PgAttribute loading + ColummnTableModel

Required enchancement to PgContainer to make multifield key work.

pglab/PgAttributeContainer.cpp

@@ -0,0 +1,30 @@
+#include "PgAttributeContainer.h"
+#include "Pgsql_Col.h"
+
+std::string PgAttributeContainer::getLoadQuery() const
+{
+	return
+		"SELECT attrelid, attname, atttypid, attstattarget, \n"
+		"    attnum, attndims, atttypmod, attnotnull, atthasdef, \n"
+		"    attcollation, attacl, attoptions \n"
+		"  FROM pg_catalog.pg_attribute";
+}
+
+PgAttribute PgAttributeContainer::loadElem(const Pgsql::Row &row)
+{
+	Pgsql::Col col(row);
+	PgAttribute v;
+	col >> v.relid >> v.name >> v.typid >> v.stattarget
+			>> v.num >> v.ndims >> v.typmod >> v.notnull >> v.hasdef
+			>> v.collation >> v.acl >> v.options;
+	return v;
+}
+
+std::vector<PgAttribute> PgAttributeContainer::getColumnsForRelation(Oid oid) const
+{
+	std::vector<PgAttribute> result;
+	for (const auto &e : m_container)
+		if (e.relid == oid)
+			result.push_back(e);
+	return result;
+}