Repurpose PROC_COPYABLE_FLAGS as PROC_XMIN_FLAGS

This is a slight, convenient semantics change from what commit
0f0cfb494004 ("Fix parallel operations that prevent oldest xmin from
advancing") introduced that lets us simplify the coding in the one place
where it is used.

Backpatch to 13.  This is related to commit 6fea65508a1a ("Tighten
ComputeXidHorizons' handling of walsenders") rewriting the code site
where this is used, which has not yet been backpatched, but it may well
be in the future.

Reviewed-by: Masahiko Sawada 
Discussion: https://postgr.es/m/202204191637[email protected]

diff --git a/src/backend/storage/ipc/procarray.c b/src/backend/storage/ipc/procarray.c
index 127be9c017ad89495db298a2427f8471d6a8bc2c..08053a7e8f19fbe347c4a05dad324f7b54aac587 100644 (file)
--- a/src/backend/storage/ipc/procarray.c
+++ b/src/backend/storage/ipc/procarray.c
@@ -2686,12 +2686,13 @@ ProcArrayInstallRestoredXmin(TransactionId xmin, PGPROC *proc)
        TransactionIdIsNormal(xid) &&
        TransactionIdPrecedesOrEquals(xid, xmin))
    {
-       /* Install xmin */
+       /*
+        * Install xmin and propagate the statusFlags that affect how the
+        * value is interpreted by vacuum.
+        */
        MyProc->xmin = TransactionXmin = xmin;
-
-       /* Flags being copied must be valid copy-able flags. */
-       Assert((proc->statusFlags & (~PROC_COPYABLE_FLAGS)) == 0);
-       MyProc->statusFlags = proc->statusFlags;
+       MyProc->statusFlags = (MyProc->statusFlags & ~PROC_XMIN_FLAGS) |
+           (proc->statusFlags & PROC_XMIN_FLAGS);
        ProcGlobal->statusFlags[MyProc->pgxactoff] = MyProc->statusFlags;
 
        result = true;

diff --git a/src/include/storage/proc.h b/src/include/storage/proc.h
index 11b514c9ae8a4bef54394c9c6710da1624b16541..1464fad9b943ea7aefb7b2b8a1352cc210519c5f 100644 (file)
--- a/src/include/storage/proc.h
+++ b/src/include/storage/proc.h
@@ -66,11 +66,10 @@ struct XidCache
    (PROC_IN_VACUUM | PROC_IN_SAFE_IC | PROC_VACUUM_FOR_WRAPAROUND)
 
 /*
- * Flags that are valid to copy from another proc, the parallel leader
- * process in practice.  Currently, flags that are set during parallel
- * vacuum and parallel index creation are allowed.
+ * Xmin-related flags. Make sure any flags that affect how the process' Xmin
+ * value is interpreted by VACUUM are included here.
  */
-#define        PROC_COPYABLE_FLAGS (PROC_IN_VACUUM | PROC_IN_SAFE_IC)
+#define        PROC_XMIN_FLAGS (PROC_IN_VACUUM | PROC_IN_SAFE_IC)
 
 /*
  * We allow a small number of "weak" relation locks (AccessShareLock,