gianm commented on code in PR #13206:
URL: https://github.com/apache/druid/pull/13206#discussion_r992783183
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sql/src/main/java/org/apache/druid/sql/calcite/rel/DruidQuery.java:
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@@ -774,6 +784,53 @@ private static Filtration toFiltration(DimFilter filter,
VirtualColumnRegistry v
return
Filtration.create(filter).optimize(virtualColumnRegistry.getFullRowSignature());
}
+ /**
+ * Whether the provided combination of dataSource, filtration, and
queryGranularity is safe to use in queries.
+ *
+ * Necessary because some combinations are unsafe, mainly because they would
lead to the creation of too many
+ * time-granular buckets during query processing.
+ */
+ private static boolean canUseQueryGranularity(
+ final DataSource dataSource,
+ final Filtration filtration,
+ final Granularity queryGranularity
+ )
+ {
+ if (Granularities.ALL.equals(queryGranularity)) {
+ // Always OK: no storage adapter has problem with ALL.
+ return true;
+ }
+
+ if (DataSourceAnalysis.forDataSource(dataSource).isConcreteTableBased()) {
+ // Always OK: queries on concrete tables (regular Druid datasources) use
segment-based storage adapters
+ // (IncrementalIndex or QueryableIndex). These clip query interval to
data interval, making wide query
+ // intervals safer. They do not have special checks for granularity and
interval safety.
+ return true;
+ }
+
+ // Query is against something other than a regular Druid table. Apply
additional checks, because we can't
+ // count on interval-clipping to save us.
+
+ for (final Interval filtrationInterval : filtration.getIntervals()) {
+ // Query may be using RowBasedStorageAdapter. We don't know for sure, so
check
+ // RowBasedStorageAdapter#isQueryGranularityAllowed to be safe.
+ if
(!RowBasedStorageAdapter.isQueryGranularityAllowed(filtrationInterval,
queryGranularity)) {
+ return false;
+ }
+
+ // Validate the interval against MAX_TIME_GRAINS_NON_DRUID_TABLE.
+ // Estimate based on the size of the first bucket, to avoid computing
them all. (That's what we're
+ // trying to avoid!)
+ final Interval firstBucket =
queryGranularity.bucket(filtrationInterval.getStart());
Review Comment:
This logic is here because not all Granularities have a fixed duration.
There is DurationGranularity, which does, but also PeriodGranularity, which
does not. For example, P1Y changes durations on leap years and P1D changes
durations for daylight savings time.
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