Re: Fatal error while installing

Gibson wrote:
> I seem to get this error "user postgres could not be created, user
> account already exists" when trying to install postgres. Anyone knows
> how to fix this?

Sounds to me like the user postgres on the OS already exists.

Joshua D. Drake

>
> Erik Jones wrote:
>> Erik Jones wrote:
>>> Ok, consider the following table definition:
>>>
>>> CREATE TABLE stats (
>>> id SERIAL PRIMARY KEY,
>>> hits bigint default 0,
>>> clickthrus bigint default 0,
>>> referrals bigint default 0);
>>>
>>>
>>> Now, this table has a lot of rows that are constantly being updated
>>> by queries of the following form:
>>>
>>> UPDATE stats
>>> SET clickthrus = clickthrus + #
>>> WHERE id = blah; -- sub various values for # and blah
>>>
>>> There can be, and often are, multiple updates for the same row
>>> coming in at the same time, but never for the same field. My
>>> understanding of the locking involved is that updates take out
>>> row-exclusive locks to prevent other transactions from modifying the
>>> data and to serialize with other updates. So, multiple update
>>> statements to the same row come in, the first to arrive is granted a
>>> row-exclusive lock and the other wait. When the first is finished
>>> and commits, the second to have arrived get the lock, and so forth.
>>> Here is what I am seeing all through my logs:
>>>
>>> 2006-08-29 03:17:25 CDT 16074 192.168.1.173(35190):STATEMENT: ABORT
>>> 2006-08-29 03:17:25 CDT 8553 192.168.1.168(42707):ERROR: deadlock
>>> detected
>>> 2006-08-29 03:17:25 CDT 8553 192.168.1.168(42707):DETAIL: Process
>>> 8553 waits for ShareLock on transaction 1548224183; blocked by
>>> process 5499.
>>> Process 5499 waits for ShareLock on transaction 1548224182; blocked
>>> by process 8553.
>>> 2006-08-29 03:17:25 CDT 8553 192.168.1.168(42707):STATEMENT: UPDATE
>>> stats
>>> SET hits = hits + 3
>>> WHERE id = 271524;
>>>
>>> or,
>>>
>>> 2006-08-29 08:47:31 CDT 12479 192.168.1.168(46125):ERROR: deadlock
>>> detected
>>> 2006-08-29 08:47:31 CDT 12479 192.168.1.168(46125):DETAIL: Process
>>> 12479 waits for ExclusiveLock on tuple (3024,45) of relation 33942 of
>>> database 33325; blocked by process 12513
>>> .
>>> Process 12513 waits for ShareLock on transaction 1550567046; blocked
>>> by process 12495.
>>> Process 12495 waits for ShareLock on transaction 1550569729; blocked
>>> by process 12479.
>>> 2006-08-29 08:47:31 CDT 12479 192.168.1.168(46125):STATEMENT: UPDATE
>>> stats
>>> SET click_thrus = clickthrus + 1
>>> WHERE id = 275359;
>>>
>>> What's with ShareLock s on transactions? Where do those come from?
>>>
>>
>> I should also note that each of those updates occurs in it's own
>> transactions, but that they do not attempt to modify any other rows in
>> that table before commiting. They do, however, delete rows in
>> another common table (where they pulled the stat counts from), but the
>> rows they delete are disjunct.
>>
>> The whole process/algorithm is such:
>>
>> 1. Get rows matching X from temp table.
>> 2. Accumulate values from X and update row and field corresponding to
>> X in stats table.
>> 3. Delete rows collected in step one.
>> 4. Commit.
>> 5. Repeat from step 1.
>>
>> With multiple processes using the same algo and tables but for
>> different values of X.
>>
>>
>
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