Data types

The column types. A column definition accepts any of the words in the second column, in any letter case. The third column is the name that SHOW COLUMNS and system.columns report.

Type	Words in a column definition	Reported name	Description
`int64`	`int64`, `int`, `bigint`, `integer`	`int64`	Signed 64-bit integer. The words int and integer also mean 64 bits.
`float64`	`float64`, `float`, `double`	`float64`	64-bit floating-point number.
`varchar`	`varchar`, `string`, `text`	`varchar`	Variable-length string of bytes.
`timestamp`	`timestamp`, `datetime64`	`timestamp`	Point in time with nanosecond precision in UTC, stored as signed 64-bit nanoseconds since the Unix epoch.
`array_int64`	`array_int64`	`array_int64`	Array of Int64 values.
`array_float64`	`array_float64`	`array_float64`	Array of Float64 values.
`array_varchar`	`array_varchar`	`array_varchar`	Array of strings.
`UInt8`	`UInt8`	`UInt8`	Unsigned 8-bit integer.
`UInt16`	`UInt16`	`UInt16`	Unsigned 16-bit integer.
`UInt32`	`UInt32`	`UInt32`	Unsigned 32-bit integer.
`UInt64`	`UInt64`	`UInt64`	Unsigned 64-bit integer.
`Bool`	`Bool`, `boolean`	`Bool`	Boolean value, stored as 0 or 1.
`Int8`	`Int8`, `tinyint`	`Int8`	Signed 8-bit integer.
`Int16`	`Int16`, `smallint`	`Int16`	Signed 16-bit integer.
`Int32`	`Int32`	`Int32`	Signed 32-bit integer.
`Float32`	`Float32`, `real`	`Float32`	32-bit floating-point number.
`Date`	`Date`	`Date`	Calendar date, stored as days since the Unix epoch.
`DateTime`	`DateTime`	`DateTime`	Point in time with second precision in UTC, stored as seconds since the Unix epoch.
`FixedString`	`FixedString`, `fixed_string`	`FixedString`	String of exactly N bytes, written FixedString(N). Shorter values are padded with zero bytes and longer values are rejected.
`IPv4`	`IPv4`	`IPv4`	IPv4 address, stored as an unsigned 32-bit number and written in dotted form.
`Enum8`	`Enum8`	`Enum8`	Enumeration of named values stored as a signed 8-bit integer, written Enum8('name' = value, ...).
`Enum16`	`Enum16`	`Enum16`	Enumeration of named values stored as a signed 16-bit integer, written Enum16('name' = value, ...).
`Int128`	`Int128`	`Int128`	Signed 128-bit integer.
`UInt128`	`UInt128`	`UInt128`	Unsigned 128-bit integer.
`UUID`	`UUID`	`UUID`	Universally unique identifier, written as 32 hexadecimal digits in the 8-4-4-4-12 form.
`IPv6`	`IPv6`	`IPv6`	IPv6 address, stored as 128 bits.
`map_i64_i64`	`map_i64_i64`	`Map(Int64, Int64)`	Map from Int64 keys to Int64 values.
`map_i64_f64`	`map_i64_f64`	`Map(Int64, Float64)`	Map from Int64 keys to Float64 values.
`map_i64_str`	`map_i64_str`	`Map(Int64, String)`	Map from Int64 keys to string values.
`map_str_i64`	`map_str_i64`	`Map(String, Int64)`	Map from string keys to Int64 values.
`map_str_f64`	`map_str_f64`	`Map(String, Float64)`	Map from string keys to Float64 values.
`map_str_str`	`map_str_str`	`Map(String, String)`	Map from string keys to string values.
`AggregateFunction`	`AggregateFunction`, `agg_state`	`AggregateFunction`	Intermediate state of an aggregate function, written AggregateFunction(name, argument types).
`array_float32`	`array_float32`	`array_float32`	Array of Float32 values, such as an embedding vector.
`Decimal32`	`Decimal32`	`Decimal32`	Fixed-point number with up to 9 digits, written Decimal(P, S) with P of at most 9.
`Decimal64`	`Decimal64`	`Decimal64`	Fixed-point number with up to 18 digits, written Decimal(P, S) with P of at most 18.