GZIP Compression algorithm based on Deflate. Deflate is relevant only for the Avro file format. DEFLATE Compression algorithm based on LZSS and Huffman coding. The transformed data maintains a list of the original keys from the nested JSON separated. Relationalize transforms the nested JSON into key-value pairs at the outermost level of the JSON document. Use this feature to query JSON datasets that are in pretty print format, or break up the fields in a row with newline characters. AWS Glue has a transform called Relationalize that simplifies the extract, transform, load (ETL) process by converting nested JSON into columns that you can easily import into relational databases.
Athena supports the following compression formats: BZIP2 Format that uses the Burrows-Wheeler algorithm. Unlike other JSON SerDe libraries, the Amazon Ion SerDe doesnt expect each row of data to be on a single line.
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Interestingly enough, when I relationalized the data and made it into a parquet file, all of the fields were preserved, but I am worried of some kind of data loss, since there are multiple jsons stored in one row, so there may be some kind of overwriting issue.Īny ideas on how to proceed? I've been trying to find ways to query the json on Athena, but it may just be a problem with the json itself (I downloaded the json and looked at the structure and it looks fine visually). The same principle applies for ORC, text file, and JSON storage formats. When I go to Athena however, and I do a select *, I get the 3 base columns (elem1, elem2, attr), but the rows have each of the jsons as a whole: elem1 |elem2 For more information, see Connecting to data sources. You can also connect Athena to a variety of data sources by using ODBC and JDBC drivers, external Hive metastores, and Athena data source connectors. Encryption UNLOAD output files are encrypted. For more information, see Identifying query output files. Both files are saved to your Athena query result location in Amazon S3. The manifest tracks the files that the query wrote. I was able to upload these jsons and preserved their format correctly, and used AWS Glue to crawl the json and I got all of the proper data structure elements (attr has a lot of sub elements that were correctly extracted). For information about using Athena with AWS Glue, see Using AWS Glue to connect to data sources in Amazon S3. Amazon Athena is an interactive query service that makes it easy to analyze data directly in Amazon Simple Storage Service (Amazon S3) using standard SQL. Metadata and manifest files Athena generates a metadata file and data manifest file for each UNLOAD query. I have a json array structure similar to the following: [elem1 Trying to convert json to string (Athena AWS) Hot Network Questions Can saxophones be in orchestras, not just like the symphonic jazz orchestras/big band What does mean in Heigher weight modular forms in function fields.
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