Merge pull request #49 from MartijnVisser/current_watermark-fix

Fixing incorrect comparison for CURRENT_WATERMARK

Author: MartijnVisser

other-builtin-functions/03_current_watermark/03_current_watermark.md

@@ -55,14 +55,14 @@ CREATE TABLE `late_usage_events` (
 -- Create a view with non-late data
 CREATE TEMPORARY VIEW `mobile_data` AS
  SELECT * FROM mobile_usage
- WHERE CURRENT_WATERMARK(log_time) IS NOT NULL
- OR log_time < CURRENT_WATERMARK(log_time);
+ WHERE CURRENT_WATERMARK(log_time) IS NULL
+ OR log_time > CURRENT_WATERMARK(log_time);
 
 -- Create a view with late data
 CREATE TEMPORARY VIEW `late_mobile_data` AS 
  SELECT * FROM mobile_usage
- WHERE CURRENT_WATERMARK(log_time) IS NULL
- OR log_time > CURRENT_WATERMARK(log_time);
+ WHERE CURRENT_WATERMARK(log_time) IS NOT NULL
+ AND log_time <= CURRENT_WATERMARK(log_time);
 
 BEGIN STATEMENT SET;
 
@@ -83,3 +83,7 @@ END;
 ## Example Output
 
 ![03_current_watermark](03_current_watermark.png)
+
+### Late data
+
+![03_late_data](03_late_data.png)