Combine MERGE actions

TutorialApplies to: Unified engine deployments

Use update, insert, and delete clauses together and observe clause order. Within a match group, MERGE uses the first qualifying clause. Put narrower rules first. Only the last clause in a match group may omit its condition. A row stays unchanged when none of its group’s actions qualify.

Before you start

You need a writable Iceberg catalog with namespace creation, table creation, and MERGE support. These examples create format-v2 tables in a private namespace. They use inline data and do not need an external sample dataset. Choose an unused namespace. The examples use learn_merge_03. Replace it everywhere if it already exists. In Workbench, select your writable catalog before running any SQL. Keep that catalog selected throughout the lesson. Opening an example does not execute it.

Set up the namespace

Run this setup once:

SET spark.sql.caseSensitive = true;
CREATE NAMESPACE learn_merge_03;

Each example creates a separate table. Run an example’s setup once. To start it again, remove only that example’s table first, using the cleanup section. Scripts execute as separate operations; they are not a multi-statement transaction.

1. Delete flagged customers and insert active ones

Start with these target rows:

id	name	balance	version	is_deleted
1	Ada	100	1	false
2	Ben	200	2	false
3	Cyd	300	1	false

CREATE TABLE learn_merge_03.mixed_actions (id BIGINT, name STRING, balance BIGINT, version BIGINT, is_deleted BOOLEAN)
USING iceberg TBLPROPERTIES ('format-version' = '2');
INSERT INTO learn_merge_03.mixed_actions VALUES (1, 'Ada', 100, 1, false), (2, 'Ben', 200, 2, false), (3, 'Cyd', 300, 1, false);

Apply the incoming source below:

MERGE INTO learn_merge_03.mixed_actions AS t
USING (SELECT 2 AS id, 'Ben' AS name, 0 AS balance, 3 AS version, true AS is_deleted UNION ALL SELECT 4, 'Dan', 400, 1, false UNION ALL SELECT 5, 'Eve', 0, 1, true) AS s
ON t.id = s.id
WHEN MATCHED AND s.is_deleted THEN DELETE
WHEN MATCHED THEN UPDATE SET balance = s.balance
WHEN NOT MATCHED AND NOT s.is_deleted THEN INSERT *;

Check all rows:

SELECT id, name, balance, version, is_deleted FROM learn_merge_03.mixed_actions;

Expect these exact rows, in any display order:

id	name	balance	version	is_deleted
1	Ada	100	1	false
3	Cyd	300	1	false
4	Dan	400	1	false

2. Apply the first matching clause

Start with these target rows:

id	name	balance	version	is_deleted
1	Ada	100	1	false
2	Ben	200	2	false
3	Cyd	300	1	false

CREATE TABLE learn_merge_03.clause_order (id BIGINT, name STRING, balance BIGINT, version BIGINT, is_deleted BOOLEAN)
USING iceberg TBLPROPERTIES ('format-version' = '2');
INSERT INTO learn_merge_03.clause_order VALUES (1, 'Ada', 100, 1, false), (2, 'Ben', 200, 2, false), (3, 'Cyd', 300, 1, false);

Apply the incoming source below:

MERGE INTO learn_merge_03.clause_order AS t
USING (SELECT 2 AS id, 'Ben' AS name, 250 AS balance, 3 AS version, true AS is_deleted) AS s
ON t.id = s.id
WHEN MATCHED AND s.is_deleted THEN DELETE
WHEN MATCHED AND s.balance > 0 THEN UPDATE SET balance = s.balance;

Check all rows:

SELECT id, name, balance, version, is_deleted FROM learn_merge_03.clause_order;

Expect these exact rows, in any display order:

id	name	balance	version	is_deleted
1	Ada	100	1	false
3	Cyd	300	1	false

3. Reverse the clause order and compare the rows

Start with these target rows:

id	name	balance	version	is_deleted
1	Ada	100	1	false
2	Ben	200	2	false
3	Cyd	300	1	false

CREATE TABLE learn_merge_03.clause_order_reversed (id BIGINT, name STRING, balance BIGINT, version BIGINT, is_deleted BOOLEAN)
USING iceberg TBLPROPERTIES ('format-version' = '2');
INSERT INTO learn_merge_03.clause_order_reversed VALUES (1, 'Ada', 100, 1, false), (2, 'Ben', 200, 2, false), (3, 'Cyd', 300, 1, false);

Apply the incoming source below:

MERGE INTO learn_merge_03.clause_order_reversed AS t
USING (SELECT 2 AS id, 'Ben' AS name, 250 AS balance, 3 AS version, true AS is_deleted) AS s
ON t.id = s.id
WHEN MATCHED AND s.balance > 0 THEN UPDATE SET balance = s.balance
WHEN MATCHED AND s.is_deleted THEN DELETE;

Check all rows:

SELECT id, name, balance, version, is_deleted FROM learn_merge_03.clause_order_reversed;

Expect these exact rows, in any display order:

id	name	balance	version	is_deleted
1	Ada	100	1	false
2	Ben	250	2	false
3	Cyd	300	1	false

4. Leave a matching row unchanged when no action qualifies

Start with these target rows:

id	name	balance	version	is_deleted
1	Ada	100	1	false
2	Ben	200	2	false
3	Cyd	300	1	false

CREATE TABLE learn_merge_03.no_action (id BIGINT, name STRING, balance BIGINT, version BIGINT, is_deleted BOOLEAN)
USING iceberg TBLPROPERTIES ('format-version' = '2');
INSERT INTO learn_merge_03.no_action VALUES (1, 'Ada', 100, 1, false), (2, 'Ben', 200, 2, false), (3, 'Cyd', 300, 1, false);

Apply the incoming source below:

MERGE INTO learn_merge_03.no_action AS t
USING (SELECT 2 AS id, 'Ben' AS name, 250 AS balance, 3 AS version, false AS is_deleted) AS s
ON t.id = s.id
WHEN MATCHED AND s.is_deleted THEN DELETE;

Check all rows:

SELECT id, name, balance, version, is_deleted FROM learn_merge_03.no_action;

Expect these exact rows, in any display order:

id	name	balance	version	is_deleted
1	Ada	100	1	false
2	Ben	200	2	false
3	Cyd	300	1	false

Change one thing

Start the relevant example again from its original target rows. Drop only that example table, rerun its CREATE TABLE and INSERT statements, then apply the changed MERGE. Keep the lesson namespace. Remove the NOT s.is_deleted condition from the insert clause in the mixed-actions example. Customer 5 should now be inserted with is_deleted = true.

Check the result

Compare every row and field with the expected tables, including unchanged customers and the number of copies of each key. A Succeeded status alone is not the result check. Wait for confirmed publication before reading the target.

Clean up

Remove only the private tables created by this lesson:

DROP TABLE IF EXISTS learn_merge_03.mixed_actions;
DROP TABLE IF EXISTS learn_merge_03.clause_order;
DROP TABLE IF EXISTS learn_merge_03.clause_order_reversed;
DROP TABLE IF EXISTS learn_merge_03.no_action;
DROP NAMESPACE learn_merge_03;

Continue

Synchronise a complete source snapshot or review the MERGE SQL reference.

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Combine MERGE actions

Before you start

Set up the namespace

1. Delete flagged customers and insert active ones

2. Apply the first matching clause

3. Reverse the clause order and compare the rows

4. Leave a matching row unchanged when no action qualifies

Change one thing

Check the result

Clean up

Continue

​Before you start

​Set up the namespace

​1. Delete flagged customers and insert active ones

​2. Apply the first matching clause

​3. Reverse the clause order and compare the rows

​4. Leave a matching row unchanged when no action qualifies

​Change one thing

​Check the result

​Clean up

​Continue

Before you start

Set up the namespace

1. Delete flagged customers and insert active ones

2. Apply the first matching clause

3. Reverse the clause order and compare the rows

4. Leave a matching row unchanged when no action qualifies

Change one thing

Check the result

Clean up

Continue