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.
• Operations not supported on external tables are usually reported with explicit errors. The main operations that are not supported 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
• By default, there is limited support for predicate pushdown or limit pushdown on external tables. This means that all data can be scanned and processed, regardless of the query. However, this issue can be mitigated by using the Advanced Staging Tables feature.
Last modified date: 01/27/2026