expr: add switch to control pushing bit column down

[Yisaer]

Signed-off-by: yisaer [email protected]

What problem does this PR solve?

Issue Number: ref #30738

Problem Summary:

What is changed and how it works?

add switch to control pushing bit column down

Check List

Tests

• Unit test

Release note

None

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• JmPotato
• rebelice

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[sre-bot]

Code Coverage Details: https://codecov.io/github/pingcap/tidb/commit/6dc835d15c67e82b815e0cb436de0bdb85596700

[LittleFall]

will this affect tiflash?

[Yisaer]

No，The bit column won't be push down to tiflash due to following codes:

tidb/expression/expression.go

Lines 1275 to 1285 in 493eb45

	func canExprPushDown(expr Expression, pc PbConverter, storeType kv.StoreType, canEnumPush bool) bool {
	if storeType == kv.TiFlash {
	switch expr.GetType().Tp {
	case mysql.TypeEnum, mysql.TypeBit, mysql.TypeSet, mysql.TypeGeometry, mysql.TypeUnspecified:
	if expr.GetType().Tp == mysql.TypeEnum && canEnumPush {
	break
	}
	if pc.sc.InExplainStmt {
	pc.sc.AppendWarning(errors.New("Expression about '" + expr.String() + "' can not be pushed to TiFlash because it contains unsupported calculation of type '" + types.TypeStr(expr.GetType().Tp) + "'."))
	}
	return false

[Yisaer]

/merge

[ti-chi-bot]

This pull request has been accepted and is ready to merge.

Commit hash: 6dc835d