fix(sqlx): write time.Time in a MySQL-compatible format

[kayoch1n]

Fixes issue #5515: the bulk inserter used Time.String() to convert variables of type time.Time into strings. Time.String() returns a string in the format "2006-01-02 15:04:05.999999999 -0700 MST" that is not accepted by MySQL.

To fix this problem, use Time.Format() to convert time.Time into string.

Changes:

• core/stores/sqlx/utils.go: convert time variables into strings using a MySQL-compatible format
• core/stores/sqlx/utils_test.go: modify assertions and add a nil pointer case

All unittest cases passed. This change only affects bulk inserter and loggings.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

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[kevwan]

Thanks for the fix! The core change is correct — Time.String() produces a format MySQL rejects while Time.Format(time.DateTime) produces standard SQL format.

However, time.DateTime ("2006-01-02 15:04:05") truncates to second-level precision. Since writeValue is called from BulkInserter where the formatted value is actually executed as SQL, this would silently discard sub-second data. MySQL DATETIME(6) and TIMESTAMP(6) support microsecond precision.

Please consider using a format that preserves microseconds instead:

v.Format("2006-01-02 15:04:05.999999")

The .999999 pattern in Go's time formatting trims trailing zeros, so it produces clean output (2026-03-28 17:26:54.88284) while preserving precision when present. This is MySQL-compatible.

[kevwan]

Review

Clean and correct fix for the BulkInserter time.Time serialization bug (#5515).

Analysis:

time.Time.String() produces a Go-specific representation ("2006-01-02 15:04:05.999999999 -0700 MST m=+...") that MySQL rejects. Using time.Format("2006-01-02 15:04:05.999999") produces a MySQL-compatible datetime format.

Code quality:

• ✅ The format constant timeFormat = "2006-01-02 15:04:05.999999" is well-chosen — uses Go reference time, includes microsecond precision (999999 trailing zeros are omitted)
• ✅ Added nil-pointer handling for *time.Time — previously this would have been a nil dereference panic or wrong output
• ✅ Tests updated with table-driven subtests

One question — timezone handling: time.Format() formats using the time's location. If the time.Time value is in a non-UTC timezone, the formatted string won't include timezone info. MySQL will interpret the timestamp in the server's session timezone. This is consistent with how github.com/go-sql-driver/mysql handles time (with parseTime=true), but worth documenting. Users should ensure their time.Time values use the correct timezone before inserting.

Suggestion (non-blocking): Consider using v.UTC().Format(timeFormat) or at least document the timezone behavior — but this is a judgment call and not a correctness issue for most users.

LGTM — this is a clear bug fix with no downside.

[kayoch1n]

@kevwan Hi, could you please have a look at this?