Note: The following description applies both to Postgres-XC and PostgreSQL if not described explicitly.
SQL statements can, intentionally or not, require the mixing of different data types in the same expression. Postgres-XC inherits extensive facilities for evaluating mixed-type expressions from PostgreSQL.
In many cases a user does not need to understand the details of the type conversion mechanism. However, implicit conversions done by Postgres-XC can affect the results of a query. When necessary, these results can be tailored by using explicit type conversion.
This chapter introduces the Postgres-XC type conversion mechanisms and conventions inherited from PostgreSQL. Refer to the relevant sections in Chapter 8 and Chapter 9 for more information on specific data types and allowed functions and operators.