Re: [HACKERS] ADD COLUMN

>
> Can somebody explain briefly what happens when you do an ALTER TABLE ADD
> COLUMN? Obviously it doesn't seem to go through the database and update
> every record with a new attribute there and then. Does it get updated
> the next time the record is retrieved or what is the story there?

NULL fields take up no space in rows, so adding NULL to the end of a row
really doesn't change the row, you just tell the catalog the column
exists, and the system sees a NULL there by default.

On updates, it remains the same unless you put something in the column.

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