On Wednesday, May 23, 2018, a <372660931(at)qq(dot)com> wrote:
>
> How could I select the element of Ay that satisfy x=3??
>
https://www.postgresql.org/docs/10/static/arrays.html#ARRAYS-SEARCHING
The note at the end of that section applies here though, you are forcing
yourself to fight the nature of the relational database by not normalizing
your data model. Converting your array of composites to a table is going
to make life considerably easier if you expect to have to performs searches
like you requrest help for here.
David J.