Oracle之“is null”条件不走索引解决方案

使用伪列建组合索引，如下：

CREATE INDEX idx ON table_name(column_name, 0);

SELECT * FROM table_name WHERE column_name IS NULL;

创建函数索引：

CREATE INDEX idx ON table_name(DECODE(column_name, NULL, 0, NULL));

SELECT * FROM table_name WHERE column_name DECODE(column_name, NULL, 0, NULL) = 0;