Data Types
SQL data types define the type of data that a column can store. When you run the DESC TABLE command, you can see the data type of each column.
String and Binary Data Types
| Type Name | Description | Size |
|---|---|---|
String | UTF-8 encoded strings. Holds up to 2,147,483,647 bytes of data | The length of the strings |
Binary | Variable-length binary values. Holds up to 2,147,483,647 bytes of data | The length of the data + 2 bytes |
The maximum capacities of String and Binary are determined by their encodings and how the storage engine handles them. For example, String values are encoded into UTF-8. If all characters are 3 bytes in length, this field can store up to 715,827,882 characters. As for Binary types, they can store a maximum of 2,147,483,647 bytes.
Numeric Data Types
| Type Name | Description | Size |
|---|---|---|
Int8 | -128 ~ 127 | 1 Byte |
Int16 | -32768 ~ 32767 | 2 Bytes |
Int32 | -2147483648 ~ 2147483647 | 4 Bytes |
Int64 | -9223372036854775808 ~ 9223372036854775807 | 8 Bytes |
UInt8 | 0 ~ 255 | 1 Byte |
UInt16 | 0 ~ 65535 | 2 Bytes |
UInt32 | 0 ~ 4294967295 | 4 Bytes |
UInt64 | 0 ~ 18446744073709551615 | 8 Bytes |
Float32 | 32-bit IEEE754 floating point values | 4 Bytes |
Float64 | Double precision IEEE 754 floating point values | 8 Bytes |
Decimal Type
GreptimeDB supports the decimal type, a fixed-point type represented as decimal(precision, scale), where precision is the total number of digits, and scale is the number of digits in the fractional part. For example, 123.45 has a precision of 5 and a scale of 2.
precisioncan range from [1, 38].scalecan range from [0, precision].
The default decimal is decimal(38, 10) if the precision and scale are not specified.
CREATE TABLE decimals(
d DECIMAL(3, 2),
ts TIMESTAMP TIME INDEX,
);
INSERT INTO decimals VALUES ('0.1',1000), ('0.2',2000);
SELECT * FROM decimals;
Output:
+------+---------------------+
| d | ts |
+------+---------------------+
| 0.10 | 1970-01-01T00:00:01 |
| 0.20 | 1970-01-01T00:00:02 |
+------+---------------------+
Date and Time Types
| Type Name | Description | Size |
|---|---|---|
TimestampSecond | 64-bit timestamp values with seconds precision, range: [-262144-01-01 00:00:00, +262143-12-31 23:59:59] | 8 Bytes |
TimestampMillisecond | 64-bit timestamp values with milliseconds precision, range: [-262144-01-01 00:00:00.000, +262143-12-31 23:59:59.999] | 8 Bytes |
TimestampMicroSecond | 64-bit timestamp values with microseconds precision, range: [-262144-01-01 00:00:00.000000, +262143-12-31 23:59:59.999999] | 8 Bytes |
TimestampNanosecond | 64-bit timestamp values with nanoseconds precision, range: [1677-09-21 00:12:43.145225, 2262-04-11 23:47:16.854775807] | 8 Bytes |
Interval | Time interval | 4 Bytes for YearMonth, 8 Bytes for DayTime and 16 Bytes for MonthDayNano |
Boolean Type
| Type Name | Description | Size |
|---|---|---|
Boolean | Bool values | 1 Byte |
Use TRUE or FALSE to represent boolean values in SQL statements. For example:
CREATE TABLE bools(
b BOOLEAN,
ts TIMESTAMP DEFAULT CURRENT_TIMESTAMP() TIME INDEX,
);
INSERT INTO bools(b) VALUES (TRUE), (FALSE);
Data types compatible with MySQL and PostgreSQL
Type aliases
For users migrating from MySQL or PostgreSQL to GreptimeDB, GreptimeDB supports the following alias types.
| Data Type | Alias Types |
|---|---|
String | Text, Varchar, Char |
Binary | Varbinary |
Int8 | TinyInt |
Int16 | SmallInt |
Int32 | Int |
Int64 | BigInt |
UInt8 | UnsignedInt |
UInt16 | UnsignedTinyInt |
UInt32 | UnsignedSmallInt |
UInt64 | UnsignedBigInt |
Float32 | Float |
Float64 | Double |
TimestampSecond | Timestamp_s, Timestamp_sec, Timestamp(0) |
TimestampMillisecond | Timestamp, Timestamp_ms , Timestamp(3) |
TimestampMicroSecond | Timestamp_us, Timestamp(6) |
TimestampNanosecond | Timestamp_ns, Timestamp(9) |
You can use these alias types when creating tables.
For example, use Varchar instead of String, Double instead of Float64, and Timestamp(0) instead of TimestampSecond.
CREATE TABLE alias_types (
s TEXT,
i DOUBLE,
ts0 TIMESTAMP(0) DEFAULT CURRENT_TIMESTAMP() TIME INDEX,
PRIMARY KEY(s)
);
Date and time types
In addition to the Timestamp types used as the default time type in GreptimeDB, GreptimeDB also supports Date and DateTime types for compatibility with MySQL and PostgreSQL.
| Type name | Description | Size |
|---|---|---|
Date | 32-bit date values represent the days since UNIX Epoch | 4 Bytes |
DateTime | 64-bit datetime values represent the milliseconds since UNIX Epoch | 8 Bytes |
Examples
Create Table
CREATE TABLE data_types (
s STRING,
vbi BINARY,
b BOOLEAN,
tint INT8,
sint INT16,
i INT32,
bint INT64,
utint UINT8,
usint UINT16,
ui UINT32,
ubint UINT64,
f FLOAT32,
d FLOAT64,
dm DECIMAL(3, 2),
dt DATE,
dtt DATETIME,
ts0 TIMESTAMPSECOND,
ts3 TIMESTAMPMILLISECOND,
ts6 TIMESTAMPMICROSECOND,
ts9 TIMESTAMPNANOSECOND DEFAULT CURRENT_TIMESTAMP() TIME INDEX,
PRIMARY KEY(s));
Describe Table
DESC TABLE data_types;
+--------+----------------------+------+------+---------------------+---------------+
| Column | Type | Key | Null | Default | Semantic Type |
+--------+----------------------+------+------+---------------------+---------------+
| s | String | PRI | YES | | TAG |
| vbi | Binary | | YES | | FIELD |
| b | Boolean | | YES | | FIELD |
| tint | Int8 | | YES | | FIELD |
| sint | Int16 | | YES | | FIELD |
| i | Int32 | | YES | | FIELD |
| bint | Int64 | | YES | | FIELD |
| utint | UInt8 | | YES | | FIELD |
| usint | UInt16 | | YES | | FIELD |
| ui | UInt32 | | YES | | FIELD |
| ubint | UInt64 | | YES | | FIELD |
| f | Float32 | | YES | | FIELD |
| d | Float64 | | YES | | FIELD |
| dm | Decimal(3, 2) | | YES | | FIELD |
| dt | Date | | YES | | FIELD |
| dtt | DateTime | | YES | | FIELD |
| ts0 | TimestampSecond | | YES | | FIELD |
| ts3 | TimestampMillisecond | | YES | | FIELD |
| ts6 | TimestampMicrosecond | | YES | | FIELD |
| ts9 | TimestampNanosecond | PRI | NO | current_timestamp() | TIMESTAMP |
+--------+----------------------+------+------+---------------------+---------------+