Revert "Allow parallel workers to cope with a newly-created session user ID."

This reverts commit f5f30c22ed69fb37b896c4d4546b2ab823c3fd61.

Some buildfarm animals are failing with "cannot change
"client_encoding" during a parallel operation".  It looks like
assign_client_encoding is unhappy at being asked to roll back a
client_encoding setting after a parallel worker encounters a
failure.  There must be more to it though: why didn't I see this
during local testing?  In any case, it's clear that moving the
RestoreGUCState() call is not as side-effect-free as I thought.
Given that the bug f5f30c22e intended to fix has gone unreported
for years, it's not something that's urgent to fix; I'm not
willing to risk messing with it further with only days to our
next release wrap.

diff --git a/src/backend/access/transam/parallel.c b/src/backend/access/transam/parallel.c
index b9cf197d353b9ffda2e52fefed255d145bd5901d..8613fc6fb547c05d30d01a44282dba2b3f2178a3 100644 (file)
--- a/src/backend/access/transam/parallel.c
+++ b/src/backend/access/transam/parallel.c
@@ -1410,6 +1410,10 @@ ParallelWorkerMain(Datum main_arg)
    libraryspace = shm_toc_lookup(toc, PARALLEL_KEY_LIBRARY, false);
    StartTransactionCommand();
    RestoreLibraryState(libraryspace);
+
+   /* Restore GUC values from launching backend. */
+   gucspace = shm_toc_lookup(toc, PARALLEL_KEY_GUC, false);
+   RestoreGUCState(gucspace);
    CommitTransactionCommand();
 
    /* Crank up a transaction state appropriate to a parallel worker. */
@@ -1451,14 +1455,6 @@ ParallelWorkerMain(Datum main_arg)
     */
    InvalidateSystemCaches();
 
-   /*
-    * Restore GUC values from launching backend.  We can't do this earlier,
-    * because GUC check hooks that do catalog lookups need to see the same
-    * database state as the leader.
-    */
-   gucspace = shm_toc_lookup(toc, PARALLEL_KEY_GUC, false);
-   RestoreGUCState(gucspace);
-
    /*
     * Restore current role id.  Skip verifying whether session user is
     * allowed to become this role and blindly restore the leader's state for

diff --git a/src/backend/commands/variable.c b/src/backend/commands/variable.c
index e3f9f110d8765d17a97ef08e9c6c823bf88252f2..f44d942aa4d45cd3eddfc2b54326911ae6bd8538 100644 (file)
--- a/src/backend/commands/variable.c
+++ b/src/backend/commands/variable.c
@@ -577,16 +577,14 @@ check_transaction_read_only(bool *newval, void **extra, GucSource source)
  * We allow idempotent changes at any time, but otherwise this can only be
  * changed in a toplevel transaction that has not yet taken a snapshot.
  *
- * As in check_transaction_read_only, allow it if not inside a transaction,
- * or if restoring state in a parallel worker.
+ * As in check_transaction_read_only, allow it if not inside a transaction.
  */
 bool
 check_transaction_isolation(int *newval, void **extra, GucSource source)
 {
    int         newXactIsoLevel = *newval;
 
-   if (newXactIsoLevel != XactIsoLevel &&
-       IsTransactionState() && !InitializingParallelWorker)
+   if (newXactIsoLevel != XactIsoLevel && IsTransactionState())
    {
        if (FirstSnapshotSet)
        {
@@ -621,10 +619,6 @@ check_transaction_isolation(int *newval, void **extra, GucSource source)
 bool
 check_transaction_deferrable(bool *newval, void **extra, GucSource source)
 {
-   /* Just accept the value when restoring state in a parallel worker */
-   if (InitializingParallelWorker)
-       return true;
-
    if (IsSubTransaction())
    {
        GUC_check_errcode(ERRCODE_ACTIVE_SQL_TRANSACTION);

diff --git a/src/test/regress/expected/select_parallel.out b/src/test/regress/expected/select_parallel.out
index 68a629619a6eb4bd4725a6bfb1c485863c93e1e1..5a603f86b7366dbacd18080f8df658f4fcb04a51 100644 (file)
--- a/src/test/regress/expected/select_parallel.out
+++ b/src/test/regress/expected/select_parallel.out
@@ -1329,21 +1329,3 @@ SELECT 1 FROM tenk1_vw_sec
 (9 rows)
 
 rollback;
--- test that a newly-created session role propagates to workers.
-begin;
-create role regress_parallel_worker;
-set session authorization regress_parallel_worker;
-select current_setting('session_authorization');
-     current_setting     
--------------------------
- regress_parallel_worker
-(1 row)
-
-set debug_parallel_query = 1;
-select current_setting('session_authorization');
-     current_setting     
--------------------------
- regress_parallel_worker
-(1 row)
-
-rollback;

diff --git a/src/test/regress/sql/select_parallel.sql b/src/test/regress/sql/select_parallel.sql
index 1a0e7f144d02e90e626296c27eda1e678a409b44..c7df8f775cee90d6975a27239aa2847468cedb32 100644 (file)
--- a/src/test/regress/sql/select_parallel.sql
+++ b/src/test/regress/sql/select_parallel.sql
@@ -511,12 +511,3 @@ SELECT 1 FROM tenk1_vw_sec
   WHERE (SELECT sum(f1) FROM int4_tbl WHERE f1 < unique1) < 100;
 
 rollback;
-
--- test that a newly-created session role propagates to workers.
-begin;
-create role regress_parallel_worker;
-set session authorization regress_parallel_worker;
-select current_setting('session_authorization');
-set debug_parallel_query = 1;
-select current_setting('session_authorization');
-rollback;