Question

We are facing problem in the alter table SQL statement. Some time we update our database at client side and the alter table sql taking very much time. I like to know, how alter works? Does alter statement performance correlated to that table data? Means, if table have large data then alter will take much time.

There is also problem with the Oracle 11G R2. Is there any changes which need to incorporate to our code? Our code is very old and working fine till now?

Answer 1

There could be several reasons for this:

• If the table is locked by another
  query/resource. It would wait for the
  lock to be released and then execute
  the update…
• If the table contains many rows and you have added a new column in the table with a default value, it would execute an update query for whole table after altering the table to update all the existing records with the default value…