redshift unload lineage

Author: sqlparser

databases/redshift/readme.md

@@ -1,8 +1,8 @@
-# AWS redshift database column-level data lineage
+# AWS redshift database SQL column-level data lineage
 
 Discover and visualization lineage from AWS redshift database and SQL script.
 
-### Copy command
+### 1. Copy command
 
 ```sql
 copy catdemo
@@ -29,3 +29,16 @@ data lineage diagram:
 [![redshift data lineage copy ](redshift-data-linage-copy-with-columns.png)](https://sqlflow.gudusoft.com)
 
 
+### 2. Unload command
+```sql
+CREATE TABLE a_table(an_int INT, b_int INT);
+INSERT INTO a_table VALUES (1,1), (2,1), (3,1), (4,1), (1,2), (2,2), (3,2), (4,2), (5,2), (6,2);
+
+CREATE TABLE hll_table (sketch HLLSKETCH);
+INSERT INTO hll_table select hll_create_sketch(an_int) from a_table group by b_int;
+
+UNLOAD ('select * from hll_table') TO 's3://mybucket/unload/'
+IAM_ROLE 'arn:aws:iam::0123456789012:role/MyRedshiftRole' NULL AS 'null' ALLOWOVERWRITE CSV;
+```
+
+[![redshift sql data lineage unload](redshift-data-linage-unload.png)](https://sqlflow.gudusoft.com)