Wrong-cased date-separator is accepted but ignored

[kennytm]

What did you do?

1. Start a new-arch TiCDC cluster

   tiup playground-ng v8.5.7 --db 1 --kv 1 --pd 1 --tiflash 0 --ticdc 1 --ticdc.config ./ticdc-newarch.toml --without-monitor

2. Create an S3 changefeed with wrong-cased date-separator

   [sink]
   date-separator = "DAY"

   tiup cdc:v8.5.7 cli changefeed create -c test5854 --sink-uri 's3://test5854/?protocol=canal-json' --config ./test5854.toml

3. Insert some rows.

What did you expect to see?

Either one of the following:

• The events are written into a date-separated folder:

  s3://test5854/test/a/468599132522545161/2026-08-24/CDC00000000000000000001.json
  

• or Step 2 failed with error like

  Error: [CDC:ErrSinkInvalidConfig]sink config invalid: [CDC:ErrStorageSinkInvalidDateSeparator]date separator in storage sink is invalid%!(EXTRA string=DAY)
  

What did you see instead?

The date-seperator is entirely ignored. Files are written to

s3://test5854/test/a/468599132522545161/CDC00000000000000000001.json

Versions of the cluster

v8.5.7

[kennytm]

The bug is because verification used (*DateSeparator).FromString which does case-insensitive conversion:

ticdc/pkg/config/sink.go

Lines 357 to 372 in 41b855b

	func (d *DateSeparator) FromString(separator string) error {
	switch strings.ToLower(separator) {
	case "none":
	*d = DateSeparatorNone
	case "year":
	*d = DateSeparatorYear
	case "month":
	*d = DateSeparatorMonth
	case "day":
	*d = DateSeparatorDay
	default:
	return cerror.ErrStorageSinkInvalidDateSeparator.GenWithStackByArgs(separator)
	}
	return nil
	}

But in actual usage the code does not use the DateSeparator enum but instead keep using the string, which compared case-sensitively.

ticdc/pkg/sink/cloudstorage/path.go

Lines 353 to 369 in 41b855b

	func (f *FilePathGenerator) GenerateDateStr() string {
	var dateStr string
	currTime := f.pdClock.CurrentTime()
	// Note: `dateStr` is formatted using local TZ.
	switch f.config.DateSeparator {
	case config.DateSeparatorYear.String():
	dateStr = currTime.Format("2006")
	case config.DateSeparatorMonth.String():
	dateStr = currTime.Format("2006-01")
	case config.DateSeparatorDay.String():
	dateStr = currTime.Format("2006-01-02")
	default:
	}
	return dateStr
	}

We should prefer Parse, don't validate and make that field a DateSeparator instead of string.

ticdc/pkg/sink/cloudstorage/config.go

Line 83 in 41b855b

DateSeparator string

(Internal reference: TCOC-5854/TCID-13076)

[kennytm]

/label affects-8.5
/label affects-26.3
/label component/cloudstorage

[ti-chi-bot]

@kennytm: The label(s) affects-8.5, component/cloudstorage cannot be applied. These labels are supported: affects-25.10, affects-26.3, may-affects-25.10, may-affects-26.3, needs-cherry-pick-release-nextgen-20251011, needs-cherry-pick-release-nextgen-202603.

Details

In response to this:

/label affects-8.5
/label affects-26.3
/label component/cloudstorage

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[wk989898]

Does this bug affect the old arch?

[kennytm]

@wk989898 yes.