表中有A,B,C,D四个字段
对这四个字段创建索引:
1. CREATE INDEX "SWITCHTEST"."INDEX000" ON "SWITCHTEST"."CIRCUIT" ("A")
2. CREATE INDEX "SWITCHTEST"."INDEX001" ON "SWITCHTEST"."CIRCUIT" ("B")
3. CREATE INDEX "SWITCHTEST"."INDEX002" ON "SWITCHTEST"."CIRCUIT" ("C")
4. CREATE INDEX "SWITCHTEST"."INDEX003" ON "SWITCHTEST"."CIRCUIT" ("D")
查询:
select * from .. order by A,B,C,D(问题:这里ABCD的次序受不受创建索引次序的影响) ? 因为我现在遇到的问题的是将D放到A前面速度就很快,否则很慢. order by D,A,B,C这样就很慢。
对这四个字段创建索引:
1. CREATE INDEX "SWITCHTEST"."INDEX000" ON "SWITCHTEST"."CIRCUIT" ("A")
2. CREATE INDEX "SWITCHTEST"."INDEX001" ON "SWITCHTEST"."CIRCUIT" ("B")
3. CREATE INDEX "SWITCHTEST"."INDEX002" ON "SWITCHTEST"."CIRCUIT" ("C")
4. CREATE INDEX "SWITCHTEST"."INDEX003" ON "SWITCHTEST"."CIRCUIT" ("D")
查询:
select * from .. order by A,B,C,D(问题:这里ABCD的次序受不受创建索引次序的影响) ? 因为我现在遇到的问题的是将D放到A前面速度就很快,否则很慢. order by D,A,B,C这样就很慢。
“因为我现在遇到的问题的是将D放到A前面速度就很快,”
“因为我现在遇到的问题的是将A放到前面速度就很快,”order by A,B,C,D
后面的BCD的次序无所谓。