Am 22.01.12 14:22, schrieb Giuseppe Sucameli: > Hi all, > > trying to create a table with a column xmin I get the > following error message: > > test=> create table lx (xmin int); > ERROR: column name "xmin" conflicts with a system > column name > > Instead I get a different (and less understandable) error > message if I try to add a column named xmin to an > existent table: > > test=> create table lx (i int); > CREATE TABLE > test=> alter table lx add xmin int; > ERROR: column "xmin" of relation "lx" already exists. > > The same problem occurs using "xmax" as column name. > > I'm on Ubuntu 11.04. > Tried on both PostgreSQL 8.4.10 and 9.1.2
That is not a bug, but a feature. See section 5.4 of the documentation "System Columns": "Every table has several system columns that are implicitly defined by the system. Therefore, these names cannot be used as names of user-defined columns. (Note that these restrictions are separate from whether the name is a key word or not; quoting a name will not allow you to escape these restrictions.) You do not really need to be concerned about these columns; just know they exist." and further down: "xmin The identity (transaction ID) of the inserting transaction for this row version. (A row version is an individual state of a row; each update of a row creates a new row version for the same logical row.)" -- Sent via pgsql-bugs mailing list (pgsql-bugs@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-bugs
