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postgres_fdw: Perform the (ORDERED, NULL) upperrel operations remotely.

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The upper-planner pathification allows FDWs to arrange to push down
different types of upper-stage operations to the remote side.  This
commit teaches postgres_fdw to do it for the (ORDERED, NULL) upperrel,
which is responsible for evaluating the query's ORDER BY ordering.
Since postgres_fdw is already able to evaluate that ordering remotely
for foreign baserels and foreign joinrels (see commit aa09cd242f et al.),
this adds support for that for foreign grouping relations.

Author: Etsuro Fujita
Reviewed-By: Antonin Houska and Jeff Janes
Discussion: https://postgr.es/m/87pnz1aby9.fsf@news-spur.riddles.org.uk
This commit is contained in:
Etsuro Fujita
2019-04-02 19:20:30 +09:00
parent e2d28c0f40
commit ffab494a4d
4 changed files with 457 additions and 138 deletions
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12
contrib/postgres_fdw/postgres_fdw.h
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@ -49,6 +49,9 @@ typedef struct PgFdwRelationInfo
/* Bitmap of attr numbers we need to fetch from the remote server. */
Bitmapset *attrs_used;
/* True means that the query_pathkeys is safe to push down */
bool qp_is_pushdown_safe;
/* Cost and selectivity of local_conds. */
QualCost local_conds_cost;
Selectivity local_conds_sel;
@ -92,6 +95,9 @@ typedef struct PgFdwRelationInfo
/* joinclauses contains only JOIN/ON conditions for an outer join */
List *joinclauses; /* List of RestrictInfo */
/* Upper relation information */
UpperRelationKind stage;
/* Grouping information */
List *grouped_tlist;
@ -175,10 +181,14 @@ extern void deparseAnalyzeSql(StringInfo buf, Relation rel,
List **retrieved_attrs);
extern void deparseStringLiteral(StringInfo buf, const char *val);
extern Expr *find_em_expr_for_rel(EquivalenceClass *ec, RelOptInfo *rel);
extern Expr *find_em_expr_for_input_target(PlannerInfo *root,
EquivalenceClass *ec,
PathTarget *target);
extern List *build_tlist_to_deparse(RelOptInfo *foreignrel);
extern void deparseSelectStmtForRel(StringInfo buf, PlannerInfo *root,
RelOptInfo *foreignrel, List *tlist,
List *remote_conds, List *pathkeys, bool is_subquery,
List *remote_conds, List *pathkeys,
bool has_final_sort, bool is_subquery,
List **retrieved_attrs, List **params_list);
extern const char *get_jointype_name(JoinType jointype);