Heavy Sequential I/O on Index Wait

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Statement I/O is spent on sequential I/O (usually representing a range scan) on the index specified in the Object column. If the statement is DML and the index is not used in the execution plans, then the I/O represents the index maintenance overhead, caused by fetching the index blocks for update to memory.

Heavy Sequential I/O on Index findings

	Description
What to do next	Perform one of the following options: n   Click the Locate icon to see if the index is used in the execution plan. n   Select the findings type to investigate the objects used and their structure in the Objects tab. n   Select the Activity workspace, locate the statement associated with objects, and drill to the index overtime consumption for the statement in the Activity workspace.
Advice	If this is the result of a range scan, consider one of the following solutions: n   If the index is not used to prevent a sort operation, consider adding the INDEX_FFS hint and change DB_FILE_MULTIBLOCK_READ_COUNT (now standing on X) to a higher value. n   Switch to another index, add a new index, or change the index structure. n   Add columns to the index to enable index only access. n   Switch to a full table scan n   Partition the table or the index n   Create a cluster with just one table in it and a cluster key used as the index key. If this is due to an index overhead, consider reducing the index overhead by deleting unused indices, or unused columns in used indices. Findings refer to the whole statement - not to a specific execution plan. If a step doesn't exist in the selected execution plan (unless this is the result of an index overhead), switch to another plan and locate the relevant step.

    

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