I have a below scenario, I am trying
get new files list with ListFile processor
set a constant variable zipFilesBundleConstant = listBundle on each flowfile
Put the list to Database
Get all the list of files old and new from Database to process further with ExecuteSQL processor. (Here I want to make only one Database call to fetch complete list old and new, but ExecuteSQL is being called for all the flowfiles)
I tried keeping MergeContent processor with zipFilesBundleConstant as Correlation Attribute Name before ExecuteSQL to combine all the flowfiles but that is not working as expected and it merges some but always gives me multiple flowfiles.
Can anyone please help me with a solution on how to make a one call after inserting the new files list into the database.
You can use ExecuteSQL processor has separate workflow to fetch existing old files list from the database with the scheduling strategy as per the requirement.
https://nifi.apache.org/docs/nifi-docs/html/user-guide.html#scheduling-tab
Related
I'm working in NIFI with PutDataBaseRecord to insert the data of a CSV file to a database table. Everything goes well in the first execution because there is no data in the table. Then I modify the file so it contains new records and existing ones. PutDataBaseRecord fails because of existing records (primary key constraint) but it doesn´t insert the new records.
Is there any way to configure the processor to instruct it to insert the new records and ignore the ones that failed?
I attached pictures of how my processor is configured.
Thanks in advance!
Flujo NIFI
PutDataBaseRecord
This is possible. However it is not a straightforward implementation.
I would suggest you to try the following flow - ListFile -> FetchFile -> SplitRecord -> PutDatabaseRecord.
In SplitRecord processor, set 'Records per Split' property to '1'.
SplitRecord processor splits up the input flow file into multiple small flow files (1 file for each row in our case due to the setting 'Records per Split=1'). Then this individual flow files will be routed to 'split' relationship i.e. to the PutDatabaseRecord processor in our flow.
PutDatabaseRecord inserts new records into table and fails for existing records.
Tested the flow with GetFile processor and it works. Hope this solves your problem.
We have a flow where GenerateTableFetch takes inpute from splitJson which gives TableName, ColumnName as argument. At once multiple tables are passed as input to GenerateTableFetch and next ExecuteSql executes the query.
Now i want to trigger a new process when all the files for a table has been processed by the below processor (At the end there is PutFile).
How to find that all the files created for a Table has been processed?
You may need NIFI-5601 to accomplish this, there is a patch currently under review at the time of this writing, I hope to get it into NiFi 1.9.0.
EDIT: Adding potential workarounds in the meantime
If you can use ListDatabaseTables instead of getting your table names from a JSON file, then you can set Include Count to true. Then you will get attributes for the table name and the count of its rows. Then you can divide the count by the value of the Partition Size in GTF and that will give you the number of fetches (let's call it X). Then add an attribute via UpdateAttribute called "parent" or something, and set it to ${UUID()}. Keep these attributes in the flow files going into GTF and ExecuteScript, then you can use Wait/Notify to wait until X flow files are received (setting Target Signal Count to ${X}) and using ${parent} as the Release Signal Identifier.
If you can't use ListDatabaseTables, then you may be able to have ExecuteSQLRecord after your SplitJSON, you can execute something like SELECT COUNT(*) FROM ${table.name}. If using ExecuteSQL, you may need a ConvertAvroToJSON, if using ExecuteSQLRecord use a JSONRecordSetWriter. Then you can extract the count from the flow file contents using EvaluateJsonPath.
Once you have the table name and the row count in attributes, you can continue with the flow I outlined above (i.e. determine the number of flow files that GTF will generate, etc.).
My use case is like this. I have some X tables to be pulled from MySQL. I am splitting them using SplitText to put each table in a individual flow file and pull using GenerateTableFetch and ExecuteSQL.
And I want to be notified or put some other action when import is done for all the tables. At SplitText text processor I have routed original relationship to Wait on ${filename} with target count ${fragment.count}. This will track how many tables are done.
But now I am not able to figure out how to know when a particular table is done. GenerateTableFetch forks flow file into multiple based on Partition Size. But it does not write attributes like fragment.count which I can use to wait on for each table.
Is there a way I can achieve this? Or maybe is there a way to know at the end of the entire flow if all flow files in the flow have been processed and nothing is in queue or being processed?
If you have a standalone instance of NiFi (or are not distributing the flow files among a cluster to ExecuteSQL nodes), then you could use QueryDatabaseTable instead, it (by default) will only issue all flow files when the entire result set is processed. If you have all the rows go into a single flow file, then the fact that the flow file has been transferred downstream is an indication that the fetch is complete.
I have written NIFI-5601 to cover the improvement of adding fragment.* attributes to flow files generated by GTF.
Till NiFi add's support for this, I managed to make it work using MergeContent. Use table_name as Correlation attribute name and then use merged relation to Wait processor using ${merge.count} as target. Refer screenshots if someone is looking to do the same.
I am getting files from remote server using Nifi: my files are as follow:
timestamp (ms), nodeID,value
12345,x,12.4
12346,x,12.7
12348,x,13.4
12356,x,13,6
12355,y,12.0
I am now just get and fetch and split lines and send them to Kafka, but before hand, I need to apply a checksum approach on my records and aggregate them based on time stamp, what I need to do to add an additional column to my content and count the records based on aggregated time stamps, for example aggregation based on each 10 milliseconds and nodeID..
timestamp (ms), nodeID,value, counts
12345,x,12.4,3
12346,x,12.7,3
12348,x,13.4,3
12356,x,13,6,1
12355,y,12.0,1
How to do above process in NiFi. I am totally new to Nifi but need to add above functinality to my Nifi process. I am currently using below nifi process
This may not answer your question directly, but you should consider refactoring your flow to use the "record" processors. It would greatly simplify things and would probably get you closer to being able to do the aggregation.
The idea is to not split up the records, and instead process them in place. Given your current flow, the 4 processors after FetchSFTP would like change to a single ConvertRecord processor that converts CSV to JSON. You would first need to defined a simple Avro schema for your data.
Once you have the record processing setup, you might be able to use PartitionRecord to partition the records by the node id, and then from there the missing piece would be how to count by the timestamps.
Some additional resources...
https://blogs.apache.org/nifi/entry/record-oriented-data-with-nifi
https://bryanbende.com/development/2017/06/20/apache-nifi-records-and-schema-registries
https://www.slideshare.net/BryanBende/apache-nifi-record-processing
I am using Apache nifi to process the data from different resources and I have independent pipelines created for each data flow. I want to combine this data to process further. Is there any way I can aggregate the data and write it to a single file. The data is present in the form of flowfiles attributes in Nifi.
You should use the MergeContent processor, which accepts configuration values for min/max batch size, etc. and combines a number of flowfiles into a single flowfile according to the provided merge strategy.