read partitioned data of vpc flow log - amazon-athena

Question

I used this article to read my vpc flow logs and everything worked correctly.
https://aws.amazon.com/blogs/big-data/optimize-performance-and-reduce-costs-for-network-analytics-with-vpc-flow-logs-in-apache-parquet-format/
But my question is that when I refer to documentation and run the create table statement, it does not return any record.
CREATE EXTERNAL TABLE IF NOT EXISTS vpc_flow_logs (
`version` int,
`account_id` string,
`interface_id` string,
`srcaddr` string,
`dstaddr` string,
`srcport` int,
`dstport` int,
`protocol` bigint,
`packets` bigint,
`bytes` bigint,
`start` bigint,
`end` bigint,
`action` string,
`log_status` string,
`vpc_id` string,
`subnet_id` string,
`instance_id` string,
`tcp_flags` int,
`type` string,
`pkt_srcaddr` string,
`pkt_dstaddr` string,
`region` string,
`az_id` string,
`sublocation_type` string,
`sublocation_id` string,
`pkt_src_aws_service` string,
`pkt_dst_aws_service` string,
`flow_direction` string,
`traffic_path` int
)
PARTITIONED BY (
`aws-account-id` string,
`aws-service` string,
`aws-region` string,
`year` string,
`month` string,
`day` string,
`hour` string
)
ROW FORMAT SERDE
'org.apache.hadoop.hive.ql.io.parquet.serde.ParquetHiveSerDe'
STORED AS INPUTFORMAT
'org.apache.hadoop.hive.ql.io.parquet.MapredParquetInputFormat'
OUTPUTFORMAT
'org.apache.hadoop.hive.ql.io.parquet.MapredParquetOutputFormat'
LOCATION
's3://DOC-EXAMPLE-BUCKET/prefix/AWSLogs/aws-account-id={account_id}/aws-service=vpcflowlogs/aws-region={region_code}/'
TBLPROPERTIES (
'EXTERNAL'='true',
'skip.header.line.count'='1'
)
official doc:
https://docs.aws.amazon.com/athena/latest/ug/vpc-flow-logs.html
This create table statement should work after changing the variables like DOC-EXAMPLE-BUCKET/prefix, account_id and region_code. Why am I getting 0 rows returned for select * query?

Answer 1

You need to manually load the partitions first before you could use them.
From the docs:
After you create the table, you load the data in the partitions for querying. For Hive-compatible data, you run MSCK REPAIR TABLE. For non-Hive compatible data, you use ALTER TABLE ADD PARTITION to add the partitions manually.
So if your structure if hive compatible you can just run:
MSCK REPAIR TABLE `table name`;
And this will load all your new partitions.
Otherwise you'll have to manually load them using ADD PARTITION
ALTER TABLE test ADD PARTITION (aws-account-id='1', aws-acount-service='2' ...) location 's3://bucket/subfolder/data/accountid1/service2/'
Because manually adding partitions is so tedious if your data structure is not hive compatible I recommend you use partition projection for your table.
To avoid having to manage partitions, you can use partition projection. Partition projection is an option for highly partitioned tables whose structure is known in advance. In partition projection, partition values and locations are calculated from table properties that you configure rather than read from a metadata repository. Because the in-memory calculations are faster than remote look-up, the use of partition projection can significantly reduce query runtimes.