Re: Removing columns from sstables

[Claude Warren, Jr via dev]

Close.  It is still in the table so the v3.x code that reads system.local
will detect it and fail on an unknown column as that code appears to be
looking at the actual on-disk format.

It sounds like the short answer is that there is no way to physically
remove the column from the on-disk format once it is added.

On Wed, Feb 22, 2023 at 11:28 AM Erick Ramirez 
wrote:

> When a column is dropped from a table, it is added to the
> system.dropped_columns table so it doesn't get returned in the results. Is
> that what you mean? 
>
>>

Re: Removing columns from sstables

[Erick Ramirez]

When a column is dropped from a table, it is added to the
system.dropped_columns table so it doesn't get returned in the results. Is
that what you mean? 

>

Removing columns from sstables

[Claude Warren, Jr via dev]

Greetings,

I have been looking through the code and I can't find any place where
columns are removed from an sstable.   I have found that rows can be
deleted.  Columns can be marked as deleted.  But I have found no place
where the deleted cell is removed from the row.  Is there the concept of
completely removing all traces of the column from the table?

The specific case I am working on is downgrading v4.x system.local table to
v3.1 format.  This involves the removal of the broadcast_port column so
that the hardcoded definition of the v3.1 table can read the sstable from
disk.

Any assistance or pointers would be appreciated,
Claude