From: | "David G(dot) Johnston" <david(dot)g(dot)johnston(at)gmail(dot)com> |
---|---|
To: | BO ST <1599224321(at)qq(dot)com> |
Cc: | pgsql-bugs <pgsql-bugs(at)lists(dot)postgresql(dot)org> |
Subject: | Re: Bug:Create a table with 1600 fields (reaching the upper limit), then drop several fields and create new ones, but the addition failed. |
Date: | 2023-05-04 16:12:31 |
Message-ID: | CAKFQuwafVB0Bt0U2QUVHP-pkX-gggBm9bXkmCzfpWz7Z+f6YNQ@mail.gmail.com |
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Lists: | pgsql-bugs |
On Thu, May 4, 2023 at 9:09 AM BO ST <1599224321(at)qq(dot)com> wrote:
> *Create a table with 1600 fields (reaching the upper limit), then drop
> several fields and create new ones, but the addition failed.*
>
> test=# alter table t1 add column co1599 int;
> ALTER TABLE
> test=# alter table t1 add column co1600 int;
> ALTER TABLE
> test=# alter table t1 add column co1601 int;
> psql: ERROR: table can have at most 1600 columns
>
> *then, I drop column co1600 and add it again, failed:*
>
> test=# alter table t1 drop column co1600;
> ALTER TABLE
> test=# alter table t1 add column co1600 int;
> psql: ERROR: table can have at most 1600 columns
>
> *then, I drop column co1600 again:*
>
> test=# alter table t1 drop column co1600;
> psql: ERROR: column "co1600" of relation "t1" dose not exist
>
Implementation details - not all columns that are present on a table are
user-visible. In particular, dropped columns remain but are inaccessible
in order to avoid rewriting the table.
David J.
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