Maximum number of records in a MySQL database table

What is the upper limit of records for MySQL database table. I'm wondering about autoincrement field. What would happen if I add milions of records? How to handle this kind of situations? Thx!

The greatest value of an integer has little to do with the maximum number of rows you can store in a table.

It's true that if you use an int or bigint as your primary key, you can only have as many rows as the number of unique values in the data type of your primary key, but you don't have to make your primary key an integer, you could make it a CHAR(100). You could also declare the primary key over more than one column.

There are other constraints on table size besides number of rows. For instance you could use an operating system that has a file size limitation. Or you could have a 300GB hard drive that can store only 300 million rows if each row is 1KB in size.

The limits of database size is really high:

http://dev.mysql.com/doc/refman/5.1/en/source-configuration-options.html

The MyISAM storage engine supports 2³² rows per table, but you can build MySQL with the --with-big-tables option to make it support up to 2⁶⁴ rows per table.

http://dev.mysql.com/doc/refman/5.1/en/innodb-restrictions.html

The InnoDB storage engine has an internal 6-byte row ID per table, so there are a maximum number of rows equal to 2⁴⁸ or 281,474,976,710,656.

An InnoDB tablespace also has a limit on table size of 64 terabytes. How many rows fits into this depends on the size of each row.

The 64TB limit assumes the default page size of 16KB. You can increase the page size, and therefore increase the tablespace up to 256TB. But I think you'd find other performance factors make this inadvisable long before you grow a table to that size.

mysql int types can do quite a few rows: http://dev.mysql.com/doc/refman/5.0/en/numeric-types.html

unsigned int largest value is 4,294,967,295
unsigned bigint largest value is 18,446,744,073,709,551,615

I suggest, never delete data. Don't say if the tables is longer than 1000 truncate the end of the table. There needs to be real business logic in your plan like how long has this user been inactive. For example, if it is longer than 1 year then put them in a different table. You would have this happen weekly or monthly in a maintenance script in the middle of a slow time.

When you run into to many rows in your table then you should start sharding the tables or partitioning and put old data in old tables by year such as users_2011_jan, users_2011_feb or use numbers for the month. Then change your programming to work with this model. Maybe make a new table with less information to summarize the data in less columns and then only refer to the bigger partitioned tables when you need more information such as when the user is viewing their profile. All of this should be considered very carefully so in the future it isn't too expensive to re-factor. You could also put only the users which comes to your site all the time in one table and the users that never come in an archived set of tables.

In InnoDB, with a limit on table size of 64 terabytes and a MySQL row-size limit of 65,535 there can be 1,073,741,824 rows. That would be minimum number of records utilizing maximum row-size limit. However, more records can be added if the row size is smaller .

According to Scalability and Limits section in http://dev.mysql.com/doc/refman/5.6/en/features.html, MySQL support for large databases. They use MySQL Server with databases that contain 50 million records. Some users use MySQL Server with 200,000 tables and about 5,000,000,000 rows.

Row Size Limits

> The maximum row size for a given table is determined by several factors:

• The internal representation of a MySQL table has a maximum row size limit of 65,535 bytes, even if the storage engine is capable of supporting larger rows. BLOB and TEXT columns only contribute 9 to 12 bytes toward the row size limit because their contents are stored separately from the rest of the row.

• The maximum row size for an InnoDB table, which applies to data stored locally within a database page, is slightly less than half a page. For example, the maximum row size is slightly less than 8KB for the default 16KB InnoDB page size, which is defined by the innodb_page_size configuration option. “Limits on InnoDB Tables”.

• If a row containing variable-length columns exceeds the InnoDB maximum row size, InnoDB selects variable-length columns for external off-page storage until the row fits within the InnoDB row size limit. The amount of data stored locally for variable-length columns that are stored off-page differs by row format. For more information, see “InnoDB Row Storage and Row Formats”.

• Different storage formats use different amounts of page header and trailer data, which affects the amount of storage available for rows.

Link http://dev.mysql.com/doc/refman/5.7/en/column-count-limit.html

Row Size Limits

The maximum row size for a given table is determined by several factors:

The internal representation of a MySQL table has a maximum row size limit of 65,535 bytes, even if the storage engine is capable of supporting larger rows. BLOB and TEXT columns only contribute 9 to 12 bytes toward the row size limit because their contents are stored separately from the rest of the row.

The maximum row size for an InnoDB table, which applies to data stored locally within a database page, is slightly less than half a page for 4KB, 8KB, 16KB, and 32KB innodb_page_size settings. For example, the maximum row size is slightly less than 8KB for the default 16KB InnoDB page size. For 64KB pages, the maximum row size is slightly less than 16KB. See Section 15.8.8, “Limits on InnoDB Tables”.

If a row containing variable-length columns exceeds the InnoDB maximum row size, InnoDB selects variable-length columns for external off-page storage until the row fits within the InnoDB row size limit. The amount of data stored locally for variable-length columns that are stored off-page differs by row format. For more information, see Section 15.11, “InnoDB Row Storage and Row Formats”.

Different storage formats use different amounts of page header and trailer data, which affects the amount of storage available for rows.

For information about InnoDB row formats, see Section 15.11, “InnoDB Row Storage and Row Formats”, and Section 15.8.3, “Physical Row Structure of InnoDB Tables”.

For information about MyISAM storage formats, see Section 16.2.3, “MyISAM Table Storage Formats”.

http://dev.mysql.com/doc/refman/5.7/en/innodb-restrictions.html

There is no limit. It only depends on your free memory and system maximum file size. But that doesn't mean you shouldn't take precautionary measure in tackling memory usage in your database. Always create a script that can delete rows that are out of use or that will keep total no of rows within a particular figure, say a thousand.