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WITH support in MERGE
Author: Peter Geoghegan Recursive support removed, no tests Docs added by me
This commit is contained in:
Simon Riggs
@ -1210,9 +1210,6 @@ WHEN NOT MATCHED THEN
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WHEN MATCHED AND tid < 2 THEN
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DELETE
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;
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ERROR: syntax error at or near "MERGE"
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LINE 4: MERGE INTO sq_target t
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^
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ROLLBACK;
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-- RETURNING
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BEGIN;
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@ -1904,6 +1904,143 @@ RETURNING k, v;
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(0 rows)
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DROP TABLE withz;
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-- WITH referenced by MERGE statement
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CREATE TABLE m AS SELECT i AS k, (i || ' v')::text v FROM generate_series(1, 16, 3) i;
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ALTER TABLE m ADD UNIQUE (k);
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WITH RECURSIVE cte_basic AS (SELECT 1 a, 'cte_basic val' b)
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MERGE INTO m USING (select 0 k, 'merge source SubPlan' v) o ON m.k=o.k
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WHEN MATCHED THEN UPDATE SET v = (SELECT b || ' merge update' FROM cte_basic WHERE cte_basic.a = m.k LIMIT 1)
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WHEN NOT MATCHED THEN INSERT VALUES(o.k, o.v);
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ERROR: WITH RECURSIVE is not supported for MERGE statement
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-- Basic:
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WITH cte_basic AS (SELECT 1 a, 'cte_basic val' b)
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MERGE INTO m USING (select 0 k, 'merge source SubPlan' v) o ON m.k=o.k
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WHEN MATCHED THEN UPDATE SET v = (SELECT b || ' merge update' FROM cte_basic WHERE cte_basic.a = m.k LIMIT 1)
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WHEN NOT MATCHED THEN INSERT VALUES(o.k, o.v);
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-- Examine
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SELECT * FROM m where k = 0;
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k | v
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---+----------------------
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0 | merge source SubPlan
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(1 row)
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-- See EXPLAIN output for same query:
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EXPLAIN (VERBOSE, COSTS OFF)
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WITH cte_basic AS (SELECT 1 a, 'cte_basic val' b)
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MERGE INTO m USING (select 0 k, 'merge source SubPlan' v) o ON m.k=o.k
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WHEN MATCHED THEN UPDATE SET v = (SELECT b || ' merge update' FROM cte_basic WHERE cte_basic.a = m.k LIMIT 1)
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WHEN NOT MATCHED THEN INSERT VALUES(o.k, o.v);
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QUERY PLAN
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-------------------------------------------------------------------
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Merge on public.m
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CTE cte_basic
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-> Result
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Output: 1, 'cte_basic val'::text
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-> Hash Right Join
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Output: o.k, o.v, o.*, m_1.ctid
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Hash Cond: (m_1.k = o.k)
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-> Seq Scan on public.m m_1
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Output: m_1.ctid, m_1.k
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-> Hash
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Output: o.k, o.v, o.*
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-> Subquery Scan on o
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Output: o.k, o.v, o.*
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-> Result
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Output: 0, 'merge source SubPlan'::text
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SubPlan 2
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-> Limit
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Output: ((cte_basic.b || ' merge update'::text))
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-> CTE Scan on cte_basic
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Output: (cte_basic.b || ' merge update'::text)
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Filter: (cte_basic.a = m.k)
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(21 rows)
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-- InitPlan
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WITH cte_init AS (SELECT 1 a, 'cte_init val' b)
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MERGE INTO m USING (select 1 k, 'merge source InitPlan' v) o ON m.k=o.k
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WHEN MATCHED THEN UPDATE SET v = (SELECT b || ' merge update' FROM cte_init WHERE a = 1 LIMIT 1)
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WHEN NOT MATCHED THEN INSERT VALUES(o.k, o.v);
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-- Examine
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SELECT * FROM m where k = 1;
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k | v
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---+---------------------------
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1 | cte_init val merge update
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(1 row)
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-- See EXPLAIN output for same query:
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EXPLAIN (VERBOSE, COSTS OFF)
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WITH cte_init AS (SELECT 1 a, 'cte_init val' b)
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MERGE INTO m USING (select 1 k, 'merge source InitPlan' v) o ON m.k=o.k
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WHEN MATCHED THEN UPDATE SET v = (SELECT b || ' merge update' FROM cte_init WHERE a = 1 LIMIT 1)
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WHEN NOT MATCHED THEN INSERT VALUES(o.k, o.v);
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QUERY PLAN
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--------------------------------------------------------------------
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Merge on public.m
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CTE cte_init
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-> Result
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Output: 1, 'cte_init val'::text
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InitPlan 2 (returns $1)
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-> Limit
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Output: ((cte_init.b || ' merge update'::text))
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-> CTE Scan on cte_init
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Output: (cte_init.b || ' merge update'::text)
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Filter: (cte_init.a = 1)
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-> Hash Right Join
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Output: o.k, o.v, o.*, m_1.ctid
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Hash Cond: (m_1.k = o.k)
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-> Seq Scan on public.m m_1
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Output: m_1.ctid, m_1.k
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-> Hash
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Output: o.k, o.v, o.*
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-> Subquery Scan on o
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Output: o.k, o.v, o.*
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-> Result
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Output: 1, 'merge source InitPlan'::text
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(21 rows)
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-- MERGE source comes from CTE:
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WITH merge_source_cte AS (SELECT 15 a, 'merge_source_cte val' b)
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MERGE INTO m USING (select * from merge_source_cte) o ON m.k=o.a
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WHEN MATCHED THEN UPDATE SET v = (SELECT b || merge_source_cte.*::text || ' merge update' FROM merge_source_cte WHERE a = 15)
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WHEN NOT MATCHED THEN INSERT VALUES(o.a, o.b || (SELECT merge_source_cte.*::text || ' merge insert' FROM merge_source_cte));
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-- Examine
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SELECT * FROM m where k = 15;
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k | v
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----+--------------------------------------------------------------
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15 | merge_source_cte val(15,"merge_source_cte val") merge insert
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(1 row)
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-- See EXPLAIN output for same query:
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EXPLAIN (VERBOSE, COSTS OFF)
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WITH merge_source_cte AS (SELECT 15 a, 'merge_source_cte val' b)
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MERGE INTO m USING (select * from merge_source_cte) o ON m.k=o.a
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WHEN MATCHED THEN UPDATE SET v = (SELECT b || merge_source_cte.*::text || ' merge update' FROM merge_source_cte WHERE a = 15)
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WHEN NOT MATCHED THEN INSERT VALUES(o.a, o.b || (SELECT merge_source_cte.*::text || ' merge insert' FROM merge_source_cte));
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QUERY PLAN
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---------------------------------------------------------------------------------------------------------------
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Merge on public.m
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CTE merge_source_cte
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-> Result
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Output: 15, 'merge_source_cte val'::text
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InitPlan 2 (returns $1)
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-> CTE Scan on merge_source_cte merge_source_cte_1
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Output: ((merge_source_cte_1.b || (merge_source_cte_1.*)::text) || ' merge update'::text)
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Filter: (merge_source_cte_1.a = 15)
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InitPlan 3 (returns $2)
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-> CTE Scan on merge_source_cte merge_source_cte_2
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Output: ((merge_source_cte_2.*)::text || ' merge insert'::text)
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-> Hash Right Join
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Output: merge_source_cte.a, merge_source_cte.b, ROW(merge_source_cte.a, merge_source_cte.b), m_1.ctid
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Hash Cond: (m_1.k = merge_source_cte.a)
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-> Seq Scan on public.m m_1
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Output: m_1.ctid, m_1.k
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-> Hash
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Output: merge_source_cte.a, merge_source_cte.b
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-> CTE Scan on merge_source_cte
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Output: merge_source_cte.a, merge_source_cte.b
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(20 rows)
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DROP TABLE m;
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-- check that run to completion happens in proper ordering
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TRUNCATE TABLE y;
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INSERT INTO y SELECT generate_series(1, 3);
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@ -862,6 +862,62 @@ RETURNING k, v;
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DROP TABLE withz;
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-- WITH referenced by MERGE statement
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CREATE TABLE m AS SELECT i AS k, (i || ' v')::text v FROM generate_series(1, 16, 3) i;
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ALTER TABLE m ADD UNIQUE (k);
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WITH RECURSIVE cte_basic AS (SELECT 1 a, 'cte_basic val' b)
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MERGE INTO m USING (select 0 k, 'merge source SubPlan' v) o ON m.k=o.k
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WHEN MATCHED THEN UPDATE SET v = (SELECT b || ' merge update' FROM cte_basic WHERE cte_basic.a = m.k LIMIT 1)
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WHEN NOT MATCHED THEN INSERT VALUES(o.k, o.v);
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-- Basic:
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WITH cte_basic AS (SELECT 1 a, 'cte_basic val' b)
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MERGE INTO m USING (select 0 k, 'merge source SubPlan' v) o ON m.k=o.k
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WHEN MATCHED THEN UPDATE SET v = (SELECT b || ' merge update' FROM cte_basic WHERE cte_basic.a = m.k LIMIT 1)
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WHEN NOT MATCHED THEN INSERT VALUES(o.k, o.v);
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-- Examine
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SELECT * FROM m where k = 0;
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-- See EXPLAIN output for same query:
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EXPLAIN (VERBOSE, COSTS OFF)
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WITH cte_basic AS (SELECT 1 a, 'cte_basic val' b)
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MERGE INTO m USING (select 0 k, 'merge source SubPlan' v) o ON m.k=o.k
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WHEN MATCHED THEN UPDATE SET v = (SELECT b || ' merge update' FROM cte_basic WHERE cte_basic.a = m.k LIMIT 1)
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WHEN NOT MATCHED THEN INSERT VALUES(o.k, o.v);
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-- InitPlan
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WITH cte_init AS (SELECT 1 a, 'cte_init val' b)
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MERGE INTO m USING (select 1 k, 'merge source InitPlan' v) o ON m.k=o.k
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WHEN MATCHED THEN UPDATE SET v = (SELECT b || ' merge update' FROM cte_init WHERE a = 1 LIMIT 1)
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WHEN NOT MATCHED THEN INSERT VALUES(o.k, o.v);
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-- Examine
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SELECT * FROM m where k = 1;
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-- See EXPLAIN output for same query:
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EXPLAIN (VERBOSE, COSTS OFF)
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WITH cte_init AS (SELECT 1 a, 'cte_init val' b)
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MERGE INTO m USING (select 1 k, 'merge source InitPlan' v) o ON m.k=o.k
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WHEN MATCHED THEN UPDATE SET v = (SELECT b || ' merge update' FROM cte_init WHERE a = 1 LIMIT 1)
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WHEN NOT MATCHED THEN INSERT VALUES(o.k, o.v);
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-- MERGE source comes from CTE:
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WITH merge_source_cte AS (SELECT 15 a, 'merge_source_cte val' b)
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MERGE INTO m USING (select * from merge_source_cte) o ON m.k=o.a
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WHEN MATCHED THEN UPDATE SET v = (SELECT b || merge_source_cte.*::text || ' merge update' FROM merge_source_cte WHERE a = 15)
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WHEN NOT MATCHED THEN INSERT VALUES(o.a, o.b || (SELECT merge_source_cte.*::text || ' merge insert' FROM merge_source_cte));
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-- Examine
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SELECT * FROM m where k = 15;
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-- See EXPLAIN output for same query:
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EXPLAIN (VERBOSE, COSTS OFF)
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WITH merge_source_cte AS (SELECT 15 a, 'merge_source_cte val' b)
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MERGE INTO m USING (select * from merge_source_cte) o ON m.k=o.a
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WHEN MATCHED THEN UPDATE SET v = (SELECT b || merge_source_cte.*::text || ' merge update' FROM merge_source_cte WHERE a = 15)
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WHEN NOT MATCHED THEN INSERT VALUES(o.a, o.b || (SELECT merge_source_cte.*::text || ' merge insert' FROM merge_source_cte));
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DROP TABLE m;
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-- check that run to completion happens in proper ordering
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TRUNCATE TABLE y;
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