[Answer Query Using Materialized Views] Support Postgres special grammar DISTINCT ON clause on origin query.

[avamingli]

Since we have supported ORDER BY caluse and DISTINCT ON clause references are processed in target list, open it on origin query.

create incremental materialized view mv as
  select c1 as mc1, c2 as mc2, c3 as mc3, c4 as mc4
  from t1 where c1 > 90;

Origin querys:

 select DISTINCT ON(c1 - 1) c1, c2 from t1 where c1 > 90
   order by c1 - 1, c2 nulls first;

Could be rewritten to:

 select DISTINCT ON(mc1 - 1) mc1, mc2 from mv
   order by mc1 - 1, mc2 nulls first;

Authored-by: Zhang Mingli [email protected]

fix #ISSUE_Number

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