From 35bc0ec7c800b303e0629913ac336924cf979dcc Mon Sep 17 00:00:00 2001 From: Peter Geoghegan Date: Mon, 4 Mar 2019 17:57:36 -0800 Subject: [PATCH] Note case where nbtree VACUUM finishes splits. The nbtree README claims that VACUUM can never finish interrupted page splits by design. That isn't entirely accurate, though. Note an exception to the general rule. Discussion: https://postgr.es/m/CAH2-Wz=_Xvv8byzK_LvY4ci76OgsHCQzoKF7We8yG9waO7j6rA@mail.gmail.com --- src/backend/access/nbtree/README | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/src/backend/access/nbtree/README b/src/backend/access/nbtree/README index 3680e69b89..b0b4ab8b76 100644 --- a/src/backend/access/nbtree/README +++ b/src/backend/access/nbtree/README @@ -476,7 +476,10 @@ inserting a downlink might require splitting a page, it might fail if you run out of disk space. That would be bad during VACUUM - the reason for running VACUUM in the first place might be that you run out of disk space, and now VACUUM won't finish because you're out of disk space. In contrast, -an insertion can require enlarging the physical file anyway. +an insertion can require enlarging the physical file anyway. There is one +minor exception: VACUUM finishes interrupted splits of internal pages when +deleting their children. This allows the code for re-finding parent items +to be used by both page splits and page deletion. To identify missing downlinks, when a page is split, the left page is flagged to indicate that the split is not yet complete (INCOMPLETE_SPLIT).