Example: Creating Throttled Alerts

To create a throttled alerts application

1. Create a Kinesis Data Analytics application as described in the Kinesis Data Analytics Getting Started exercise.

2. In the SQL editor in Kinesis Data Analytics, replace the application code with the following:

   CREATE OR REPLACE STREAM "CHANGE_STREAM" 
              (ticker_symbol VARCHAR(4), 
               sector        VARCHAR(12), 
               change        DOUBLE, 
               price         DOUBLE);
   
   CREATE OR REPLACE PUMP "change_pump" AS 
      INSERT INTO "CHANGE_STREAM"
         SELECT STREAM ticker_symbol, sector, change, price 
         FROM   "SOURCE_SQL_STREAM_001"
         WHERE  (ABS(Change / (Price - Change)) * 100) > 1;
         
   -- ** Trigger Count and Limit **
   -- Counts "triggers" or those values that evaluated true against the previous where clause
   -- Then provides its own limit on the number of triggers per hour per ticker symbol to what
   -- is specified in the WHERE clause
   
   CREATE OR REPLACE STREAM TRIGGER_COUNT_STREAM (
      ticker_symbol VARCHAR(4), 
      change REAL,
      trigger_count INTEGER);
   
   CREATE OR REPLACE PUMP trigger_count_pump AS INSERT INTO TRIGGER_COUNT_STREAM
   SELECT STREAM ticker_symbol, change, trigger_count
   FROM (
       SELECT STREAM ticker_symbol, change, COUNT(*) OVER W1 as trigger_count
       FROM "CHANGE_STREAM"
       --window to perform aggregations over last minute to keep track of triggers
       WINDOW W1 AS (PARTITION BY ticker_symbol RANGE INTERVAL '1' MINUTE PRECEDING)
   )
   WHERE trigger_count >= 1;

   The SELECT statement in the application code filters rows in the SOURCE_SQL_STREAM_001 for stock price changes greater than 1 percent and inserts those rows into another in-application stream CHANGE_STREAM using a pump.

   The application then creates a second stream named TRIGGER_COUNT_STREAM for the throttled alerts. A second query selects records from a window that hops forward every time a record is admitted into it, such that only one record per stock ticker per minute is written to the stream.

3. Choose Save and run SQL.