Insert statement in plpython function greenplum database

Question

I am creating a plpython function in greenplum. for plpy.prepare("INSERT INTO ....") fails with error:
ERROR: plpy.SPIError: function cannot execute on segment because it issues a non-SELECT statement (plpython.c:4656) (seg4 slice1 den-gp5-seg03:40000 pid=119213) (cdbdisp.c:1322)
Are inserts not allowed in plpython functions? I don't see much help with inserts in documentation. greenplum plpython doc

Answer 1

You can use plpy.execute("INSERT INTO ....") rather than plpy.prepare("INSERT INTO ....").

plpy.prepare() is used for prepared statement. If you want to use it, please refer to the following example.

postgres=# create table your_table (yourstr char(2), yournum int);
CREATE TABLE
postgres=# do $$
postgres$# plan = plpy.prepare("insert into your_table values($1,$2)", ["text", "int"]);
postgres$# plpy.execute(plan, ["Gx", 7]);
postgres$# $$ language plpython3u;
DO
postgres=# select * from your_table;
 yourstr | yournum 
---------+---------
 Gx      |       7
(1 row)
postgres=# 

Here are available pypl functions (Greenplum 5.10 doc here)

Answer 2

I'm not sure if insert will work here; put insert statement in a gp function and fire a "select my_func(arg1, arg2)" from plpython func