From 3894e6e02c4b7364bc57498ed165f37dda4dba63 Mon Sep 17 00:00:00 2001 From: Peter Geoghegan Date: Mon, 30 Apr 2018 12:28:54 -0700 Subject: [PATCH] Don't truncate away non-key attributes for leftmost downlinks. nbtsort.c does not need to truncate away non-key attributes for the minimum key of the leftmost page on a level, since this is only used to build a minus infinity downlink for the level's leftmost page. Truncating away non-key attributes in advance of truncating away all attributes in _bt_sortaddtup() does not affect the correctness of CREATE INDEX, but it is misleading. Author: Peter Geoghegan --- src/backend/access/nbtree/nbtsort.c | 30 ++++++++++++++---------------- 1 file changed, 14 insertions(+), 16 deletions(-) diff --git a/src/backend/access/nbtree/nbtsort.c b/src/backend/access/nbtree/nbtsort.c index 0587e42573..e012df596e 100644 --- a/src/backend/access/nbtree/nbtsort.c +++ b/src/backend/access/nbtree/nbtsort.c @@ -934,7 +934,10 @@ _bt_buildadd(BTWriteState *wstate, BTPageState *state, IndexTuple itup) state->btps_next = _bt_pagestate(wstate, state->btps_level + 1); Assert(BTreeTupleGetNAtts(state->btps_minkey, wstate->index) == - IndexRelationGetNumberOfKeyAttributes(wstate->index)); + IndexRelationGetNumberOfKeyAttributes(wstate->index) || + P_LEFTMOST(opageop)); + Assert(BTreeTupleGetNAtts(state->btps_minkey, wstate->index) == 0 || + !P_LEFTMOST(opageop)); BTreeInnerTupleSetDownLink(state->btps_minkey, oblkno); _bt_buildadd(wstate, state->btps_next, state->btps_minkey); pfree(state->btps_minkey); @@ -974,24 +977,16 @@ _bt_buildadd(BTWriteState *wstate, BTPageState *state, IndexTuple itup) * If the new item is the first for its page, stash a copy for later. Note * this will only happen for the first item on a level; on later pages, * the first item for a page is copied from the prior page in the code - * above. + * above. Since the minimum key for an entire level is only used as a + * minus infinity downlink, and never as a high key, there is no need to + * truncate away non-key attributes at this point. */ if (last_off == P_HIKEY) { - BTPageOpaque npageop; - Assert(state->btps_minkey == NULL); - - npageop = (BTPageOpaque) PageGetSpecialPointer(npage); - - /* - * Truncate included attributes of the tuple that we're going to - * insert into the parent page as a downlink - */ - if (indnkeyatts != indnatts && P_ISLEAF(npageop)) - state->btps_minkey = _bt_nonkey_truncate(wstate->index, itup); - else - state->btps_minkey = CopyIndexTuple(itup); + state->btps_minkey = CopyIndexTuple(itup); + /* _bt_sortaddtup() will perform full truncation later */ + BTreeTupleSetNAtts(state->btps_minkey, 0); } /* @@ -1044,7 +1039,10 @@ _bt_uppershutdown(BTWriteState *wstate, BTPageState *state) else { Assert(BTreeTupleGetNAtts(s->btps_minkey, wstate->index) == - IndexRelationGetNumberOfKeyAttributes(wstate->index)); + IndexRelationGetNumberOfKeyAttributes(wstate->index) || + P_LEFTMOST(opaque)); + Assert(BTreeTupleGetNAtts(s->btps_minkey, wstate->index) == 0 || + !P_LEFTMOST(opaque)); BTreeInnerTupleSetDownLink(s->btps_minkey, blkno); _bt_buildadd(wstate, s->btps_next, s->btps_minkey); pfree(s->btps_minkey); -- 2.14.1