sql: Add Logical Column ID field to ColumnDescriptor

pkg/sql/information_schema.go

@@ -387,11 +387,11 @@ https://www.postgresql.org/docs/9.5/infoschema-columns.html`,
 					collationName = tree.NewDString(locale)
 				}
 				return addRow(
-					dbNameStr,                                            // table_catalog
-					scNameStr,                                            // table_schema
-					tree.NewDString(table.Name),                          // table_name
-					tree.NewDString(column.Name),                         // column_name
-					tree.NewDInt(tree.DInt(column.ID)),                   // ordinal_position
+					dbNameStr,                    // table_catalog
+					scNameStr,                    // table_schema
+					tree.NewDString(table.Name),  // table_name
+					tree.NewDString(column.Name), // column_name
+					tree.NewDInt(tree.DInt(column.GetLogicalColumnID())), // ordinal_position
 					dStringPtrOrNull(column.DefaultExpr),                 // column_default
 					yesOrNoDatum(column.Nullable),                        // is_nullable
 					tree.NewDString(column.Type.InformationSchemaName()), // data_type

pkg/sql/logictest/testdata/logic_test/pg_catalog

@@ -2279,3 +2279,26 @@ indexname  indexdef
 primary    CREATE UNIQUE INDEX "primary" ON test.public.geospatial_table USING btree (id ASC)
 idxa       CREATE INDEX idxa ON test.public.geospatial_table USING gin (a ASC)
 idxb       CREATE INDEX idxb ON test.public.geospatial_table USING gin (b ASC)
+
+subtest regression_46799
+statement ok
+create table t(x INT DEFAULT 1, y INT DEFAULT 1);
+
+query I
+select adnum from pg_attrdef WHERE adrelid = 85
+----
+1
+2
+3
+
+statement ok
+alter table t drop column y;
+alter table t add column y int default 1;
+
+# make sure after adding and dropping the same column, the adnum for the re-added column increases.
+query I
+select adnum from pg_attrdef WHERE adrelid = 85
+----
+1
+3
+4

pkg/sql/pg_catalog.go

@@ -412,11 +412,11 @@ CREATE TABLE pg_catalog.pg_attrdef (
 				defSrc = tree.NewDString(ctx.String())
 			}
 			return addRow(
-				h.ColumnOid(table.ID, column.ID), // oid
-				tableOid(table.ID),               // adrelid
-				tree.NewDInt(tree.DInt(colNum)),  // adnum
-				defSrc,                           // adbin
-				defSrc,                           // adsrc
+				h.ColumnOid(table.ID, column.ID),                     // oid
+				tableOid(table.ID),                                   // adrelid
+				tree.NewDInt(tree.DInt(column.GetLogicalColumnID())), // adnum
+				defSrc, // adbin
+				defSrc, // adsrc
 			)
 		})
 	})
@@ -502,7 +502,7 @@ CREATE TABLE pg_catalog.pg_attribute (
 		// Columns for table.
 		if err := forEachColumnInTable(table, func(column *sqlbase.ColumnDescriptor) error {
 			tableID := tableOid(table.ID)
-			return addColumn(column, tableID, column.ID)
+			return addColumn(column, tableID, column.GetLogicalColumnID())
 		}); err != nil {
 			return err
 		}
@@ -512,7 +512,7 @@ CREATE TABLE pg_catalog.pg_attribute (
 			return forEachColumnInIndex(table, index,
 				func(column *sqlbase.ColumnDescriptor) error {
 					idxID := h.IndexOid(table.ID, index.ID)
-					return addColumn(column, idxID, column.ID)
+					return addColumn(column, idxID, column.GetLogicalColumnID())
 				},
 			)
 		})

pkg/sql/sqlbase/structured.go

@@ -4130,3 +4130,14 @@ func GenerateUniqueConstraintName(prefix string, nameExistsFunc func(name string
 	}
 	return name
 }
+
+// GetLogicalColumnID returns the LogicalColumnID of the ColumnDescriptor
+// if the LogicalColumnID is set (non-zero). Returns the ID of the
+// ColumnDescriptor if the LogicalColumnID is not set.
+func (desc ColumnDescriptor) GetLogicalColumnID() ColumnID {
+	if desc.LogicalColumnID != 0 {
+		return desc.LogicalColumnID
+	}
+
+	return desc.ID
+}