Data Types

Timeplus Proton supports a comprehensive set of data types compatible with ClickHouse. This page provides a complete reference for all available data types, their usage, and examples.

Numeric Types

Integer Types

Fixed-length integers with or without a sign.

Signed Integers

int8 — Range: [-128 : 127]
int16 — Range: [-32768 : 32767]
int32 — Range: [-2147483648 : 2147483647]
int64 — Range: [-9223372036854775808 : 9223372036854775807]
int128 — Range: [-170141183460469231731687303715884105728 : 170141183460469231731687303715884105727]
int256 — Range: [-57896044618658097711785492504343953926634992332820282019728792003956564819968 : 57896044618658097711785492504343953926634992332820282019728792003956564819967]

Aliases:

int8 — TINYINT, BOOL, BOOLEAN, INT1
int16 — SMALLINT, INT2
int32 — INT, INT4, INTEGER
int64 — BIGINT

Example:

CREATE STREAM temperature_readings (
    sensor_id int32,
    temperature int16,
    timestamp datetime
);

INSERT INTO temperature_readings VALUES (101, 72, now());

Unsigned Integers

uint8 — Range: [0 : 255]
uint16 — Range: [0 : 65535]
uint32 — Range: [0 : 4294967295]
uint64 — Range: [0 : 18446744073709551615]
uint128 — Range: [0 : 340282366920938463463374607431768211455]
uint256 — Range: [0 : 115792089237316195423570985008687907853269984665640564039457584007913129639935]

Example:

CREATE STREAM user_events (
    user_id uint64,
    event_count uint32,
    timestamp datetime
);

Floating Point Types

float32 — 32-bit floating point number (IEEE 754 single precision)
float64 — 64-bit floating point number (IEEE 754 double precision)

Aliases:

float32 — FLOAT, REAL, SINGLE
float64 — DOUBLE, DOUBLE PRECISION

Example:

CREATE STREAM sensor_data (
    sensor_id int32,
    measurement float64,
    precision_value float32,
    timestamp datetime
);

INSERT INTO sensor_data VALUES (1, 23.456789, 23.45, now());

Decimal Types

Fixed-precision decimal numbers. Syntax: decimal(P, S) where P is precision (total digits) and S is scale (decimal places).

decimal32(S) — Precision up to 9 digits
decimal64(S) — Precision up to 18 digits
decimal128(S) — Precision up to 38 digits
decimal256(S) — Precision up to 76 digits

Example:

CREATE STREAM financial_transactions (
    transaction_id uint64,
    amount decimal(18, 2),  -- Up to 16 digits before decimal, 2 after
    fee decimal(10, 4),
    timestamp datetime
);

INSERT INTO financial_transactions VALUES (1, 1234.56, 0.0025, now());

String Types

String

Variable-length strings with no size limit. Can contain arbitrary bytes including null bytes. Aliases: LONGTEXT, MEDIUMTEXT, TINYTEXT, TEXT, LONGBLOB, MEDIUMBLOB, TINYBLOB, BLOB, VARCHAR, CHAR Example:

CREATE STREAM user_messages (
    user_id uint64,
    message string,
    timestamp datetime
);

INSERT INTO user_messages VALUES (1, 'Hello, Timeplus!', now());

Fixed String

Fixed-length strings. Syntax: fixed_string(N) where N is the string length in bytes.

Strings shorter than N are padded with null bytes
Strings longer than N cause an error
Maximum size: 0xFFFFFF (16,777,215 bytes)

Example:

CREATE STREAM device_codes (
    device_id uint64,
    code fixed_string(8),  -- Always 8 bytes
    timestamp datetime
);

INSERT INTO device_codes VALUES (1, 'ABC12345', now());

Date and Time Types

Date

Stores calendar dates (year, month, day).

Storage: 2 bytes (as uint16)
Range: [1970-01-01 : 2149-06-06]
Resolution: 1 day
Format: YYYY-MM-DD

Example:

CREATE STREAM daily_summary (
    report_date date,
    total_events uint64
);

INSERT INTO daily_summary VALUES ('2024-03-15', 1000);
INSERT INTO daily_summary VALUES (to_date('2024-03-16'), 1500);

Date32

Extended date type with wider range.

Storage: 4 bytes (as int32)
Range: [1900-01-01 : 2299-12-31]
Resolution: 1 day
Format: YYYY-MM-DD

Example:

CREATE STREAM historical_data (
    event_date date32,
    value int64
);

INSERT INTO historical_data VALUES ('1950-01-01', 100);

DateTime

Stores timestamp as Unix time (seconds since epoch). Syntax: datetime([timezone])

Storage: 4 bytes (as uint32)
Range: [1970-01-01 00:00:00 : 2105-12-31 23:59:59]
Resolution: 1 second
Format: YYYY-MM-DD hh:mm:ss

Example:

CREATE STREAM events (
    event_id uint64,
    event_time datetime,
    event_time_utc datetime('UTC'),
    event_time_ny datetime('America/New_York')
);

INSERT INTO events VALUES (1, now(), now(), now());
INSERT INTO events VALUES (2, '2024-03-15 14:30:00', '2024-03-15 14:30:00', '2024-03-15 14:30:00');

Timezone Behavior:

Timezone only affects text format parsing and display
Internal storage is always Unix timestamp (UTC)
Timezone conversion has no computation cost (metadata only)

DateTime64

High-precision timestamp with sub-second resolution. Syntax: datetime64(precision, [timezone])

Storage: 8 bytes (as int64)
Precision: 0-9 decimal places (default: 3 for milliseconds)
Format: YYYY-MM-DD hh:mm:ss.sss

Example:

CREATE STREAM high_frequency_trades (
    trade_id uint64,
    trade_time datetime64(3),        -- Millisecond precision
    trade_time_micro datetime64(6),  -- Microsecond precision
    trade_time_nano datetime64(9),   -- Nanosecond precision
    price decimal(18, 8)
);

INSERT INTO high_frequency_trades VALUES 
    (1, '2024-03-15 14:30:15.123', '2024-03-15 14:30:15.123456', '2024-03-15 14:30:15.123456789', 100.5);

Complex Types

Array

Dynamic array of elements of the same type. Syntax: array(T) where T is any data type

Maximum size: 1 million elements
Supports nested arrays
Elements must be of the same type

Example:

CREATE STREAM user_sessions (
    user_id uint64,
    page_views array(string),
    click_times array(datetime),
    scores array(float64)
);

INSERT INTO user_sessions VALUES 
    (1, ['home', 'products', 'checkout'], [now(), now(), now()], [1.5, 2.3, 4.1]);

-- Using array() function
SELECT array(1, 2, 3) AS numbers;

-- Using bracket notation
SELECT [1, 2, 3] AS numbers;

-- Nested arrays
SELECT [[1, 2], [3, 4]] AS matrix;

Array Operations:

-- Access elements (1-based indexing)
SELECT page_views[1] FROM user_sessions;

-- Array size
SELECT length(page_views) FROM user_sessions;

-- Check if element exists
SELECT has(page_views, 'home') FROM user_sessions;

Tuple

Ordered collection of elements with individual types. Syntax: tuple(T1, T2, ...) or tuple(name1 T1, name2 T2, ...)

Elements can have different types
Can be named or unnamed
Used for temporary column grouping

Example:

CREATE STREAM user_locations (
    user_id uint64,
    coordinates tuple(float64, float64),
    location tuple(city string, country string, zip_code int32)
);

INSERT INTO user_locations VALUES 
    (1, (37.7749, -122.4194), ('San Francisco', 'USA', 94102));

-- Creating tuples
SELECT tuple(1, 'a', 3.14) AS my_tuple;
SELECT (1, 'a', 3.14) AS my_tuple;  -- Alternative syntax

-- Accessing named tuple elements
SELECT location.city, location.country FROM user_locations;

-- Accessing by index
SELECT coordinates.1, coordinates.2 FROM user_locations;

Map

Key-value pair storage. Syntax: map(K, V) where K is the key type and V is the value type

Keys can be any type except nullable or low cardinality nullable
Values can be any type
Maps can contain duplicate keys (internally array(tuple(K, V)))
Non-unique keys allowed

Example:

CREATE STREAM user_preferences (
    user_id uint64,
    settings map(string, string),
    feature_flags map(string, bool),
    scores map(string, uint32)
);

INSERT INTO user_preferences VALUES 
    (1, {'theme': 'dark', 'language': 'en'}, {'beta': true, 'advanced': false}, {'points': 100, 'level': 5});

-- Access map values
SELECT settings['theme'] FROM user_preferences;

-- Check if key exists
SELECT map_contains(settings, 'theme') FROM user_preferences;

-- Get all keys and values
SELECT map_keys(settings), map_values(settings) FROM user_preferences;

JSON

The JSON object type is deprecated in Timeplus Proton. For working with JSON data, use one of these approaches:

Store as string type and use JSON functions for parsing
Use map(string, string) for simple key-value JSON
Parse into strongly-typed columns using JSON functions

Example: Working with JSON data:

-- Store JSON as string
CREATE STREAM json_events (
    event_id uint64,
    json_data string,
    timestamp datetime
);

INSERT INTO json_events VALUES 
    (1, '{"user": "alice", "action": "login", "ip": "192.168.1.1"}', now());

-- Extract JSON fields
SELECT 
    json_extract_string(json_data, 'user') AS user,
    json_extract_string(json_data, 'action') AS action
FROM json_events;

Nullable Types

Wraps any base type to allow NULL values. Syntax: nullable(T) where T is any data type

Adds special NULL marker alongside normal values
Cannot be used in table indexes
Adds storage overhead (separate NULL mask file)
Performance impact: almost always negative
Default value for nullable type is NULL

Restrictions:

Cannot wrap array or tuple directly
Can wrap elements: array(nullable(int32)) is valid
nullable(array(int32)) is invalid

Example:

CREATE STREAM user_profiles (
    user_id uint64,
    email string,
    phone nullable(string),      -- Phone is optional
    age nullable(uint8),          -- Age is optional
    last_login nullable(datetime) -- Last login is optional
);

INSERT INTO user_profiles VALUES (1, 'user@example.com', NULL, 25, now());
INSERT INTO user_profiles VALUES (2, 'user2@example.com', '+1234567890', NULL, NULL);

-- Check for NULL values
SELECT * FROM user_profiles WHERE phone IS NULL;
SELECT * FROM user_profiles WHERE age IS NOT NULL;

-- Using null subcolumn
SELECT phone.null FROM user_profiles;  -- Returns 1 for NULL, 0 otherwise

Type Conversion

Implicit Conversion

Timeplus Proton automatically converts between compatible types in many situations. Example:

-- Integer to larger integer
SELECT to_uint64(123::uint8);

-- Integer to float
SELECT 42::float64;

-- String to number (in INSERT)
INSERT INTO sensor_data (sensor_id, value) VALUES ('123', '45.6');

Explicit Conversion

Use CAST or conversion functions for explicit type conversion. CAST Syntax:

-- CAST function
SELECT CAST(x AS T);

-- :: operator (PostgreSQL style)
SELECT x::T;

Common Conversion Functions:

-- To integer types
SELECT to_int8('123'), to_uint64('456');

-- To floating point
SELECT to_float32('3.14'), to_float64('2.718');

-- To string
SELECT to_string(123), to_string(3.14);

-- To date/time
SELECT to_date('2024-03-15');
SELECT to_datetime('2024-03-15 14:30:00');
SELECT to_datetime64('2024-03-15 14:30:15.123', 3);

-- To array
SELECT to_array([1, 2, 3]);

-- Type name inspection
SELECT to_type_name(x);

Complete Conversion Example:

CREATE STREAM conversions (
    str_value string,
    int_value int32
);

INSERT INTO conversions VALUES ('123', 456);

SELECT 
    -- String to numeric
    to_int32(str_value) AS str_to_int,
    to_float64(str_value) AS str_to_float,
    
    -- Numeric to string
    to_string(int_value) AS int_to_str,
    
    -- Numeric conversions
    CAST(int_value AS float64) AS int_to_float,
    int_value::uint64 AS int_to_uint,
    
    -- Get type names
    to_type_name(str_value) AS str_type,
    to_type_name(int_value) AS int_type
FROM conversions;

Decimal Conversions

-- Decimal to integer
SELECT CAST(123.456::decimal(10,3) AS int32);  -- Result: 123

-- Decimal to decimal (different precision)
SELECT CAST(123.456::decimal(10,3) AS decimal(10,2));  -- Result: 123.46

-- Float to decimal
SELECT to_decimal64(3.14159, 2);  -- Result: 3.14

-- Decimal to float
SELECT CAST(123.45::decimal(10,2) AS float64);

ClickHouse Compatibility

Timeplus Proton maintains compatibility with ClickHouse data types:

Fully Compatible Types

All integer types (int8 through int256, uint8 through uint256)
Floating point types (float32, float64)
Decimal types (decimal32, decimal64, decimal128, decimal256)
String types (string, fixed_string)
Date types (date, date32, datetime, datetime64)
Complex types (array, tuple, map)
nullable wrapper type

Type Aliases

Most ClickHouse type aliases are supported for compatibility:

SQL standard names: INT, BIGINT, VARCHAR, DOUBLE, etc.
MySQL-style names: TINYINT, TEXT, BLOB, etc.

Best Practices

Choose appropriate precision: Use the smallest integer type that fits your data range
Avoid nullable when possible: Nullable types have performance overhead
Use appropriate string types: Use fixed_string for fixed-width codes, string for variable content
Consider timezone handling: Always specify timezone for datetime types when dealing with multi-region data
Array size limits: Keep arrays under 1 million elements
Decimal vs Float: Use decimal for financial data, float for scientific measurements

Statements

Functions

Data Types

Numeric Types

Integer Types

Signed Integers

Unsigned Integers

Floating Point Types

Decimal Types

String Types

String

Fixed String

Date and Time Types

Date

Date32

DateTime

DateTime64

Complex Types

Array

Tuple

Map

JSON

Nullable Types

Type Conversion

Implicit Conversion

Explicit Conversion

Decimal Conversions

ClickHouse Compatibility

Fully Compatible Types

Type Aliases

Best Practices

See Also

Build docs developers (and LLMs) love

Statements

Functions

Data Types

Documentation Index

​Numeric Types

​Integer Types

​Signed Integers

​Unsigned Integers

​Floating Point Types

​Decimal Types

​String Types

​String

​Fixed String

​Date and Time Types

​Date

​Date32

​DateTime

​DateTime64

​Complex Types

​Array

​Tuple

​Map

​JSON

​Nullable Types

​Type Conversion

​Implicit Conversion

​Explicit Conversion

​Decimal Conversions

​ClickHouse Compatibility

​Fully Compatible Types

​Type Aliases

​Best Practices

​See Also

Build docs developers (and LLMs) love

Numeric Types

Integer Types

Signed Integers

Unsigned Integers

Floating Point Types

Decimal Types

String Types

String

Fixed String

Date and Time Types

Date

Date32

DateTime

DateTime64

Complex Types

Array

Tuple

Map

JSON

Nullable Types

Type Conversion

Implicit Conversion

Explicit Conversion

Decimal Conversions

ClickHouse Compatibility

Fully Compatible Types

Type Aliases

Best Practices

See Also