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PrestoDB (Trino) SQL Error - ORC ACID file should have 6 columns, found Y

 

We faced this error while querying Hive Table using Trino - 

Error - 

  • SQL Error [16777223]: Query failed (#20230505_155701_00194_n2vdp): ORC ACID file should have 6 columns, found 17


This was happening because Table being queried was Hive Managed Internal Table, which by default in CDP ( Cloudera ) distribution is ACID compliant. 

Now, in order for a Hive Table to be ACID complaint - 

  • The underlying file system should be ORC, 
  • and there were a few a changes on ORC file structure like the root column should be a struct with 6 nested columns (which encloses the data and the type of operation). Something like below 
            struct<     operation: int,     originalTransaction: bigInt,     bucket: int,     rowId: bigInt,     currentTransaction: bigInt,      row: struct<...>      >

For more ORC ACID related internals - please take a look here 

  • https://orc.apache.org/docs/acid.html

Now, problem in our case was that though Hive Table was declared Internal but ORC Files present were not having header column containing required 6 fields to be ACID compliant. Hence, SQL was failing from Trino.

Solution- 
So, we created another Hive External Table on same HDFS location as Hive Internal Table and started executing SQL's on same. 

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