Normalizing an extremely big table

Question

I face the following issue. I have an extremely big table. This table is a heritage from the people who previously worked on the project. The table is in MS SQL Server.

Answer 1

You'll find other benefits to normalizing the data besides the speed of queries running against it... such as size and maintainability, which alone should justify normalizing it...

However, it will also likely improve the speed of queries; currently having a single row containing 300 text columns is massive, and is almost certainly past the 8,060 byte limit for storing the row data page... and is instead being stored in the ROW_OVERFLOW_DATA or LOB_DATA Allocation Units.

By reducing the size of each row through normalization, such as replacing redundant text data with a TINYINT foreign key, and by also removing columns that aren't dependent on this large table's primary key into another table, the data should no longer overflow, and you'll also be able to store more rows per page.

As far as the overhead added by performing JOIN to get the normalized data... if you properly index your tables, this shouldn't add a substantial amount of overhead. However, if it does add an unacceptable overhead, you can then selectively de-normalize the data as necessary.