What is the difference between two.. For row migration another block has also 8kb.. How can it be fit as entire row ? If it holds half of the info then again it will be same as row chaining.. Its confusing!!
How It Works: Row Migration Example Initial State: Block A contains Row 1. Block A has 3 KB of free space. Row 1 size: 4 KB (fits in Block A initially). Update: Row 1 is updated and grows to 5 KB. Block A no longer has enough space for Row 1. Migration Process: Oracle finds a new block, Block B, with sufficient space (8 KB free). Row 1 is moved entirely to Block B. Block A retains a pointer to Block B. Result: Row 1 resides entirely in Block B. Block A has a pointer to Block B. No part of Row 1 remains in Block A.
Row Chaining Example: Initial State: A new row (Row 2) is being inserted. Row 2 size: 12 KB. Chaining Process: Block C has 8 KB free. Block D has 8 KB free. Insert: Row 2 cannot fit into a single block. The first 8 KB of Row 2 is stored in Block C. The remaining 4 KB of Row 2 is stored in Block D. Block C has a pointer to Block D. Result: Row 2 spans Block C and Block D. Block C contains the first part of Row 2 and a pointer to Block D. Block D contains the remaining part of Row 2.
This was very helpful. Thank you for the videos.
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Tq bro
Bro plz upload more videos
Will upload soon. Thanks for watching !! :)
What is the difference between two.. For row migration another block has also 8kb.. How can it be fit as entire row ? If it holds half of the info then again it will be same as row chaining.. Its confusing!!
How It Works:
Row Migration Example
Initial State:
Block A contains Row 1.
Block A has 3 KB of free space.
Row 1 size: 4 KB (fits in Block A initially).
Update:
Row 1 is updated and grows to 5 KB.
Block A no longer has enough space for Row 1.
Migration Process:
Oracle finds a new block, Block B, with sufficient space (8 KB free).
Row 1 is moved entirely to Block B.
Block A retains a pointer to Block B.
Result:
Row 1 resides entirely in Block B.
Block A has a pointer to Block B.
No part of Row 1 remains in Block A.
Row Chaining Example:
Initial State:
A new row (Row 2) is being inserted.
Row 2 size: 12 KB.
Chaining Process:
Block C has 8 KB free.
Block D has 8 KB free.
Insert:
Row 2 cannot fit into a single block.
The first 8 KB of Row 2 is stored in Block C.
The remaining 4 KB of Row 2 is stored in Block D.
Block C has a pointer to Block D.
Result:
Row 2 spans Block C and Block D.
Block C contains the first part of Row 2 and a pointer to Block D.
Block D contains the remaining part of Row 2.
Hope it helped !! :)
Thanks for ur explanation here.. Its clear now..