MemSQL supports the following data types. The sizes given are for in-memory rowstore tables. Columnstore (on-disk) tables are stored differently, and often compressed.

Integer Numbers

Note:

• BOOL and BOOLEAN are synonymous with TINYINT. A value of 0 is considered FALSE, non-zero values are considered TRUE.

Real Numbers

Time and Date

Timestamp Behavior

The TIMESTAMP and TIMESTAMP(6) types support automatic initialization and update of timestamp values. If you don’t need automatic initialization or update support, it is recommended that you use the DATETIME or DATETIME(6) types instead. The size and resolution of TIMESTAMP and TIMESTAMP(6) are the same as DATETIME and DATETIME(6), respectively.

By default, the first field in a table declared as TIMESTAMP behaves the same as one defined with DEFAULT CURRENT_TIMESTAMP and ON UPDATE CURRENT_TIMESTAMP. Or, alternatively, if the first TIMESTAMP type field is declared as a TIMESTAMP(6), then it behaves as if it was defined with both DEFAULT CURRENT_TIMESTAMP(6) and UPDATE CURRENT_TIMESTAMP(6).

If any column other than the first TIMESTAMP column is updated, then the TIMESTAMP column is also updated to the value of CURRENT_TIMESTAMP. If a row is inserted in the table and no value is provided for the first TIMESTAMP field, that field defaults to the CURRENT_TIMESTAMP value. If the first timestamp-type column is a TIMESTAMP(6), the behavior is similar except that the higher-resolution timestamp CURRENT_TIMESTAMP(6) is used.

For example, see below how the value of the ts column is chosen after insert and update operations:

memsql> CREATE TABLE r(d DATETIME(6), ts TIMESTAMP(6), id INT);

memsql> INSERT r(d, id) VALUES("2017-07-01", 1);

memsql> SELECT * FROM r;
+----------------------------+----------------------------+------+
| d                          | ts                         | id   |
+----------------------------+----------------------------+------+
| 2017-07-01 00:00:00.000000 | 2017-05-09 23:32:38.815242 |    1 |
+----------------------------+----------------------------+------+

memsql> UPDATE r SET id = 2 WHERE id = 1;

memsql> SELECT * FROM r;
+----------------------------+----------------------------+------+
| d                          | ts                         | id   |
+----------------------------+----------------------------+------+
| 2017-07-01 00:00:00.000000 | 2017-05-09 23:33:53.549569 |    2 |
+----------------------------+----------------------------+------+

CREATE TABLE s (
  ts TIMESTAMP DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
  id INT);

String Types

Fixed-Length String

There are three fixed-size string types in MemSQL. The space consumed is directly proportional to their length definitions. Values of type CHAR require 3 x LENGTH bytes of memory, as MemSQL supports only the UTF8 character set. Values of type BINARY require LENGTH bytes of memory.

Variable-Length Strings

There are several variable-length string types. The data for these variable types are stored in a memory allocation designed for them, and pointers to their locations in memory are stored in the main table structure. This means that the space consumed by a particular value is the byte length of the string, plus an 8-byte overhead for the pointer, and a 4-byte overhead for storing the length. (There is an additional 4-byte overhead if the field is nullable.) One exception is values less than 7 bytes long. Those small values are stored directly in the pointer area.

The three main types are VARCHAR, VARBINARY, and LONGTEXT. While they all operate similarly for most English-language alphanumeric strings, there are several important differences in their behavior. The length limit of the VARCHAR is measured in Unicode characters, not in bytes. VARBINARY fields store data verbatim, regardless of whether they are valid Unicode strings. Sorting and comparing a VARBINARY uses the exact binary representation.

JSON Type

The JSON type can contain any valid Javascript Object Notation data, including maps, arrays, and nested types. For more information see the JSON Guide .

Geospatial Types

Geospatial types contain information about points, paths, and polygons on the surface of the Earth. For more information, see the Geospatial Guide.

Other Types

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