What type of Compiler to SQL? Memory-Image (Load-and-Go) Format?

[Wen Yi]

Hi team,
I am a newbie to the postgres.
When I am studying the compiler,the text book tell me there is there type of 
compiler.

  1.  Assembly Language Format
  2.  Relocatable Binary Format
  3.  Memory-Image (Load-and-Go) Format

I check the postgres's sql compiler, and it's achieved by lex & yacc.
So What type of Compiler to SQL? Is Memory-Image (Load-and-Go) Format ?

Thanks in advance!

Yours,
WenYi