github-actions[bot] commented on code in PR #68648:
URL: https://github.com/apache/doris/pull/68648#discussion_r4230756657
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fe/fe-core/src/main/java/org/apache/doris/mtmv/MTMVRewriteUtil.java:
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@@ -94,6 +111,18 @@ public static Collection<Partition>
getMTMVCanRewritePartitions(MTMV mtmv, Conne
return res;
}
}
+ if (mtmvNeedComparePartitions.isEmpty()) {
+ // A base partition the query reads is mapped from no MV
partition of this one -- a partition
+ // the mapping left out, an expired one for instance -- so no
MV partition holds its rows.
+ // None of them may answer this query, whatever the state of
the partitions in grace below:
+ // the answer is the base table.
+ return Lists.newArrayList();
+ }
+ if (gracePeriodMills > 0 && currentTimeMills <=
(partition.getVisibleVersionTime()
+ + gracePeriodMills) && !forceConsistent) {
Review Comment:
[P1] Do not grant grace to a newly aligned partition before its first
refresh snapshot. For a LIST(d,k) base, let p12 contain ((1,1),(2,1)) and a
committed d=1 row, then refresh a PARTITION BY d aggregate MV. Adding empty
p23=((2,2),(3,2)) expands the projected component from {1,2} to {1,2,3};
alignment drops the populated MV partition and adds an empty one before
refresh. This branch treats the new partition's creation timestamp as fresh and
admits it without a refresh snapshot. Thus Aggregate(d,SUM(v)) ->
Scan(base[p12,p23]) can rewrite to Scan(MV[empty {1,2,3}]) and omit the
committed d=1 group while refresh runs or after it fails. The prior key-order
thread concerned an unchanged key set; sorting cannot prevent this genuine
expansion. Require a successful snapshot before grace can admit the replacement.
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