space optimization in a mysql database

Question

I am building a database that contains a large number of pairs, each of which consists of two parts, an ID and a long string. Each ID is unique however there are only a handful of these long string attributes. To save space I was considering doing the following:

I'd have two tables, the first with pairs of the form ID and stringID and the second with pairs of the form stringID longString.

I'd like to know if this kind of space optimization is already done automatically in a mysql database. If it is then I won't bother implementing it myself. If this kind of space optimization is not done automatically, is there a better way of doing it? What is considered the best practice with regards to this type of optimization? Thanks

To make my question more concrete, consider the following original table:

employee   WorkAddress (an extremely long string)  
name1      address1  
name2      address1  
name3      address1  
name4      address1  
...  
name1000   address2  
name1001   address2  
name1002   address2  
...
etc

And the new more space efficient table:

employee   addressID (much shorter than the long string)
name1      ID1
name2      ID1
...
name1000   ID2
name1001   ID2
name1002   ID2
...
etc

In addition to the second table:

addressID  WorkAddress
ID1        address1
ID2        address2
...
etc

NOTE: If you think this question is not suited for stackoverflow, please recommend one of the other stackexchange sites for this type of question. Thanks

Answer 1

The solution with the two tables is certainly the right one. Not because of any space considerations (if you're in an environment where (external) space is really short, a fully blown DBMS is probably not the right tool anyway) but because of securing data integrity by normalization.

If that string values is directly in the table with the IDs and it changes, that means that every row in that table with that values has to be changed. For one that's more writing than just changing one row in the two table approach. But even worse, if you forget to update one or some rows by whatever circumstance you data is corrupted.