- SQL statements are stored as part of the query instance for the object. If the same query is being made across multiple users using private connections, the SQL must be shared and entered by individual users.
- SQL statements must be valid for the syntax of the target relational system. Syntax examples are provided below.
- If you modify the custom SQL statement when reading from a source, all samples generated based on the previous SQL are invalidated.
Declared variables are not supported.
- When using custom SQL to read from a Hive view, the results of a nested function are saved to a temporary name, unless explicitly aliased.
- If aliases are not used, the temporary column names can cause jobs to fail, on Spark in particular.
- For more information, see Using Hive.
- If you are using custom SQL to query an AWS Glue metadata store, you cannot apply use the
LIMITkeyword. For more information, see Enable AWS Glue Access.