Correct obsolete nbtree recovery comments.

Commit 40dae7ec537, which made the handling of interrupted nbtree page
splits more robust, removed an nbtree-specific end-of-recovery cleanup
step.  This meant that it was no longer possible to complete an
interrupted page split during recovery.  However, a reference to
recovery as a reason for using a NULL stack while inserting into a
parent page was missed.  Remove the reference.

Remove a similar obsolete reference to recovery that was introduced much
more recently, as part of the btree fastpath optimization enhancement
that made it into Postgres 11 (commit 2b272734, and follow-up commits).

Backpatch: 11-, where the fastpath optimization was introduced.

diff --git a/src/backend/access/nbtree/nbtinsert.c b/src/backend/access/nbtree/nbtinsert.c
index 582e5b0652d40e72272d5f941fb776a79f0ff1f3..80437cc83169f308ed23cafb5ebdab3c5015e464 100644 (file)
--- a/src/backend/access/nbtree/nbtinsert.c
+++ b/src/backend/access/nbtree/nbtinsert.c
@@ -876,10 +876,10 @@ _bt_insertonpg(Relation rel,
                 * all the required conditions, including the fact that this page has
                 * enough freespace. Note that this routine can in theory deal with
                 * the situation where a NULL stack pointer is passed (that's what
-                * would happen if the fastpath is taken), like it does during crash
-                * recovery. But that path is much slower, defeating the very purpose
-                * of the optimization.  The following assertion should protect us
-                * from any future code changes that invalidate those assumptions.
+                * would happen if the fastpath is taken). But that path is much
+                * slower, defeating the very purpose of the optimization.  The
+                * following assertion should protect us from any future code changes
+                * that invalidate those assumptions.
                 *
                 * Note that whenever we fail to take the fastpath, we clear the
                 * cached block. Checking for a valid cached block at this point is
@@ -1807,8 +1807,8 @@ _bt_checksplitloc(FindSplitData *state,
  * and it'd be possible for some other process to try to split or delete
  * one of these pages, and get confused because it cannot find the downlink.)
  *
- * stack - stack showing how we got here.  May be NULL in cases that don't
- *                     have to be efficient (concurrent ROOT split, WAL recovery)
+ * stack - stack showing how we got here.  Will be NULL when splitting true
+ *                     root, or during concurrent root split, where we can be inefficient
  * is_root - we split the true root
  * is_only - we split a page alone on its level (might have been fast root)
  */