Check the example in the processor's additional details docs [1] for how you could set size and sort fields for the query - size is used to determine the number of documents returned per page, sorry is required if using a "search after" or "point in time" query type.
If the Query property is set, the incoming FlowFile content should be ignored, i.e. it doesn't need to be empty. Use the "Search Results Split" property to determine how the results are output. This defaults to "per response", which outputs a flowfile for every page of results. As PaginatedJsonQueryElasticsearch takes an input flowfile, its internal "process session" remains active until the processor completes and commits is session - this happens when there are no more results to retrieve from Elasticsearch, at which point the input flowfile disappears from the input queue and all output flowfiles appear in the output queues. This is how the nifi framework handles sessions, but can be confusing if you're not aware of that beforehand. SearchElasticsearch is different in this regard because its session ends after every iteration (determined by the "Search Results Split", e.g. this could be per page or per entire query), then uses nifi state to setup the next iteration. This means you could start to see output flowfiles sooner. [1] https://nifi.apache.org/docs/nifi-docs/components/org.apache.nifi/nifi-elasticsearch-restapi-nar/1.23.0/org.apache.nifi.processors.elasticsearch.PaginatedJsonQueryElasticsearch/additionalDetails.html On 2023/08/17 22:13:22 Richard Beare wrote: > Thanks, that makes sense. I've had trouble getting a size parameter > accepted, but will work on that later. > > However, I'm unsure what I should expect to see in the following test > scenario. > > A fixed query in the Query parameter - a match all. i.e. nothing dynamic > set by upstream processing > > An empty input flowfile to trigger activity. > > The test index is large. (20M docs) > > Do I expect the processor to begin filling the output queue as fast as it > can, with one flowfile per received page, pausing as the queue fills? > That was what I was anticipating, but at the moment I'm getting no output > and the input flowfile isn't being consumed. I suspect one flag is wrong, > but can't see it. > > > > > > > > On Fri, Aug 18, 2023 at 12:06 AM Chris Sampson <chr...@apache.org> wrote: > > > Again, sounds like it's working as documented [1] - an input is required > > to trigger the PaginatedJsonQueryElasticsearch processor, so something like > > GenerateFlowFile is a way to achieve that if you want to periodically > > execute a paginated query, e.g. by setting the Generate processor's > > schedule to run every hour, or use cron syntax, etc. The advantage with > > this processor is that you can use the output of another processor (e.g. > > build a query using the results of another processor, such as an initial > > query of Elasticsearch) to trigger the paginated query of Elasticsearch, > > but once the query is finished, the processor won't keep firing. > > > > Conversely, SearchElasticsearch does not allow incoming connections, but > > only triggers the same query on the defined schedule. If the query needs to > > use parameters (or some sort of variable), you need to figure out how to > > apply that in the Query parameter of the processor - it could be by > > Elasticsearch notation (e.g. "now/d" for the start of the current day in a > > date range filter), or something that can be achieved using NiFi Expression > > Language [2], but without the flexibility of providing inputs in FlowFile > > content, which could be the output of a previous query, or > > GenerateFlowFile, etc. > > > > You need to figure out what query you want to run, what input(s) are > > appropriate, and the schedule to which you want to execute. > > > > The Search processor is aimed more at a use case of "I want to continually > > retrieve the contents of an Elasticsearch index/query as it is populated > > from an extremal source", PaginatedQuery is more for "I want to retrieve > > data from Elasticsearch that match a query"; both processors are meant to > > "allow for the possibility of many documents to be retrieved". > > > > For various reasons, neither processor was designed to hold state between > > initiation of paginated queries, e.g. they don't follow the pattern of a > > "Consume" or "List" processor that attempts to retain the knowledge of the > > "last timestamp" within NiFi itself. That's something that could be > > considered, but would need a code change (feel free to raise a jira ticket > > for the future [3] if you think that would be helpful). One of the reasons > > for this is that, unlike an S3 Bucket (for example), documents are not > > guaranteed to always be indexed within Elasticsearch in order/with such an > > "updated at" field, although one could design their system that way, of > > course. > > > > [1] > > https://nifi.apache.org/docs/nifi-docs/components/org.apache.nifi/nifi-elasticsearch-restapi-nar/1.23.0/org.apache.nifi.processors.elasticsearch.PaginatedJsonQueryElasticsearch/index.html > > > > [2] > > https://nifi.apache.org/docs/nifi-docs/html/expression-language-guide.html > > > > [3] https://issues.apache.org/jira/browse/NIFI > > > > On 2023/08/17 12:43:31 Richard Beare wrote: > > > I must be missing something simple. I've copied the parameters and query > > > from the SearchElasticSearch processor and I'm not getting errors, but no > > > flowfiles are produced. > > > > > > I'm forced to add an input connection, despite coding the query in the > > > Query property. I have a GenerateFlowFile processor connected. I'm > > using.a > > > basic match all as a starting point > > > { > > > "query" : > > > { > > > "match_all" : {} > > > } > > > } > > > > > > Sending the query via curl appears to work OK - I get a page of stuff > > back. > > > I'm using nifi 1.20. > > > > > > > > > > > > On Thu, Aug 17, 2023 at 2:24 PM Chris Sampson <chr...@apache.org> wrote: > > > > > > > Elasticsearch doesn't have a CDC-like capability (it doesn't maintain a > > > > transaction log or such), so that approach isn't possible. > > > > > > > > What I've done previously is to maintain an audit log in a separate > > index > > > > within elasticsearch to track what data I've previously posted, e.g. > > this > > > > might be the last "updated_date" value read from the data index in a > > > > previous run of the nifi processor. So your nifi Flow would be > > something > > > > like: > > > > > > > > Query for latest processed updated_date > paginated query for all new > > data > > > > > determine new latest updated_date (e.g. using QueryRecord) > put new > > > > latest updated_date into elasticsearch, ready for the next run > > > > > > > > On 2023/08/16 23:15:19 Richard Beare wrote: > > > > > One further question - what is the recommended way of checking for > > > > updates > > > > > in an index and fetching new records in a similar manner to > > > > > GenerateTableFetch for an sql DB? > > > > > Thanks > > > > > > > > > > On Thu, Aug 17, 2023 at 7:21 AM Richard Beare < > > richard.be...@gmail.com> > > > > > wrote: > > > > > > > > > > > Sounds perfect. Thanks > > > > > > > > > > > > On Thu, Aug 17, 2023 at 5:11 AM Chris Sampson <chr...@apache.org> > > > > wrote: > > > > > > > > > > > >> What you describe sounds like the processor is working as > > designed & > > > > > >> documented, i.e. it will restart the same query once it has > > reached > > > > the end > > > > > >> of the paginated scroll (or search_after, or point-in-time) query. > > > > > >> > > > > > >> Instead, it sounds like you want to try using the > > > > > >> PaginatedJsonQueryElasticsearch [1] processor instead. This will > > > > execute > > > > > >> the query given to it, either as the query property or the body > > of an > > > > > >> incoming FlowFile, output the results, and then stop. > > > > > >> > > > > > >> > > > > > >> [1] > > > > > >> > > > > > > https://nifi.apache.org/docs/nifi-docs/components/org.apache.nifi/nifi-elasticsearch-restapi-nar/1.23.0/org.apache.nifi.processors.elasticsearch.PaginatedJsonQueryElasticsearch/index.html > > > > > >> > > > > > >> On 2023/08/16 07:57:43 Richard Beare wrote: > > > > > >> > Hi, > > > > > >> > I am using the SearchElasticSearch (1.20.0) processor to > > retrieve > > > > all > > > > > >> > documents (~20M) from an index, process and eventually return > > > > results > > > > > >> to a > > > > > >> > new index, although for this test I'm retrieving and processing > > then > > > > > >> > discarding. I'm using opensearch. > > > > > >> > > > > > > >> > My problem is that the process restarts after completion - I > > > > discovered > > > > > >> > this, and docs confirm, after seeing warnings from my processing > > > > code > > > > > >> > (which reformats json ready for other work) being repeated for > > the > > > > same > > > > > >> > document ID. > > > > > >> > > > > > > >> > How do I configure the processor to stop after the completing > > the > > > > first > > > > > >> > query. > > > > > >> > > > > > > >> > I've tried the following: > > > > > >> > > > > > > >> > Query: {"query" : {"match_all" :{}}} > > > > > >> > > > > > > >> > with pagination_type SCROLL > > > > > >> > > > > > > >> > I haven't found a combination of the properties that doesn't > > lead to > > > > > >> > repeated cycles through the index. > > > > > >> > > > > > > >> > I've also tried {"query" : {"match_all" :{}}, "sort" : > > > > > >> [{"Visit_DateTime" : > > > > > >> > "asc"]}} > > > > > >> > > > > > > >> > and SEARCH_AFTER pagination type, with the same problem. > > > > > >> > > > > > > >> > What am I missing? > > > > > >> > Thanks > > > > > >> > > > > > > >> > > > > > > > > > > > > > > > > > > > > >
