Fix skipping compression of first to last chunk

CHANGELOG.md

@@ -19,6 +19,7 @@ We use the following categories for changes:
 
 ### Fixed
 - Fix broken `promscale_packager` telemetry field for docker envs [#1077]
+- Fix compression of old chunks thus reducing storage requirements [#1081]
 
 ## [0.8.0] - 2022-01-18
 

pkg/migrations/sql/idempotent/base.sql

@@ -2911,21 +2911,22 @@ BEGIN
     DECLARE
         chunk_schema_name name;
         chunk_table_name name;
+        chunk_range_end timestamptz;
         chunk_num INT;
     BEGIN
-        FOR chunk_schema_name, chunk_table_name, chunk_num IN
+        FOR chunk_schema_name, chunk_table_name, chunk_range_end, chunk_num IN
             SELECT
                 chunk_schema,
                 chunk_name,
+                range_end,
                 row_number() OVER (ORDER BY range_end DESC)
             FROM timescaledb_information.chunks
             WHERE hypertable_schema = 'SCHEMA_DATA'
                 AND hypertable_name = metric_table
                 AND NOT is_compressed
-                AND range_end <= compress_before
             ORDER BY range_end ASC
         LOOP
-            CONTINUE WHEN chunk_num <= 1;
+            CONTINUE WHEN chunk_num <= 1 OR chunk_range_end > compress_before;
             PERFORM SCHEMA_CATALOG.compress_chunk_for_metric(metric_table, chunk_schema_name, chunk_table_name);
             COMMIT;
         END LOOP;

pkg/tests/end_to_end_tests/create_test.go

@@ -1233,6 +1233,19 @@ func TestCustomCompressionJob(t *testing.T) {
 		if chunkIsCompressed("1970-03-01 00:00:00.001+00") {
 			t.Error("third chunk compressed too soon")
 		}
+
+		// Add an chunk at current time
+		insert = fmt.Sprintf(`INSERT INTO prom_data."%s" VALUES (NOW(), 0.1, 1);`, tableName)
+		_, err = db.Exec(context.Background(), insert)
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		runCompressionJob()
+		// third chunk should be compressed since its not the last chunk anymore
+		if !chunkIsCompressed("1970-03-01 00:00:00.001+00") {
+			t.Error("third chunk not compressed when it should have been")
+		}
 	})
 }