Often people in newsgroups ask about maximum size of various objects defined in databases.
The following tables shows the maximum sizes and numbers of various objects defined in MYSql, SQL Server.
| Char | 255 Bytes |
| Varchar | 65,535 Bytes |
| Binary | 255 Bytes |
| Varbinary | 65,535 Bytes |
| TinyBlob | 255 Bytes |
| TinyText | 255 Bytes |
| Blob | 65,535 Bytes (2^16 -1) |
| Text | 65,535 Bytes (2^16 -1) |
| Medium Blob | 16,777,215 Bytes (2^24 -1) |
| Medium Text | 16,777,215 Bytes (2^24 -1) |
| LongBlog | 4,294,967,295 Bytes (2^32 -1) |
| LongText | 4,294,967,295 Bytes (2^32 -1) |
| Bit | Range from 1 to 64 |
| Tinyint | The signed range is -128 to 127. The unsigned range is 0 to 255. |
| BOOL, BOOLEAN | true or false |
| SmallInt | The signed range is -32768 to 32767. The unsigned range is 0 to 65535. |
| MediumInt | The signed range is -8388608 to 8388607. The unsigned range is 0 to 16777215. |
| Int/Integer | The signed range is -2147483648 to 2147483647. The unsigned range is 0 to 4294967295. |
| BigInt | The signed range is -9223372036854775808 to 9223372036854775807. The unsigned range is 0 to 18446744073709551615. |
| Float | Allowable values are -3.402823466E+38 to -1.175494351E-38, 0, and 1.175494351E-38 to 3.402823466E+38. |
| Double | Allowable values are -1.7976931348623157E+308 to -2.2250738585072014E-308, 0, and 2.2250738585072014E-308 to 1.7976931348623157E+308. |
| char | 8,000 Char |
| nchar | 4,000 char |
| varchar | 8,000 char |
| nvarchar | 8,000 char |
| varchar(max) | 1,073,741,824 char |
| nvarchar(max) | 536,870,912 char |
| Tinyint | The range is 0 to 255. |
| SmallInt | The signed range is -32768 to 32767. |
| BigInt | The signed range is -9,223,372,036,854,775,808 to 9,223,372,036,854,775,807. |
| Int | The signed range is -2,147,483,648 to 2,147,483,647. |
| money | The signed range is -922,337,203,685,477.5808 to 922,337,203,685,477.5807. |
| smallmoney | Allowable values are -214,748.3648 to 214,748.3647. |
| bit | single bit. |
| binary | 8,000 bytes. |
| varbinary | 8,000 bytes. |
| varbinary(max) | 2 GB Data. |
| image | 2 GB Data. |
| Bytes per short string column | 8,000 |
| Bytes per GROUP BY, ORDER BY | 8,060 |
| Columns in GROUP BY, ORDER BY | Limited only by number of bytes |
| Bytes per index key | 900 |
| Bytes per foreign key | 900 |
| Bytes per primary key | 900 |
| Bytes per row | 8,060 |
| Bytes per varchar(max), varbinary(max), xml, text, or image column | 2^31-1 |
| Characters per ntext or nvarchar(max) column | 2^30-1 |
| Clustered indexes per table | 1 |
| Columns per index key | 16 |
| Columns per foreign key | 16 |
| Columns per primary key | 16 |
| Columns per base table | 1,024 |
| Columns per SELECT statement | 4,096 |
| Columns per INSERT statement | 1,024 |
| Connections per client | 32,767 |
| Database size | 1,048,516 terabytes |
| Databases per instance of SQL Server | 32,767 |
| Filegroups per database | 32,767 |
| Files per database | 32,767 |
| File size (data) | 16 terabytes |
| File size (log) | 2 terabytes |
| Foreign key table references per table | 253 |
| Identifier length (in characters) | 128 |
| Instances per computer | 50 (Workgroup Edition only 16) |
| Locks per connection | Maximum locks per server |
| Locks per instance of SQL Server | Up to 2,147,483,647 |
| Nested stored procedure levels | 32 |
| Nested subqueries | 32 |
| Nested trigger levels | 32 |
| Nonclustered indexes per table | 249 |
| Parameters per stored procedure | 2,100 |
| Parameters per user-defined function | 2,100 |
| REFERENCES per table | 253 |
| Rows per table | Limited by available storage |
| Tables per database | Limited by number of objects in a database |
| Partitions per partitioned table or index | 1,000 |
| Statistics on non-indexed columns | 2,000 |
| Tables per SELECT statement | 256 |
| Triggers per table | Limited by number of objects in a database |
| UNIQUE indexes or constraints per table | 249 nonclustered and 1 clustered |
| User connections | 32,767 |
| XML indexes | 249 |