Is there a way to update rows in Google BigQuery when publishing from Cloud Dataprep? I can't find anything in the documentation.
I have a dataset I'm preprocessing with Dataprep that contains new rows and updated rows on every (daily) run. I would like to incrementally write it to BigQuery adding new rows and updating existing changed rows.
So Trifacta (CDP) can either append, replace or create new file each time the Job is run.
You're refering to an Upsert\Merge action.
So this can be done by 2 steps.
for new rows, you can use the "append" run option
for updating existing rows - 2 options.
Either -
A. do a Union transformation with the output file (already in bigquery), then deduplicate\aggregate and choose how you'd like to merge between the duped rows. this then can be done each time a new file is made\created\updated.
B. create a new file, then through parameterization import all files within the folder - unioning them and do the grouping mentioned in A.
Obviously - option A seems more simplistic.
Does that make sense?
Related
I am trying to build a cloud data warehouse where I have staged the on-prem tables as parquet files in data lake.
I implemented the metadata driven incremental load.
In the above data flow I am trying to implement merge query passing the table name as parameter so that the data flow dynamically locate respective parquet files for full data and incremental data and then go through some ETL steps to implement merge query.
The merge query is working fine. But I found that projection is not correct. As the source files are dynamic, I also want to "import projection" dynamically during the runtime. So that the same data flow can be used to implement merge query for any table.
In the picture, you see it is showing 104 columns (which is a static projection that it imported at the development time). Actually for this table it should be 38 columns.
Can I dynamically (i.e run-time) assign the projection? If so how?
Or anyone has any suggestion regarding this?
Thanking
Muntasir Joarder
Enable Schema drift in your source transformation when the metadata is often changed. This removes or adds columns in the run time.
The source projection displays what has been imported at the run time but it changes based on the source schema at run time.
Refer to this document for more details with examples.
I want to export the data from Cloud SQL (postgres) to a CSV file periodically (once a day for example) and each time the DB rows are exported it must not be exported in the next export task.
I'm currently using a POST request to perform the export task using cloud scheduler. The problem here (or at least until I know) is that it won't be able to export and delete (or update the rows to mark them as exported) in a single http export request.
Is there any possibility to delete (or update) the rows which have been exported automatically with any Cloud SQL parameter in the http export request?
If not, I assume it should be done it a cloud function triggered by a pub/sub (using scheduler to send data once a day to pub/sub) but, is there any optimal way to take all the ID of the rows retrieved from the select statment (which will be use in the export) to delete (or update) them later?
You can export and delete (or update) at the same time using RETURNING.
\copy (DELETE FROM pgbench_accounts WHERE aid<1000 RETURNING *) to foo.txt
The problem would be in the face of crashes. How can you know that foo.txt has been writing and flushed to disk, before the DELETE is allowed to commit? Or the reverse, foo.txt is partially (or fully) written, but a crash prevents DELETE from committing.
Can't you make the system idempotent, so that exporting the same row more than once doesn't create problems?
You could use a set up to achieve what you are looking for:
1.Create a Cloud Function to extract the information from the database that subscribes to a Pub/Sub topic.
2.Create a Pub/Sub topic to trigger that function.
3.Create a Cloud Scheduler job that invokes the Pub/Sub trigger.
4.Run the Cloud Scheduler job.
5.Then create a trigger which activate another Cloud Function to delete all the data require from the database once the csv has been created.
Here I leave you some documents which could help you if you decide to follow this path.
Using Pub/Sub to trigger a Cloud Function:https://cloud.google.com/scheduler/docs/tut-pub-sub
Connecting to Cloud SQL from Cloud Functions:https://cloud.google.com/sql/docs/mysql/connect-functionsCloud
Storage Tutorial:https://cloud.google.com/functions/docs/tutorials/storage
Another method aside from #jjanes would be to partition your database by date. This would allow you to create an index on the date, making exporting or deleting a days entries very easy. With this implementation, you could also create a Cron Job that deletes all tables older then X days ago.
The documentation provided will walk you through setting up a Ranged partition
The table is partitioned into “ranges” defined by a key column or set of columns, with no overlap between the ranges of values assigned to different partitions. For example, one might partition by date ranges, or by ranges of identifiers for particular business objects.
Thank you for all your answers. There are multiples ways of doing this, so I'm goint to explain how I did it.
In the database I have included a column which contains the date when the data was inserted.
I used a cloud scheduler with the following body:
{"exportContext":{"fileType": "CSV", "csvExportOptions" :{"selectQuery" : "select \"column1\", \"column2\",... , \"column n\" from public.\"tablename\" where \"Insertion_Date\" = CURRENT_DATE - 1" },"uri": "gs://bucket/filename.csv","databases": ["postgres"]}}
This scheduler will be triggered once a day and it will export only the data of the previous day
Also, I have to noticed that in the query I used in cloud scheduler you can choose which columns you want to export, doing this you can avoid to export the column which include the Insertion_Date and use this column only an auxiliary.
Finally, the cloud scheduler will create automatically the csv file in a bucket
I am running into an issue where I have a set up a pipeline that gets a list of tables from Teradata using a Lookup activity and then passes those items to a ForEach activity that then copies the data in parallel and saves them as a gzipped file. The requirement is to essentially archive some tables that are no longer being used.
For this pipeline I am not using any partition options as most of the tables are small and I kept it to be flexible.
Pipeline
COPY activity within ForEach activity
99% of the tables ran without issues and were copied as gz files into blob storage, but two tables in particular run for long time (apprx 4 to 6 hours) without any of the data being written into a blob storage account.
Note that the image above says "Cancelled", but that was done by me. Before that I had a run time as described above, but still no data being written. This is affecting only 2 tables.
I checked with our Teradata team and those tables are not being used by any one (hence its not locked). I also looked at "Teradata Viewpoint" (admin tool) and looked at the query monitor and saw that the query was running on Teradata without issues.
Any insight would be greatly apreciated.
Onlooking issue mention it look the data size of table is more than a blob can store ( As you are not using any partition options )
Use partition option for optimize performance and hold the data
Link
Just in case someone else comes across this, the way I solved this was to create a new data store connection called "TD_Prod_datasetname". The purpose of this dataset is to not point to a specific table, but to just accept a "item().TableName" value.
This datasource contains two main values. 1st is the #dataset().TeradataName
Dataset property
I only came up with that after doing a little bit of digging in Google.
I then created a parameter called "TeradataTable" as String.
I then updated my pipeline. As above the main two activities remain the same. I have a lookup and then a ForEach Activity (where for each will get the item values):
However, in the COPY command inside the ForEach activity I updated the source. Instead of getting "item().Name" I am passing through #item().TableName:
This then enabled me to then select the "Table" option and because I am using Table instead of query I can then use the "Hash" partition. I left it blank because according to Microsoft documentation it will automatically find the Primary Key that will be used for this.
The only issue that I ran into when using this was that if you run into a table that does not have a Primary Key then this item will fail and will need to be run through either a different process or manually outside of this job.
Because of this change the previously files that just hung there and did not copy now copied successfully into our blob storage account.
Hope this helps someone else that wants to see how to create parallel copies using Teradata as a source and pass through multiple table values.
I am new to talend and need guidance on below scenario:
We have set of 10 Json files with different structure/schema and needs to be loaded into 10 different tables in Redshift db.
Is there a way we can write generic script/job which can iterate through each file and load it into database?
For e.g.:
File Name: abc_< date >.json
Table Name: t_abc
File Name: xyz< date >.json
Table Name: t_xyz
and so on..
Thanks in advance
With Talend Enterprise version one can benefit of dynamic schema. However based on my experiences with json-s they are somewhat nested structures usually. So you'd have to figure out how to flatten them, once thats done it becomes a 1:1 load. However with open studio this will not work due to the missing dynamic schema.
Basically what you could do is: write some java code that transforms your JSON into CSV. Use either psql from commandline or if your Talend contains new enough PostgreSQL JDBC driver then invoke the client side \COPY from it to load the data. If your file and the database table column order matches it should work without needing to specify how many columns you have, so its dynamic, but the data newer "flows" through talend.
Really not cool but also theoretically possible solution: If Redshift supports JSON (Postgres does) then one can create a staging table, with 2 columns: filename, content. Once the whole content is in this staging table, INSERT-SELECT SQL could be created that transforms the JSON into tabular format that can be inserted into the final table.
However, with your toolset you probably have no other choice than to load these files with 1 job per file. And I'd suggest 1 dedicated job to each file. They would each look for their own files and triggered / scheduled individually or be part of a bigger job where you scan the folders and trigger the right job for the right file.
I have 3 questions, for the following context:
I'm trying to migrate my historical from RDS postgresql to S3. I have about a billion rows of dat in my database,
Q1) Is there a way for me to tell an aws glue job what rows to load? For example i want it to load data from a certain date onwards? There is no bookmarking feature for a PostgreSQL data source,
Q2) Once my data is processed, the glue job automatically creates a name for the s3 output objects, I know i can speciofy the path in DynamicFrame write, but can I specify the object name? if so, how? I cannot find an option for this.
Q3) I tried my glue job on a sample table with 100 rows of data, and it automatically separated the output into 20 files with 5 rows in each of those files, how can I specify the batch size in a job?
Thanks in advance
This is a question I have also posted in AWS Glue forum as well, here is a link to that: https://forums.aws.amazon.com/thread.jspa?threadID=280743
Glue supports pushdown predicates feature, however currently it works with partitioned data on s3 only. There is a feature request to support it for JDBC connections though.
It's not possible to specify name of output files. However, looks like there is an option with renaming files (note that renaming on s3 means copying file from one location into another so it's costly and not atomic operation)
You can't really control the size of output files. There is an option to control min number of files using coalesce though. Also starting from Spark 2.2 there is a possibility to set max number of records per file by setting config spark.sql.files.maxRecordsPerFile