On Sun, Feb 18, 2024 at 1:59 PM Andy Fan <zhihuifan1...@163.com> wrote: > > > Hi Ashutosh, > > > data_type is described on that page as "Data type of the new column, > > or new data type for an existing column." but CREATE TABLE > > documentation [2] redirects data_type to [3], which mentions serial. > > The impression created by the documentation is the second statement > > above is a valid statement as should not throw an error; instead > > change the data type of the column (and create required sequence). > > I didn't find out a reason to not support it, if have any reason, I > think it is better have some explaination in the document. > > > In code ATPrepAlterColumnType() calls typenameTypeIdAndMod(), whereas > > transformColumnDefinition() (called for ALTER TABLE ... ADD COLUMN and > > CREATE TABLE) handles "serial" data type separately. Looks like we are > > missing a call to transformColumnDefinition() in > > transformAlterTableStmt() under case AT_AlterColumnType. > > I tried your idea with the attatchment, it is still in a drafted state > but it can be used as a prove-of-concept and for better following > communicating. Just one point needs to metion is serial implies > "default value" + "not null" constaint. So when we modify a column into > serial, we need to modify the 'NULL value' and only to the default value > at the RewriteTable stage. >
I am surprised that this requires changes in ReWrite. I thought adding NOT NULL constraint and default value commands would be done by transformColumnDefinition(). But I haven't looked at the patch close enough. -- Best Wishes, Ashutosh Bapat
