Add nbtree page deletion assertion.

petergeoghegan · petergeoghegan · commit a451b7d44249 · 2020-08-03T13:04:42.000-07:00
Add a documenting assertion that's similar to the nearby assertion added by commit cd8c73a. This conveys that the entire call to _bt_pagedel() does no work if it isn't possible to get a descent stack for the initial scanblkno page.
diff --git a/src/backend/access/nbtree/nbtpage.c b/src/backend/access/nbtree/nbtpage.c
@@ -1697,6 +1697,7 @@ _bt_pagedel(Relation rel, Buffer leafbuf, TransactionId *oldestBtpoXact)
 				if (_bt_leftsib_splitflag(rel, leftsib, leafblkno))
 				{
 					ReleaseBuffer(leafbuf);
+					Assert(ndeleted == 0);
 					return ndeleted;
 				}
 

Original file line number	Diff line number	Diff line change
`@@ -1697,6 +1697,7 @@ _bt_pagedel(Relation rel, Buffer leafbuf, TransactionId *oldestBtpoXact)`
`1697`	`1697`	`if (_bt_leftsib_splitflag(rel, leftsib, leafblkno))`
`1698`	`1698`	`{`
`1699`	`1699`	`ReleaseBuffer(leafbuf);`
	`1700`	`+ Assert(ndeleted == 0);`
`1700`	`1701`	`return ndeleted;`
`1701`	`1702`	`}`
`1702`	`1703`