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sidebar_label: Writes title: Flink Writes sidebar_position: 3

Flink Writes

You can directly insert or update data into a Fluss table using the INSERT INTO statement. Fluss primary key tables can accept all types of messages (INSERT, UPDATE_BEFORE, UPDATE_AFTER, DELETE), while Fluss log table can only accept INSERT type messages.

INSERT INTO

INSERT INTO statements are used to write data to Fluss tables. They support both streaming and batch modes and are compatible with primary-key tables (for upserting data) as well as log tables (for appending data).

Appending Data to the Log Table

Create a Log Table.

CREATE TABLE log_table (
  order_id BIGINT,
  item_id BIGINT,
  amount INT,
  address STRING
);

Insert Data into the Log Table.

CREATE TEMPORARY TABLE source (
  order_id BIGINT,
  item_id BIGINT,
  amount INT,
  address STRING
) WITH ('connector' = 'datagen');

INSERT INTO log_table
SELECT * FROM source;

Perform Data Upserts to the PrimaryKey Table.

Create a primary key table.

CREATE TABLE pk_table (
  shop_id BIGINT,
  user_id BIGINT,
  num_orders INT,
  total_amount INT,
  PRIMARY KEY (shop_id, user_id) NOT ENFORCED
);

Updates All Columns

CREATE TEMPORARY TABLE source (
  shop_id BIGINT,
  user_id BIGINT,
  num_orders INT,
  total_amount INT
) WITH ('connector' = 'datagen');

INSERT INTO pk_table
SELECT * FROM source;

Partial Updates

CREATE TEMPORARY TABLE source (
  shop_id BIGINT,
  user_id BIGINT,
  num_orders INT,
  total_amount INT
) WITH ('connector' = 'datagen');

-- only partial-update the num_orders column
INSERT INTO pk_table (shop_id, user_id, num_orders)
SELECT shop_id, user_id, num_orders FROM source;

DELETE FROM

Fluss supports deleting data for primary-key tables in batch mode via DELETE FROM statement. Currently, only single data deletions based on the primary key are supported.

• the Primary Key Table

-- DELETE statement requires batch mode
SET 'execution.runtime-mode' = 'batch';

-- The condition must include all primary key equality conditions.
DELETE FROM pk_table WHERE shop_id = 10000 AND user_id = 123456;

UPDATE

Fluss enables data updates for primary-key tables in batch mode using the UPDATE statement. Currently, only single-row updates based on the primary key are supported.

-- Execute the flink job in batch mode for current session context
SET execution.runtime-mode = batch;

-- The condition must include all primary key equality conditions.
UPDATE pk_table SET total_amount = 2 WHERE shop_id = 10000 AND user_id = 123456;