jtuglu1 commented on code in PR #18568:
URL: https://github.com/apache/druid/pull/18568#discussion_r2395978203
##########
processing/src/main/java/org/apache/druid/query/scan/ScanQueryQueryToolChest.java:
##########
@@ -191,6 +198,76 @@ public Sequence<Object[]> resultsAsArrays(final ScanQuery
query, final Sequence<
);
}
+ @Override
+ public CacheStrategy<ScanResultValue, ScanResultValue, ScanQuery>
getCacheStrategy(
+ final ScanQuery query,
+ @Nullable final ObjectMapper objectMapper
+ )
+ {
+ return new CacheStrategy<>()
+ {
+ @Override
+ public boolean isCacheable(ScanQuery query, boolean willMergeRunners,
boolean segmentLevel)
+ {
+ // Currently, there is no bijective mapping from ScanResultValue to
Result<BySegmentResultValueClass<ScanResultValue>>.
+ // This means queries will fail if:
+ // - A query is issued with bySegment:true
+ // - Segment-level cache is enabled on the broker (in which case it
sends bySegment queries to data nodes).
+ return !query.context().isBySegment() && (!segmentLevel ||
willMergeRunners);
+ }
+
+ @Override
+ public byte[] computeCacheKey(ScanQuery query)
+ {
+ CacheKeyBuilder builder = new CacheKeyBuilder(SCAN_QUERY)
+ .appendByte(CACHE_STRATEGY_VERSION)
+ .appendCacheable(query.getDataSource())
+ .appendCacheable(query.getVirtualColumns())
+ .appendString(query.getResultFormat().toString())
+ .appendLong(query.getScanRowsOffset())
+ .appendLong(query.getScanRowsLimit())
+ .appendCacheable(query.getFilter())
+ .appendStrings(query.getColumns() != null ? query.getColumns() :
List.of())
+ .appendString(query.getTimeOrder().toString());
+
+ List<OrderBy> orderBys = query.getOrderBys();
+ if (orderBys != null) {
+ for (OrderBy orderBy : orderBys) {
+ builder.appendString(orderBy.getColumnName())
+ .appendString(orderBy.getOrder().toString());
+ }
+ }
+
+ return builder.build();
+ }
+
+ @Override
+ public byte[] computeResultLevelCacheKey(ScanQuery query)
+ {
+ // Use the same key as segment-level cache no result-level
transformations like aggregations
+ return computeCacheKey(query);
+ }
+
+ @Override
+ public TypeReference<ScanResultValue> getCacheObjectClazz()
+ {
+ return TYPE_REFERENCE;
+ }
+
+ @Override
+ public Function<ScanResultValue, ScanResultValue>
prepareForCache(boolean isResultLevelCache)
Review Comment:
Because of perSegment query type. See the explanation in the PR description.
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