expression: support ConstItem() for expression (#10004) #10167
Conversation
|
/run-all-tests tidb-test=release-2.1 tikv=release-2.1 pd=release-2.1 |
| @@ -124,6 +124,11 @@ func (col *CorrelatedColumn) IsCorrelated() bool { | |||
| return true | |||
| } | |||
|
|
|||
| // ConstItem implements Expression interface. | |||
| func (col *CorrelatedColumn) ConstItem() bool { | |||
| return false | |||
There was a problem hiding this comment.
I'm afraid it would cause some other problems.
For example, when building some scalar function like from_unixtime(CorCol), we may use it to decide if we can evaluate the argument at that time.
If it is true, we may call CorCol.Eval(NullRow) and this function call is invalid.
There was a problem hiding this comment.
In my opinion, ConstItem means 1) this expression has no column reference, 2) this expression doesn't include some special scalar functions which behave differently according to time like Rand and SysDate.
CorrelatedColumn breaks the rule 1).
Maybe name ConsistentItem is more closer to its meaning.
|
This function has some problems for |
cherry-pick for #10004
some bugs can be fixed by
ConstItem()like #9033, #10156