Add support for INSERT ... ON CONFLICT DO NOTHING/UPDATE.

The newly added ON CONFLICT clause allows to specify an alternative to
raising a unique or exclusion constraint violation error when inserting.
ON CONFLICT refers to constraints that can either be specified using a
inference clause (by specifying the columns of a unique constraint) or
by naming a unique or exclusion constraint.  DO NOTHING avoids the
constraint violation, without touching the pre-existing row.  DO UPDATE
SET ... [WHERE ...] updates the pre-existing tuple, and has access to
both the tuple proposed for insertion and the existing tuple; the
optional WHERE clause can be used to prevent an update from being
executed.  The UPDATE SET and WHERE clauses have access to the tuple
proposed for insertion using the "magic" EXCLUDED alias, and to the
pre-existing tuple using the table name or its alias.

This feature is often referred to as upsert.

This is implemented using a new infrastructure called "speculative
insertion". It is an optimistic variant of regular insertion that first
does a pre-check for existing tuples and then attempts an insert.  If a
violating tuple was inserted concurrently, the speculatively inserted
tuple is deleted and a new attempt is made.  If the pre-check finds a
matching tuple the alternative DO NOTHING or DO UPDATE action is taken.
If the insertion succeeds without detecting a conflict, the tuple is
deemed inserted.

To handle the possible ambiguity between the excluded alias and a table
named excluded, and for convenience with long relation names, INSERT
INTO now can alias its target table.

Bumps catversion as stored rules change.

Author: Peter Geoghegan, with significant contributions from Heikki
    Linnakangas and Andres Freund. Testing infrastructure by Jeff Janes.
Reviewed-By: Heikki Linnakangas, Andres Freund, Robert Haas, Simon Riggs,
    Dean Rasheed, Stephen Frost and many others.

4 files changed, 95 insertions, 0 deletions

diff --git a/src/test/isolation/expected/insert-conflict-do-nothing.out b/src/test/isolation/expected/insert-conflict-do-nothing.out
new file mode 100644
index 0000000000..0a0958f034
--- /dev/null
+++ b/src/test/isolation/expected/insert-conflict-do-nothing.out
@@ -0,0 +1,23 @@
+Parsed test spec with 2 sessions
+
+starting permutation: donothing1 donothing2 c1 select2 c2
+step donothing1: INSERT INTO ints(key, val) VALUES(1, 'donothing1') ON CONFLICT DO NOTHING;
+step donothing2: INSERT INTO ints(key, val) VALUES(1, 'donothing2') ON CONFLICT DO NOTHING; <waiting ...>
+step c1: COMMIT;
+step donothing2: <... completed>
+step select2: SELECT * FROM ints;
+key            val            
+
+1              donothing1     
+step c2: COMMIT;
+
+starting permutation: donothing1 donothing2 a1 select2 c2
+step donothing1: INSERT INTO ints(key, val) VALUES(1, 'donothing1') ON CONFLICT DO NOTHING;
+step donothing2: INSERT INTO ints(key, val) VALUES(1, 'donothing2') ON CONFLICT DO NOTHING; <waiting ...>
+step a1: ABORT;
+step donothing2: <... completed>
+step select2: SELECT * FROM ints;
+key            val            
+
+1              donothing2     
+step c2: COMMIT;
diff --git a/src/test/isolation/expected/insert-conflict-do-update-2.out b/src/test/isolation/expected/insert-conflict-do-update-2.out
new file mode 100644
index 0000000000..05fb06f8d8
--- /dev/null
+++ b/src/test/isolation/expected/insert-conflict-do-update-2.out
@@ -0,0 +1,23 @@
+Parsed test spec with 2 sessions
+
+starting permutation: insert1 insert2 c1 select2 c2
+step insert1: INSERT INTO upsert(key, payload) VALUES('FooFoo', 'insert1') ON CONFLICT (lower(key)) DO UPDATE set key = EXCLUDED.key, payload = upsert.payload || ' updated by insert1';
+step insert2: INSERT INTO upsert(key, payload) VALUES('FOOFOO', 'insert2') ON CONFLICT (lower(key)) DO UPDATE set key = EXCLUDED.key, payload = upsert.payload || ' updated by insert2'; <waiting ...>
+step c1: COMMIT;
+step insert2: <... completed>
+step select2: SELECT * FROM upsert;
+key            payload        
+
+FOOFOO         insert1 updated by insert2
+step c2: COMMIT;
+
+starting permutation: insert1 insert2 a1 select2 c2
+step insert1: INSERT INTO upsert(key, payload) VALUES('FooFoo', 'insert1') ON CONFLICT (lower(key)) DO UPDATE set key = EXCLUDED.key, payload = upsert.payload || ' updated by insert1';
+step insert2: INSERT INTO upsert(key, payload) VALUES('FOOFOO', 'insert2') ON CONFLICT (lower(key)) DO UPDATE set key = EXCLUDED.key, payload = upsert.payload || ' updated by insert2'; <waiting ...>
+step a1: ABORT;
+step insert2: <... completed>
+step select2: SELECT * FROM upsert;
+key            payload        
+
+FOOFOO         insert2        
+step c2: COMMIT;
diff --git a/src/test/isolation/expected/insert-conflict-do-update-3.out b/src/test/isolation/expected/insert-conflict-do-update-3.out
new file mode 100644
index 0000000000..6600410618
--- /dev/null
+++ b/src/test/isolation/expected/insert-conflict-do-update-3.out
@@ -0,0 +1,26 @@
+Parsed test spec with 2 sessions
+
+starting permutation: update2 insert1 c2 select1surprise c1
+step update2: UPDATE colors SET is_active = true WHERE key = 1;
+step insert1: 
+    WITH t AS (
+        INSERT INTO colors(key, color, is_active)
+        VALUES(1, 'Brown', true), (2, 'Gray', true)
+        ON CONFLICT (key) DO UPDATE
+        SET color = EXCLUDED.color
+        WHERE colors.is_active)
+    SELECT * FROM colors ORDER BY key; <waiting ...>
+step c2: COMMIT;
+step insert1: <... completed>
+key            color          is_active      
+
+1              Red            f              
+2              Green          f              
+3              Blue           f              
+step select1surprise: SELECT * FROM colors ORDER BY key;
+key            color          is_active      
+
+1              Brown          t              
+2              Green          f              
+3              Blue           f              
+step c1: COMMIT;
diff --git a/src/test/isolation/expected/insert-conflict-do-update.out b/src/test/isolation/expected/insert-conflict-do-update.out
new file mode 100644
index 0000000000..a634918784
--- /dev/null
+++ b/src/test/isolation/expected/insert-conflict-do-update.out
@@ -0,0 +1,23 @@
+Parsed test spec with 2 sessions
+
+starting permutation: insert1 insert2 c1 select2 c2
+step insert1: INSERT INTO upsert(key, val) VALUES(1, 'insert1') ON CONFLICT (key) DO UPDATE set val = upsert.val || ' updated by insert1';
+step insert2: INSERT INTO upsert(key, val) VALUES(1, 'insert2') ON CONFLICT (key) DO UPDATE set val = upsert.val || ' updated by insert2'; <waiting ...>
+step c1: COMMIT;
+step insert2: <... completed>
+step select2: SELECT * FROM upsert;
+key            val            
+
+1              insert1 updated by insert2
+step c2: COMMIT;
+
+starting permutation: insert1 insert2 a1 select2 c2
+step insert1: INSERT INTO upsert(key, val) VALUES(1, 'insert1') ON CONFLICT (key) DO UPDATE set val = upsert.val || ' updated by insert1';
+step insert2: INSERT INTO upsert(key, val) VALUES(1, 'insert2') ON CONFLICT (key) DO UPDATE set val = upsert.val || ' updated by insert2'; <waiting ...>
+step a1: ABORT;
+step insert2: <... completed>
+step select2: SELECT * FROM upsert;
+key            val            
+
+1              insert2        
+step c2: COMMIT;