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Add scan plan logic for remote joins

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This patch adds the missing functionality to create scan plans for
remote joins. Most of the code is a backport from PG Upstream.
This commit is contained in:
Jan Nidzwetzki 2023-01-18 14:47:48 +01:00 committed by Jan Nidzwetzki
parent f211294c61
commit 9ae3ae33b7
4 changed files with 98 additions and 17 deletions
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2
tsl/src/fdw/data_node_scan_plan.c
View File

@ -836,7 +836,7 @@ data_node_scan_plan_create(PlannerInfo *root, RelOptInfo *rel, CustomPath *best_
memset(&scaninfo, 0, sizeof(ScanInfo));
fdw_scan_info_init(&scaninfo, root, rel, &best_path->path, clauses);
fdw_scan_info_init(&scaninfo, root, rel, &best_path->path, clauses, NULL);
cscan->methods = &data_node_scan_plan_methods;
cscan->custom_plans = custom_plans;

2
tsl/src/fdw/fdw.c
View File

@ -139,7 +139,7 @@ get_foreign_plan(PlannerInfo *root, RelOptInfo *foreignrel, Oid foreigntableid,
memset(&info, 0, sizeof(ScanInfo));
fdw_scan_info_init(&info, root, foreignrel, &best_path->path, scan_clauses);
fdw_scan_info_init(&info, root, foreignrel, &best_path->path, scan_clauses, outer_plan);
/*
* Create the ForeignScan node for the given relation.

109
tsl/src/fdw/scan_plan.c
View File

@ -132,7 +132,7 @@ add_paths_with_pathkeys_for_rel(PlannerInfo *root, RelOptInfo *rel, Path *epq_pa
if (create_scan_path)
{
Assert(IS_SIMPLE_REL(rel));
Assert(IS_SIMPLE_REL(rel) || IS_JOIN_REL(rel));
scan_path = create_scan_path(root,
rel,
NULL,
@ -437,11 +437,11 @@ eval_stable_functions(PlannerInfo *root, Node *node)
void
fdw_scan_info_init(ScanInfo *scaninfo, PlannerInfo *root, RelOptInfo *rel, Path *best_path,
List *scan_clauses)
List *scan_clauses, Plan *outer_plan)
{
TsFdwRelInfo *fpinfo = fdw_relinfo_get(rel);
List *remote_where = NIL;
List *remote_having = NIL;
List *remote_exprs = NIL;
List *local_exprs = NIL;
List *params_list = NIL;
List *fdw_scan_tlist = NIL;
@ -487,11 +487,11 @@ fdw_scan_info_init(ScanInfo *scaninfo, PlannerInfo *root, RelOptInfo *rel, Path
continue;
if (list_member_ptr(fpinfo->remote_conds, rinfo))
remote_where = lappend(remote_where, rinfo->clause);
remote_exprs = lappend(remote_exprs, rinfo->clause);
else if (list_member_ptr(fpinfo->local_conds, rinfo))
local_exprs = lappend(local_exprs, rinfo->clause);
else if (ts_is_foreign_expr(root, rel, rinfo->clause))
remote_where = lappend(remote_where, rinfo->clause);
remote_exprs = lappend(remote_exprs, rinfo->clause);
else
local_exprs = lappend(local_exprs, rinfo->clause);
}
@ -500,13 +500,95 @@ fdw_scan_info_init(ScanInfo *scaninfo, PlannerInfo *root, RelOptInfo *rel, Path
* For a base-relation scan, we have to support EPQ recheck, which
* should recheck all the remote quals.
*/
fdw_recheck_quals = remote_where;
fdw_recheck_quals = remote_exprs;
}
else if (IS_JOIN_REL(rel))
{
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("foreign joins are not supported")));
/*
* Join relation or upper relation - set scan_relid to 0.
*/
scan_relid = 0;
/*
* For a join rel, baserestrictinfo is NIL and we are not considering
* parameterization right now, so there should be no scan_clauses for
* a joinrel or an upper rel either.
*/
Assert(!scan_clauses);
/*
* Instead we get the conditions to apply from the fdw_private
* structure.
*/
remote_exprs = extract_actual_clauses(fpinfo->remote_conds, false);
local_exprs = extract_actual_clauses(fpinfo->local_conds, false);
/*
* We leave fdw_recheck_quals empty in this case, since we never need
* to apply EPQ recheck clauses. In the case of a joinrel, EPQ
* recheck is handled elsewhere --- see postgresGetForeignJoinPaths().
* If we're planning an upperrel (ie, remote grouping or aggregation)
* then there's no EPQ to do because SELECT FOR UPDATE wouldn't be
* allowed, and indeed we *can't* put the remote clauses into
* fdw_recheck_quals because the unaggregated Vars won't be available
* locally.
*/
/* Build the list of columns to be fetched from the foreign server. */
fdw_scan_tlist = build_tlist_to_deparse(rel);
/*
* Ensure that the outer plan produces a tuple whose descriptor
* matches our scan tuple slot. Also, remove the local conditions
* from outer plan's quals, lest they be evaluated twice, once by the
* local plan and once by the scan.
*/
if (outer_plan)
{
ListCell *lc;
/*
* Right now, we only consider grouping and aggregation beyond
* joins. Queries involving aggregates or grouping do not require
* EPQ mechanism, hence should not have an outer plan here.
*/
Assert(!IS_UPPER_REL(rel));
/*
* First, update the plan's qual list if possible. In some cases
* the quals might be enforced below the topmost plan level, in
* which case we'll fail to remove them; it's not worth working
* harder than this.
*/
foreach (lc, local_exprs)
{
Node *qual = lfirst(lc);
outer_plan->qual = list_delete(outer_plan->qual, qual);
/*
* For an inner join the local conditions of foreign scan plan
* can be part of the joinquals as well. (They might also be
* in the mergequals or hashquals, but we can't touch those
* without breaking the plan.)
*/
if (IsA(outer_plan, NestLoop) || IsA(outer_plan, MergeJoin) ||
IsA(outer_plan, HashJoin))
{
Join *join_plan = (Join *) outer_plan;
if (join_plan->jointype == JOIN_INNER)
join_plan->joinqual = list_delete(join_plan->joinqual, qual);
}
}
/*
* Now fix the subplan's tlist --- this might result in inserting
* a Result node atop the plan tree.
*/
outer_plan =
change_plan_targetlist(outer_plan, fdw_scan_tlist, best_path->parallel_safe);
}
}
else
{
@ -530,7 +612,7 @@ fdw_scan_info_init(ScanInfo *scaninfo, PlannerInfo *root, RelOptInfo *rel, Path
*/
TsFdwRelInfo *ofpinfo;
ofpinfo = fdw_relinfo_get(fpinfo->outerrel);
remote_where = extract_actual_clauses(ofpinfo->remote_conds, false);
remote_exprs = extract_actual_clauses(ofpinfo->remote_conds, false);
remote_having = extract_actual_clauses(fpinfo->remote_conds, false);
local_exprs = extract_actual_clauses(fpinfo->local_conds, false);
@ -559,7 +641,7 @@ fdw_scan_info_init(ScanInfo *scaninfo, PlannerInfo *root, RelOptInfo *rel, Path
* the whitelisted stable functions, see `function_is_whitelisted()`. So
* this code only has to deal with such functions.
*/
remote_where = (List *) eval_stable_functions(root, (Node *) remote_where);
remote_exprs = (List *) eval_stable_functions(root, (Node *) remote_exprs);
remote_having = (List *) eval_stable_functions(root, (Node *) remote_having);
/*
@ -571,7 +653,7 @@ fdw_scan_info_init(ScanInfo *scaninfo, PlannerInfo *root, RelOptInfo *rel, Path
root,
rel,
fdw_scan_tlist,
remote_where,
remote_exprs,
remote_having,
best_path->pathkeys,
false,
@ -580,7 +662,7 @@ fdw_scan_info_init(ScanInfo *scaninfo, PlannerInfo *root, RelOptInfo *rel, Path
fpinfo->sca);
/* Remember remote_exprs for possible use by PlanDirectModify */
fpinfo->final_remote_exprs = remote_where;
fpinfo->final_remote_exprs = remote_exprs;
/* Build the chunk oid list for use by EXPLAIN. */
List *chunk_oids = NIL;
@ -602,7 +684,6 @@ fdw_scan_info_init(ScanInfo *scaninfo, PlannerInfo *root, RelOptInfo *rel, Path
makeInteger(fpinfo->fetch_size),
makeInteger(fpinfo->server->serverid),
chunk_oids);
Assert(!IS_JOIN_REL(rel));
if (IS_UPPER_REL(rel))
fdw_private = lappend(fdw_private, makeString(fpinfo->relation_name->data));

2
tsl/src/fdw/scan_plan.h
View File

@ -40,7 +40,7 @@ typedef Path *(*CreateUpperPathFunc)(PlannerInfo *root, RelOptInfo *rel, PathTar
List *pathkeys, Path *fdw_outerpath, List *fdw_private);
extern void fdw_scan_info_init(ScanInfo *scaninfo, PlannerInfo *root, RelOptInfo *rel,
Path *best_path, List *scan_clauses);
Path *best_path, List *scan_clauses, Plan *outer_plan);
extern void fdw_add_paths_with_pathkeys_for_rel(PlannerInfo *root, RelOptInfo *rel, Path *epq_path,
CreatePathFunc create_scan_path);