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https://issues.apache.org/jira/browse/ORC-1553?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17799341#comment-17799341
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Alexander Petrossian (PAF) commented on ORC-1553:
-------------------------------------------------
I looked at data and discovered that key column is totally missing from it:
{noformat}
orc-tools data MAJOR-2023-11-21.orc >MAJOR-2023-11-21.orc.dump.txt
head -40000 ./MAJOR-2023-11-21.orc.jsons |tail -10000
{noformat}
{code:js}
{
"data": {
"request": {
"eventItem": [
{
"InformationEventItem": null,
"NotificationEventItem": {...},
"UsageEventItem": null,
"UsagePolicyEventItem": null
}
],
{code}
The column in question
{noformat}
data.request.eventItem._elem.UsageEventItem.usage.CustomerFacingServiceUsage.relatedParty._elem.resource._elem.value
{code}
Lies inside *UsageEventItem*, which is *null* in all records of that row group.
Hence the column being search for is not null, it just non-existent.
> Reading information from Row group, where there are 0 records of SArg column
> ----------------------------------------------------------------------------
>
> Key: ORC-1553
> URL: https://issues.apache.org/jira/browse/ORC-1553
> Project: ORC
> Issue Type: Bug
> Affects Versions: 1.9.2
> Reporter: Alexander Petrossian (PAF)
> Priority: Major
> Attachments: MAJOR-2023-11-21.orc, Снимок экрана 2023-12-21 в
> 10.00.23.png
>
>
> We have created .orc file using Apache ORC library, I can not provide a
> reproducible way to create such a file.
> We have statistics for 100% row groups, checked with orc dump.
> But I see that when we search by that file we get a very strange behavior:
> {code}
> TRACE org.apache.orc.impl.RecordReaderImpl: Stats = numberOfValues: 0
> stringStatistics {
> }
> hasNull: false
> TRACE org.apache.orc.impl.RecordReaderImpl: Setting (EQUALS value
> 71231231212) to YES_NO_NULL
> DEBUG org.apache.orc.impl.RecordReaderImpl: Row group 340000 to 349999 is
> included.
> {code}
> If there are 0 values according to existing statistics, so there is obviously
> no need to read that row group.
> And yet we have YES_NO_NULL decision which forces inclusion of that row group
> in subsequent operation, which meaningless and bad for performance.
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