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https://issues.apache.org/jira/browse/NIFI-3248?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16195076#comment-16195076
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ASF GitHub Bot commented on NIFI-3248:
--------------------------------------
GitHub user JohannesDaniel opened a pull request:
https://github.com/apache/nifi/pull/2199
NIFI-3248: Improvement of GetSolr Processor
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This closes #2199
----
commit 8a5f7e54edc5640655edd19f15d22fada6ca9900
Author: JohannesDaniel <johannesdaniel.pe...@gmx.de>
Date: 2017-10-05T20:57:53Z
NIFI-3248: Improvement of GetSolr Processor
----
> GetSolr can miss recently updated documents
> -------------------------------------------
>
> Key: NIFI-3248
> URL: https://issues.apache.org/jira/browse/NIFI-3248
> Project: Apache NiFi
> Issue Type: Bug
> Components: Extensions
> Affects Versions: 1.0.0, 0.5.0, 0.6.0, 0.5.1, 0.7.0, 0.6.1, 1.1.0, 0.7.1,
> 1.0.1
> Reporter: Koji Kawamura
> Assignee: Johannes Peter
> Attachments: nifi-flow.png, query-result-with-curly-bracket.png,
> query-result-with-square-bracket.png
>
>
> GetSolr holds the last query timestamp so that it only fetches documents
> those have been added or updated since the last query.
> However, GetSolr misses some of those updated documents, and once the
> documents date field value becomes older than last query timestamp, the
> document won't be able to be queried by GetSolr any more.
> This JIRA is for tracking the process of investigating this behavior, and
> discussion on them.
> Here are things that can be a cause of this behavior:
> |#|Short description|Should we address it?|
> |1|Timestamp range filter, curly or square bracket?|No|
> |2|Timezone difference between update and query|Additional docs might be
> helpful|
> |3|Lag comes from NearRealTIme nature of Solr|Should be documented at least,
> add 'commit lag-time'?|
> h2. 1. Timestamp range filter, curly or square bracket?
> At the first glance, using curly and square bracket in mix looked strange
> ([source
> code|https://github.com/apache/nifi/blob/support/nifi-0.5.x/nifi-nar-bundles/nifi-solr-bundle/nifi-solr-processors/src/main/java/org/apache/nifi/processors/solr/GetSolr.java#L202]).
> But these difference has a meaning.
> The square bracket on the range query is inclusive and the curly bracket is
> exclusive. If we use inclusive on both sides and a document has a time stamp
> exactly on the boundary then it could be returned in two consecutive
> executions, and we only want it in one.
> This is intentional, and it should be as it is.
> h2. 2. Timezone difference between update and query
> Solr treats date fields as [UTC
> representation|https://cwiki.apache.org/confluence/display/solr/Working+with+Dates|].
> If date field String value of an updated document represents time without
> timezone, and NiFi is running on an environment using timezone other than
> UTC, GetSolr can't perform date range query as users expect.
> Let's say NiFi is running with JST(UTC+9). A process added a document to Solr
> at 15:00 JST. But the date field doesn't have timezone. So, Solr indexed it
> as 15:00 UTC. Then GetSolr performs range query at 15:10 JST, targeting any
> documents updated from 15:00 to 15:10 JST. GetSolr formatted dates using UTC,
> i.e. 6:00 to 6:10 UTC. The updated document won't be matched with the date
> range filter.
> To avoid this, updated documents must have proper timezone in date field
> string representation.
> If one uses NiFi expression language to set current timestamp to that date
> field, following NiFi expression can be used:
> {code}
> ${now():format("yyyy-MM-dd'T'HH:mm:ss.SSSZ")}
> {code}
> It will produce a result like:
> {code}
> 2016-12-27T15:30:04.895+0900
> {code}
> Then it will be indexed in Solr with UTC and will be queried by GetSolr as
> expected.
> h2. 3. Lag comes from NearRealTIme nature of Solr
> Solr provides Near Real Time search capability, that means, the recently
> updated documents can be queried in Near Real Time, but it's not real time.
> This latency can be controlled by either on client side which requests the
> update operation by specifying "commitWithin" parameter, or on the Solr
> server side, "autoCommit" and "autoSoftCommit" in
> [solrconfig.xml|https://cwiki.apache.org/confluence/display/solr/UpdateHandlers+in+SolrConfig#UpdateHandlersinSolrConfig-Commits].
> Since commit and updating index can be costly, it's recommended to set this
> interval long enough up to the maximum tolerable latency.
> However, this can be problematic with GetSolr. For instance, as shown in the
> simple NiFi flow below, GetSolr can miss updated documents:
> {code}
> t1: GetSolr queried
> t2: GenerateFlowFile set date = t2
> t3: PutSolrContentStream stored new doc
> t4: GetSolr queried again, from t1 to t4, but the new doc hasn't been indexed
> t5: Solr completed index
> t6: GetSolr queried again, from t4 to t6, the doc didn't match query
> {code}
> This behavior should be at least documented.
> Plus, it would be helpful to add a new configuration property to GetSolr, to
> specify commit lag-time so that GetSolr aims older timestamp range to query
> documents.
> {code}
> // with commit lag-time
> t1: GetSolr queried
> t2: GenerateFlowFile set date = t2
> t3: PutSolrContentStream stored new doc
> t4: GetSolr queried again, from (t1 - lag) to (t4 - lag), but the new doc
> hasn't been indexed
> t5: Solr completed index
> t6: GetSolr queried again, from (t4 - lag) to (t6 - lag), the doc can match
> query
> {code}
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