Good morning!
We are a little bit puzzled because running the following command on a 9.6 cluster is apparently requiring a table rewrite, or at least a very long operation of some kind, even though the docs say that as of 9.2:
Increasing the length limit for a varchar or varbit column, or removing the limit altogether, no longer requires a table rewrite. Similarly, increasing the allowable precision of a numeric column, or changing a column from constrained numeric to unconstrained numeric, no longer requires a table rewrite. Table rewrites are also avoided in similar cases involving the interval, timestamp, and timestamptz types.
I have a table foo with 100 million rows, and a column:
The following command is the one that we expect to execute very quickly (we are not seeing any locking), but it is instead taking a very long time:
- ALTER TABLE foo ALTER COLUMN id TYPE varchar(100);
I attempted the same operation instead cast to text - same problem.
Why do the docs seem wrong in our case? I have a guess: if the table was created prior to version 9.2, perhaps they are not binary coercible to text after 9.2? In any case, I would be very grateful for an explanation!
Thank you!
Jeremy