[support] User ID in users table

[Kamal Palei]

Jamie, All
Thanks for info.

If this is the case, I would expect user id to be monotonically increase.
I can see my users table, the UIDs follow as

0,1,2,3,4,5,6,24,25,26,33,40,41,42

I do uninstall / install of my custom modules, but I hope that is no way
related to uid selection.

Just wondering what may cause this.

Also I delete nodes sometimes.., can that cause this issue, I hope it is
unlikely...

Regards
kamal
necs, blr

On Sat, Dec 1, 2012 at 1:26 PM, Jamie Holly <hovercrafter at earthlink.net>wrote:

> UID is figured by select max(uid). Here is the exact code from user.module:
>
>   if (empty($account->uid)) {
>          $account->uid = db_next_id(db_query('SELECT MAX(uid) FROM
> {users}')->fetchField());
>        }
>        // Allow 'created' to be set by the caller.
>        if (!isset($account->created)) {
>          $account->created = REQUEST_TIME;
>        }
>        $success = drupal_write_record('users', $account);
>
> $account->uid == 0, which is the same as empty.
>
> Other modules can influence this via the API, such as hook_user_presave,
> but for the core functionality, this is how the UID is figured.
>
>
> Jamie Holly
> http://www.intoxination.net
> http://www.hollyit.net
>
> On 11/30/2012 9:44 PM, Michael Prasuhn wrote:
> > No. If if was just using SELECT MAX(uid) FROM {users} then it wouldn't
> have gaps like the OP was experiencing.
> >
> > Note that the result from that query is actually fed to db_next_id()
> which in turn uses a DBMS specific method to ensure unique IDs. (In MySQL
> this means using an insert query into a table that is set to auto increment
> and then reading the ID of the inserted record. This cannot produce
> duplicate keys. see
> http://api.drupal.org/api/drupal/includes%21database%21mysql%21database.inc/function/DatabaseConnection_mysql%3A%3AnextId/7)
> >
> > -Mike
> > __________________
> > Michael Prasuhn
> > http://mikeyp.net
> >
> > On Nov 30, 2012, at 5:42 AM, Earnie Boyd <earnie at users.sourceforge.net>
> wrote:
> >
> > > On Fri, Nov 30, 2012 at 8:32 AM, Jamie Holly wrote:
> > >> This isn't the case in D7.  UID is assigned by a SELECT MAX(uid) FROM
> > >> {users}. Check user.module line 571.
> > >
> > > Unless the whole users table is locked then this is guaranteed to fail
> > > under heavy use.  Some poor user is going to get a DB error of
> > > duplicate key.  The chances may be small but there is a chance it will
> > > happen.  Do you know the issue # that caused this to happen?
> > >
> > > --
> > > Earnie
> > > -- https://sites.google.com/site/earnieboyd
> > > --
> > > [ Drupal support list | http://lists.drupal.org/ ]
> >
>
> --
> [ Drupal support list | http://lists.drupal.org/ ]
>
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