Re: Safe operations?

On Sun, Aug 12, 2018 at 11:06 PM, Tim Cross <theophilusx(at)gmail(dot)com> wrote:

>
> On Mon, 13 Aug 2018 at 11:24, Adrian Klaver <adrian(dot)klaver(at)aklaver(dot)com>
> wrote:
>
>> On 08/12/2018 05:41 PM, Samuel Williams wrote:
>> > I wish the documentation would include performance details, i.e. this
>> > operation is O(N) or O(1) relative to the number of rows.
>> >
>> > I found renaming a table was okay.
>> >
>> > How about renaming a column? Is it O(1) or proportional to the amount
>> of
>> > data?
>> >
>> > Is there any documentation about this?
>>
>> https://www.postgresql.org/docs/10/static/sql-altertable.html
>>
>> "RENAME
>>
>> The RENAME forms change the name of a table (or an index, sequence,
>> view, materialized view, or foreign table), the name of an individual
>> column in a table, or the name of a constraint of the table. There is no
>> effect on the stored data.
>> "
>>
>> Just wondering - what about the case when the column being renamed is
>> also referenced in an index or check constraint? (I would guess you cannot
>> rename a column used in a check constraint without first removing it, but
>> for an index, would this result in the index being rebuilt (or do you have
>> to take care of that manually or are such references abstracted such that
>> the column name "text" is irrelevant tot he actual structure of the
>> index?).
>
>
Tim, as far as I know, names are only an attribute tagged to an OID.
Internal relations are though these OIDs, not names, so renaming a column
is really one-shot. Names are mainly a more convenient way of referring to
objects.

Olivier