Add support for deparsing semi-joins to contrib/postgres_fdw SEMI-JOIN is deparsed as the EXISTS subquery. It references outer and inner relations, so it should be evaluated as the condition in the upper-level WHERE clause. The signatures of deparseFromExprForRel() and deparseRangeTblRef() are revised so that they can add conditions to the upper level.
PgFdwRelationInfo now has a hidden_subquery_rels field, referencing the relids used in the inner parts of semi-join. They can't be referred to from upper relations and should be used internally for equivalence member searches. The planner can create semi-join, which refers to inner rel vars in its target list. However, we deparse semi-join as an exists() subquery. So we skip the case when the target list references to inner rel of semi-join. Author: Alexander Pyhalov Reviewed-by: Ashutosh Bapat, Ian Lawrence Barwick, Yuuki Fujii, Tomas Vondra Discussion: https://postgr.es/m/c9e2a757cf3ac2333714eaf83a9cc...@postgrespro.ru Branch ------ master Details ------- https://git.postgresql.org/pg/commitdiff/824dbea3e41efa3b35094163c834988dea7eb139 Modified Files -------------- contrib/postgres_fdw/deparse.c | 234 ++++++++++++++---- contrib/postgres_fdw/expected/postgres_fdw.out | 320 ++++++++++++++++++++++--- contrib/postgres_fdw/postgres_fdw.c | 94 +++++++- contrib/postgres_fdw/postgres_fdw.h | 4 + contrib/postgres_fdw/sql/postgres_fdw.sql | 126 +++++++++- 5 files changed, 697 insertions(+), 81 deletions(-)
