避免在运行Postgres查询时在解释计划中使用Materialize
在查询中尽可能减少使用Materialize。以下是几个示例：
- 使用WITH语句代替子查询：
SELECT * FROM ( SELECT col1, col2 FROM table1 WHERE col1 = 'value' ) sub_query JOIN table2 ON sub_query.col2 = table2.col2;
可以改写为：
WITH sub_query AS ( SELECT col1, col2 FROM table1 WHERE col1 = 'value' ) SELECT * FROM sub_query JOIN table2 ON sub_query.col2 = table2.col2;
- 使用连接（JOIN）代替IN子句：
SELECT * FROM table1 WHERE col1 IN ( SELECT col2 FROM table2 );
可以改写为：
SELECT * FROM table1 JOIN table2 ON table1.col1 = table2.col2;
- 将复杂查询拆分为多个查询：
SELECT * FROM ( SELECT col1, col2 FROM table1 WHERE col1 = 'value1' ) sub_query1 JOIN ( SELECT col1, col2 FROM table1 WHERE col1 = 'value2' ) sub_query2 ON sub_query1.col2 = sub_query2.col2;
可以改写为：
WITH sub_query1 AS ( SELECT col1, col2 FROM table1 WHERE col1 = 'value1' ), sub_query2 AS ( SELECT col1, col2 FROM table1 WHERE col1 = 'value2' ) SELECT * FROM sub_query1 JOIN sub_query2 ON sub_query1.col2 = sub_query2.col2;
这些方法可以减少使用Materialize，提高查询性能和效率。