问题
What's the data format of the .csv.metadata files written by Amazon Athena?
Alongside the output file of every query there is a metadata file. It looks like it describes the schema of the result. I assume this is what Athena uses to create the ResultSet.ResultSetMetadata part of the response of GetQueryResults requests, and that it is somehow created by Hive or Presto.
2019-04-23 14:51:29 27 e7629796-9b91-476a-bfb7-2fe6c9595bce.csv
2019-04-23 14:51:29 56 e7629796-9b91-476a-bfb7-2fe6c9595bce.csv.metadata
2019-04-27 14:23:53 1591958 ebe432ac-db7b-4ea1-b5de-529350d1a02a.csv
2019-04-27 14:23:53 712 ebe432ac-db7b-4ea1-b5de-529350d1a02a.csv.metadata
2019-04-25 16:31:23 10152 eeb6f4ab-9ac3-4a7e-81c4-0cc155187acb.csv
2019-04-25 16:31:23 494 eeb6f4ab-9ac3-4a7e-81c4-0cc155187acb.csv.metadata
2019-04-25 22:30:56 22384376 f0160ff7-e5b3-466d-926a-a660a5208c5f.csv
2019-04-25 22:30:56 494 f0160ff7-e5b3-466d-926a-a660a5208c5f.csv.metadata
Here's a hexdump of e7629796-9b91-476a-bfb7-2fe6c9595bce.csv.metadata from the listing above:
00000000 0a 1b 32 30 31 39 30 34 32 33 5f 31 32 35 31 32 |..20190423_12512|
00000010 38 5f 30 30 30 30 31 5f 65 68 74 75 72 22 19 0a |8_00001_ehtur"..|
00000020 04 68 69 76 65 22 03 61 72 79 2a 03 61 72 79 32 |.hive".ary*.ary2|
00000030 05 61 72 72 61 79 48 03 |.arrayH.|
It's ResultSet.ResultSetMetadata looks like this:
"ResultSetMetadata": {
"ColumnInfo": [
{
"CatalogName": "hive",
"SchemaName": "",
"TableName": "",
"Name": "ary",
"Label": "ary",
"Type": "array",
"Precision": 0,
"Scale": 0,
"Nullable": "UNKNOWN",
"CaseSensitive": false
}
]
}
I realise that these are internal file to Athena, but I'm curious.
来源：https://stackoverflow.com/questions/55991018/whats-the-data-format-of-athenas-csv-metadata-files