Re: BUG #16909: On update (not insert) the attisdropped flag is set for tables which are recreated with the same col

Can you please share the complete output?

Seems like a false alarm per my testing.

On Tue, Mar 2, 2021 at 3:58 PM PG Bug reporting form <noreply(at)postgresql(dot)org>
wrote:

> The following bug has been logged on the website:
>
> Bug reference: 16909
> Logged by: Grumpylittleted
> Email address: grumpylittleted(at)googlemail(dot)com
> PostgreSQL version: 13.2
> Operating system: Linux 5.8.0-44-generic #50~20.04.1-Ubuntu S
> Description:
>
> /*
>
> BUG:
>
> Using 13.2
> On update (not insert) the attisdropped flag is set for tables which are
> recreated with the same column names as the original but where preceding
> columns have been dropped
>
> METHOD:
> Create a table t with more than two columns: x, y, z
> Drop that table
> Create a table t with a subset of the columns with the same name as the
> previous table: here we remove y
> Insert a new row: there are two attributes (correct), neither of which
> have the attisdropped flag set (correct) (so bug not apparent with
> inserts)
> Update the row: there are two attributes (correct), the first attribute
> has the attisdropped flag unset (correct) BUT the second attribute has the
> attisdropped flag set (incorrect)
>
>
>
> make
> sudo cp ./f.so `pg_config --pkglibdir`
>
>
> SQL:
>
> create or replace function f() returns trigger as './f.so','f' language c
> strict;
>
> drop table if exists t cascade;
> create table t(x int, y int, z int);
>
> drop table t cascade;
> create table t(x int, z int);
> create trigger tf before insert or update on t for each row execute
> procedure f();
> insert into t values(4,5); -- attr num=1 attisdropped=0
> update t set x=2;
>
>
>
>
> */
>
> #include <stdlib.h>
> #include <stdio.h>
> #include <limits.h>
> #include "postgres.h"
> #include "fmgr.h"
> #include "executor/spi.h"
> #include "commands/trigger.h"
> #include "utils/rel.h"
> #include "utils/fmgrprotos.h"
>
>
>
> PG_MODULE_MAGIC;
> PG_FUNCTION_INFO_V1( f );
> Datum f( PG_FUNCTION_ARGS ) {
>
> TriggerData *trigdata = ( TriggerData * ) fcinfo->context;
> const TupleDesc tupdesc = trigdata->tg_relation->rd_att;
> HeapTuple tuple = TRIGGER_FIRED_BY_UPDATE( trigdata->tg_event ) ?
> trigdata->tg_newtuple : trigdata->tg_trigtuple;
>
> for( int i = 1; i <= tupdesc->natts; i++ ) {
> elog( INFO, "attr num=%d attisdropped=%d", i, TupleDescAttr( tupdesc, i
> )->attisdropped );
> }
>
> return PointerGetDatum( tuple );
>
> }
>
>