Always copy into non-compressed slot of arrow slot

When copying from a non-arrow slot to a arrow slot, we should always
copy the data into the non-compressed slot and never to the compressed
slot.

The previous check for matching number of attributes fail when you drop
one column from the hyperstore.

tsl/src/hyperstore/arrow_tts.c

@@ -638,39 +638,14 @@ tts_arrow_copyslot(TupleTableSlot *dstslot, TupleTableSlot *srcslot)
 
 	ExecClearTuple(dstslot);
 
-	/* Check if copying from another slot implementation */
+	/* Check if copying from another slot implementation. */
 	if (dstslot->tts_ops != srcslot->tts_ops)
 	{
+		/* If we are copying from another slot implementation to arrow slot,
+		   we always copy the data into the non-compressed slot. */
 		child_srcslot = srcslot;
-
-		/*
-		 * The source slot is not an Arrow slot so it is necessary to identify
-		 * which destination child slot to copy the source slot into. It
-		 * should normally be the non-compressed slot, but double check the
-		 * number of attributes to sure. If the source and the target tuple
-		 * descriptor has the same number of attributes, then it should a
-		 * non-compressed slot since the compressed slot has extra metadata
-		 * attributes. If the compressed table is changed in the future to not
-		 * have extra metadata attributes, this check needs to be updated.
-		 *
-		 * Note that it is not possible to use equalTupleDescs() because it
-		 * compares the tuple's composite ID. If the source slot is, e.g.,
-		 * virtual, with no connection to a physical relation, the composite
-		 * ID is often RECORDID while the arrow slot has the ID of the
-		 * relation.
-		 */
-		if (dstslot->tts_tupleDescriptor->natts == srcslot->tts_tupleDescriptor->natts)
-		{
-			/* non-compressed tuple slot */
-			child_dstslot = arrow_slot_get_noncompressed_slot(dstslot);
-			adstslot->tuple_index = InvalidTupleIndex;
-		}
-		else
-		{
-			child_dstslot = arrow_slot_get_compressed_slot(dstslot, srcslot->tts_tupleDescriptor);
-			/* compressed tuple slot */
-			adstslot->tuple_index = 1;
-		}
+		child_dstslot = arrow_slot_get_noncompressed_slot(dstslot);
+		adstslot->tuple_index = InvalidTupleIndex;
 	}
 	else
 	{

tsl/test/expected/hyperstore_insert.out

@@ -301,3 +301,37 @@ order by location_id;
 (3 rows)
 
 drop table :hypertable;
+-- Check that we can write to a hyperstore table from another kind of
+-- slot even if we have dropped and added attributes.
+create table test2 (itime integer, b bigint, t text);
+select create_hypertable('test2', by_range('itime', 10));
+NOTICE:  adding not-null constraint to column "itime"
+ create_hypertable 
+-------------------
+ (3,t)
+(1 row)
+
+create table test2_source(itime integer, d int, t text);
+insert into test2_source values (9, '9', 90), (17, '17', 1700);
+-- this will create a single chunk.
+insert into test2 select t, 10,  'first'::text from generate_series(1, 7) t;
+alter table test2 drop column b;
+alter table test2 add column c int default -15;
+alter table test2 add column d int;
+-- Since we have chunk sizes of 10, this will create a second chunk
+-- with a second set of attributes where one is dropped.
+insert into test2 select t, 'second'::text, 120, 1 from generate_series(11, 15) t;
+alter table test2
+      set access method hyperstore,
+      set (timescaledb.compress_segmentby = '', timescaledb.compress_orderby = 'c, itime desc');
+WARNING:  there was some uncertainty picking the default segment by for the hypertable: You do not have any indexes on columns that can be used for segment_by and thus we are not using segment_by for compression. Please make sure you are not missing any indexes
+NOTICE:  default segment by for hypertable "test2" is set to ""
+select compress_chunk(show_chunks('test2'));
+             compress_chunk              
+-----------------------------------------
+ _timescaledb_internal._hyper_3_13_chunk
+ _timescaledb_internal._hyper_3_14_chunk
+(2 rows)
+
+-- Insert into both chunks using a select.
+insert into test2(itime ,t , d) select itime, t, d from test2_source;

tsl/test/sql/hyperstore_insert.sql

@@ -173,3 +173,32 @@ select * from :hypertable where location_id between 11 and 22
 order by location_id;
 
 drop table :hypertable;
+
+-- Check that we can write to a hyperstore table from another kind of
+-- slot even if we have dropped and added attributes.
+create table test2 (itime integer, b bigint, t text);
+select create_hypertable('test2', by_range('itime', 10));
+
+create table test2_source(itime integer, d int, t text);
+insert into test2_source values (9, '9', 90), (17, '17', 1700);
+
+
+-- this will create a single chunk.
+insert into test2 select t, 10,  'first'::text from generate_series(1, 7) t;
+
+alter table test2 drop column b;
+alter table test2 add column c int default -15;
+alter table test2 add column d int;
+
+-- Since we have chunk sizes of 10, this will create a second chunk
+-- with a second set of attributes where one is dropped.
+insert into test2 select t, 'second'::text, 120, 1 from generate_series(11, 15) t;
+
+alter table test2
+      set access method hyperstore,
+      set (timescaledb.compress_segmentby = '', timescaledb.compress_orderby = 'c, itime desc');
+
+select compress_chunk(show_chunks('test2'));
+
+-- Insert into both chunks using a select.
+insert into test2(itime ,t , d) select itime, t, d from test2_source;