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Commit97cda93

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Consistently truncate non-key suffix columns.
INCLUDE indexes failed to have their non-key attributes physicallytruncated away in certain rare cases. This led to physically largerpivot tuples that contained useless non-key attribute values. Theimpact on users should be negligible, but this is still clearly aregression (Postgres 11 supports INCLUDE indexes, and yet was notaffected).The bug appeared in commitdd299df, which introduced "true" suffixtruncation of key attributes.Discussion:https://postgr.es/m/CAH2-Wz=E8pkV9ivRSFHtv812H5ckf8s1-yhx61_WrJbKccGcrQ@mail.gmail.comBackpatch: 12-, where "true" suffix truncation was introduced.
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‎src/backend/access/nbtree/nbtutils.c

Lines changed: 6 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -2143,7 +2143,8 @@ _bt_truncate(Relation rel, IndexTuple lastleft, IndexTuple firstright,
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{
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IndexTupletidpivot;
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pivot=index_truncate_tuple(itupdesc,firstright,keepnatts);
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pivot=index_truncate_tuple(itupdesc,firstright,
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Min(keepnatts,nkeyatts));
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/*
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* If there is a distinguishing key attribute within new pivot tuple,
@@ -2173,6 +2174,10 @@ _bt_truncate(Relation rel, IndexTuple lastleft, IndexTuple firstright,
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/*
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* No truncation was possible, since key attributes are all equal.
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* It's necessary to add a heap TID attribute to the new pivot tuple.
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*
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* This path is only taken when rel is not an INCLUDE index. It
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* avoids a second palloc0() by avoiding the index_truncate_tuple()
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* call completely.
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*/
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Assert(natts==nkeyatts);
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newsize=IndexTupleSize(firstright)+MAXALIGN(sizeof(ItemPointerData));

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