For Read Stability locks are not applicable for phantoms,
What is Phantoms?
Answers were Sorted based on User's Feedback
Answer / santoshkumar jangamashetti
example for Phantoms:
• Transaction1 opens a cursor and reads account
information, keeping a running sum of the total balance for
the selected accounts.
• Transaction2 inserts a new account that falls
within the range of accounts being processed by
Transaction1, but the insert occurs after Transaction1 has
passed the new account.
• Transaction2 commits the insert.
• Transaction1 runs a query to sum the values to
check the accuracy of the running total. But the totals
will not match.
Is This Answer Correct ? | 5 Yes | 2 No |
Answer / prachi
In read stability,
if t1 is performing read and t2 has done some changes in
the database which has same crieteria as T1, these new
updates or rows added by t2 is called phantom, which will
not be read during the read stability lock...
Is This Answer Correct ? | 1 Yes | 0 No |
if suppose i am having an ACCOUNT table with 3 coloumns ACC. NO,ACC. NAME,ACC. AMOUNT . If a unique index is also defined on ACC.NO and ACC.NAME then write a query to retrieve account holders records who have more than 1 ACC.
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