mcvsubbu commented on a change in pull request #5470:
URL: https://github.com/apache/incubator-pinot/pull/5470#discussion_r432897362
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File path:
pinot-core/src/main/java/org/apache/pinot/core/indexsegment/mutable/MutableSegmentImpl.java
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@@ -330,8 +330,32 @@ public long getLatestIngestionTimestamp() {
*/
private boolean isNoDictionaryColumn(Set<String> noDictionaryColumns,
Set<String> invertedIndexColumns,
Set<String> textIndexColumns, FieldSpec fieldSpec, String column) {
- return textIndexColumns.contains(column) ||
(noDictionaryColumns.contains(column) && fieldSpec.isSingleValueField()
- && !invertedIndexColumns.contains(column));
+ if (textIndexColumns.contains(column)) {
+ // text column is no dictionary currently
+ return true;
+ }
+ FieldSpec.DataType dataType = fieldSpec.getDataType();
+ if (noDictionaryColumns.contains(column)) {
+ // Earlier we didn't support noDict in consuming segments for STRING and
BYTES columns.
+ // So even if the user had the column in noDictionaryColumns set in
table config, we still
+ // created dictionary in consuming segments.
+ // Later on we added this support. There is a particular impact of this
change on the use cases
+ // that have set noDict on their STRING dimension columns for other
performance
+ // reasons and also want metricsAggregation. These use cases don't get to
+ // aggregateMetrics because the new implementation is able to honor
their table config setting
+ // of noDict on STRING/BYTES. Without metrics aggregation, memory
pressure increases.
+ // So to continue aggregating metrics for such cases, we will create
dictionary even
+ // if the column is part of noDictionary set from table config
+ if (fieldSpec instanceof DimensionFieldSpec && _aggregateMetrics &&
(dataType == FieldSpec.DataType.STRING ||
Review comment:
should the name of the method be changed to
`shouldCreateDictionaryForColumn()`?
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