Query #Joins #Groups #Expressions #Rule apps 1 0 10 21 43 2 4 340 1388 3666 3 2 57 197 483 4 1 38 93 192 5 5 312 1128 3094 6 0 23 32 42 7 5 89 746 1764 8 7 1523 5763 16538 8y 6 697 2572 7242 9 5 75 736 1737 10 3 101 337 841 11 2 64 237 849 12 1 34 70 127 13 1 17 40 58 14 1 17 38 75 15 1 18 38 45 16 2 42 99 196 17 3 34 109 184 * Using left deep joins.
Many different rules for generating join orders were written for Model D. By experimenting with choice of these rules both on the TPC-D queries and simpler join only queries (based on the TPC-D schema) the quality/efficiency trade-off can be explored.
To judge the impact of the join order heuristics, the heuristics can be turned on and off, the optimizer run and the cost of the resulting plans compared. So for eight TPC-D queries, the join order heuristics were turned off, and the resulting plans compared with the plans produced when the join order heuristics were on.
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