The STRING
data type stores a string of Unicode characters.
Aliases
In CockroachDB, the following are aliases for STRING
:
CHARACTER
CHAR
VARCHAR
TEXT
And the following are aliases for STRING(n)
:
CHARACTER(n)
CHARACTER VARYING(n)
CHAR(n)
CHAR VARYING(n)
VARCHAR(n)
Length
To limit the length of a string column, use STRING(n)
, where n
is the maximum number of Unicode code points (normally thought of as "characters") allowed.
When inserting a string:
- If the value exceeds the column's length limit, CockroachDB gives an error.
- If the value is cast as a string with a length limit (e.g.,
CAST('hello world' AS STRING(5))
), CockroachDB truncates to the limit. - If the value is under the column's length limit, CockroachDB does not add padding. This applies to
STRING(n)
and all its aliases.
Syntax
A value of type STRING
can be expressed using a variety of formats.
See string literals for more details.
When printing out a STRING
value in the SQL shell, the shell uses the simple
SQL string literal format if the value doesn't contain special character,
or the escaped format otherwise.
Collations
STRING
values accept collations, which lets you sort strings according to language- and country-specific rules.
Size
The size of a STRING
value is variable, but it's recommended to keep values under 64 kilobytes to ensure performance. Above that threshold, write amplification and other considerations may cause significant performance degradation.
Examples
> CREATE TABLE strings (a STRING PRIMARY KEY, b STRING(4), c TEXT);
> SHOW COLUMNS FROM strings;
+-------+-----------+-------+---------+
| Field | Type | Null | Default |
+-------+-----------+-------+---------+
| a | STRING | false | NULL |
| b | STRING(4) | true | NULL |
| c | STRING | true | NULL |
+-------+-----------+-------+---------+
> INSERT INTO strings VALUES ('a1b2c3d4', 'e5f6', 'g7h8i9');
> SELECT * FROM strings;
+----------+------+--------+
| a | b | c |
+----------+------+--------+
| a1b2c3d4 | e5f6 | g7h8i9 |
+----------+------+--------+
Supported Casting & Conversion
STRING
values can be cast to any of the following data types:
Type | Details |
---|---|
INT |
Requires supported INT string format, e.g., '10' . |
DECIMAL |
Requires supported DECIMAL string format, e.g., '1.1' . |
FLOAT |
Requires supported FLOAT string format, e.g., '1.1' . |
BOOL |
Requires supported BOOL string format, e.g., 'true' . |
DATE |
Requires supported DATE string format, e.g., '2016-01-25' . |
TIMESTAMP |
Requires supported TIMESTAMP string format, e.g., ''2016-01-25 10:10:10.555555'' . |
INTERVAL |
Requires supported INTERVAL string format, e.g., '1h2m3s4ms5us6ns' . |
BYTES |
Requires supported BYTES string format, e.g., b'\141\061\142\062\143\063' . |