What happens when a table in a database has more rows than the max size of the index data type?

For example if i have a unsigned int in开发者_开发百科dex in my table, what happens when i get more rows than sizeof(unsigned int) ? I'm interested in MySQL/PostgreSQL/MsSQL.

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Your question asks what happens when there are more than 4 or 8 rows (sizeof (unsigned int)). But I think you mean What happens when trying to insert a row when there will be 2^32 (or 2^64) rows?

I've never seen it, and I've worked with some really big databases. I expect the insert fails and causes the transaction to roll back. It can be sensed in MySQL with an insert probe.