SQL-standard function body

This adds support for writing CREATE FUNCTION and CREATE PROCEDURE
statements for language SQL with a function body that conforms to the
SQL standard and is portable to other implementations.

Instead of the PostgreSQL-specific AS $$ string literal $$ syntax,
this allows writing out the SQL statements making up the body
unquoted, either as a single statement:

    CREATE FUNCTION add(a integer, b integer) RETURNS integer
        LANGUAGE SQL
        RETURN a + b;

or as a block

    CREATE PROCEDURE insert_data(a integer, b integer)
    LANGUAGE SQL
    BEGIN ATOMIC
      INSERT INTO tbl VALUES (a);
      INSERT INTO tbl VALUES (b);
    END;

The function body is parsed at function definition time and stored as
expression nodes in a new pg_proc column prosqlbody.  So at run time,
no further parsing is required.

However, this form does not support polymorphic arguments, because
there is no more parse analysis done at call time.

Dependencies between the function and the objects it uses are fully
tracked.

A new RETURN statement is introduced.  This can only be used inside
function bodies.  Internally, it is treated much like a SELECT
statement.

psql needs some new intelligence to keep track of function body
boundaries so that it doesn't send off statements when it sees
semicolons that are inside a function body.

Tested-by: Jaime Casanova <[email protected]>
Reviewed-by: Julien Rouhaud <[email protected]>
Discussion: https://www.postgresql.org/message-id/flat/[email protected]

1 files changed, 11 insertions, 4 deletions

diff --git a/src/bin/psql/describe.c b/src/bin/psql/describe.c
index 440249ff69d..52f7b2ce78c 100644
--- a/src/bin/psql/describe.c
+++ b/src/bin/psql/describe.c
@@ -505,11 +505,18 @@ describeFunctions(const char *functypes, const char *pattern, bool verbose, bool
 		appendPQExpBufferStr(&buf, ",\n ");
 		printACLColumn(&buf, "p.proacl");
 		appendPQExpBuffer(&buf,
-						  ",\n l.lanname as \"%s\""
-						  ",\n p.prosrc as \"%s\""
+						  ",\n l.lanname as \"%s\"",
+						  gettext_noop("Language"));
+		if (pset.sversion >= 140000)
+			appendPQExpBuffer(&buf,
+							  ",\n COALESCE(p.prosrc, pg_catalog.pg_get_function_sqlbody(p.oid)) as \"%s\"",
+							  gettext_noop("Source code"));
+		else
+			appendPQExpBuffer(&buf,
+							  ",\n p.prosrc as \"%s\"",
+							  gettext_noop("Source code"));
+		appendPQExpBuffer(&buf,
 						  ",\n pg_catalog.obj_description(p.oid, 'pg_proc') as \"%s\"",
-						  gettext_noop("Language"),
-						  gettext_noop("Source code"),
 						  gettext_noop("Description"));
 	}