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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.
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
The upper limit of Indexes can be modified via index-limit.
Limitation on a single row
Type
Upper limit
Size
6 MB by default. You can adjust the size limit via the txn-entry-size-limit configuration item.
Limitation on a single column
Type
Upper limit
Size
6 MB
Limitations on string types
Type
Upper limit
CHAR
256 characters
BINARY
256 characters
VARBINARY
65535 characters
VARCHAR
16383 characters
TEXT
6 MB
BLOB
6 MB
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 default upper limit is 5000, which can be modified using stmt-count-limit.