#include "catalog/pg_collation.h"
#include "catalog/pg_namespace.h"
#include "catalog/pg_operator.h"
+#include "catalog/pg_opfamily.h"
#include "catalog/pg_proc.h"
#include "catalog/pg_type.h"
#include "commands/defrem.h"
Index ignore_rel, List **ignore_conds, List **params_list);
static void deparseAggref(Aggref *node, deparse_expr_cxt *context);
static void appendGroupByClause(List *tlist, deparse_expr_cxt *context);
+static void appendOrderBySuffix(Oid sortop, Oid sortcoltype, bool nulls_first,
+ deparse_expr_cxt *context);
static void appendAggOrderBy(List *orderList, List *targetList,
deparse_expr_cxt *context);
static void appendFunctionName(Oid funcid, deparse_expr_cxt *context);
return false;
}
+/*
+ * Returns true if it's safe to push down the sort expression described by
+ * 'pathkey' to the foreign server.
+ */
+bool
+is_foreign_pathkey(PlannerInfo *root,
+ RelOptInfo *baserel,
+ PathKey *pathkey)
+{
+ EquivalenceClass *pathkey_ec = pathkey->pk_eclass;
+ PgFdwRelationInfo *fpinfo = (PgFdwRelationInfo *) baserel->fdw_private;
+
+ /*
+ * is_foreign_expr would detect volatile expressions as well, but checking
+ * ec_has_volatile here saves some cycles.
+ */
+ if (pathkey_ec->ec_has_volatile)
+ return false;
+
+ /* can't push down the sort if the pathkey's opfamily is not shippable */
+ if (!is_shippable(pathkey->pk_opfamily, OperatorFamilyRelationId, fpinfo))
+ return false;
+
+ /* can push if a suitable EC member exists */
+ return (find_em_for_rel(root, pathkey_ec, baserel) != NULL);
+}
+
/*
* Convert type OID + typmod info into a type name we can ship to the remote
* server. Someplace else had better have verified that this type name is
{
SortGroupClause *srt = (SortGroupClause *) lfirst(lc);
Node *sortexpr;
- Oid sortcoltype;
- TypeCacheEntry *typentry;
if (!first)
appendStringInfoString(buf, ", ");
first = false;
+ /* Deparse the sort expression proper. */
sortexpr = deparseSortGroupClause(srt->tleSortGroupRef, targetList,
false, context);
- sortcoltype = exprType(sortexpr);
- /* See whether operator is default < or > for datatype */
- typentry = lookup_type_cache(sortcoltype,
- TYPECACHE_LT_OPR | TYPECACHE_GT_OPR);
- if (srt->sortop == typentry->lt_opr)
- appendStringInfoString(buf, " ASC");
- else if (srt->sortop == typentry->gt_opr)
- appendStringInfoString(buf, " DESC");
- else
- {
- HeapTuple opertup;
- Form_pg_operator operform;
-
- appendStringInfoString(buf, " USING ");
-
- /* Append operator name. */
- opertup = SearchSysCache1(OPEROID, ObjectIdGetDatum(srt->sortop));
- if (!HeapTupleIsValid(opertup))
- elog(ERROR, "cache lookup failed for operator %u", srt->sortop);
- operform = (Form_pg_operator) GETSTRUCT(opertup);
- deparseOperatorName(buf, operform);
- ReleaseSysCache(opertup);
- }
+ /* Add decoration as needed. */
+ appendOrderBySuffix(srt->sortop, exprType(sortexpr), srt->nulls_first,
+ context);
+ }
+}
- if (srt->nulls_first)
- appendStringInfoString(buf, " NULLS FIRST");
- else
- appendStringInfoString(buf, " NULLS LAST");
+/*
+ * Append the ASC, DESC, USING <OPERATOR> and NULLS FIRST / NULLS LAST parts
+ * of an ORDER BY clause.
+ */
+static void
+appendOrderBySuffix(Oid sortop, Oid sortcoltype, bool nulls_first,
+ deparse_expr_cxt *context)
+{
+ StringInfo buf = context->buf;
+ TypeCacheEntry *typentry;
+
+ /* See whether operator is default < or > for sort expr's datatype. */
+ typentry = lookup_type_cache(sortcoltype,
+ TYPECACHE_LT_OPR | TYPECACHE_GT_OPR);
+
+ if (sortop == typentry->lt_opr)
+ appendStringInfoString(buf, " ASC");
+ else if (sortop == typentry->gt_opr)
+ appendStringInfoString(buf, " DESC");
+ else
+ {
+ HeapTuple opertup;
+ Form_pg_operator operform;
+
+ appendStringInfoString(buf, " USING ");
+
+ /* Append operator name. */
+ opertup = SearchSysCache1(OPEROID, ObjectIdGetDatum(sortop));
+ if (!HeapTupleIsValid(opertup))
+ elog(ERROR, "cache lookup failed for operator %u", sortop);
+ operform = (Form_pg_operator) GETSTRUCT(opertup);
+ deparseOperatorName(buf, operform);
+ ReleaseSysCache(opertup);
}
+
+ if (nulls_first)
+ appendStringInfoString(buf, " NULLS FIRST");
+ else
+ appendStringInfoString(buf, " NULLS LAST");
}
/*
}
/*
- * Deparse ORDER BY clause according to the given pathkeys for given base
- * relation. From given pathkeys expressions belonging entirely to the given
- * base relation are obtained and deparsed.
+ * Deparse ORDER BY clause defined by the given pathkeys.
+ *
+ * We find a suitable pathkey expression (some earlier step
+ * should have verified that there is one) and deparse it.
*/
static void
appendOrderByClause(List *pathkeys, deparse_expr_cxt *context)
{
ListCell *lcell;
int nestlevel;
- char *delim = " ";
- RelOptInfo *baserel = context->scanrel;
+ const char *delim = " ";
StringInfo buf = context->buf;
/* Make sure any constants in the exprs are printed portably */
foreach(lcell, pathkeys)
{
PathKey *pathkey = lfirst(lcell);
+ EquivalenceMember *em;
Expr *em_expr;
+ Oid oprid;
- em_expr = find_em_expr_for_rel(pathkey->pk_eclass, baserel);
- Assert(em_expr != NULL);
+ em = find_em_for_rel(context->root,
+ pathkey->pk_eclass,
+ context->scanrel);
+
+ /*
+ * We don't expect any error here; it would mean that shippability
+ * wasn't verified earlier. For the same reason, we don't recheck
+ * shippability of the sort operator.
+ */
+ if (em == NULL)
+ elog(ERROR, "could not find pathkey item to sort");
+
+ em_expr = em->em_expr;
+
+ /*
+ * Lookup the operator corresponding to the strategy in the opclass.
+ * The datatype used by the opfamily is not necessarily the same as
+ * the expression type (for array types for example).
+ */
+ oprid = get_opfamily_member(pathkey->pk_opfamily,
+ em->em_datatype,
+ em->em_datatype,
+ pathkey->pk_strategy);
+ if (!OidIsValid(oprid))
+ elog(ERROR, "missing operator %d(%u,%u) in opfamily %u",
+ pathkey->pk_strategy, em->em_datatype, em->em_datatype,
+ pathkey->pk_opfamily);
appendStringInfoString(buf, delim);
deparseExpr(em_expr, context);
- if (pathkey->pk_strategy == BTLessStrategyNumber)
- appendStringInfoString(buf, " ASC");
- else
- appendStringInfoString(buf, " DESC");
- if (pathkey->pk_nulls_first)
- appendStringInfoString(buf, " NULLS FIRST");
- else
- appendStringInfoString(buf, " NULLS LAST");
+ /*
+ * Here we need to use the expression's actual type to discover
+ * whether the desired operator will be the default or not.
+ */
+ appendOrderBySuffix(oprid, exprType((Node *) em_expr),
+ pathkey->pk_nulls_first, context);
delim = ", ";
}
Remote SQL: SELECT "C 1", c2 FROM "S 1"."T 1" WHERE (("C 1" < 100)) AND ((c2 = 6))
(6 rows)
+-- This should not be pushed either.
+explain (verbose, costs off)
+select * from ft2 order by c1 using operator(public.<^);
+ QUERY PLAN
+-------------------------------------------------------------------------------
+ Sort
+ Output: c1, c2, c3, c4, c5, c6, c7, c8
+ Sort Key: ft2.c1 USING <^
+ -> Foreign Scan on public.ft2
+ Output: c1, c2, c3, c4, c5, c6, c7, c8
+ Remote SQL: SELECT "C 1", c2, c3, c4, c5, c6, c7, c8 FROM "S 1"."T 1"
+(6 rows)
+
-- Add into extension
alter extension postgres_fdw add operator class my_op_class using btree;
alter extension postgres_fdw add function my_op_cmp(a int, b int);
{6,16,26,36,46,56,66,76,86,96}
(1 row)
+-- This should be pushed too.
+explain (verbose, costs off)
+select * from ft2 order by c1 using operator(public.<^);
+ QUERY PLAN
+-----------------------------------------------------------------------------------------------------------------------------
+ Foreign Scan on public.ft2
+ Output: c1, c2, c3, c4, c5, c6, c7, c8
+ Remote SQL: SELECT "C 1", c2, c3, c4, c5, c6, c7, c8 FROM "S 1"."T 1" ORDER BY "C 1" USING OPERATOR(public.<^) NULLS LAST
+(3 rows)
+
-- Remove from extension
alter extension postgres_fdw drop operator class my_op_class using btree;
alter extension postgres_fdw drop function my_op_cmp(a int, b int);
#include "access/htup_details.h"
#include "access/sysattr.h"
#include "catalog/pg_class.h"
+#include "catalog/pg_opfamily.h"
#include "commands/defrem.h"
#include "commands/explain.h"
#include "commands/vacuum.h"
foreach(lc, root->query_pathkeys)
{
PathKey *pathkey = (PathKey *) lfirst(lc);
- EquivalenceClass *pathkey_ec = pathkey->pk_eclass;
- Expr *em_expr;
/*
* The planner and executor don't have any clever strategy for
* getting it to be sorted by all of those pathkeys. We'll just
* end up resorting the entire data set. So, unless we can push
* down all of the query pathkeys, forget it.
- *
- * is_foreign_expr would detect volatile expressions as well, but
- * checking ec_has_volatile here saves some cycles.
*/
- if (pathkey_ec->ec_has_volatile ||
- !(em_expr = find_em_expr_for_rel(pathkey_ec, rel)) ||
- !is_foreign_expr(root, rel, em_expr))
+ if (!is_foreign_pathkey(root, rel, pathkey))
{
query_pathkeys_ok = false;
break;
foreach(lc, useful_eclass_list)
{
EquivalenceClass *cur_ec = lfirst(lc);
- Expr *em_expr;
PathKey *pathkey;
/* If redundant with what we did above, skip it. */
if (cur_ec == query_ec)
continue;
+ /* Can't push down the sort if the EC's opfamily is not shippable. */
+ if (!is_shippable(linitial_oid(cur_ec->ec_opfamilies),
+ OperatorFamilyRelationId, fpinfo))
+ continue;
+
/* If no pushable expression for this rel, skip it. */
- em_expr = find_em_expr_for_rel(cur_ec, rel);
- if (em_expr == NULL || !is_foreign_expr(root, rel, em_expr))
+ if (find_em_for_rel(root, cur_ec, rel) == NULL)
continue;
/* Looks like we can generate a pathkey, so let's do it. */
}
/*
- * Find an equivalence class member expression, all of whose Vars, come from
- * the indicated relation.
+ * Given an EquivalenceClass and a foreign relation, find an EC member
+ * that can be used to sort the relation remotely according to a pathkey
+ * using this EC.
+ *
+ * If there is more than one suitable candidate, return an arbitrary
+ * one of them. If there is none, return NULL.
+ *
+ * This checks that the EC member expression uses only Vars from the given
+ * rel and is shippable. Caller must separately verify that the pathkey's
+ * ordering operator is shippable.
*/
-Expr *
-find_em_expr_for_rel(EquivalenceClass *ec, RelOptInfo *rel)
+EquivalenceMember *
+find_em_for_rel(PlannerInfo *root, EquivalenceClass *ec, RelOptInfo *rel)
{
- ListCell *lc_em;
+ ListCell *lc;
- foreach(lc_em, ec->ec_members)
+ foreach(lc, ec->ec_members)
{
- EquivalenceMember *em = lfirst(lc_em);
+ EquivalenceMember *em = (EquivalenceMember *) lfirst(lc);
+ /*
+ * Note we require !bms_is_empty, else we'd accept constant
+ * expressions which are not suitable for the purpose.
+ */
if (bms_is_subset(em->em_relids, rel->relids) &&
- !bms_is_empty(em->em_relids))
- {
- /*
- * If there is more than one equivalence member whose Vars are
- * taken entirely from this relation, we'll be content to choose
- * any one of those.
- */
- return em->em_expr;
- }
+ !bms_is_empty(em->em_relids) &&
+ is_foreign_expr(root, rel, em->em_expr))
+ return em;
}
- /* We didn't find any suitable equivalence class expression */
return NULL;
}
projects / thirdparty / postgresql.git / commitdiff
