vitessio/vitess · error

invalid --%s value %q: expected name=value

Error message

invalid --%s value %q: expected name=value

What it means

After locating the token following --session-variable, SessionVariables() requires it to contain '=' via strings.Cut. This error means the value token lacks the name=value form — only a name (or a value without '='), so the assignment cannot be parsed.

Source

Thrown at go/vt/schema/ddl_strategy.go:270

// SessionVariables returns the ordered assignments from repeatable
// --session-variable name=value options.
func (setting *DDLStrategySetting) SessionVariables() ([]SessionVariable, error) {
	opts, err := shlex.Split(setting.Options)
	if err != nil {
		return nil, fmt.Errorf("invalid DDL strategy options: %w", err)
	}
	var variables []SessionVariable
	for i := 0; i < len(opts); i++ {
		if !isFlag(opts[i], sessionVariableFlag) {
			continue
		}
		if i+1 >= len(opts) {
			return nil, fmt.Errorf("--%s requires name=value", sessionVariableFlag)
		}
		i++
		name, value, found := strings.Cut(opts[i], "=")
		if !found {
			return nil, fmt.Errorf("invalid --%s value %q: expected name=value", sessionVariableFlag, opts[i])
		}
		variables = append(variables, SessionVariable{Name: name, Value: value})
	}
	if err := ValidateSessionVariables(variables); err != nil {
		return nil, err
	}
	return variables, nil
}

// IsPostponeLaunch checks if strategy options include --postpone-launch
func (setting *DDLStrategySetting) IsPostponeLaunch() bool {
	return setting.hasFlag(postponeLaunchFlag)
}

// IsPostponeCompletion checks if strategy options include --postpone-completion
func (setting *DDLStrategySetting) IsPostponeCompletion() bool {
	return setting.hasFlag(postponeCompletionFlag)
}

View on GitHub (pinned to 01a25a7d17)

Solutions

1. Use exactly name=value form: --session-variable wait_timeout=100.
2. Do not put spaces around '='; quote the whole token if the shell requires it.
3. Ensure each variable is a single --session-variable flag rather than separate name and value flags.

Example fix

// before
setting := schema.ParseDDLStrategy("online --session-variable wait_timeout")
// after
setting := schema.ParseDDLStrategy("online --session-variable wait_timeout=100")

for _, sv := range sessionVarTokens {
    if !strings.Contains(sv, "=") {
        // rewrite to name=value before building the strategy
    }
}

if _, err := setting.SessionVariables(); err != nil {
    return fmt.Errorf("bad session variable token: %w", err)
}

When it happens

Trigger: "--session-variable wait_timeout" (name only, no =value), or a quoted "--session-variable 'wait_timeout 100'" where a space replaced '='; triggered inside DDLStrategySetting.SessionVariables() when found is false.

Common situations: Users writing MySQL SET syntax (SET wait_timeout = 100) instead of name=value; flags split into two separate --session-variable occurrences; shell ate the '=' or value.

Related errors

• --%s requires name=value
• invalid DDL strategy options: %w
• stray %% at the end of pattern
• overflow
• too many .s

AI-assisted analysis of vitessio/vitess@01a25a7d17 (2026-09-01). Data as JSON: /api/errors/cd3881ce51bda22f. Report an issue: GitHub.