I/O Isn’t the RDBMS Bottleneck - It’s CPU
Search Algorithms are Based on Disk Addresses
- Multiple look-ups before you get to a memory pointer
Data is Frequently Copied
- Buffers must be available to be used by other pages
Tables and Indices are Turned Into Random Pages
- Serial table scans require a separate lookup sequence for each page
- An index search invokes several page look-ups, then a data page search
Optimization is Biased Toward I/O-Avoidance
- No attention to instruction path length to perform memory operations
- Optimizer must assume a page is on disk - it’s usually not
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