Data Types

Schema DataTypes

DataType	Description
DataType::Boolean()	Boolean value
DataType::TinyInt()	8-bit signed integer
DataType::SmallInt()	16-bit signed integer
DataType::Int()	32-bit signed integer
DataType::BigInt()	64-bit signed integer
DataType::Float()	32-bit floating point
DataType::Double()	64-bit floating point
DataType::String()	UTF-8 string
DataType::Bytes()	Binary data
DataType::Date()	Date (days since epoch)
DataType::Time()	Time (milliseconds since midnight)
DataType::Timestamp()	Timestamp without timezone (default precision 6, microseconds)
DataType::TimestampLtz()	Timestamp with timezone (default precision 6, microseconds)
DataType::Decimal(p, s)	Decimal with precision and scale

GenericRow Setters

SetInt32 is used for TinyInt, SmallInt, and Int columns. For TinyInt and SmallInt, the value is validated at write time — an error is returned if it overflows the column's range (e.g., [-128, 127] for TinyInt, [-32768, 32767] for SmallInt).

fluss::GenericRow row;
row.SetNull(0);
row.SetBool(1, true);
row.SetInt32(2, 42);
row.SetInt64(3, 1234567890L);
row.SetFloat32(4, 3.14f);
row.SetFloat64(5, 2.71828);
row.SetString(6, "hello");
row.SetBytes(7, {0x01, 0x02, 0x03});

Name-Based Setters

When using table.NewRow(), you can set fields by column name. The setter automatically routes to the correct type based on the schema:

auto row = table.NewRow();
row.Set("user_id", 1);
row.Set("name", "Alice");
row.Set("score", 95.5f);
row.Set("balance", "1234.56");   // decimal as string
row.Set("birth_date", fluss::Date::FromYMD(1990, 3, 15));
row.Set("login_time", fluss::Time::FromHMS(9, 30, 0));
row.Set("created_at", fluss::Timestamp::FromMillis(1700000000000));
row.Set("nickname", nullptr);    // set to null

Reading Field Values

Field values are read through RowView (from scan results) and LookupResult (from lookups), not through GenericRow. Both provide the same getter interface with zero-copy access to string and bytes data.

ScanRecord is a value type — it can be freely copied, stored, and accumulated across multiple Poll() calls via reference counting.

string_view Lifetime

GetString() returns std::string_view that borrows from the underlying data. The string_view is valid as long as any ScanRecord referencing the same poll result is alive. Copy to std::string if you need the value after all records are gone.

// ScanRecord is a value type — safe to store and accumulate:
std::vector<fluss::ScanRecord> all_records;
fluss::ScanRecords records;
scanner.Poll(5000, records);
for (const auto& rec : records) {
    all_records.push_back(rec);                    // safe! ref-counted
    auto name = rec.row.GetString(0);              // zero-copy string_view
    auto owned = std::string(rec.row.GetString(0)); // explicit copy when needed
}

// DON'T — string_view dangles after all records referencing the data are destroyed:
std::string_view dangling;
{
    fluss::ScanRecords records;
    scanner.Poll(5000, records);
    dangling = records[0].row.GetString(0);
}
// dangling is undefined behavior here — no ScanRecord keeps the data alive!

From Scan Results (RowView)

for (const auto& rec : records) {
    auto name = rec.row.GetString(1);          // zero-copy string_view
    float score = rec.row.GetFloat32(3);
    auto balance = rec.row.GetDecimalString(4); // std::string (already owned)
    fluss::Date date = rec.row.GetDate(5);
    fluss::Time time = rec.row.GetTime(6);
    fluss::Timestamp ts = rec.row.GetTimestamp(7);
}

From Lookup Results (LookupResult)

fluss::LookupResult result;
lookuper.Lookup(pk_row, result);
if (result.Found()) {
    auto name = result.GetString(1);  // zero-copy string_view
    int64_t age = result.GetInt64(2);
}

TypeId Enum

TinyInt and SmallInt values are widened to int32_t on read.

TypeId	C++ Type	Getter
Boolean	bool	GetBool(idx)
TinyInt	int32_t	GetInt32(idx)
SmallInt	int32_t	GetInt32(idx)
Int	int32_t	GetInt32(idx)
BigInt	int64_t	GetInt64(idx)
Float	float	GetFloat32(idx)
Double	double	GetFloat64(idx)
String	std::string_view	GetString(idx)
Bytes	std::pair<const uint8_t*, size_t>	GetBytes(idx)
Date	Date	GetDate(idx)
Time	Time	GetTime(idx)
Timestamp	Timestamp	GetTimestamp(idx)
TimestampLtz	Timestamp	GetTimestamp(idx)
Decimal	std::string	GetDecimalString(idx)

Type Checking

if (rec.row.GetType(0) == fluss::TypeId::Int) {
    int32_t value = rec.row.GetInt32(0);
}
if (rec.row.IsNull(1)) {
    // field is null
}
if (rec.row.IsDecimal(2)) {
    std::string decimal_str = rec.row.GetDecimalString(2);
}

Constants

constexpr int64_t fluss::EARLIEST_OFFSET = -2;  // Start from earliest

To start reading from the latest offset, resolve the current offset via ListOffsets before subscribing:

std::unordered_map<int32_t, int64_t> offsets;
admin.ListOffsets(table_path, {0}, fluss::OffsetSpec::Latest(), offsets);
scanner.Subscribe(0, offsets[0]);