Goal/Help Requested:
Given a bunch of tables in Athena, write an sql query that writes a scheduled new file into s3 to be used for other purposes.
Limited aws background - currently teaching myself but could use some help if possible.
Background
I have a very large number of Athena tables that draw upon a very large number of s3 folders with extensive nesting.
For example a 'sales' Athena table that draws upon a 'sales' s3 bucket that has depth of countries>regions>states>cities>stores>week>day. I have similar other types of information.
I want to write various sql queries that take this information and apply some logic that writes back single files into s3 to be used for various other purposes I have.
What I'm looking for
Any sort of links/direction on how to do this. Again I'm pretty new to aws and maybe this is a simple ask, I just can't articulate it properly.
At my organization, we are using a stack of AWS S3, AWS Glue, and Athena to drive some reporting of internal metrics. In general, this stack is great for quick set up for reporting off of raw data (stored in S3). The problem we've come against is what to do if we notice we need to somehow update the data that's already stored in S3. For example, we want to update values in a column that have a certain string to update that value.
Unlike a database, we can't just run a query to update all the existing data. I've tried to see if we can utilize Glue Jobs to accomplish this, but from my limited understanding, it doesn't seem like it's meant to do ETL from a bucket back to the same bucket.
The only thing I can think is to write a custom tool that iterates through an S3 bucket, loads a file, provides the transformation, and puts it back, overwriting the original. It seems there has to be a better way though.
Updates are not handled in a native way in a traditional hive-like warehousing solution, which I deem Athena to be. A common solution is a kind of engineering workaround where you do "insert overwrite" a partition (borrowing Hive syntax, possible in Presto and hopefully also possible in Athena, which is based on Presto).
Other solutions include creating new tables and atomically replacing a view, which users are supposed to query, instead of querying the underlying table(s) directly.
As this is a common problem, there are also some ready to use solutions to it, but I do not know whether which/whether they are possible with Athena. They are certainly possible with Presto (Presto SQL):
Hive ACID transactional tables (updates currently required Hive runtime)
Data Lake (open sourced by Databricks; updates currently require Spark runtime)
Hudi (I know little about this one)
I have looked into this post on s3 vs database. But I have a different use case and want to know whether s3 is enough. The primary reason for using s3 instead of other databases on cloud is because of cost.
I have multiple __scraper__s that download data from websites and apis everyday. Most of them return data as Json format. Currently, I will insert them into mongodb. I will then run analysis by querying data out on a specific date or some specific fields or records that match a certain criteria. After querying the data, usually I will load them into a dataframe and do what is needed.
The data will not be updated. They need to be stored and ready for retrieval according to some criteria. I am aware of S3 Select which may be able to do the retrieval task.
Any recommendations?
The use cases you have mentioned above, it seems that you are not using the MongoDB capabilities(any database capability for say) to a greater degree.
I think S3 suites well for your use cases, in fact, you should go for S3-Infrequent access with life cycle policy to archive and then finally purge to be cost efficient.
I hope it will helps!
I think your code will be more efficient if you use dynamodb with all its feature. using s3 for database or data storage will make you code more complex. since you need to retrieve file from s3 every time and have to iterate thorough the file every time. And in case of dynamodb you can easily query and filter the data which is required. At the end s3 is a file storage and dynmodb is a database.
We have raw data stored in S3 as parquet.
I want a subset of that data loaded into Redshift.
To be clear, the Redshift data would be the result of a query (joins, filters, aggregations) of the raw data.
I originally thought that I could build views in Athena, and load the results into Redshift - but seems that it's not that simple !
Glue ETL jobs need an S3 or RDS source - will not accept a view from Athena.
(Cannot crawl a view either).
Next solution, was to have a play with the Athena CTAS functionality, write the results of the view to S3, and then load into RedShift.
However, there is no 'overwrite' option with CTAS.
So questions ...
Is there an easier way to approach this ? (seems a simple requirement)
Is there an easy workaround to execute a CTAS with 'overwrite' behaviour ?
With that, would have to be a solution that could be bundled up into a scheduled job - and already I think is leading into a custom script.
When a simple job becomes so difficult - I cannot help but think I'm missing something simple !?
Thanks
Ol' reliable: use a lambda! Lambda functions can programmatically connect to both s3 and redshift to execute SQL statements, and you have many options for what will trigger the lambda (if it's just a one-time thing, you can just have it be a scheduled lambda). You will be able use cloudwatch logs to examine the process too.
But beware: I noticed that you stored your data as a parquet... Normal Redshift does not support parquet formatted data. So, if you want to store types like structs, etc. you will need to use Redshift Spectrum.
I have a web app that needs to send reports on its usage, I want to use Amazon RedShift as a data warehouse for that purpose,
How should i collect the data ?
Every time, the user interact with my app, i want to report that.. so when should i write the files to S3 ? and how many ?
What i mean is:
- If do not send the info immediately, then I might lose it as a result of a connection lost, or from some bug in my system while its been collected and get ready to be sent to S3...
- If i do write files to S3 on each user interaction, i will end up with hundreds of files (on each file has minimal data), that need to be managed, sorted, deleted after been copied to RedShift.. that dose not seems like a good solution .
What am i missing? Should i use DynamoDB instead, Should i use simple insert into Redshift instead !?
If i do need to write the data to DynamoDB, should i delete the hold table after been copied .. what are the best practices ?
On any case what are the best practices to avoid data duplication in RedShift ?
Appreciate the help!
It is preferred to aggregate event logs before ingesting them into Amazon Redshift.
The benefits are:
You will use the parallel nature of Redshift better; COPY on a set of larger files in S3 (or from a large DynamoDB table) will be much faster than individual INSERT or COPY of a small file.
You can pre-sort your data (especially if the sorting is based on event time) before loading it into Redshift. This is also improve your load performance and reduce the need for VACUUM of your tables.
You can accumulate your events in several places before aggregating and loading them into Redshift:
Local file to S3 - the most common way is to aggregate your logs on the client/server and every x MB or y minutes upload them to S3. There are many log appenders that are supporting this functionality, and you don't need to make any modifications in the code (for example, FluentD or Log4J). This can be done with container configuration only. The down side is that you risk losing some logs and these local log files can be deleted before the upload.
DynamoDB - as #Swami described, DynamoDB is a very good way to accumulate the events.
Amazon Kinesis - the recently released service is also a good way to stream your events from the various clients and servers to a central location in a fast and reliable way. The events are in order of insertion, which makes it easy to load it later pre-sorted to Redshift. The events are stored in Kinesis for 24 hours, and you can schedule the reading from kinesis and loading to Redshift every hour, for example, for better performance.
Please note that all these services (S3, SQS, DynamoDB and Kinesis) allow you to push the events directly from the end users/devices, without the need to go through a middle web server. This can significantly improve the high availability of your service (how to handle increased load or server failure) and the cost of the system (you only pay for what you use and you don't need to have underutilized servers just for logs).
See for example how you can get temporary security tokens for mobile devices here: http://aws.amazon.com/articles/4611615499399490
Another important set of tools to allow direct interaction with these services are the various SDKs. For example for Java, .NET, JavaScript, iOS and Android.
Regarding the de-duplication requirement; in most of the options above you can do that in the aggregation phase, for example, when you are reading from a Kinesis stream, you can check that you don't have duplications in your events, but analysing a large buffer of events before putting into the data store.
However, you can do this check in Redshift as well. A good practice is to COPY the data into a staging tables and then SELECT INTO a well organized and sorted table.
Another best practice you can implement is to have a daily (or weekly) table partition. Even if you would like to have one big long events table, but the majority of your queries are running on a single day (the last day, for example), you can create a set of tables with similar structure (events_01012014, events_01022014, events_01032014...). Then you can SELECT INTO ... WHERE date = ... to each of this tables. When you want to query the data from multiple days, you can use UNION_ALL.
One option to consider is to create time series tables in DynamoDB where you create a table every day or week in DynamoDB to write every user interaction. At the end of the time period (day, hour or week), you can copy the logs on to Redshift.
For more details, on DynamoDB time series table see this pattern: http://docs.aws.amazon.com/amazondynamodb/latest/developerguide/GuidelinesForTables.html#GuidelinesForTables.TimeSeriesDataAccessPatterns
and this blog:
http://aws.typepad.com/aws/2012/09/optimizing-provisioned-throughput-in-amazon-dynamodb.html
For Redshift DynamoDB copy: http://docs.aws.amazon.com/amazondynamodb/latest/developerguide/RedshiftforDynamoDB.html
Hope this helps.
Though there is already an accepted answer here, AWS launched a new service called Kinesis Firehose which handles the aggregation according to user defined intervals, a temporary upload to s3 and the upload (SAVE) to redshift, retries and error handling, throughput management,etc...
This is probably the easiest and most reliable way to do so.
You can write data to CSV file on local disk and then run Python/boto/psycopg2 script to load data to Amazon Redshift.
In my CSV_Loader_For_Redshift I do just that:
Compress and load data to S3 using boto Python module and multipart upload.
conn = boto.connect_s3(AWS_ACCESS_KEY_ID,AWS_SECRET_ACCESS_KEY)
bucket = conn.get_bucket(bucket_name)
k = Key(bucket)
k.key = s3_key_name
k.set_contents_from_file(file_handle, cb=progress, num_cb=20,
reduced_redundancy=use_rr )
Use psycopg2 COPY command to append data to Redshift table.
sql="""
copy %s from '%s'
CREDENTIALS 'aws_access_key_id=%s;aws_secret_access_key=%s'
DELIMITER '%s'
FORMAT CSV %s
%s
%s
%s;""" % (opt.to_table, fn, AWS_ACCESS_KEY_ID, AWS_SECRET_ACCESS_KEY,opt.delim,quote,gzip, timeformat, ignoreheader)
Just being a little selfish here and describing exactly what Snowplow ,an event analytics platform does. They use this awesome unique way of collecting event logs from the client and aggregating it on S3.
They use Cloudfront for this. What you can do is, host a pixel in one of the S3 buckets and put that bucket behind a CloudFront distribution as an origin. Enable logs to an S3 bucket for the same CloudFront.
You can send logs as url parameters whenever you call that pixel on your client (similar to google analytics). These logs can then be enriched and added to Redshift database using Copy.
This solves the purpose of aggregation of logs. This setup will handle all of that for you.
You can also look into Piwik which is an open source analytics service and see if you can modify it specific to your needs.