Forcing a specific rollback segment on a transaction does not seem to work

Question

Hi!
We're using Oracle 9.2.0.5.0 on Sun Solaris and we're still configured to use Rollback Segments.
We have an issue with Snapshot too old due to RBS too small on a long query I attach below for reference:
set heading off
set pagesize 0
set feedback off
set linesize 200
<<<<< SET TRANSACTION USE ROLLBACK SEGMENT UMF_RBS_LARGE_TRAN; <<<<<
SELECT ucms_cards.msisdn
|| ';;' || to_char(to_date(substr(ucms_cards.notes,14+length(ucms_cards.msisdn),19),'MM-DD-YYYY.HH24-MI-SS'),'DD/MM/YYYY HH24:MI:SS')
|| ';;' || to_char(ucms_batches.expiry_date,'dd/mm/yyyy')
|| ';;' || ucms_cards.serial_no
|| ';;' || ucms_cards.serial_no
|| ';;' || ucms_cards.batch_serial_no
|| ';;' || ' '
|| ';;' || CASE ucms_cards.card_status
WHEN 'used' THEN '1'
ELSE '0'
END
|| ';;' || CASE WHEN date_booked_in is null THEN '01/01/1970 00:00:00' ELSE to_char(date_booked_in,'DD/MM/YYYY') || ' 00:00:00' END
|| ';;' || ' '
from ucms_batches,ucms_cards, UCMS_EVENT_LOG
WHERE ucms_cards.batch_serial_no = ucms_batches.serial_no
AND ucms_cards.serial_no = substr(UCMS_EVENT_LOG.ENTITY_ID,11,length(UCMS_EVENT_LOG.ENTITY_ID)-9)
AND UCMS_EVENT_LOG.PARTY_NO in (0)
AND UCMS_EVENT_LOG.TIMESTAMP>=TO_TIMESTAMP(TO_CHAR(SYSDATE-1, 'DD-MM-YYYY') || ' 00:00:01', 'DD-MM-YYYY HH24:MI:SS')
AND UCMS_EVENT_LOG.TIMESTAMP<=TO_TIMESTAMP(TO_CHAR(SYSDATE-1, 'DD-MM-YYYY') || ' 23:59:59', 'DD-MM-YYYY HH24:MI:SS')
AND UCMS_EVENT_LOG.USER_ID LIKE 'SCP-AGENT1%'
AND UCMS_EVENT_LOG.EVENT_TYPE_ID IN (1,2)
AND UCMS_EVENT_LOG.ENTITY_TYPE_ID LIKE 'ucms_cards%'
UNION
SELECT ucms_imported_cards.msisdn
|| ';;' || to_char(to_date(substr(ucms_imported_cards.notes,14+length(ucms_imported_cards.msisdn),19),'MM-DD-YYYY.HH24-MI-SS'),'DD/MM/YYYY H24:MI:SS')
|| ';;' || to_char(ucms_imported_cards.expiry_date,'dd/mm/yyyy')
|| ';;' || ucms_imported_cards.serial_no
|| ';;' || ucms_imported_cards.serial_no
|| ';;' || DBMS_UTILITY.GET_HASH_VALUE(ucms_imported_cards.card_type,1,65536)
|| ';;' || ' '
|| ';;' || CASE ucms_imported_cards.card_status
WHEN 'used' THEN '1'
ELSE '0'
END
|| ';;' || '01/01/1970 00:00:00'
|| ';;' || ' '
from ucms_imported_cards, UCMS_EVENT_LOG
where ucms_imported_cards.serial_no = substr(UCMS_EVENT_LOG.ENTITY_ID,11,length(UCMS_EVENT_LOG.ENTITY_ID)-9)
AND UCMS_EVENT_LOG.PARTY_NO in (0)
AND UCMS_EVENT_LOG.TIMESTAMP>=TO_TIMESTAMP(TO_CHAR(SYSDATE-1, 'DD-MM-YYYY') || ' 00:00:01', 'DD-MM-YYYY HH24:MI:SS')
AND UCMS_EVENT_LOG.TIMESTAMP<=TO_TIMESTAMP(TO_CHAR(SYSDATE-1, 'DD-MM-YYYY') || ' 23:59:59', 'DD-MM-YYYY HH24:MI:SS')
AND UCMS_EVENT_LOG.USER_ID LIKE 'SCP-AGENT1%'
AND UCMS_EVENT_LOG.EVENT_TYPE_ID LIKE '2%'
AND UCMS_EVENT_LOG.ENTITY_TYPE_ID LIKE 'ucms_imported_cards%';
As you see we forced the session to use a huge RBS created for the purpose, but strangely after a long while the query fails with a RBS too small failure due to another RBS, not the one specified.
Is there any chance the UNION or any other component of the query is implicitly opening a new transaction with a different RBS associated?
Any chance to force the same RBS specified explicitly?
Thanks!
Mike

Answer 1

albertone wrote:
but strangely after a long while the query fails with a RBS too small failure due to another RBS, not the one specified.You misunderstand snapshot too old. It can be caused by other sessions same as by your session. Assume AFTER your session issued select some other session modified one (or more) tables ucms_batches, ucms_cards, UCMS_EVENT_LOG and committed changes. By the time your select reaches to fetch rows modified by that other session rollback extents in rollback segment used by that other session were reused. You will get snapshot too old. Bottom line - all sessions modifying table(s) used by your select must use rollback segments large enough so they are not overwritten before corresponding rows are needed by your select.
SY.