ksql MATERIALIZED VIEW İçin CREATE TABLE

Giriş

CREATE TABLE ile yaratılan tablo her key için en son değeri gösterir.

CREATE TABLE Söz Dizimi

Şöyledir

CREATE TABLE tablename as SELECT QUERY

Normal CREATE TABLE Söz Dizimi şöyle. Yani SELECT QUERY kısmı yok

CREATE TABLE customers (
  id INT PRIMARY KEY,
  first_name VARCHAR,
  last_name VARCHAR,
  gender VARCHAR,
  country VARCHAR
) WITH (
  kafka_topic='customers',
  partitions=1,
  value_format='avro'
);

SELECT QUERY

SELECT QUERY içinde

CAST

COLLECT_LIST

COUNT

GEO_DISTANCE

GROUP BY

LATEST_BY_OFFSET

ROUND

SUBSTRING

gibi metodlar kullanılabilir

LATEST_BY_OFFSET

Açıklaması şöyle

The LATEST_BY_OFFSET aggregation allows you to select any column and retains only the last value it receives, where “last” is in terms of offsets.

Örnek

Şöyle yaparız

CREATE STREAM customers WITH (
  kafka_topic = 'mysql.customers_db.customers',
  value_format = 'avro'
);


CREATE TABLE customers_meta AS
 SELECT 
  id,
  latest_by_offset(first_name) AS first_name,
  latest_by_offset(last_name) AS last_name,
  latest_by_offset(gender) AS gender,
  latest_by_offset(country) AS country
 FROM customers
 GROUP BY id
 EMIT CHANGES;