sample

type Batch struct {
	Rows map[int][]KV // the rows of each lookup, by its index
	// Complete marks the lookups that ran to their end. The others were
	// cut short by the byte budget or an error, or never ran, and may have
	// some rows or none.
	Complete []bool
	Bytes    int64 // keys and values read
}

type KV struct {
	Key   string
	PK    string
	Value string
	Null  bool
}

type Lookup struct {
	Key    string
	Prefix bool // Key is a prefix: rows whose key starts with it
	Limit  int
}

type Querier interface {
	QueryContext(ctx context.Context, query string, args ...any) (*sql.Rows, error)
	QueryRowContext(ctx context.Context, query string, args ...any) *sql.Row
}

type Sample struct {
	Columns []*model.Column
	Rows    [][]sql.NullString
	Method  string
	// Hex marks the columns read as HEX(column), in the order of Columns.
	Hex []bool
}

type Sampler struct {
	DB          Querier
	MaxValueLen int           // longer text values are cut on the server
	Timeout     time.Duration // client-side limit per query
	// Hex, when set, picks short binary columns (see ShortBinary) that Table
	// reads as HEX(column), such as IP addresses stored as bytes. No other
	// read selects a binary column.
	Hex func(t *model.Table, c *model.Column) bool
}