plan: eliminate tablescan's cost more precisely. #2243
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hanfei1991
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shenli
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Dec 13, 2016
| @@ -65,26 +65,30 @@ type physicalDistSQLPlan interface { | |||
| addAggregation(ctx context.Context, agg *PhysicalAggregation) expression.Schema | |||
| addTopN(ctx context.Context, prop *requiredProperty) bool | |||
| addLimit(limit *Limit) | |||
| calculateCost(count uint64) float64 | |||
| calculateCost(count uint64, scanCount uint64) float64 | |||
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Add comment for the two parameters.
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Should we rename count to resultCount?
coocood
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Dec 13, 2016
| } | ||
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| func (p *PhysicalIndexScan) calculateCost(count uint64) float64 { | ||
| cnt := float64(count) | ||
| func (p *PhysicalIndexScan) calculateCost(resultCount uint64, scanCount uint64) float64 { |
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Why scanCount is not used here?
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I have added a todo list here. index elimination is more complex, which need to consider index filter and table filter in the same time.
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LGTM |
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@coocood PTAL |
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LGTM |
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We forget to consider cpu cost when the table scan has a condition.
@shenli @coocood @zimulala PTAL