I have unstructured data in the form of document images. We are converting these documents to JSON files. I now want to have technical metadata captured for this. Can someone please give me some tips/best practices for building a data catalog on unstructured data in Google Cloud Platform?
This answer comes with the assumption that you are not using any tool to create schemas around your unstructured data and query your data, like BigQuery, Hive, Presto. And you simply want to catalog your files.
I had a similar use case, Google Data Catalog has an option to create custom entries.
Some tips on building a Data Catalog on unstructured files data:
Use meaningful file names on your JSON files. That way searching for them will become easier.
Since you are already using GCP, use their managed Data Catalog, and leverage their custom entries API to ingest the files metadata into it.
In case you also want to look for sensitive data in your JSON files, you could run DLP on them.
Use Data Catalog Tags to enrich the files metadata. The tutorial on the link shows how to do it on Big Query tables, but you can do the same on custom entries.
I would add some information about your ETL jobs that convert these documents in JSON files as Tags. Like execution time, data quality score, user, business owner, etc.
In case you are wondering how to do the step 2, I put together one script that automatically does that:
link for the GitHub. Another option is to work with Data Catalog Filesets.
So between using custom entries or filesets, I'd ask you this, do you need information about your files name?
If not then filesets might easier, since at the time of this writing it does not show any info about your files name, but are good to manage file patterns in GCS buckets: It is defined by one or more file patterns that specify a set of one or more Cloud Storage files.
The datatalog-util also has an option to enrich your filesets, in case you just want to have statistics about them, like average file size, types, etc.
Related
I need to pull two companies' data from their respective AWS S3 buckets, map their columns in Glue, and export them to a specific schema in a Microsoft SQL database. The schema is to have one table, with the companies' data being distinguished with attributes for each of their sites (each company has multiple sites).
I am completely new to AWS and SQL, would someone mind explaining to me how to add an attribute to the data, or point me to some good literature on this? I feel like manipulating the .csv in the Python script I'm already running to automatically download the data from another site then upload it to S3 could be an option (deleting NaN columns and adding a column for site name), but I'm not entirely sure.
I apologize if this has already been answered elsewhere. Thanks!
I find this website to generally be pretty helpful with figuring out SQL stuff. I've linked to the ALTER TABLE commands that would allow you to do this through SQL.
If you are running a python script to edit the .csv to start, then I would edit the data there, personally. Depending on the size of the data sets, you can run your script as a Lambda or Batch job to grab, edit, and then upload to s3. Then you can run your Glue crawler or whatever process you're using to map the columns.
I am working on a POC where we have millions of existing S3 compressed json files (uncompressed 3+ MB, with nested objects and arrays) and more being added every few minutes. We need to perform computations on top of the uncompressed data (per file basis) and store it to a DB table where we can then perform some column operations. The most common solution I found online is
S3 (Add/update event notification) => SQS (main queue => dlq queue) <=> AWS lambda
We have a DB table for all S3 bucket key names that are being successfully loaded, so I can query this table and use the AWS SDK Node.js package to send messages to the SQS main queue. For newly added/updated files, S3 event notification will take care of it.
I think the above architecture will work in my case, but are there any other AWS services I should look at?
I looked at AWS Athena which can read my compressed files and can give me the raw output but since I have big nested objects and arrays on top of which I need to perform computation, I am not sure if it's ideal to write such complex logic in SQL.
I would really appreciate some guidance here.
If you plan to query the data in the future in ways you can't anticipate, I would strongly suggest you explore the Athena solution, since you would be plugging a very powerful SQL engine on top of your data. Athena can query directly compressed json and export to other data formats that are a lot more efficient to query (like parquet or orc) and support complex data structures.
The flow would be:
S3 (new file) => Athena ETL (json to, say, parquet)
see e.g. here.
For already existing data you can do a one-off query to convert it to the appropriate format (partitioning would be useful if your data volume is big as it seems it is). Having good partitioning is key to obtain good performance on Athena and you will need to think carefully about it on your ETL. More on partitioning, e.g., there.
Using CSV upload in Apache Superset works as expected. I can use it to add data from CSV to a databse, e.g. Postgres. Now I want to apped data from a different CSV to this table/dataset. But how?
The CSVs all have the same format. But there is a new one for every day. In the end I want to have a dashboard which updates every day, taking the new data into account.
Generally, I agree with Ana that if you want to repeatedly upload new CSV data then you're better off operationalizing this into some type of process, pipeline, etc that runs on a schedule.
But if you need to stick with the uploading CSV route through the Superset UI, then you can set the Table Exists field to Append instead of Replace.
You can find a helpful GIF in the Preset docs: https://docs.preset.io/docs/tips-tricks#append-csv-to-a-database
Probably you'll be better served by creating a simple process to load the CSV to a table in the database and then querying that table in Superset.
Superset is a tool to visualize data, it allows uploading CSV for quick and dirty "only once" kind of charts, but if this is going to be a recurrent and structured periodical load of data, it's better to use whatever integrating tool you want to load the data, there are zillions of ETL (Extract-Transform-Load) tools out there (or scripting programs to do it), ask if your company is already using one, or choose the one that is simpler for you.
I have two problems in my intended solution:
1.
My S3 store structure is as following:
mainfolder/date=2019-01-01/hour=14/abcd.json
mainfolder/date=2019-01-01/hour=13/abcd2.json.gz
...
mainfolder/date=2019-01-15/hour=13/abcd74.json.gz
All json files have the same schema and I want to make a crawler pointing to mainfolder/ which can then create a table in Athena for querying.
I have already tried with just one file format, e.g. if the files are just json or just gz then the crawler works perfectly but I am looking for a solution through which I can automate either type of file processing. I am open to write a custom script or any out of the box solution but need pointers where to start.
2.
The second issue that my json data has a field(column) which the crawler interprets as struct data but I want to make that field type as string. Reason being that if the type remains struct the date/hour partitions get a mismatch error as obviously struct data has not the same internal schema across the files. I have tried to make a custom classifier but there are no options there to describe data types.
I would suggest skipping using a crawler altogether. In my experience Glue crawlers are not worth the problems they cause. It's easy to create tables with the Glue API, and so is adding partitions. The API is a bit verbose, especially adding partitions, but it's much less pain than trying to make a crawler do what you want it to do.
You can of course also create the table from Athena, that way you can be sure you get tables that work with Athena (otherwise there are some details you need to get right). Adding partitions is also less verbose using SQL through Athena, but slower.
Crawler will not take compressed and uncompressed data together , so it will not work out of box.
It is better to write spark job in glue and use spark.read()
For a project we've inherited we have a large-ish set of legacy data, 600GB, that we would like to archive, but still have available if need be.
We're looking at using the AWS data pipeline to move the data from the database to be in S3, according to this tutorial.
https://docs.aws.amazon.com/datapipeline/latest/DeveloperGuide/dp-object-copyactivity.html
However, we would also like to be able to retrieve a 'row' of that data if we find the application is actually using a particular row.
Apparently that tutorial puts all of the data from a table into a single massive CSV file.
Is it possible to split the data up into separate files, with 100 rows of data in each file, and giving each file a predictable file name, such as:
foo_data_10200_to_10299.csv
So that if we realise we need to retrieve row 10239, we can know which file to retrieve, and download just that, rather than all 600GB of the data.
If your data is stored in CSV format in Amazon S3, there are a couple of ways to easily retrieve selected data:
Amazon Athena is an interactive query service that makes it easy to analyze data in Amazon S3 using standard SQL.
S3 Select (currently in preview) enables applications to retrieve only a subset of data from an object by using simple SQL expressions.
These work on compressed (gzip) files too, to save storage space.
See:
Welcome - Amazon Athena
S3 Select and Glacier Select – Retrieving Subsets of Objects