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Cost Model¶

The cost model estimates execution cost for plan selection.

Cost Components¶

Component	Weight	Description
CPU	1.0	Computation cost
I/O	10.0	Disk access cost
Memory	0.5	Memory allocation
Network	100.0	Data transfer (future)

Cost Formula¶

Total Cost = CPU_cost * cpu_weight
           + IO_cost * io_weight
           + Mem_cost * mem_weight

Operator Costs¶

Operator	Cost Formula
Scan	rows * column_count
Filter	input_rows * selectivity
Hash Join	build_rows + probe_rows
Sort	rows * log(rows)