Race condition in create table

I wonder if it is considered to be expected behavior that concurrent
execution of "create table if not exists" may return errors:

knizhnik(at)knizhnik:~/dtm-data$ pgbench -n -c 8 -t 20 -f create_table.sql
postgres
client 2 aborted in command 0 (SQL) of script 0; ERROR:  duplicate key
value violates unique constraint "pg_type_typname_nsp_index"
DETAIL:  Key (typname, typnamespace)=(t2, 2200) already exists.

client 0 aborted in command 0 (SQL) of script 0; ERROR:  duplicate key
value violates unique constraint "pg_type_typname_nsp_index"
DETAIL:  Key (typname, typnamespace)=(t2, 2200) already exists.

client 1 aborted in command 0 (SQL) of script 0; ERROR:  duplicate key
value violates unique constraint "pg_type_typname_nsp_index"
DETAIL:  Key (typname, typnamespace)=(t2, 2200) already exists.

client 3 aborted in command 0 (SQL) of script 0; ERROR:  duplicate key
value violates unique constraint "pg_type_typname_nsp_index"
DETAIL:  Key (typname, typnamespace)=(t2, 2200) already exists.

NOTICE:  relation "t2" already exists, skipping
client 5 aborted in command 0 (SQL) of script 0; ERROR:  duplicate key
value violates unique constraint "pg_type_typname_nsp_index"
DETAIL:  Key (typname, typnamespace)=(t2, 2200) already exists.

client 6 aborted in command 0 (SQL) of script 0; ERROR:  duplicate key
value violates unique constraint "pg_type_typname_nsp_index"
DETAIL:  Key (typname, typnamespace)=(t2, 2200) already exists.

NOTICE:  relation "t2" already exists, skipping
NOTICE:  relation "t2" already exists, skipping
NOTICE:  relation "t2" already exists, skipping
NOTICE:  relation "t2" already exists, skipping
client 7 aborted in command 0 (SQL) of script 0; ERROR:  duplicate key
value violates unique constraint "pg_type_typname_nsp_index"
DETAIL:  Key (typname, typnamespace)=(t2, 2200) already exists.

NOTICE:  relation "t2" already exists, skipping
NOTICE:  relation "t2" already exists, skipping
NOTICE:  relation "t2" already exists, skipping
NOTICE:  relation "t2" already exists, skipping
NOTICE:  relation "t2" already exists, skipping
NOTICE:  relation "t2" already exists, skipping
NOTICE:  relation "t2" already exists, skipping
NOTICE:  relation "t2" already exists, skipping
NOTICE:  relation "t2" already exists, skipping
NOTICE:  relation "t2" already exists, skipping
NOTICE:  relation "t2" already exists, skipping
NOTICE:  relation "t2" already exists, skipping
NOTICE:  relation "t2" already exists, skipping
NOTICE:  relation "t2" already exists, skipping

--------------------------------------------------------------------------------

For partitions behavior is slightly different:

knizhnik(at)knizhnik:~/dtm-data$ pgbench -n -c 8 -t 20 -f create_part.sql
postgres
NOTICE:  relation "t_1" already exists, skipping
client 0 aborted in command 0 (SQL) of script 0; ERROR:  relation "t_1"
already exists

NOTICE:  relation "t_1" already exists, skipping
NOTICE:  relation "t_1" already exists, skipping
NOTICE:  relation "t_1" already exists, skipping
client 1 aborted in command 0 (SQL) of script 0; ERROR:  relation "t_1"
already exists

NOTICE:  relation "t_1" already exists, skipping
NOTICE:  relation "t_1" already exists, skipping
NOTICE:  relation "t_1" already exists, skipping
NOTICE:  relation "t_1" already exists, skipping
client 3 aborted in command 0 (SQL) of script 0; ERROR:  relation "t_1"
already exists

NOTICE:  relation "t_1" already exists, skipping
NOTICE:  relation "t_1" already exists, skipping
NOTICE:  relation "t_1" already exists, skipping
NOTICE:  relation "t_1" already exists, skipping
client 6 aborted in command 0 (SQL) of script 0; ERROR:  relation "t_1"
already exists

NOTICE:  relation "t_1" already exists, skipping
NOTICE:  relation "t_1" already exists, skipping
NOTICE:  relation "t_1" already exists, skipping
NOTICE:  relation "t_1" already exists, skipping
client 2 aborted in command 0 (SQL) of script 0; ERROR:  relation "t_1"
already exists

NOTICE:  relation "t_1" already exists, skipping
NOTICE:  relation "t_1" already exists, skipping
NOTICE:  relation "t_1" already exists, skipping
client 5 aborted in command 0 (SQL) of script 0; ERROR:  relation "t_1"
already exists

client 4 aborted in command 0 (SQL) of script 0; ERROR:  relation "t_1"
already exists

--
Konstantin Knizhnik
Postgres Professional: http://www.postgrespro.com
The Russian Postgres Company