Returns the version of libpq PostgreSQL client library that is being used.
The result of this property can be used to determine, at run time, if specific functionality is available in the currently loaded version of libpq. The property can be used, for example, to determine which connection options are available or if the hex bytea output added in PostgreSQL 9.0 is supported.
The number is formed by converting the major, minor, and revision numbers into two-decimal-digit numbers and appending them together. For example, version 9.1 will be returned as 90100, and version 9.1.2 will be returned as 90102 (leading zeroes are not shown).
If no library loaded yet then property returns InvalidOID value, which is 0.
This example checks if server supports tablespaces: