arrays returned in text format

[Konstantin Izmailov <pgfizm@xxxxxxxxx>]

I'm using libpq to read array values, and I noticed that sometimes the values are returned in Binary and sometimes - in Text format.

1. Returned in Binary format:

   int formats[1] = { 1 }; // request binary format

   res = PQexec(conn, "SELECT rgField FROM aTable", 1, formats);

   assert(PQfformat(res, 0) == 1);  // this is OK

2. Returned in Text format:
   res = PQexec(conn, "SELECT ARRAY[1,2,3]", 1, formats);
   assert(PQfformat(res, 0) == 1);  // this fails???

This is not a big issue, I can parse the text representation of the array. But I wanted to understand why Postgres returns data in Text format when Binary was requested. Am I missing something?