Issue after 11g upgarde.

Question

after upgarding to 11g the code piece did not work for some of the records -
forall bulk_index in v_blockBegin..v_blockEnd
save exceptions
insert into ofr_pop_stng( FILE_NM,
OFR_ID,
ACSIN_NB,
FILE_DTL_ID,
ACCT_REF_NB,
LAST_ACSIN_IN,
OPT_FILE_DTL_ID)
select g_DataFileName,
g_offerId,
g_validRecords(bulk_index),
g_fileDetailId,
g_arn_c(bulk_index),
'Y',
g_OPTfileDetailId
from dual
where not exists( select /*+ index(ofr_pop pk_ofr_pop) */
null
from ofr_pop
where ofr_id = g_offerId
and acsin_nb = g_validRecords(bulk_index)
union all
select /*+ index(ofr_pop_stng ofr_pop_stng_idx) */
null
from ofr_pop_stng
where ofr_id = g_offerId
and acsin_nb = g_validRecords(bulk_index));
two issues were found - 1. even though conditions have been identified to make sure if record already exists in ofr_pop and ofr_pop_stng table than should not insrted again
2. Some if the records even though are present in collections did not insert in staging table.
This is really weierd and annoying. A Hight priority ticket has been opened and prod rollback to 10g in progress.

Answer 1

This leads me to believe that your production environment differs from UAT/Dev environments in some way, that is causing this issue (assuming it is a valid issue) to show up consistently in prod and not in other environments. Can you determine what that difference is ?
When the issue showed up in your Dev/UAT environments, what did you do ? Open an SR ? If so, what was the resolution ? If not, why not ?
HTH
Srini