On Fri, Oct 8, 2021, at 6:03 AM, nikolai.berkoff wrote:
The current documentation does not mention that the column statistics are removed which I can see they are in src/backend/commands/tablecmds.c
ATExecAlterColumnType
/*
* Drop any pg_statistic entry for the column, since it's now wrong type
*/
RemoveStatistics(RelationGetRelid(rel), attnum);
Although this might be obvious it tripped me up. For example renaming and SET STATISTICS preserves statistics. Patch attached.
I agree that it might surprise an user and it would be good to document it.
However, it does not belong to the description. I would add it to the Notes
section at the end of the ALTER TABLE page.