Allow anonymization of tables without an AID column.

[Cristian Berneanu]

In such cases, a synthetic row index value should be used as the AID.

[pdobacz]

do you have any way of accomplishing this in mind? Only silly idea that occurred to me is to use ctid but it segfaults :P .

If no prior thoughts on this, I'll start looking for options.

[pdobacz]

my (un)educated guess points me towards these bits:

static void append_aid_args(Aggref *aggref, List *aid_refs)
{...
  foreach (cell, aid_refs)
  {
    AidRef *aid_ref = (AidRef *)lfirst(cell);
    TargetEntry *aid_entry = make_aid_target(aid_ref, list_length(aggref->args) + 1, false);

    /* Append the AID argument to function's arguments. */
    aggref->args = lappend(aggref->args, aid_entry);
    aggref->aggargtypes = lappend_oid(aggref->aggargtypes, aid_ref->aid_column->atttype);
...

and

static TargetEntry *make_aid_target(AidRef *aid_ref, AttrNumber resno, bool resjunk)
{
  TargetEntry *te = makeTargetEntry(make_aid_expr(aid_ref), resno, "aid", resjunk);

  te->resorigtbl = aid_ref->relation->oid;
  te->resorigcol = aid_ref->aid_column->attnum;

  return te;
}

but around the make_aid_expr I make an expression doing something like row_number() OVER (). Plugging a row_number into the query manually segfaults in publish_* access level (EDIT: this segfault looks unrelated to row_number, more likely it's #289) looks like exactly what we need.

Does this sound sane? CC @edongashi

[Edon Gashi]

Maybe there's a way to export CTID. Row number is not good because it can change once we have filters. If there's no straightforward system column which we can expose, I would put this on hold for now.

[Edon Gashi]

The downside of a physical location is that we have different aid noise samples if the same dataset is hosted multiple times. I can't think of a good solution as of right now.

[Cristian Berneanu]

Since there is no straightforward solution in sight and this feature is not that important, let's drop it.