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Don't truncate away non-key attributes for leftmost downlinks.

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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
Discussion: https://www.postgresql.org/message-id/CAH2-WzkAS2M3ussHG-s_Av=Zo6dPjOxyu5fNRkYnxQV+YzGQ4w@mail.gmail.com
This commit is contained in:
Teodor Sigaev 2018-05-04 12:38:23 +03:00
parent 0bef1c0678
commit 2a9e04f0a8
1 changed files with 14 additions and 16 deletions
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30
src/backend/access/nbtree/nbtsort.c
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@ -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);