perf: the performance of calculating index selectivity #1938
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optimize the performance of calculate selectivity in the case of large tables @winfredLIN
winfredLIN
commented
Oct 24, 2023
sqle/driver/mysql/session/context.go
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| func queryValue(schema, table, index string) string { | ||
| return fmt.Sprintf("('%s', '%s', '%s')", schema, table, index) | ||
| } | ||
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| func indexSelectivity(queryValues []string) string { | ||
| return fmt.Sprintf( | ||
| `SELECT (s.CARDINALITY / t.TABLE_ROWS) AS index_selectivity FROM INFORMATION_SCHEMA.STATISTICS s JOIN INFORMATION_SCHEMA.TABLES t ON s.TABLE_SCHEMA = t.TABLE_SCHEMA AND s.TABLE_NAME = t.TABLE_NAME WHERE (s.TABLE_SCHEMA , s.TABLE_NAME , s.COLUMN_NAME) IN (%s);`, | ||
| strings.Join(queryValues, ","), | ||
| ) | ||
| } | ||
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在给出三星索引建议的规则中，也需要获取到列的选择性，这里会考虑将其重构成更通用的工具方法
use GetSelectivityOfColumns instead of GetMaxIndexOptionForTable in checkIndexOption use GetSelectivityOfIndex instead of GetMaxIndexOptionForTable in checkIndexSelectivity
rules: 1. DDLCheckIndexOption 2. DMLCheckIndexSelectivity
winfredLIN
commented
Oct 25, 2023
sqle/driver/mysql/rule/rule.go
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| Message: "索引字段 %v 未超过区分度阈值 百分之%v, 不建议选为索引字段", | ||
| AllowOffline: false, | ||
| Func: checkIndexOption, |
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修改了名称，在DDL语句中，对添加/修改索引的操作，检查的是添加的索引字段的区分度，细粒度到某一列
sjjian
reviewed
Oct 25, 2023
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| results, err := c.e.Db.Query( | ||
| fmt.Sprintf( | ||
| "SELECT %v FROM (SELECT %v FROM %v.%v LIMIT 50000) t;", |
sjjian
approved these changes
Oct 26, 2023
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#1918
optimize the performance of calculate index selectivity in the case of large tables
modify test case of rules about index selectivity