In data file it contains committed data and uncommitted data when server process want to bring the db block to buffer cache how it will differentiate the difference between committed and uncommitted data.
Thanks in advance!
In the data block header, there are transaction slots of 23 bytes each which stores the information whether it is commited or uncommited.
In the datafile block header, there are ITL entries (Interested transaction list). From here, server process comes to know that the block was modified or not i.e. it has to read from block or it has to go to undo block to find consistent data.
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