Tablestore limits-Tablestore(Tablestore)-阿里云帮助中心

This topic describes the limits of Tablestore.

Instances

Restrictions	Limitations	Description
Number of instances	10	If your business requirements exceed this limit, submit a ticket to contact us.
Instance name	Unique within a region	In VCU mode, instance names are generated automatically, and you can set a custom alias. In CU mode, the instance name naming conventions are as follows: Consists of letters, digits, or hyphens (-). The name is case-insensitive and must be 3 to 16 characters in length. Must start with a letter and cannot end with a hyphen (-). The instance name cannot contain the words `ali`, `ay`, `ots`, `taobao`, or `admin`.
Number of tables in an instance	64	This limit includes the number of data tables, secondary index tables, time series tables, Lastpoint index tables, and analytics stores. If your business requirements exceed this limit, submit a ticket to contact us. Important A time series table uses two table quotas because it includes a timeline metadata table and a timeline data table.

Wide table model

Limitations	Limit	Description
Data table name	Unique within an instance	The naming conventions for data tables are as follows: Consists of letters, digits, or underscores (_). The name is case-sensitive and must be 1 to 255 bytes in length. Must start with a letter or an underscore (_).
Number of primary key columns	1 to 4	The first primary key column is the partition key.
Data type of primary key columns	String, Integer, Binary	String: UTF-8 encoded, with a maximum length of 1 KB. Integer: 64-bit signed integer, with a length of 8 bytes. Binary: Binary data, with a maximum length of 1 KB.
Number of attribute columns	Unlimited	Tablestore does not limit the number of attribute columns. If you read a very wide row with hundreds of thousands of attribute columns at once, the operation may time out and fail. To avoid this, specify the attribute columns to read or use paging. We recommend keeping the number of attribute columns under 10,000.
Data type of attribute columns	String, Integer, Double, Boolean, Binary	String: UTF-8 encoded, with a maximum length of 2 MB. Integer: 64-bit signed integer, with a length of 8 bytes. Double: 64-bit double-precision floating-point number, with a length of 8 bytes. Boolean: True or False, with a length of 1 byte. Binary: Binary data, with a maximum length of 2 MB.
Number of predefined columns	0 to 32	Predefined columns are non-primary key columns and their data types that are defined in advance for a data table. They can be used as fields for secondary indexes.

For more information, see Wide table model limits.

Time series model

Limit item	Limitations	Description
Time series table name	Unique within an instance	The naming conventions for time series tables are as follows: Consists of letters, digits, or underscores (_). The name is case-sensitive and must be 1 to 128 characters in length. Must start with a letter or an underscore (_).
Storage Count for Analysis	1	You can create a maximum of one analytics store for each time series table.
Number of Lastpoint indexes	10	The total number of Lastpoint index tables and analytics stores for a time series table cannot exceed 10.

For more information, see Time series model limits.

Search index

Limits	Limit	Description
Number of search indexes	Unlimited	We recommend creating only one search index that includes all the fields you need to retrieve.
Number of search index fields	1,000	None.
Row count limit	100 billion	If your business requirements exceed this limit, submit a ticket to contact us.
Total size limit	100 TB	If your business requirements exceed this limit, submit a ticket to contact us.
Read/write rate	50,000 rows/s	Load balancing may take several minutes during initial or burst writes. For text fields, the limit is 10,000 rows/s due to the high CPU consumption of tokenization. If your business requirements exceed this limit, submit a ticket to contact us.
Synchronization latency	3s	In 99% of cases, the latency is within 3 seconds. A new index may take up to 1 minute to initialize.
Multiple data versions	Not supported	None.

For more information, see Search index limits.

Secondary index limits

Limit item	Limitations	Description
Number of secondary indexes	5	If your business requirements exceed this limit, submit a ticket to contact us.
Number of secondary index fields	36	A maximum of 8 primary key columns, which consist of index columns and primary key columns automatically added from the data table. A maximum of 4 of these can be index columns, which consist of primary key columns and any predefined columns from the data table. A maximum of 32 attribute columns, which consist of predefined columns from the data table.
Multiple data versions	Not supported	None.

For more information, see Secondary index limits.

SQL query limits

Limit item	Limitations	Description
Mapping table and column names	Cannot be the same as reserved keywords	The naming conventions for table and column names are as follows: Consists of letters, digits, or underscores (_). The name must be 1 to 255 bytes in length. Must start with a letter or an underscore (_). Cannot be a reserved word or keyword in SQL. For more information, see Reserved words and keywords.
One-time execution timeout	30 s	The execution time of a single SQL statement depends on its complexity and the data volume in the table. The maximum execution time is 30 seconds. If the execution time exceeds this limit, the system returns an error.
Data volume for a one-time scan	128 MB or 100,000 rows	The maximum number of rows for a single scan is 100,000, and the maximum data size is 128 MB. If a scan exceeds these limits, the system returns an error.

For more information, see SQL query limits.