Re: dropdb --force

On Thu, Sep 19, 2019 at 12:14 AM Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com> wrote:
>
> Hi
>
> I am sending updated version - the changes against last patch are two. I use pg_terminate_backed for killing other terminates like Tom proposed. I am not sure if it is 100% practical - on second hand the necessary right to kill other sessions is almost available - and consistency with pg_terminal_backend has sense. More - native implementation is significantly better then solution implemented outer. I fixed docs little bit - the timeout for logout (as reaction on SIGTERM is only 5 sec).
>

Few comments on the patch.

@@ -598,10 +598,20 @@ standard_ProcessUtility(PlannedStmt *pstmt,
case T_DropdbStmt:
{
DropdbStmt *stmt = (DropdbStmt *) parsetree;
+ bool force = false;
+ ListCell *lc;
+
+ foreach(lc, stmt->options)
+ {
+ DefElem *item = (DefElem *) lfirst(lc);
+
+ if (strcmp(item->defname, "force") == 0)
+ force = true;
+ }

/* no event triggers for global objects */
PreventInTransactionBlock(isTopLevel, "DROP DATABASE");
- dropdb(stmt->dbname, stmt->missing_ok);
+ dropdb(stmt->dbname, stmt->missing_ok, force);

If you see the createdb, then options are processed inside the
createdb function but here we are processing outside
the function. Wouldn't it be good to keep them simmilar and also it
will be expandable in case we add more options
in the future?

initPQExpBuffer(&sql);

- appendPQExpBuffer(&sql, "DROP DATABASE %s%s;",
- (if_exists ? "IF EXISTS " : ""), fmtId(dbname));
-
/* Avoid trying to drop postgres db while we are connected to it. */
if (maintenance_db == NULL && strcmp(dbname, "postgres") == 0)
maintenance_db = "template1";
@@ -134,6 +136,10 @@ main(int argc, char *argv[])
host, port, username, prompt_password,
progname, echo);
+ appendPQExpBuffer(&sql, "DROP DATABASE %s%s%s;",
+ (force ? " (FORCE) " : ""),
+ (if_exists ? "IF EXISTS " : ""), fmtId(dbname));
+

I did not understand why you have moved this code after
connectMaintenanceDatabase function? I don't see any problem but in
earlier code
initPQExpBuffer and appendPQExpBuffer were together now you have moved
appendPQExpBuffer after the connectMaintenanceDatabase so if there is
no reason to do that then better to keep it how it was earlier.

-extern bool CountOtherDBBackends(Oid databaseId,
- int *nbackends, int *nprepared);
+extern bool CountOtherDBBackends(Oid databaseId, int *nbackends, int
*nprepared);

Unrelated change

--
Regards,
Dilip Kumar
EnterpriseDB: http://www.enterprisedb.com