PageAddItemExtended(): Add LP_UNUSED assertion.

Assert that LP_UNUSED items have no storage.  If it's worth having
defensive code in non-assert builds then it's worth having an assertion
as well.

diff --git a/src/backend/storage/page/bufpage.c b/src/backend/storage/page/bufpage.c
index 9ac556b4ae0a731c26806bf039790eafe02dc405..5d5989c2f526f006301153ea48934417f96dbd1a 100644 (file)
--- a/src/backend/storage/page/bufpage.c
+++ b/src/backend/storage/page/bufpage.c
@@ -250,14 +250,18 @@ PageAddItemExtended(Page page,
        /* if no free slot, we'll put it at limit (1st open slot) */
        if (PageHasFreeLinePointers(phdr))
        {
-           /*
-            * Look for "recyclable" (unused) ItemId.  We check for no storage
-            * as well, just to be paranoid --- unused items should never have
-            * storage.
-            */
+           /* Look for "recyclable" (unused) ItemId */
            for (offsetNumber = 1; offsetNumber < limit; offsetNumber++)
            {
                itemId = PageGetItemId(phdr, offsetNumber);
+
+               /*
+                * We check for no storage as well, just to be paranoid;
+                * unused items should never have storage.  Assert() that the
+                * invariant is respected too.
+                */
+               Assert(ItemIdIsUsed(itemId) || !ItemIdHasStorage(itemId));
+
                if (!ItemIdIsUsed(itemId) && !ItemIdHasStorage(itemId))
                    break;
            }
@@ -676,7 +680,9 @@ compactify_tuples(itemIdCompact itemidbase, int nitems, Page page, bool presorte
  *
  * This routine is usable for heap pages only, but see PageIndexMultiDelete.
  *
- * As a side effect, the page's PD_HAS_FREE_LINES hint bit is updated.
+ * Caller had better have a super-exclusive lock on page's buffer.  As a side
+ * effect the page's PD_HAS_FREE_LINES hint bit will be set or unset as
+ * needed.
  */
 void
 PageRepairFragmentation(Page page)
@@ -771,7 +777,7 @@ PageRepairFragmentation(Page page)
        compactify_tuples(itemidbase, nstorage, page, presorted);
    }
 
-   /* Set hint bit for PageAddItem */
+   /* Set hint bit for PageAddItemExtended */
    if (nunused > 0)
        PageSetHasFreeLinePointers(page);
    else