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数据类型

GreptimeDB 支持下列数据类型：

类型 描述 别名 大小
tinyint -128 ~ 127 Int8 1 Byte
smallint -32768 ~ 32767 Int16 2 Bytes
int -2147483648 ~ 2147483647 Int32 4 Bytes
bigint -9223372036854775808 ~ 9223372036854775807 Int64 8 Bytes
varchar UTF-8 encoded strings Text
/String
/ Char 		The length of the strings
float 32-bit IEEE754 floating point values Float32 4 Bytes
double Double precision IEEE 754 floating point values Float64 8 Bytes
boolean bool values Boolean 1 Byte
varbinary Variable length binary values Binary The length of the data + 2 bytes
date 32-bit date values represent the days since UNIX Epoch Date 4 Bytes
datetime 64-bit datetime values represent the milliseconds since UNIX Epoch DateTime 8 Bytes
timestamp[(0/3/6/9)] 64-bit timestamp values with optional precision.
For example, timestamp(0) represents timestamp type with seconds precision, timestamp(3) represents milliseconds precision, timestamp(6) for microseconds and timestamp(9) for nanoseconds. If no precision is given, the timestamp is in milliseconds precision by default.		 TimestampSecond
/TimestampMillisecond
/TimestampMicroSecond
/TimestampNanosecond		 8 Bytes

整数类型的 Unsigned 版本

int / tinyint / smallint / bigint 有 unsigned 版本，相应的值范围如下：

  • int unsigned / UInt8 : 0 ~ 4294967295
  • tinyint unsigned / UInt16 : 0 ~ 255
  • smallint unsigned / UInt32 : 0 ~ 65535
  • bigint unsigned / UInt64 : 0 ~ 18446744073709551615

Variable-sized 类型的限制

variable-sized 类型的最大容量, 例如 string 和 varbinary，取决于它们的编码和存储引擎处理它们的方式。

例如，string 值被编码为 UTF-8。如果所有字符都是 3 字节长度，则该字段可以存储 715827882 个字符。对于 varbinary 类型，最多可以存储 2147483647 字节。

Timestamp 类型别名

timestamp 类型带有各种别名，建议使用 TimestampSecond、TimestampMillisecond、TimestampMicrosecond 和 TimestampNanosecond。下表列出了对应的别名。

Type name Alias
TimestampSecond Timestamp_s, Timestamp_sec , Timestamp(0)
TimestampMillisecond Timestamp, Timestamp_ms , Timestamp(3)
TimestampMicrosecond Timestamp_us , Timestamp(6)
TimestampNanosecond Timestamp_ns , Timestamp(9)

Decimal

GreptimeDB 支持 decimal 类型，这是一种定点类型。

它表示为 decimal(precision, scale), precision 是数位的总数， scale 是小数部分的位数。 例如, 123.45 的 precision = 5 ， scale = 2.

  • precision 的范围 [1, 38].
  • scale 的范围 [0, precision].

如果没有指定 precision 和 scale，默认的 decimal 类型是 decimal(38, 10).

Simple Usage

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 |
+------+---------------------+

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,
  dt Date,
  dtt DateTime,
  ts0 TimestampSecond,
  ts3 TimestampMillisecond,
  ts6 TimestampMicrosecond,
  ts9 TimestampNanosecond DEFAULT CURRENT_TIMESTAMP() TIME INDEX,
  PRIMARY KEY(s));

Describe Table

> describe 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         |
| 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     |
+--------+----------------------+------+------+---------------------+---------------+