Limitations of the wide column model

Item

Limit

Description

Data table name

Unique within an instance

The following naming conventions apply to data tables:

• The name must be 1 to 255 bytes in length, can contain letters, digits, and underscores (_), and is case-sensitive.

• The first character must be a letter or an underscore (_).

Reserved read/write throughput of a single table

0 to 100,000 CU

For higher limits, contact technical support or join our DingTalk group: 36165029092.

Number of predefined columns

0 to 32

A predefined column is a non-primary key column with a defined name and data type. It can be used as an indexed field for a secondary index.

For higher limits, contact technical support or join our DingTalk group: 36165029092.

Item

Limit

Description

Column name

Unique within a table

The following naming conventions apply to columns:

• The name must be 1 to 255 bytes in length, can contain letters, digits, and underscores (_), and is case-sensitive.

• The first character must be a letter or an underscore (_).

Number of primary key columns

1 to 4

The first primary key column is the partition key.

Data types of primary key columns

String, Integer, Binary

• String: A UTF-8 encoded string with a maximum length of 1 KB.

• Integer: A 64-bit signed integer that is 8 bytes in length.

• Binary: Binary data with a maximum length of 1 KB.

Number of attribute columns

Unlimited

Although Tablestore does not limit the number of attribute columns, requests may time out when reading extremely wide rows. To prevent this, specify which columns to read or paginate the results. We recommend using fewer than 10,000 attribute columns per row.

Data types of attribute columns

String, Integer, Double, Boolean, Binary

• String: A UTF-8 encoded string with a maximum length of 2 MB.

• Integer: A 64-bit signed integer that is 8 bytes in length.

• Double: A 64-bit double value that is 8 bytes in length.

• Boolean: A boolean value, True or False, that is 1 byte in length.

• Binary: Binary data with a maximum length of 2 MB.

Item

Limit

Description

Number of attribute columns in a row

Unlimited

The number of attribute columns in a single row is not limited.

Size of data in a row

Unlimited

The total data size of a single row is not limited.

Item

Limit

Description

Data size per PutRow request

4 MB

This limit applies to the total size of primary keys and attribute columns in a single request.

Data size per UpdateRow request

4 MB

This limit applies to the total size of primary keys and attribute columns in a single request.

Number of rows per BatchWriteRow request

200

This is the maximum number of rows that can be processed in a single BatchWriteRow request.

Data size per BatchWriteRow request

4 MB

This limit applies to the total data size of all rows in a single BatchWriteRow request.

Number of rows per BatchGetRow request

100

This is the maximum number of rows that can be retrieved in a single BatchGetRow request.

Data scanned per GetRange request

5,000 rows or 4 MB

The scan stops when either 5,000 rows have been scanned or the data size reaches 4 MB. The primary key of the next row is returned to enable pagination.

Number of attribute columns per write request

1,024

A single PutRow, UpdateRow, or BatchWriteRow operation cannot write more than 1,024 attribute columns to a single row.

Number of columns in the columns_to_get parameter

0 to 128

Specifies the maximum number of columns to retrieve from a single row in one read request.

Size of an HTTP request body

5 MB

This is the maximum size of a request body.

Number of filters in a read request

10

This is the maximum number allowed per read request.

QPS for table metadata operations

10 per second

The total QPS for all table metadata operations on an instance cannot exceed 10. For more information, see Data table operations.

Number of UpdateTable operations on a single table

Unlimited

The number of calls is unlimited but constrained by the frequency limit described below.

Frequency of UpdateTable operations on a single table

Once every 2 minutes

You can adjust a table's reserved read/write throughput at most once every 2 minutes.