Re: dropdb --force

vignesh C <vignesh21@gmail.com>

From: vignesh C <vignesh21@gmail.com>
To: Pavel Stehule <pavel.stehule@gmail.com>
Cc: Ryan Lambert <ryan@rustprooflabs.com>, Tom Lane <tgl@sss.pgh.pa.us>, Thomas Munro <thomas.munro@gmail.com>, Anthony Nowocien <anowocien@gmail.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>, Filip Rembiałkowski <filip.rembialkowski@gmail.com>
Date: 2019-09-18T03:59:39Z
Lists: pgsql-hackers
On Wed, Sep 18, 2019 at 8:30 AM Pavel Stehule <pavel.stehule@gmail.com> wrote:
>
>
Hi Pavel,

One Comment:
In the documentation we say drop database will fail after 60 seconds
  <varlistentry>
    <term><literal>FORCE</literal></term>
    <listitem>
     <para>
      Attempt to terminate all existing connections to the target database.
     </para>
     <para>
      This will fail, if current user has no permissions to terminate other
      connections. Required permissions are the same as with
      <literal>pg_terminate_backend</literal>, described
      in <xref linkend="functions-admin-signal"/>.

      This will also fail, if the connections do not terminate in 60 seconds.
     </para>
    </listitem>
   </varlistentry>


But in TerminateOtherDBBackends:
foreach (lc, pids)
+ {
+ int pid = lfirst_int(lc);
+
+ (void) kill(pid, SIGTERM); /* ignore any error */
+ }
+
+ /* sleep 100ms */
+ pg_usleep(100 * 1000L);
+ }

We check for any connected backends after sending kill signal in
CountOtherDBBackends and throw error immediately.

I had also tested this scenario to get the following error immediately:
test=# drop database (force) test1;
ERROR:  database "test1" is being accessed by other users
DETAIL:  There is 1 other session using the database.

I feel some change is required to keep documentation and code in sync.

Regards,
Vignesh
EnterpriseDB: http://www.enterprisedb.com



Commits

  1. Add tests for '-f' option in dropdb utility.

  2. Move pump_until to TestLib.pm.

  3. Add the support for '-f' option in dropdb utility.

  4. Introduce the 'force' option for the Drop Database command.

  5. Improve CREATE/DROP/RENAME DATABASE so that when failing because the source