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PLW-07204:

conversion away from column type may result in sub-optimal query plan
Cause: The column type and the bind type do not exactly match. This may result in the column being converted to the type of the bind variable. This type conversion may prevent the SQL optimizer from using any index the column participates in. This may adversely affect the execution performance of this statement.
Action: To make use of any index for this column, make sure the bind type is the same type as the column type.