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TiDB Limitations
Learn the usage limitations of TiDB.
/docs/dev/tidb-limitations/

TiDB Limitations

This document describes the common usage limitations of TiDB, including the maximum identifier length and the maximum number of supported databases, tables, indexes, partitioned tables, and sequences.

Note:

TiDB offers high compatibility with the MySQL protocol and syntax, including many MySQL limitations. For example, a single index can include a maximum of 16 columns. For more information, see MySQL Compatibility and the official MySQL documentation.

Limitations on identifier length

Identifier type Maximum length (number of characters allowed)
Database 64
Table 64
Column 64
Index 64
View 64
Sequence 64

Limitations on the total number of databases, tables, views, and connections

Type Maximum number
Databases unlimited
Tables unlimited
Views unlimited
Connections unlimited

Limitations on a single database

Type Upper limit
Tables unlimited

Limitations on a single table

Type Upper limit (default value)
Columns Defaults to 1017 and can be adjusted up to 4096
Indexes Defaults to 64 and can be adjusted up to 512
Rows unlimited
Size unlimited
Partitions 8192

Limitation on a single row

Type Upper limit (default value)
Size Defaults to 6 MiB and can be adjusted to 120 MiB

You can adjust the size limit via the txn-entry-size-limit configuration item.

Limitations on data types

Type Upper limit
CHAR 256 characters
BINARY 256 characters
VARBINARY 65535 characters
VARCHAR 16383 characters
TEXT Defaults to 6 MiB and can be adjusted to 120 MiB
BLOB Defaults to 6 MiB and can be adjusted to 120 MiB

Limitations on SQL statements

Type Upper limit
The maximum number of SQL statements in a single transaction When the optimistic transaction is used and the transaction retry is enabled, the upper limit is 5000.

You can modify the limit via the stmt-count-limit configuration item.

Limitations on TiKV version

In your cluster, if the version of the TiDB component is v6.2.0 or later, the version of TiKV must be v6.2.0 or later.