siddharthteotia commented on a change in pull request #5470:
URL: https://github.com/apache/incubator-pinot/pull/5470#discussion_r432898453
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File path:
pinot-core/src/main/java/org/apache/pinot/core/segment/creator/impl/SegmentColumnarIndexCreator.java
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@@ -213,6 +215,14 @@ public void init(SegmentGeneratorConfig
segmentCreationSpec, SegmentIndexCreatio
}
}
+ public static boolean shouldDeriveNumDocsPerChunk(String columnName,
Map<String, Map<String, String>> columnProperties) {
+ if (columnProperties != null) {
+ Map<String, String> properties = columnProperties.get(columnName);
+ return properties != null &&
Boolean.parseBoolean(properties.get(FieldConfig.DERIVE_NUM_DOCS_PER_CHUNK_RAW_INDEX_KEY));
Review comment:
> Defaults to false, right?
Yes
> Can we derive it automatically? (e.g. if column is text index then we
derive it from metadata) Or, do you see this being usefiul in other cases as
well?
We could. Even for columns with text indexes, I don't think we should use it
by default (since now that we have seen the potential -ve impact related to
access pattern). Yes, most likely this will be used for columns with text index
but only if the average column value size is very large (around 1-2MB) since
that is the case which takes the chunk size and compressed chunk size (2 * raw)
> 2GB and deriving the numDocsPerChunk becomes useful.
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