# Security

> Source chapter 3.9 for PostgreSQL 9.6.

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LLMS index: [llms.txt](/en/llms.txt)

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#### 3.9.1 Default Role {#pg9-6-3-9-1-default-role}

Pg_signal_backend role is created in default. This role allow the transmission of the signal to the backend processes.

#### 3.9.2 Namespace {#pg9-6-3-9-2-namespace}

Role (user) names that begin with pg_ are no longer able to use because those are reserved.

**Example 47.** Role names starting from \&quot\;pg\_\&quot\;

```text
postgres=# CREATE ROLE pg_test1 ;
ERROR:  role name "pg_test1" is reserved
DETAIL:  Role names starting with "pg_" are reserved.
$ initdb --username=pg_admin data
initdb: superuser name "pg_admin" is disallowed; role names cannot begin
with "pg_"
$
```