15. Using External Tables : External Table Limitations
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External Table Limitations
The external table feature has the following limitations:
WARNING! The options retained in the CREATE EXTERNAL TABLE definition are not secure; they can be shown in clear text in tracing and logging. We recommend that no sensitive information be used in the OPTIONS portion of the definition. This has implications for JDBC data sources.
The Spark-Vector Provider is a Spark application running under the user that is the owner of the Vector installation, typically actian. This means that only data sources for which that user has permissions to access (read or write) can be used in Vector.
Operations not supported on external tables are usually reported with explicit errors. The main such unsupported operations are:
Creating keys (of any type) and creating indexes (of any type) are not supported because they cannot be enforced (that is, they can be violated by the actions of an external entity)
Adding and dropping columns
Updates and deletes
There is no support for predicate pushdown or limit pushdown on external tables. This means that all data will be scanned and processed, regardless of the query.