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[DNM] An experimental branch to try to push down aggregate functions #22

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5ab6c73
An experimental branch to try to push down aggregate functions
Aug 2, 2019
625debf
Add ROW back (easier for debugging)
Aug 2, 2019
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138 changes: 111 additions & 27 deletions contrib/postgres_fdw/deparse.c
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Original file line number Diff line number Diff line change
Expand Up @@ -182,6 +182,7 @@ static void appendGroupByClause(List *tlist, deparse_expr_cxt *context);
static void appendAggOrderBy(List *orderList, List *targetList,
deparse_expr_cxt *context);
static void appendFunctionName(Oid funcid, deparse_expr_cxt *context);
static void deparseRowExpr(RowExpr *node, deparse_expr_cxt *context);
static Node *deparseSortGroupClause(Index ref, List *tlist, bool force_colno,
deparse_expr_cxt *context);

Expand Down Expand Up @@ -338,8 +339,10 @@ foreign_expr_walker(Node *node,
*/
if (var->varattno < 0 &&
var->varattno != SelfItemPointerAttributeNumber &&
var->varattno != ObjectIdAttributeNumber)
var->varattno != ObjectIdAttributeNumber) {
elog(WARNING, "RTORRE return false 1");
return false;
}

/* Else check the collation */
collation = var->varcollid;
Expand Down Expand Up @@ -407,23 +410,31 @@ foreign_expr_walker(Node *node,
ArrayRef *ar = (ArrayRef *) node;

/* Assignment should not be in restrictions. */
if (ar->refassgnexpr != NULL)
if (ar->refassgnexpr != NULL) {
elog(WARNING, "RTORRE return false 2");
return false;
}

/*
* Recurse to remaining subexpressions. Since the array
* subscripts must yield (noncollatable) integers, they won't
* affect the inner_cxt state.
*/
if (!foreign_expr_walker((Node *) ar->refupperindexpr,
glob_cxt, &inner_cxt))
glob_cxt, &inner_cxt)) {
elog(WARNING, "RTORRE return false 3");
return false;
}
if (!foreign_expr_walker((Node *) ar->reflowerindexpr,
glob_cxt, &inner_cxt))
glob_cxt, &inner_cxt)) {
elog(WARNING, "RTORRE return false 4");
return false;
}
if (!foreign_expr_walker((Node *) ar->refexpr,
glob_cxt, &inner_cxt))
elog(WARNING, "RTORRE return false 5"); {
return false;
}

/*
* Array subscripting should yield same collation as input,
Expand All @@ -450,15 +461,19 @@ foreign_expr_walker(Node *node,
* can't be sent to remote because it might have incompatible
* semantics on remote side.
*/
if (!is_shippable(fe->funcid, ProcedureRelationId, fpinfo))
if (!is_shippable(fe->funcid, ProcedureRelationId, fpinfo)) {
elog(WARNING, "RTORRE return false 6");
return false;
}

/*
* Recurse to input subexpressions.
*/
if (!foreign_expr_walker((Node *) fe->args,
glob_cxt, &inner_cxt))
glob_cxt, &inner_cxt)) {
elog(WARNING, "RTORRE return false 7");
return false;
}

/*
* If function's input collation is not derived from a foreign
Expand All @@ -467,8 +482,10 @@ foreign_expr_walker(Node *node,
if (fe->inputcollid == InvalidOid)
/* OK, inputs are all noncollatable */ ;
else if (inner_cxt.state != FDW_COLLATE_SAFE ||
fe->inputcollid != inner_cxt.collation)
fe->inputcollid != inner_cxt.collation) {
elog(WARNING, "RTORRE return false 8");
return false;
}

/*
* Detect whether node is introducing a collation not derived
Expand Down Expand Up @@ -498,15 +515,19 @@ foreign_expr_walker(Node *node,
* (If the operator is shippable, we assume its underlying
* function is too.)
*/
if (!is_shippable(oe->opno, OperatorRelationId, fpinfo))
if (!is_shippable(oe->opno, OperatorRelationId, fpinfo)) {
elog(WARNING, "RTORRE return false 9");
return false;
}

/*
* Recurse to input subexpressions.
*/
if (!foreign_expr_walker((Node *) oe->args,
glob_cxt, &inner_cxt))
glob_cxt, &inner_cxt)) {
elog(WARNING, "RTORRE return false 10");
return false;
}

/*
* If operator's input collation is not derived from a foreign
Expand All @@ -515,8 +536,10 @@ foreign_expr_walker(Node *node,
if (oe->inputcollid == InvalidOid)
/* OK, inputs are all noncollatable */ ;
else if (inner_cxt.state != FDW_COLLATE_SAFE ||
oe->inputcollid != inner_cxt.collation)
oe->inputcollid != inner_cxt.collation) {
elog(WARNING, "RTORRE return false 11");
return false;
}

/* Result-collation handling is same as for functions */
collation = oe->opcollid;
Expand All @@ -538,15 +561,19 @@ foreign_expr_walker(Node *node,
/*
* Again, only shippable operators can be sent to remote.
*/
if (!is_shippable(oe->opno, OperatorRelationId, fpinfo))
if (!is_shippable(oe->opno, OperatorRelationId, fpinfo)) {
elog(WARNING, "RTORRE return false 12");
return false;
}

/*
* Recurse to input subexpressions.
*/
if (!foreign_expr_walker((Node *) oe->args,
glob_cxt, &inner_cxt))
glob_cxt, &inner_cxt)) {
elog(WARNING, "RTORRE return false 13");
return false;
}

/*
* If operator's input collation is not derived from a foreign
Expand All @@ -555,8 +582,10 @@ foreign_expr_walker(Node *node,
if (oe->inputcollid == InvalidOid)
/* OK, inputs are all noncollatable */ ;
else if (inner_cxt.state != FDW_COLLATE_SAFE ||
oe->inputcollid != inner_cxt.collation)
oe->inputcollid != inner_cxt.collation) {
elog(WARNING, "RTORRE return false 14");
return false;
}

/* Output is always boolean and so noncollatable. */
collation = InvalidOid;
Expand All @@ -571,8 +600,10 @@ foreign_expr_walker(Node *node,
* Recurse to input subexpression.
*/
if (!foreign_expr_walker((Node *) r->arg,
glob_cxt, &inner_cxt))
glob_cxt, &inner_cxt)) {
elog(WARNING, "RTORRE return false 15");
return false;
}

/*
* RelabelType must not introduce a collation not derived from
Expand All @@ -598,8 +629,10 @@ foreign_expr_walker(Node *node,
* Recurse to input subexpressions.
*/
if (!foreign_expr_walker((Node *) b->args,
glob_cxt, &inner_cxt))
glob_cxt, &inner_cxt)) {
elog(WARNING, "RTORRE return false 16");
return false;
}

/* Output is always boolean and so noncollatable. */
collation = InvalidOid;
Expand All @@ -614,8 +647,10 @@ foreign_expr_walker(Node *node,
* Recurse to input subexpressions.
*/
if (!foreign_expr_walker((Node *) nt->arg,
glob_cxt, &inner_cxt))
glob_cxt, &inner_cxt)) {
elog(WARNING, "RTORRE return false 17");
return false;
}

/* Output is always boolean and so noncollatable. */
collation = InvalidOid;
Expand All @@ -630,8 +665,10 @@ foreign_expr_walker(Node *node,
* Recurse to input subexpressions.
*/
if (!foreign_expr_walker((Node *) a->elements,
glob_cxt, &inner_cxt))
glob_cxt, &inner_cxt)) {
elog(WARNING, "RTORRE return false 18");
return false;
}

/*
* ArrayExpr must not introduce a collation not derived from
Expand Down Expand Up @@ -660,8 +697,10 @@ foreign_expr_walker(Node *node,
foreach(lc, l)
{
if (!foreign_expr_walker((Node *) lfirst(lc),
glob_cxt, &inner_cxt))
glob_cxt, &inner_cxt)) {
elog(WARNING, "RTORRE return false 19");
return false;
}
}

/*
Expand All @@ -681,16 +720,22 @@ foreign_expr_walker(Node *node,
ListCell *lc;

/* Not safe to pushdown when not in grouping context */
if (!IS_UPPER_REL(glob_cxt->foreignrel))
if (!IS_UPPER_REL(glob_cxt->foreignrel)) {
elog(WARNING, "RTORRE return false 20");
return false;
}

/* Only non-split aggregates are pushable. */
if (agg->aggsplit != AGGSPLIT_SIMPLE)
if (agg->aggsplit != AGGSPLIT_SIMPLE) {
elog(WARNING, "RTORRE return false 21");
return false;
}

/* As usual, it must be shippable. */
if (!is_shippable(agg->aggfnoid, ProcedureRelationId, fpinfo))
if (!is_shippable(agg->aggfnoid, ProcedureRelationId, fpinfo)) {
elog(WARNING, "RTORRE return false 22");
return false;
}

/*
* Recurse to input args. aggdirectargs, aggorder and
Expand All @@ -709,8 +754,10 @@ foreign_expr_walker(Node *node,
n = (Node *) tle->expr;
}

if (!foreign_expr_walker(n, glob_cxt, &inner_cxt))
if (!foreign_expr_walker(n, glob_cxt, &inner_cxt)) {
elog(WARNING, "RTORRE return false 23");
return false;
}
}

/*
Expand All @@ -737,25 +784,31 @@ foreign_expr_walker(Node *node,
if (srt->sortop != typentry->lt_opr &&
srt->sortop != typentry->gt_opr &&
!is_shippable(srt->sortop, OperatorRelationId,
fpinfo))
fpinfo)) {
elog(WARNING, "RTORRE return false 24");
return false;
}
}
}

/* Check aggregate filter */
if (!foreign_expr_walker((Node *) agg->aggfilter,
glob_cxt, &inner_cxt))
glob_cxt, &inner_cxt)) {
elog(WARNING, "RTORRE return false 25");
return false;
}

/*
* If aggregate's input collation is not derived from a
* foreign Var, it can't be sent to remote.
*/
if (agg->inputcollid == InvalidOid)
if (agg->inputcollid == InvalidOid || inner_cxt.state == FDW_COLLATE_NONE)
/* OK, inputs are all noncollatable */ ;
else if (inner_cxt.state != FDW_COLLATE_SAFE ||
agg->inputcollid != inner_cxt.collation)
agg->inputcollid != inner_cxt.collation) {
elog(WARNING, "RTORRE return false 26");
return false;
}

/*
* Detect whether node is introducing a collation not derived
Expand All @@ -775,12 +828,21 @@ foreign_expr_walker(Node *node,
state = FDW_COLLATE_UNSAFE;
}
break;
default:
case T_RowExpr:
/*
* rtorre: this is a bold move, let's consider it true. Trying to
* cover the st_asmvt(ROW(st_asmvtgeom(...)) case. I guess the
* proper solution is to examine the row expression carefully.
*/
ereport(WARNING, (errmsg_internal("RTORRE in a T_RowExpr")));
return true;
default:

/*
* If it's anything else, assume it's unsafe. This list can be
* expanded later, but don't forget to add deparse support below.
*/
elog(WARNING, "RTORRE unrecognized node type: %d", (int) nodeTag(node));
return false;
}

Expand Down Expand Up @@ -2354,13 +2416,35 @@ deparseExpr(Expr *node, deparse_expr_cxt *context)
case T_Aggref:
deparseAggref((Aggref *) node, context);
break;
case T_RowExpr:
deparseRowExpr((RowExpr *) node, context);
break;
default:
elog(ERROR, "unsupported expression type for deparse: %d",
(int) nodeTag(node));
break;
}
}

static void
deparseRowExpr(RowExpr *node, deparse_expr_cxt *context)
{
StringInfo buf = context->buf;
bool first;
ListCell *lc;

appendStringInfoString(buf, "ROW(");
first = true;
foreach(lc, node->args)
{
if (!first)
appendStringInfo(buf, ", ");
deparseExpr((Expr *) lfirst(lc), context);
first = false;
}
appendStringInfoChar(buf, ')');
}

/*
* Deparse given Var node into context->buf.
*
Expand Down