Re: Stuck Query

From: Stephane Faroult <sfaroult_at_oriole.com>
Date: Fri, 19 Sep 2003 15:19:40 -0800
Message-ID: <F001.005D0873.20030919151940@fatcity.com>

"MacGregor, Ian A." wrote:
>
> SQL> describe chanarch_nlc.archive_wave_i
> Name Null? Type
> ----------------------------------------- -------- --------------------------
> PV_ID NUMBER(38)
> TIMESTAMP DATE
> NANOSECS NUMBER(9)
> STAT NUMBER(8)
> SEVR NUMBER(8)
> OSTAT NUMBER(16)
> VALUE CHANARCH_NLC.INT_VALUES
>
> SQL> describe chanarch_nlc.arch_wave_i
> Name Null? Type
> ----------------------------------------- -------- --------------------------
> PV_ID NUMBER(38)
> TIMESTAMP DATE
> NANOSECS NUMBER(9)
> STAT NUMBER(8)
> SEVR NUMBER(8)
> OSTAT NUMBER(16)
> VALUE CHANARCH_NLC.INT_VALUES
>
> SQL> describe chanarch_nlc.int_values
> chanarch_nlc.int_values VARRAY(16384) OF NUMBER(38)
>
> Select * from chanarch_nlc.arch_wave_i
> Where pv_id = 433 and
> Timestamp between '18-SEP-2003:13:48:00' AND '18-SEP-2003:13:49:00'
> ORDER BY TIMESTAMP, NANOSECONDS
> /
>
> Returns 1 row plus the associated varray data in one second
>
> Select * from chanarch_nlc.archive_wave_i
> Where pv_id = 433 and
> Timestamp between '18-SEP-2003:13:48:00' AND '18-SEP-2003:13:49:00'
> ORDER BY TIMESTAMP, NANOSECONDS
>
> Returns 0 rows in about a second
>
> Select * from chanarch_nlc.arch_wave_i
> Where pv_id = 433 and
> Timestamp between '18-SEP-2003:13:48:00' AND '18-SEP-2003:13:49:00'
> Union all
> Select * from chanarch_nlc.archive_wave_i
> Where pv_id = 433 and
> Timestamp between '18-SEP-2003:13:48:00' AND '18-SEP-2003:13:49:00'
>
> Returns a single row with the varray data in a second
>
> However
>
> Select * from chanarch_nlc.arch_wave_i
> Where pv_id = 433 and
> Timestamp between '18-SEP-2003:13:48:00' AND '18-SEP-2003:13:49:00'
> Union all
> Select * from chanarch_nlc.archive_wave_i
> Where pv_id = 433 and
> Timestamp between '18-SEP-2003:13:48:00' AND '18-SEP-2003:13:49:00'
> Order by 2,3
>
> Never returns. It waits forever on a sequential dbfile read event of one the files used by the lob segment which contains the varray data for the value column of chanarch_nlc.arch_wave_i. Nothing appears to be blocking the session. The query plan is as one would expect.
>
> Similar queries against different tables with the same structure proceed without incident.
>
> Ian MacGregor
> Stanford Linear Accelerator Center
> ian_at_SLAC.Stanford.edu
> --

Ian,

  Independently from the fact that you have hit a bug, does

  select *
  from (Select * from chanarch_nlc.arch_wave_i

        Where pv_id = 433 and
        Timestamp between '18-SEP-2003:13:48:00' AND
'18-SEP-2003:13:49:00'
        Union all
        Select * from chanarch_nlc.archive_wave_i
        Where pv_id = 433 and
        Timestamp between '18-SEP-2003:13:48:00' AND

'18-SEP-2003:13:49:00')
 Order by 2,3

 return ? (Perhaps /*+ NO_MERGE */ would help)

-- 
Regards,

Stephane Faroult
Oriole Software
-- 
Please see the official ORACLE-L FAQ: http://www.orafaq.net
-- 
Author: Stephane Faroult
  INET: sfaroult_at_oriole.com

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Received on Fri Sep 19 2003 - 18:19:40 CDT