Troubleshooting External Tables
You might encounter the following issues when creating or querying external tables. For general data-load troubleshooting, see Troubleshooting Data Loads.
File Not Found or Permission Denied
If a query against an external table produces a file or permission error, ensure that the user executing the query has the necessary permissions in both Vertica and the file system. See the permissions section in Creating External Tables.
Queries on Parquet Tables Show No Results
A query against an external table can incorrectly report 0 rows if the Parquet file was written using an unsupported format. When this happens, Vertica records a message like the following:
WARNING> @db_node0001: 01000/9226: Number of rows  do not match with number of rows  in metadata for parquet source path /data/filename.parquet
This mismatch occurs for Parquet files that were written using the DATA_PAGE_V2 page type. Vertica cannot read this format.
Error 7226: Cannot Find Partition Column
When querying ORC or Parquet data, you might see an error message stating that a partition column is missing:
ERROR 7226: Cannot find partition column [region] in parquet source [/data/table_int/int_original/000000_0]
This error can occur if you partition your ORC or Parquet data (see Using Partition Columns). If you create an external table and then change the partition structure, for example by renaming a column, you must then re-create the external table. If you see this error, update your table to match the partitioning on disk.
Error 6766: Is a Directory
When querying data you might see an error message stating that an input file is a directory:
ERROR 6766: Error reading from orc parser input stream [/tmp/orc_glob/more_nations]: Is a directory
This error occurs if the glob in the table's COPY FROM clause matches an empty directory. This error occurs only for files in the Linux file system; empty directories in HDFS are ignored.
To correct the error, make the glob more specific. Instead of *, for example, use *.orc.