Function buildNSItemFromTupleDesc

src/backend/parser/parse_relation.c:1249–1294

* buildNSItemFromTupleDesc * Build a ParseNamespaceItem, given a tupdesc describing the columns. * * rte: the new RangeTblEntry for the rel * rtindex: its index in the rangetable list * tupdesc: the physical column information */

 * tupdesc: the physical column information
 */
static ParseNamespaceItem *
buildNSItemFromTupleDesc(RangeTblEntry *rte, Index rtindex, TupleDesc tupdesc)
{
	ParseNamespaceItem *nsitem;
	ParseNamespaceColumn *nscolumns;
	int			maxattrs = tupdesc->natts;
	int			varattno;

	/* colnames must have the same number of entries as the nsitem */
	Assert(maxattrs == list_length(rte->eref->colnames));

	/* extract per-column data from the tupdesc */
	nscolumns = (ParseNamespaceColumn *)
		palloc0(maxattrs * sizeof(ParseNamespaceColumn));

	for (varattno = 0; varattno < maxattrs; varattno++)
	{
		Form_pg_attribute attr = TupleDescAttr(tupdesc, varattno);

		/* For a dropped column, just leave the entry as zeroes */
		if (attr->attisdropped)
			continue;

		nscolumns[varattno].p_varno = rtindex;
		nscolumns[varattno].p_varattno = varattno + 1;
		nscolumns[varattno].p_vartype = attr->atttypid;
		nscolumns[varattno].p_vartypmod = attr->atttypmod;
		nscolumns[varattno].p_varcollid = attr->attcollation;
		nscolumns[varattno].p_varnosyn = rtindex;
		nscolumns[varattno].p_varattnosyn = varattno + 1;
	}

	/* ... and build the nsitem */
	nsitem = (ParseNamespaceItem *) palloc(sizeof(ParseNamespaceItem));
	nsitem->p_names = rte->eref;
	nsitem->p_rte = rte;
	nsitem->p_rtindex = rtindex;
	nsitem->p_nscolumns = nscolumns;
	/* set default visibility flags; might get changed later */
	nsitem->p_rel_visible = true;
	nsitem->p_cols_visible = true;
	nsitem->p_lateral_only = false;
	nsitem->p_lateral_ok = true;

	return nsitem;
}

/*
 * buildNSItemFromLists