Update backfill-populate-mv-in-a-controlled-manner.md

finalizeAggregation

content/en/altinity-kb-schema-design/materialized-views/backfill-populate-mv-in-a-controlled-manner.md

@@ -53,12 +53,22 @@ SELECT id,                              -- ORDER BY column
    initializeAggregation(argMax,v3,ts)  -- we need to convert from values to States for columns with AggregatingFunction type
 FROM huge_table
 WHERE toYYYYMM(ts) = 202105;
-
-ATTACH  ...
 ```
 
 Actually, the first GROUP BY run will happen just before 1M rows will be stored on disk as a data part. You may disable that behavior by switching off [optimize_on_insert](https://clickhouse.com/docs/en/operations/settings/settings#optimize-on-insert) setting if you have heavy calculations during aggregation.
 
+You may attach such a table (with AggregatingFunction columns) to the main table as in the example above, but if you don't like to have States in the aggregated table, data should be finalized and converted back to normal values.  In that case, you have to move data by INSERT ... SELECT again:
+
+```sql
+INSERT INTO MV
+SELECT id,ts,v1,v2,  -- nothing special for SimpleAggregatingFunction columns
+  finalizeAggregation(v3)
+from mv_import FINAL
+```
+
+The last run of GROUP BY will happen during FINAL execution and AggregatingFunction types converted back to normal values.
+
+