Re: Issues with ON CONFLICT UPDATE and REINDEX CONCURRENTLY - Mailing list pgsql-hackers

Hello,

We ran into one more problem with the new test, evidenced by timeouts by
buildfarm member prion.  For CATCACHE_FORCE_RELEASE builds on two of the
tests, we get a few invalidations of the catalog snapshot ahead of what
we expect, and because we have an injection point to sleep there, those
tests get stuck.

Here's one possible fix.  I had to take the attach operation on
invalidate-catalog-snapshot-end to a new step of s1, instead of
occurring in the setup block.  I understand that this is because no step
can run until the setup of all steps completes, so if one setup gets
stuck, we're out of luck.  And then, session s4 can do a conditional
wakeup of session s1.

Patch attached.  Thoughts?

Maybe there's some other way to go about this -- for instance I
considered the idea of moving the injection point somewhere else from
InvalidateCatalogSnapshot().  I don't have any ideas about that though,
but I'm willing to listen if anybody has any.


The output in both cases is different (we get more notices in the weird
build and also s1 goes to sleep in different order), so I had to add an
alternative expected file.  The diffs look okay to me -- essentially
they say, in the normal case, the injection_points_attach() returns
immediately, but in the other case, s1 goes to sleep and is awakened
when it sees the 'case' expression by session 4:

--- expected/index-concurrently-upsert-predicate.out    2025-11-26 19:13:58.702213673 +0100
+++ expected/index-concurrently-upsert-predicate_1.out    2025-11-26 19:04:16.745666956 +0100
@@ -1,8 +1,9 @@
 Parsed test spec with 5 sessions
 
 starting permutation: s1_attach_invalidate_catalog_snapshot s4_wakeup_s1_setup s5_noop s3_start_create_index
s1_start_upserts4_wakeup_define_index_before_set_valid s2_start_upsert s5_wakeup_s1_from_invalidate_catalog_snapshot
s4_wakeup_s2s4_wakeup_s1
 
+s1: NOTICE:  notice triggered for injection point pre-invalidate-catalog-snapshot-end
 injection_points_attach
 -----------------------
                        
 (1 row)
 
@@ -14,18 +15,15 @@
 injection_points_attach
 -----------------------
                        
 (1 row)
 
+s1: NOTICE:  notice triggered for injection point pre-invalidate-catalog-snapshot-end
+s1: NOTICE:  notice triggered for injection point pre-invalidate-catalog-snapshot-end
 step s1_attach_invalidate_catalog_snapshot: 
     SELECT injection_points_attach('invalidate-catalog-snapshot-end', 'wait');
-
-injection_points_attach
------------------------
-                       
-(1 row)
-
+ <waiting ...>
 step s4_wakeup_s1_setup: 
     select case when
             (select pid from pg_stat_activity
                   where wait_event_type = 'InjectionPoint' and
                   wait_event = 'invalidate-catalog-snapshot-end') is not null
@@ -35,10 +33,16 @@
 case
 ----
     
 (1 row)
 
+step s1_attach_invalidate_catalog_snapshot: <... completed>
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
 step s5_noop: 
  <waiting ...>
 step s3_start_create_index: 
     CREATE UNIQUE INDEX CONCURRENTLY tbl_pkey_special_duplicate ON test.tbl(abs(i)) WHERE i < 10000;
  <waiting ...>


-- 
Álvaro Herrera               48°01'N 7°57'E  —  https://www.EnterpriseDB.com/
"Los minutos y los segundos son mercadería de la ciudad, donde un infeliz se
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