I execute following two queries on an oracle database:
select * from qsn join plc on plc.fk_qsn = qsn.id where rownum < 48507
which returns result in less than a second and with following execution plan
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and
select * from qsn join plc on plc.fk_qsn = qsn.id where rownum < 48508
which takes more than 10 seconds to execute and uses following execution plan
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Can anyone help me understand the reason why this strange behavior happens?
