PREPARE SQL plan for Postgresql - with bind varible list -

i have sql-command want use prepare statment googling found syntax :

prepare sqlplan (bigint) select * employees  employee id in ($1); execute usrrptplan2(123); 

i have 2 question :

1. how can use list/array (size unknown) in bind variable part?

2. this sqls works - want can use "prepare plan if not exists ?"

since running second time get: error: prepared statement "sqlplan" exists

https://www.postgresql.org/docs/current/static/sql-prepare.html

prepare if not exists not work - have https://www.postgresql.org/docs/current/static/sql-deallocate.html deallocate first.

regarding array in argument, eg:

t=# prepare a(text[]) select * pg_class relname = any($1); prepare t=# execute ('{pg_tables,pg_indexes}');   relname   | relnamespace | reltype | reloftype | relowner | relam | relfilenode | reltablespace | relpages | reltuples | relallvisible | reltoastrelid | reltoastidxid | relhasindex | relisshared | relpersistence | relkind | relnatts | relchecks | relhasoids |  relhaspkey | relhasrules | relhastriggers | relhassubclass | relispopulated | relfrozenxid | relminmxid |    relacl     | reloptions ------------+--------------+---------+-----------+----------+-------+-------------+---------------+----------+-----------+---------------+---------------+---------------+-------------+-------------+----------------+---------+----------+-----------+------------+ ------------+-------------+----------------+----------------+----------------+--------------+------------+---------------+------------  pg_tables  |           11 |   11075 |         0 |       10 |     0 |       11074 |             0 |        0 |         0 |             0 |             0 |             0 | f           | f           | p              | v       |        7 |         0 | f          |  f          | t           | f              | f              | t              |            0 |          0 | {=r/postgres} |  pg_indexes |           11 |   11083 |         0 |       10 |     0 |       11082 |             0 |        0 |         0 |             0 |             0 |             0 | f           | f           | p              | v       |        5 |         0 | f          |  f          | t           | f              | f              | t              |            0 |          0 | {=r/postgres} | (2 rows) 

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