRS = \
delay_execution \
dummy_index_am \
dummy_seclabel \
+ plsample \
snapshot_too_old \
test_bloomfilter \
test_ddl_deparse \
diff --git a/src/test/modules/plsample/.gitignore b/src/test/modules/plsample/.gitignore
new file mode 100644
index 0000000000..44d119cfcc
--- /dev/null
+++ b/src/test/modules/plsample/.gitignore
@@ -0,0 +1,3 @@
+# Generated subdirectories
+/log/
+/results/
diff --git a/src/test/modules/plsample/Makefile b/src/test/modules/plsample/Makefile
new file mode 100644
index 0000000000..f1bc334bfc
--- /dev/null
+++ b/src/test/modules/plsample/Makefile
@@ -0,0 +1,20 @@
+# src/test/modules/plsample/Makefile
+
+MODULES = plsample
+
+EXTENSION = plsample
+DATA = plsample--1.0.sql
+PGFILEDESC = "PL/Sample - template for procedural language"
+
+REGRESS = plsample
+
+ifdef USE_PGXS
+PG_CONFIG = pg_config
+PGXS := $(shell $(PG_CONFIG) --pgxs)
+include $(PGXS)
+else
+subdir = src/test/modules/plsample
+top_builddir = ../../../..
+include $(top_builddir)/src/Makefile.global
+include $(top_srcdir)/contrib/contrib-global.mk
+endif
diff --git a/src/test/modules/plsample/README b/src/test/modules/plsample/README
new file mode 100644
index 0000000000..0ed319308d
--- /dev/null
+++ b/src/test/modules/plsample/README
@@ -0,0 +1,6 @@
+PL/Sample
+=========
+
+PL/Sample is an example template of procedural-language handler. It is
+a simple implementation, yet demonstrates some of the things that can be done
+to build a fully functional procedural-language handler.
diff --git a/src/test/modules/plsample/expected/plsample.out b/src/test/modules/plsample/expected/plsample.out
new file mode 100644
index 0000000000..a0c318b6df
--- /dev/null
+++ b/src/test/modules/plsample/expected/plsample.out
@@ -0,0 +1,36 @@
+CREATE EXTENSION plsample;
+-- Create and test some dummy functions
+CREATE FUNCTION plsample_result_text(a1 numeric, a2 text, a3 integer[])
+RETURNS TEXT
+AS $$
+ Example of source with text result.
+$$ LANGUAGE plsample;
+SELECT plsample_result_text(1.23, 'abc', '{4, 5, 6}');
+NOTICE: source text of function "plsample_result_text":
+ Example of source with text result.
+
+NOTICE: argument: 0; name: a1; value: 1.23
+NOTICE: argument: 1; name: a2; value: abc
+NOTICE: argument: 2; name: a3; value: {4,5,6}
+ plsample_result_text
+---------------------------------------
+ +
+ Example of source with text result.+
+
+(1 row)
+
+CREATE FUNCTION plsample_result_void(a1 text[])
+RETURNS VOID
+AS $$
+ Example of source with void result.
+$$ LANGUAGE plsample;
+SELECT plsample_result_void('{foo, bar, hoge}');
+NOTICE: source text of function "plsample_result_void":
+ Example of source with void result.
+
+NOTICE: argument: 0; name: a1; value: {foo,bar,hoge}
+ plsample_result_void
+----------------------
+
+(1 row)
+
diff --git a/src/test/modules/plsample/plsample--1.0.sql b/src/test/modules/plsample/plsample--1.0.sql
new file mode 100644
index 0000000000..fc5b280bd4
--- /dev/null
+++ b/src/test/modules/plsample/plsample--1.0.sql
@@ -0,0 +1,14 @@
+/* src/test/modules/plsample/plsample--1.0.sql */
+
+-- complain if script is sourced in psql, rather than via CREATE EXTENSION
+\echo Use "CREATE EXTENSION plsample" to load this file. \quit
+
+CREATE FUNCTION plsample_call_handler() RETURNS language_handler
+ AS 'MODULE_PATHNAME' LANGUAGE C;
+
+CREATE TRUSTED LANGUAGE plsample
+ HANDLER plsample_call_handler;
+
+ALTER LANGUAGE plsample OWNER TO @extowner@;
+
+COMMENT ON LANGUAGE plsample IS 'PL/Sample procedural language';
diff --git a/src/test/modules/plsample/plsample.c b/src/test/modules/plsample/plsample.c
new file mode 100644
index 0000000000..4083669066
--- /dev/null
+++ b/src/test/modules/plsample/plsample.c
@@ -0,0 +1,183 @@
+/*-------------------------------------------------------------------------
+ *
+ * plsample.c
+ * Handler for the PL/Sample procedural language
+ *
+ * Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ *
+ * IDENTIFICATION
+ * src/test/modules/plsample/plsample.c
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#include "postgres.h"
+
+#include "catalog/pg_proc.h"
+#include "catalog/pg_type.h"
+#include "commands/event_trigger.h"
+#include "commands/trigger.h"
+#include "funcapi.h"
+#include "utils/builtins.h"
+#include "utils/lsyscache.h"
+#include "utils/syscache.h"
+
+PG_MODULE_MAGIC;
+
+PG_FUNCTION_INFO_V1(plsample_call_handler);
+
+static Datum plsample_func_handler(PG_FUNCTION_ARGS);
+
+/*
+ * Handle function, procedure, and trigger calls.
+ */
+Datum
+plsample_call_handler(PG_FUNCTION_ARGS)
+{
+ Datum retval = (Datum) 0;
+
+ PG_TRY();
+ {
+ /*
+ * Determine if called as function or trigger and call appropriate
+ * subhandler.
+ */
+ if (CALLED_AS_TRIGGER(fcinfo))
+ {
+ /*
+ * This function has been called as a trigger function, where
+ * (TriggerData *) fcinfo->context includes the information of the
+ * context.
+ */
+ }
+ else if (CALLED_AS_EVENT_TRIGGER(fcinfo))
+ {
+ /*
+ * This function is called as an event trigger function, where
+ * (EventTriggerData *) fcinfo->context includes the information
+ * of the context.
+ */
+ }
+ else
+ {
+ /* Regular function handler */
+ retval = plsample_func_handler(fcinfo);
+ }
+ }
+ PG_FINALLY();
+ {
+ }
+ PG_END_TRY();
+
+ return retval;
+}
+
+/*
+ * plsample_func_handler
+ *
+ * Function called by the call handler for function execution.
+ */
+static Datum
+plsample_func_handler(PG_FUNCTION_ARGS)
+{
+ HeapTuple pl_tuple;
+ Datum ret;
+ char *source;
+ bool isnull;
+ FmgrInfo *arg_out_func;
+ Form_pg_type type_struct;
+ HeapTuple type_tuple;
+ Form_pg_proc pl_struct;
+ volatile MemoryContext proc_cxt = NULL;
+ Oid *argtypes;
+ char **argnames;
+ char *argmodes;
+ char *proname;
+ Form_pg_type pg_type_entry;
+ Oid result_typioparam;
+ FmgrInfo result_in_func;
+ int numargs;
+
+ /* Fetch the source text of the function. */
+ pl_tuple = SearchSysCache(PROCOID,
+ ObjectIdGetDatum(fcinfo->flinfo->fn_oid), 0, 0, 0);
+ if (!HeapTupleIsValid(pl_tuple))
+ elog(ERROR, "cache lookup failed for function %u",
+ fcinfo->flinfo->fn_oid);
+
+ /*
+ * Extract and print the source text of the function. This can be used as
+ * a base for the function validation and execution.
+ */
+ pl_struct = (Form_pg_proc) GETSTRUCT(pl_tuple);
+ proname = pstrdup(NameStr(pl_struct->proname));
+ ret = SysCacheGetAttr(PROCOID, pl_tuple, Anum_pg_proc_prosrc, &isnull);
+ if (isnull)
+ elog(ERROR, "could not find source text of function \"%s\"",
+ proname);
+ ReleaseSysCache(pl_tuple);
+ source = DatumGetCString(DirectFunctionCall1(textout, ret));
+ ereport(NOTICE,
+ (errmsg("source text of function \"%s\": %s",
+ proname, source)));
+
+ /*
+ * Allocate a context that will hold all the Postgres data for the
+ * procedure.
+ */
+ proc_cxt = AllocSetContextCreate(TopMemoryContext,
+ "PL/Sample function",
+ ALLOCSET_SMALL_SIZES);
+
+ arg_out_func = (FmgrInfo *) palloc0(fcinfo->nargs * sizeof(FmgrInfo));
+ numargs = get_func_arg_info(pl_tuple, &argtypes, &argnames, &argmodes);
+
+ /*
+ * Iterate through all of the function arguments, printing each input
+ * value.
+ */
+ for (int i = 0; i < numargs; i++)
+ {
+ Oid argtype = pl_struct->proargtypes.values[i];
+ char *value;
+
+ type_tuple = SearchSysCache1(TYPEOID, ObjectIdGetDatum(argtype));
+ if (!HeapTupleIsValid(type_tuple))
+ elog(ERROR, "cache lookup failed for type %u", argtype);
+
+ type_struct = (Form_pg_type) GETSTRUCT(type_tuple);
+ fmgr_info_cxt(type_struct->typoutput, &(arg_out_func[i]), proc_cxt);
+ ReleaseSysCache(type_tuple);
+
+ value = OutputFunctionCall(&arg_out_func[i], fcinfo->args[i].value);
+ ereport(NOTICE,
+ (errmsg("argument: %d; name: %s; value: %s",
+ i, argnames[i], value)));
+ }
+
+ /*
+ * Get the required information for input conversion of the return value.
+ *
+ * If the function uses VOID as result, it is better to return NULL.
+ * Anyway, let's be honest. This is just a template, so there is not much
+ * we can do here. This returns NULL except if the result type is text,
+ * where the result is the source text of the function.
+ */
+ if (pl_struct->prorettype != TEXTOID)
+ PG_RETURN_NULL();
+
+ type_tuple = SearchSysCache1(TYPEOID,
+ ObjectIdGetDatum(pl_struct->prorettype));
+ if (!HeapTupleIsValid(type_tuple))
+ elog(ERROR, "cache lookup failed for type %u", pl_struct->prorettype);
+ pg_type_entry = (Form_pg_type) GETSTRUCT(type_tuple);
+ result_typioparam = getTypeIOParam(type_tuple);
+
+ fmgr_info_cxt(pg_type_entry->typinput, &result_in_func, proc_cxt);
+ ReleaseSysCache(type_tuple);
+
+ ret = InputFunctionCall(&result_in_func, source, result_typioparam, -1);
+ PG_RETURN_DATUM(ret);
+}
diff --git a/src/test/modules/plsample/plsample.control b/src/test/modules/plsample/plsample.control
new file mode 100644
index 0000000000..1e67251a1e
--- /dev/null
+++ b/src/test/modules/plsample/plsample.control
@@ -0,0 +1,8 @@
+# plsample extension
+comment = 'PL/Sample'
+default_version = '1.0'
+module_pathname = '$libdir/plsample'
+relocatable = false
+schema = pg_catalog
+superuser = false
+trusted = true
diff --git a/src/test/modules/plsample/sql/plsample.sql b/src/test/modules/plsample/sql/plsample.sql
new file mode 100644
index 0000000000..bf0fddac7f
--- /dev/null
+++ b/src/test/modules/plsample/sql/plsample.sql
@@ -0,0 +1,15 @@
+CREATE EXTENSION plsample;
+-- Create and test some dummy functions
+CREATE FUNCTION plsample_result_text(a1 numeric, a2 text, a3 integer[])
+RETURNS TEXT
+AS $$
+ Example of source with text result.
+$$ LANGUAGE plsample;
+SELECT plsample_result_text(1.23, 'abc', '{4, 5, 6}');
+
+CREATE FUNCTION plsample_result_void(a1 text[])
+RETURNS VOID
+AS $$
+ Example of source with void result.
+$$ LANGUAGE plsample;
+SELECT plsample_result_void('{foo, bar, hoge}');