[Beginner Question]What is query jumbling?

Hi community,

I am reading the 'Generate code for query jumbling through gen_node_support.pl' (https://www.postgresql.org/message-id/E1pMk51-000puf-55%40gemulon.postgresql.org) to understand the principle of the postgres's node, but I really don't know the meaning of the word 'query jumbling'.

Can someone provide me some advice?

Thanks in advance!

Yours,

Wen Yi