Some articles on io, logical io:
... DUAL was originally a table and the database engine would perform disk IO on the table when selecting from DUAL ... This disk IO was usually logical IO (not involving physical disk access) as the disk blocks were usually already cached in memory ... This resulted in a large amount of logical IO against the DUAL table ...
Famous quotes containing the word logical:
“The truth is, that common-sense, or thought as it first emerges above the level of the narrowly practical, is deeply imbued with that bad logical quality to which the epithet metaphysical is commonly applied; and nothing can clear it up but a severe course of logic.”
—Charles Sanders Peirce (18391914)