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You are evaluating the performance of a SQL statement that accesses a very large table, and
have run the following query producing the output shown:
59ddf586ac627 - which two reasons would the; “physical read total bytes” statistic be greater than the “cell physical IO

For which two reasons would the; “physical read total bytes” statistic be greater than the “cell
physical IO bytes eligible for predicate offload” statistic?

A.
There is an index on the column used in the where clause, causing “cell multiblock physical
reads” to be requested by the database instance, resulting in additional I/O for blocks in the cells.

B.
The table is an IOT and has an overflow segment, causing “cell multiblock physical reads” to be
requested by the database instance, resulting in additional I/O for block in the cells.

C.
There is an uncommitted transaction that has modified some of the table blocks, causing some
“cell single block physical reads” to be requested by the database instance, resulting in additional
I/O for block in the cells.

D.
The table is an indexed clustered table, causing “cell single block physical reads” to be
requested by the database instance, resulting in additional I/O forblocks in the cells.

E.
There are migrated rows in the table, causing some “cell single block physical reads” to be
requested by the database instance, resulting in additional I/O for blocks in the cells.

Explanation:
Note:
* physical read total bytes: the size of the segment to read is known by the database, and must be
read entirely from the database’s perspective.
*cell physical IO bytes eligible for predicate offload: this statistic shows the amount of data which
the cell server is able to process on behalf of the database, instead of the database processing
and the cell server just delivering blocks.
*Cell physical IO bytes eligible for predicate offload — This number should be high
The higher the number more MB/GB is filtered out at the cell level itself rather sending it to the
buffer cache to filter the rows.
*In this case, all bytes are processed on the cellserver (cell physical IO bytes eligible for predicate
offload=physical read total bytes)
*Cell Offloading:-The storage cells are intelligent enough to process some workload inside them, saving the
database nodes from that work. This process is referred to as cell offloading.

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