Fix compaction of non-presorted tuples (#21)

It covers the case when line pointers (lp) point to unsorted offsets
(tuples):
```
SELECT lp, lp_off, t_ctid FROM heap_page_items(get_raw_page('sbtest1', 0));
 lp | lp_off | t_ctid
----+--------+--------
  1 |   7960 | (0,1)
  2 |   7264 | (0,2)
  3 |   7032 | (0,3)
  4 |   6800 | (0,4)
  5 |   7728 | (0,5)
  6 |      0 |
  7 |   7496 | (0,7)
(7 rows)
```

This condition can be achieved by deleting some tuples and running
VACUUM

Also, the encoded bytes printing is hidden behind higher ENCRYPTION_DEBUG.
It floods log a lot otherwise.

src/access/pg_tde_prune.c

@@ -1417,7 +1417,6 @@ pgtde_compactify_tuples(Relation rel, Buffer buffer, itemIdCompact itemidbase, i
 	}
 	else
 	{
-		Assert(0); // TODO: to be implemented with encryption
 		PGAlignedBlock scratch;
 		char	   *scratchptr = scratch.data;
 
@@ -1491,6 +1490,30 @@ pgtde_compactify_tuples(Relation rel, Buffer buffer, itemIdCompact itemidbase, i
 			ItemId		lp;
 
 			itemidptr = &itemidbase[i];
+			if(copy_head < copy_tail) { // TODO: recheck this condition
+				// We leave the original loop as-is, and recrypt tuples one by one
+				// This is definitely not the fastest, but simple
+				Oid tableOid = RelationGetRelid(rel);
+				BlockNumber bn = BufferGetBlockNumber(buffer);
+				unsigned long headerSize = sizeof(HeapTupleHeaderData);
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wvla"
+				char tmpData[itemidptr->alignedlen];
+#pragma GCC diagnostic pop
+
+#ifdef ENCRYPTION_DEBUG
+				fprintf(stderr, " >>>> [non-sorted] RELOCATING FROM %u to %u tail %u\n", copy_head, upper, copy_tail);
+				/* Decrypt with old offset */
+				fprintf(stderr, " >>>>> DECRYPTING\n");
+#endif
+				PGTdeCryptTupInternal(tableOid, bn, copy_head, scratchptr + copy_head, tmpData, headerSize, itemidptr->len);
+				/* Reencrypt with new offset */
+#ifdef ENCRYPTION_DEBUG
+				fprintf(stderr, " >>>>> ENCRYPTING\n");
+#endif
+				PGTdeCryptTupInternal(tableOid, bn, upper, tmpData, scratchptr + copy_head, headerSize, itemidptr->len);
+			}
+
 			lp = PageGetItemId(page, itemidptr->offsetindex + 1);
 
 			/* copy pending tuples when we detect a gap */
@@ -1516,6 +1539,29 @@ pgtde_compactify_tuples(Relation rel, Buffer buffer, itemIdCompact itemidbase, i
 			lp->lp_off = upper;
 		}
 
+		/* Recrypt the remaining chunk */
+		if(copy_head < copy_tail) { // TODO: recheck this condition
+			Oid tableOid = RelationGetRelid(rel);
+			BlockNumber bn = BufferGetBlockNumber(buffer);
+			unsigned long headerSize = sizeof(HeapTupleHeaderData);
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wvla"
+			char tmpData[itemidptr->alignedlen];
+#pragma GCC diagnostic pop
+
+#ifdef ENCRYPTION_DEBUG
+			fprintf(stderr, " >>>> [non-sorted] RELOCATING FROM %u to %u tail %u\n", copy_head, upper, copy_tail);
+			/* Decrypt with old offset */
+			fprintf(stderr, " >>>>> DECRYPTING\n");
+#endif
+			PGTdeCryptTupInternal(tableOid, bn, copy_head, scratchptr + copy_head, tmpData, headerSize, itemidptr->len);
+			/* Reencrypt with new offset */
+#ifdef ENCRYPTION_DEBUG
+			fprintf(stderr, " >>>>> ENCRYPTING\n");
+#endif
+			PGTdeCryptTupInternal(tableOid, bn, upper, tmpData, scratchptr + copy_head, headerSize, itemidptr->len);
+		}
+
 		/* Copy the remaining chunk */
 		memcpy((char *) page + upper,
 			   scratchptr + copy_head,

src/encryption/enc_tuple.c

@@ -48,7 +48,7 @@ void PGTdeCryptTupInternal(Oid tableOid, BlockNumber bn, unsigned long offsetInP
 	for(unsigned i = 0; i < to - from; ++i) {
 		const char v = ((char*)(t_data))[i + from];
 		char realKey = encKey[aesBlockOffset + i];
-#if ENCRYPTION_DEBUG
+#if ENCRYPTION_DEBUG > 1
 	    fprintf(stderr, " >> 0x%02hhX 0x%02hhX\n", v & 0xFF, (v ^ realKey) & 0xFF);
 #endif
 		out[i + from] = v ^ realKey;

src/test/non_sorted_off_compact.sql

@@ -0,0 +1,48 @@
+-- A test case for https://github.com/Percona-Lab/postgres-tde-ext/pull/21
+-- 
+DROP TABLE IF EXISTS sbtest1;
+CREATE TABLE sbtest1(
+	  id SERIAL,
+	  k INTEGER DEFAULT '0' NOT NULL,
+	  PRIMARY KEY (id)
+	) USING pg_tde;
+
+INSERT INTO sbtest1(k) VALUES
+(1),
+(2),
+(3),
+(4),
+(5),
+(6),
+(7),
+(8),
+(9),
+(10);
+DELETE FROM sbtest1 WHERE id IN (4,5,6);
+
+VACUUM sbtest1;
+
+INSERT INTO sbtest1(k) VALUES
+(11),
+(12),
+(13);
+
+-- Line pointers (lp) point to non-sorted offsets (lp_off):
+-- CREATE EXTENSION pageinspect;
+-- SELECT lp, lp_off, t_ctid FROM heap_page_items(get_raw_page('sbtest1', 0));
+--  lp | lp_off | t_ctid
+-- ----+--------+--------
+--   1 |   8160 | (0,1)
+--   2 |   8128 | (0,2)
+--   3 |   8096 | (0,3)
+--   4 |   7936 | (0,4)
+--   5 |   7904 | (0,5)
+--   6 |   7872 | (0,6)
+--   7 |   8064 | (0,7)
+--   8 |   8032 | (0,8)
+--   9 |   8000 | (0,9)
+--  10 |   7968 | (0,10)
+
+---- Trigger comapction
+delete from sbtest1 where id in (2);
+VACUUM sbtest1;