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Commitcc592c4

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postgres_fdw: More preliminary refactoring for upcoming join pushdown.
The code that generates a complete SQL query for a given foreign relationwas repeated in two places, and they didn't quite agree: the EXPLAIN caseleft out the locking clause. Centralize the code so we get the samebehavior everywhere, and adjust calling conventions and which functionsare static vs. extern accordingly . Centralize the code so we get the samebehavior everywhere, and adjust calling conventions and which functionsare static vs. extern accordingly.Ashutosh Bapat, reviewed and slightly adjusted by me.
1 parent2251179 commitcc592c4

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3 files changed

+93
-90
lines changed

3 files changed

+93
-90
lines changed

‎contrib/postgres_fdw/deparse.c

Lines changed: 76 additions & 51 deletions
Original file line numberDiff line numberDiff line change
@@ -141,6 +141,11 @@ static void printRemoteParam(int paramindex, Oid paramtype, int32 paramtypmod,
141141
deparse_expr_cxt*context);
142142
staticvoidprintRemotePlaceholder(Oidparamtype,int32paramtypmod,
143143
deparse_expr_cxt*context);
144+
staticvoiddeparseSelectSql(Bitmapset*attrs_used,List**retrieved_attrs,
145+
deparse_expr_cxt*context);
146+
staticvoiddeparseLockingClause(deparse_expr_cxt*context);
147+
staticvoidappendWhereClause(List*exprs,deparse_expr_cxt*context);
148+
staticvoidappendOrderByClause(List*pathkeys,deparse_expr_cxt*context);
144149

145150

146151
/*
@@ -697,6 +702,51 @@ deparse_type_name(Oid type_oid, int32 typemod)
697702
returnformat_type_with_typemod_qualified(type_oid,typemod);
698703
}
699704

705+
/*
706+
* Deparse SELECT statement for given relation into buf.
707+
*
708+
* remote_conds is the list of conditions to be deparsed as WHERE clause.
709+
*
710+
* pathkeys is the list of pathkeys to order the result by.
711+
*
712+
* List of columns selected is returned in retrieved_attrs.
713+
*
714+
* If params_list is not NULL, it receives a list of Params and other-relation
715+
* Vars used in the clauses; these values must be transmitted to the remote
716+
* server as parameter values.
717+
*
718+
* If params_list is NULL, we're generating the query for EXPLAIN purposes,
719+
* so Params and other-relation Vars should be replaced by dummy values.
720+
*/
721+
externvoid
722+
deparseSelectStmtForRel(StringInfobuf,PlannerInfo*root,RelOptInfo*rel,
723+
List*remote_conds,List*pathkeys,
724+
List**retrieved_attrs,List**params_list)
725+
{
726+
PgFdwRelationInfo*fpinfo= (PgFdwRelationInfo*)rel->fdw_private;
727+
deparse_expr_cxtcontext;
728+
729+
/* Initialize params_list if caller needs one */
730+
if (params_list)
731+
*params_list=NIL;
732+
733+
context.buf=buf;
734+
context.root=root;
735+
context.foreignrel=rel;
736+
context.params_list=params_list;
737+
738+
deparseSelectSql(fpinfo->attrs_used,retrieved_attrs,&context);
739+
740+
if (remote_conds)
741+
appendWhereClause(remote_conds,&context);
742+
743+
/* Add ORDER BY clause if we found any useful pathkeys */
744+
if (pathkeys)
745+
appendOrderByClause(pathkeys,&context);
746+
747+
/* Add any necessary FOR UPDATE/SHARE. */
748+
deparseLockingClause(&context);
749+
}
700750

701751
/*
702752
* Construct a simple SELECT statement that retrieves desired columns
@@ -707,13 +757,13 @@ deparse_type_name(Oid type_oid, int32 typemod)
707757
* returned to *retrieved_attrs.
708758
*/
709759
void
710-
deparseSelectSql(StringInfobuf,
711-
PlannerInfo*root,
712-
RelOptInfo*baserel,
713-
Bitmapset*attrs_used,
714-
List**retrieved_attrs)
760+
deparseSelectSql(Bitmapset*attrs_used,List**retrieved_attrs,
761+
deparse_expr_cxt*context)
715762
{
716-
RangeTblEntry*rte=planner_rt_fetch(baserel->relid,root);
763+
StringInfobuf=context->buf;
764+
RelOptInfo*foreignrel=context->foreignrel;
765+
PlannerInfo*root=context->root;
766+
RangeTblEntry*rte=planner_rt_fetch(foreignrel->relid,root);
717767
Relationrel;
718768

719769
/*
@@ -726,7 +776,7 @@ deparseSelectSql(StringInfo buf,
726776
* Construct SELECT list
727777
*/
728778
appendStringInfoString(buf,"SELECT ");
729-
deparseTargetList(buf,root,baserel->relid,rel,attrs_used,
779+
deparseTargetList(buf,root,foreignrel->relid,rel,attrs_used,
730780
retrieved_attrs);
731781

732782
/*
@@ -811,11 +861,15 @@ deparseTargetList(StringInfo buf,
811861

812862
/*
813863
* Deparse the appropriate locking clause (FOR SELECT or FOR SHARE) for a
814-
* given relation.
864+
* given relation (context->foreignrel).
815865
*/
816-
void
817-
deparseLockingClause(StringInfobuf,PlannerInfo*root,RelOptInfo*rel)
866+
staticvoid
867+
deparseLockingClause(deparse_expr_cxt*context)
818868
{
869+
StringInfobuf=context->buf;
870+
PlannerInfo*root=context->root;
871+
RelOptInfo*rel=context->foreignrel;
872+
819873
/*
820874
* Add FOR UPDATE/SHARE if appropriate. We apply locking during the
821875
* initial row fetch, rather than later on as is done for local tables.
@@ -868,39 +922,16 @@ deparseLockingClause(StringInfo buf, PlannerInfo *root, RelOptInfo *rel)
868922
}
869923

870924
/*
871-
* Deparse WHERE clauses in given list of RestrictInfos and append them to buf.
872-
*
873-
* baserel is the foreign table we're planning for.
874-
*
875-
* If no WHERE clause already exists in the buffer, is_first should be true.
876-
*
877-
* If params is not NULL, it receives a list of Params and other-relation Vars
878-
* used in the clauses; these values must be transmitted to the remote server
879-
* as parameter values.
880-
*
881-
* If params is NULL, we're generating the query for EXPLAIN purposes,
882-
* so Params and other-relation Vars should be replaced by dummy values.
925+
* Deparse WHERE clauses in given list of RestrictInfos and append them to
926+
* context->buf.
883927
*/
884-
void
885-
appendWhereClause(StringInfobuf,
886-
PlannerInfo*root,
887-
RelOptInfo*baserel,
888-
List*exprs,
889-
boolis_first,
890-
List**params)
928+
staticvoid
929+
appendWhereClause(List*exprs,deparse_expr_cxt*context)
891930
{
892-
deparse_expr_cxtcontext;
893931
intnestlevel;
894932
ListCell*lc;
895-
896-
if (params)
897-
*params=NIL;/* initialize result list to empty */
898-
899-
/* Set up context struct for recursion */
900-
context.root=root;
901-
context.foreignrel=baserel;
902-
context.buf=buf;
903-
context.params_list=params;
933+
boolis_first= true;
934+
StringInfobuf=context->buf;
904935

905936
/* Make sure any constants in the exprs are printed portably */
906937
nestlevel=set_transmission_modes();
@@ -916,7 +947,7 @@ appendWhereClause(StringInfo buf,
916947
appendStringInfoString(buf," AND ");
917948

918949
appendStringInfoChar(buf,'(');
919-
deparseExpr(ri->clause,&context);
950+
deparseExpr(ri->clause,context);
920951
appendStringInfoChar(buf,')');
921952

922953
is_first= false;
@@ -1946,20 +1977,14 @@ printRemotePlaceholder(Oid paramtype, int32 paramtypmod,
19461977
* relation. From given pathkeys expressions belonging entirely to the given
19471978
* base relation are obtained and deparsed.
19481979
*/
1949-
void
1950-
appendOrderByClause(StringInfobuf,PlannerInfo*root,RelOptInfo*baserel,
1951-
List*pathkeys)
1980+
staticvoid
1981+
appendOrderByClause(List*pathkeys,deparse_expr_cxt*context)
19521982
{
19531983
ListCell*lcell;
1954-
deparse_expr_cxtcontext;
19551984
intnestlevel;
19561985
char*delim=" ";
1957-
1958-
/* Set up context struct for recursion */
1959-
context.root=root;
1960-
context.foreignrel=baserel;
1961-
context.buf=buf;
1962-
context.params_list=NULL;
1986+
RelOptInfo*baserel=context->foreignrel;
1987+
StringInfobuf=context->buf;
19631988

19641989
/* Make sure any constants in the exprs are printed portably */
19651990
nestlevel=set_transmission_modes();
@@ -1974,7 +1999,7 @@ appendOrderByClause(StringInfo buf, PlannerInfo *root, RelOptInfo *baserel,
19741999
Assert(em_expr!=NULL);
19752000

19762001
appendStringInfoString(buf,delim);
1977-
deparseExpr(em_expr,&context);
2002+
deparseExpr(em_expr,context);
19782003
if (pathkey->pk_strategy==BTLessStrategyNumber)
19792004
appendStringInfoString(buf," ASC");
19802005
else

‎contrib/postgres_fdw/postgres_fdw.c

Lines changed: 14 additions & 24 deletions
Original file line numberDiff line numberDiff line change
@@ -1003,19 +1003,9 @@ postgresGetForeignPlan(PlannerInfo *root,
10031003
* expressions to be sent as parameters.
10041004
*/
10051005
initStringInfo(&sql);
1006-
deparseSelectSql(&sql,root,baserel,fpinfo->attrs_used,
1007-
&retrieved_attrs);
1008-
if (remote_conds)
1009-
appendWhereClause(&sql,root,baserel,remote_conds,
1010-
true,&params_list);
1011-
1012-
/* Add ORDER BY clause if we found any useful pathkeys */
1013-
if (best_path->path.pathkeys)
1014-
appendOrderByClause(&sql,root,baserel,best_path->path.pathkeys);
1015-
1016-
/* Add any necessary FOR UPDATE/SHARE. */
1017-
deparseLockingClause(&sql,root,baserel);
1018-
1006+
deparseSelectStmtForRel(&sql,root,baserel,remote_conds,
1007+
best_path->path.pathkeys,&retrieved_attrs,
1008+
&params_list);
10191009
/*
10201010
* Build the fdw_private list that will be available to the executor.
10211011
* Items in the list must match enum FdwScanPrivateIndex, above.
@@ -1909,6 +1899,7 @@ estimate_path_cost_size(PlannerInfo *root,
19091899
PGconn*conn;
19101900
Selectivitylocal_sel;
19111901
QualCostlocal_cost;
1902+
List*remote_conds;
19121903

19131904
/*
19141905
* join_conds might contain both clauses that are safe to send across,
@@ -1917,24 +1908,23 @@ estimate_path_cost_size(PlannerInfo *root,
19171908
classifyConditions(root,baserel,join_conds,
19181909
&remote_join_conds,&local_join_conds);
19191910

1911+
/*
1912+
* The complete list of remote conditions includes everything from
1913+
* baserestrictinfo plus any extra join_conds relevant to this
1914+
* particular path.
1915+
*/
1916+
remote_conds=list_concat(list_copy(remote_join_conds),
1917+
fpinfo->remote_conds);
1918+
19201919
/*
19211920
* Construct EXPLAIN query including the desired SELECT, FROM, and
19221921
* WHERE clauses. Params and other-relation Vars are replaced by
19231922
* dummy values.
19241923
*/
19251924
initStringInfo(&sql);
19261925
appendStringInfoString(&sql,"EXPLAIN ");
1927-
deparseSelectSql(&sql,root,baserel,fpinfo->attrs_used,
1928-
&retrieved_attrs);
1929-
if (fpinfo->remote_conds)
1930-
appendWhereClause(&sql,root,baserel,fpinfo->remote_conds,
1931-
true,NULL);
1932-
if (remote_join_conds)
1933-
appendWhereClause(&sql,root,baserel,remote_join_conds,
1934-
(fpinfo->remote_conds==NIL),NULL);
1935-
1936-
if (pathkeys)
1937-
appendOrderByClause(&sql,root,baserel,pathkeys);
1926+
deparseSelectStmtForRel(&sql,root,baserel,remote_conds,pathkeys,
1927+
&retrieved_attrs,NULL);
19381928

19391929
/* Get the remote estimate */
19401930
conn=GetConnection(fpinfo->user, false);

‎contrib/postgres_fdw/postgres_fdw.h

Lines changed: 3 additions & 15 deletions
Original file line numberDiff line numberDiff line change
@@ -83,19 +83,6 @@ extern void classifyConditions(PlannerInfo *root,
8383
externboolis_foreign_expr(PlannerInfo*root,
8484
RelOptInfo*baserel,
8585
Expr*expr);
86-
externvoiddeparseSelectSql(StringInfobuf,
87-
PlannerInfo*root,
88-
RelOptInfo*baserel,
89-
Bitmapset*attrs_used,
90-
List**retrieved_attrs);
91-
externvoiddeparseLockingClause(StringInfobuf,
92-
PlannerInfo*root,RelOptInfo*rel);
93-
externvoidappendWhereClause(StringInfobuf,
94-
PlannerInfo*root,
95-
RelOptInfo*baserel,
96-
List*exprs,
97-
boolis_first,
98-
List**params);
9986
externvoiddeparseInsertSql(StringInfobuf,PlannerInfo*root,
10087
Indexrtindex,Relationrel,
10188
List*targetAttrs,booldoNothing,List*returningList,
@@ -113,8 +100,9 @@ extern void deparseAnalyzeSql(StringInfo buf, Relation rel,
113100
List**retrieved_attrs);
114101
externvoiddeparseStringLiteral(StringInfobuf,constchar*val);
115102
externExpr*find_em_expr_for_rel(EquivalenceClass*ec,RelOptInfo*rel);
116-
externvoidappendOrderByClause(StringInfobuf,PlannerInfo*root,
117-
RelOptInfo*baserel,List*pathkeys);
103+
externvoiddeparseSelectStmtForRel(StringInfobuf,PlannerInfo*root,
104+
RelOptInfo*baserel,List*remote_conds,List*pathkeys,
105+
List**retrieved_attrs,List**params_list);
118106

119107
/* in shippable.c */
120108
externboolis_builtin(OidobjectId);

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