CODEWITHSUNDEEP
sql
decon
decon

Reputation:

Do extra empty columns affect sql table size significantly?

I have a few columns that I know won't be used initially. Is it a good practice to add columns only when needed or just leave those extra columns there?

Is it just a little more space in the header or every row?

Upvotes: 4

Views: 4690

Answers (3)

Mitch Wheat
Mitch Wheat

Reputation: 300669

Depends on the column type to some extent.

Variable sized columns (such as varchar(n)) will only use 4 extra bytes (approx) per row.

I would add columns only when required, since it is less likely that redundant columns will be added and never removed.

Upvotes: 2

Noam
Noam

Reputation: 3391

I would like to add that although empty columns take up space (as mentioned in the other answers), when dealing with a big db, adding a column is not an easy task. So sometimes, it's good to have an additional column ready, even if it's just for future use.

Upvotes: 2

Sasha Chedygov
Sasha Chedygov

Reputation: 130847

Yes, they do still take up space, if only a couple bytes per row (depends on the column type). If you're not going to use them until later, what good is it to keep them there?

Upvotes: 2

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