maedhroz commented on code in PR #3916:
URL: https://github.com/apache/cassandra/pull/3916#discussion_r1968021601
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src/java/org/apache/cassandra/service/reads/ReplicaFilteringProtection.java:
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@@ -538,14 +538,19 @@ private UnfilteredPartitionIterator fetchFromSource()
Tracing.trace("Requesting {} rows in partition {} from {} for
replica filtering protection",
clusterings.size(), key, source);
- // build the read command taking into account that we could be
requesting only in the static row
- DataLimits limits = clusterings.isEmpty() ?
DataLimits.cqlLimits(1) : DataLimits.NONE;
- ClusteringIndexFilter filter = unresolvedStatic ?
command.clusteringIndexFilter(key) : new
ClusteringIndexNamesFilter(clusterings, command.isReversed());
+ // If there is an unresolved static column, we must fetch the
entire partition, as static column predicates
+ // may produce row matches across the entire partition. If there
are only non-static rows to complete, we
+ // query the partition specifically for the corresponding
cluterings by name. In either case, we do not
+ // provide a limit. (In the unresolved static case, we have no way
of knowing how many stale rows we might
+ // read on a silent replica before finding a live one.)
+ ClusteringIndexFilter filter = unresolvedStatic ?
command.clusteringIndexFilter(key)
+ : new
ClusteringIndexNamesFilter(clusterings, command.isReversed());
Review Comment:
The only way I can imagine improving this is perhaps paging so that we don't
fetch every row from a very large partition at once. Not 100% sure how to do
that yet, but looking around the code to try to find some example of doing this
w/ an `UnfilteredPartitionIterator`
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