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-rw-r--r--src/backend/parser/parse_clause.c504
1 files changed, 460 insertions, 44 deletions
diff --git a/src/backend/parser/parse_clause.c b/src/backend/parser/parse_clause.c
index 6b1bbe57d0e..a90bcf40c9d 100644
--- a/src/backend/parser/parse_clause.c
+++ b/src/backend/parser/parse_clause.c
@@ -15,6 +15,8 @@
#include "postgres.h"
+#include "miscadmin.h"
+
#include "access/heapam.h"
#include "catalog/catalog.h"
#include "access/htup_details.h"
@@ -43,7 +45,6 @@
#include "utils/rel.h"
#include "utils/syscache.h"
-
/* Convenience macro for the most common makeNamespaceItem() case */
#define makeDefaultNSItem(rte) makeNamespaceItem(rte, true, true, false, true)
@@ -1725,40 +1726,181 @@ findTargetlistEntrySQL99(ParseState *pstate, Node *node, List **tlist,
return target_result;
}
+/*-------------------------------------------------------------------------
+ * Flatten out parenthesized sublists in grouping lists, and some cases
+ * of nested grouping sets.
+ *
+ * Inside a grouping set (ROLLUP, CUBE, or GROUPING SETS), we expect the
+ * content to be nested no more than 2 deep: i.e. ROLLUP((a,b),(c,d)) is
+ * ok, but ROLLUP((a,(b,c)),d) is flattened to ((a,b,c),d), which we then
+ * normalize to ((a,b,c),(d)).
+ *
+ * CUBE or ROLLUP can be nested inside GROUPING SETS (but not the reverse),
+ * and we leave that alone if we find it. But if we see GROUPING SETS inside
+ * GROUPING SETS, we can flatten and normalize as follows:
+ * GROUPING SETS (a, (b,c), GROUPING SETS ((c,d),(e)), (f,g))
+ * becomes
+ * GROUPING SETS ((a), (b,c), (c,d), (e), (f,g))
+ *
+ * This is per the spec's syntax transformations, but these are the only such
+ * transformations we do in parse analysis, so that queries retain the
+ * originally specified grouping set syntax for CUBE and ROLLUP as much as
+ * possible when deparsed. (Full expansion of the result into a list of
+ * grouping sets is left to the planner.)
+ *
+ * When we're done, the resulting list should contain only these possible
+ * elements:
+ * - an expression
+ * - a CUBE or ROLLUP with a list of expressions nested 2 deep
+ * - a GROUPING SET containing any of:
+ * - expression lists
+ * - empty grouping sets
+ * - CUBE or ROLLUP nodes with lists nested 2 deep
+ * The return is a new list, but doesn't deep-copy the old nodes except for
+ * GroupingSet nodes.
+ *
+ * As a side effect, flag whether the list has any GroupingSet nodes.
+ *-------------------------------------------------------------------------
+ */
+static Node *
+flatten_grouping_sets(Node *expr, bool toplevel, bool *hasGroupingSets)
+{
+ /* just in case of pathological input */
+ check_stack_depth();
+
+ if (expr == (Node *) NIL)
+ return (Node *) NIL;
+
+ switch (expr->type)
+ {
+ case T_RowExpr:
+ {
+ RowExpr *r = (RowExpr *) expr;
+ if (r->row_format == COERCE_IMPLICIT_CAST)
+ return flatten_grouping_sets((Node *) r->args,
+ false, NULL);
+ }
+ break;
+ case T_GroupingSet:
+ {
+ GroupingSet *gset = (GroupingSet *) expr;
+ ListCell *l2;
+ List *result_set = NIL;
+
+ if (hasGroupingSets)
+ *hasGroupingSets = true;
+
+ /*
+ * at the top level, we skip over all empty grouping sets; the
+ * caller can supply the canonical GROUP BY () if nothing is left.
+ */
+
+ if (toplevel && gset->kind == GROUPING_SET_EMPTY)
+ return (Node *) NIL;
+
+ foreach(l2, gset->content)
+ {
+ Node *n2 = flatten_grouping_sets(lfirst(l2), false, NULL);
+
+ result_set = lappend(result_set, n2);
+ }
+
+ /*
+ * At top level, keep the grouping set node; but if we're in a nested
+ * grouping set, then we need to concat the flattened result into the
+ * outer list if it's simply nested.
+ */
+
+ if (toplevel || (gset->kind != GROUPING_SET_SETS))
+ {
+ return (Node *) makeGroupingSet(gset->kind, result_set, gset->location);
+ }
+ else
+ return (Node *) result_set;
+ }
+ case T_List:
+ {
+ List *result = NIL;
+ ListCell *l;
+
+ foreach(l, (List *)expr)
+ {
+ Node *n = flatten_grouping_sets(lfirst(l), toplevel, hasGroupingSets);
+ if (n != (Node *) NIL)
+ {
+ if (IsA(n,List))
+ result = list_concat(result, (List *) n);
+ else
+ result = lappend(result, n);
+ }
+ }
+
+ return (Node *) result;
+ }
+ default:
+ break;
+ }
+
+ return expr;
+}
+
/*
- * transformGroupClause -
- * transform a GROUP BY clause
+ * Transform a single expression within a GROUP BY clause or grouping set.
*
- * GROUP BY items will be added to the targetlist (as resjunk columns)
- * if not already present, so the targetlist must be passed by reference.
+ * The expression is added to the targetlist if not already present, and to the
+ * flatresult list (which will become the groupClause) if not already present
+ * there. The sortClause is consulted for operator and sort order hints.
*
- * This is also used for window PARTITION BY clauses (which act almost the
- * same, but are always interpreted per SQL99 rules).
+ * Returns the ressortgroupref of the expression.
+ *
+ * flatresult reference to flat list of SortGroupClause nodes
+ * seen_local bitmapset of sortgrouprefs already seen at the local level
+ * pstate ParseState
+ * gexpr node to transform
+ * targetlist reference to TargetEntry list
+ * sortClause ORDER BY clause (SortGroupClause nodes)
+ * exprKind expression kind
+ * useSQL99 SQL99 rather than SQL92 syntax
+ * toplevel false if within any grouping set
*/
-List *
-transformGroupClause(ParseState *pstate, List *grouplist,
- List **targetlist, List *sortClause,
- ParseExprKind exprKind, bool useSQL99)
+static Index
+transformGroupClauseExpr(List **flatresult, Bitmapset *seen_local,
+ ParseState *pstate, Node *gexpr,
+ List **targetlist, List *sortClause,
+ ParseExprKind exprKind, bool useSQL99, bool toplevel)
{
- List *result = NIL;
- ListCell *gl;
+ TargetEntry *tle;
+ bool found = false;
+
+ if (useSQL99)
+ tle = findTargetlistEntrySQL99(pstate, gexpr,
+ targetlist, exprKind);
+ else
+ tle = findTargetlistEntrySQL92(pstate, gexpr,
+ targetlist, exprKind);
- foreach(gl, grouplist)
+ if (tle->ressortgroupref > 0)
{
- Node *gexpr = (Node *) lfirst(gl);
- TargetEntry *tle;
- bool found = false;
+ ListCell *sl;
- if (useSQL99)
- tle = findTargetlistEntrySQL99(pstate, gexpr,
- targetlist, exprKind);
- else
- tle = findTargetlistEntrySQL92(pstate, gexpr,
- targetlist, exprKind);
+ /*
+ * Eliminate duplicates (GROUP BY x, x) but only at local level.
+ * (Duplicates in grouping sets can affect the number of returned
+ * rows, so can't be dropped indiscriminately.)
+ *
+ * Since we don't care about anything except the sortgroupref,
+ * we can use a bitmapset rather than scanning lists.
+ */
+ if (bms_is_member(tle->ressortgroupref,seen_local))
+ return 0;
- /* Eliminate duplicates (GROUP BY x, x) */
- if (targetIsInSortList(tle, InvalidOid, result))
- continue;
+ /*
+ * If we're already in the flat clause list, we don't need
+ * to consider adding ourselves again.
+ */
+ found = targetIsInSortList(tle, InvalidOid, *flatresult);
+ if (found)
+ return tle->ressortgroupref;
/*
* If the GROUP BY tlist entry also appears in ORDER BY, copy operator
@@ -1770,35 +1912,308 @@ transformGroupClause(ParseState *pstate, List *grouplist,
* sort step, and it allows the user to choose the equality semantics
* used by GROUP BY, should she be working with a datatype that has
* more than one equality operator.
+ *
+ * If we're in a grouping set, though, we force our requested ordering
+ * to be NULLS LAST, because if we have any hope of using a sorted agg
+ * for the job, we're going to be tacking on generated NULL values
+ * after the corresponding groups. If the user demands nulls first,
+ * another sort step is going to be inevitable, but that's the
+ * planner's problem.
*/
- if (tle->ressortgroupref > 0)
+
+ foreach(sl, sortClause)
{
- ListCell *sl;
+ SortGroupClause *sc = (SortGroupClause *) lfirst(sl);
- foreach(sl, sortClause)
+ if (sc->tleSortGroupRef == tle->ressortgroupref)
{
- SortGroupClause *sc = (SortGroupClause *) lfirst(sl);
+ SortGroupClause *grpc = copyObject(sc);
+ if (!toplevel)
+ grpc->nulls_first = false;
+ *flatresult = lappend(*flatresult, grpc);
+ found = true;
+ break;
+ }
+ }
+ }
- if (sc->tleSortGroupRef == tle->ressortgroupref)
- {
- result = lappend(result, copyObject(sc));
- found = true;
+ /*
+ * If no match in ORDER BY, just add it to the result using default
+ * sort/group semantics.
+ */
+ if (!found)
+ *flatresult = addTargetToGroupList(pstate, tle,
+ *flatresult, *targetlist,
+ exprLocation(gexpr),
+ true);
+
+ /*
+ * _something_ must have assigned us a sortgroupref by now...
+ */
+
+ return tle->ressortgroupref;
+}
+
+/*
+ * Transform a list of expressions within a GROUP BY clause or grouping set.
+ *
+ * The list of expressions belongs to a single clause within which duplicates
+ * can be safely eliminated.
+ *
+ * Returns an integer list of ressortgroupref values.
+ *
+ * flatresult reference to flat list of SortGroupClause nodes
+ * pstate ParseState
+ * list nodes to transform
+ * targetlist reference to TargetEntry list
+ * sortClause ORDER BY clause (SortGroupClause nodes)
+ * exprKind expression kind
+ * useSQL99 SQL99 rather than SQL92 syntax
+ * toplevel false if within any grouping set
+ */
+static List *
+transformGroupClauseList(List **flatresult,
+ ParseState *pstate, List *list,
+ List **targetlist, List *sortClause,
+ ParseExprKind exprKind, bool useSQL99, bool toplevel)
+{
+ Bitmapset *seen_local = NULL;
+ List *result = NIL;
+ ListCell *gl;
+
+ foreach(gl, list)
+ {
+ Node *gexpr = (Node *) lfirst(gl);
+
+ Index ref = transformGroupClauseExpr(flatresult,
+ seen_local,
+ pstate,
+ gexpr,
+ targetlist,
+ sortClause,
+ exprKind,
+ useSQL99,
+ toplevel);
+ if (ref > 0)
+ {
+ seen_local = bms_add_member(seen_local, ref);
+ result = lappend_int(result, ref);
+ }
+ }
+
+ return result;
+}
+
+/*
+ * Transform a grouping set and (recursively) its content.
+ *
+ * The grouping set might be a GROUPING SETS node with other grouping sets
+ * inside it, but SETS within SETS have already been flattened out before
+ * reaching here.
+ *
+ * Returns the transformed node, which now contains SIMPLE nodes with lists
+ * of ressortgrouprefs rather than expressions.
+ *
+ * flatresult reference to flat list of SortGroupClause nodes
+ * pstate ParseState
+ * gset grouping set to transform
+ * targetlist reference to TargetEntry list
+ * sortClause ORDER BY clause (SortGroupClause nodes)
+ * exprKind expression kind
+ * useSQL99 SQL99 rather than SQL92 syntax
+ * toplevel false if within any grouping set
+ */
+static Node *
+transformGroupingSet(List **flatresult,
+ ParseState *pstate, GroupingSet *gset,
+ List **targetlist, List *sortClause,
+ ParseExprKind exprKind, bool useSQL99, bool toplevel)
+{
+ ListCell *gl;
+ List *content = NIL;
+
+ Assert(toplevel || gset->kind != GROUPING_SET_SETS);
+
+ foreach(gl, gset->content)
+ {
+ Node *n = lfirst(gl);
+
+ if (IsA(n, List))
+ {
+ List *l = transformGroupClauseList(flatresult,
+ pstate, (List *) n,
+ targetlist, sortClause,
+ exprKind, useSQL99, false);
+
+ content = lappend(content, makeGroupingSet(GROUPING_SET_SIMPLE,
+ l,
+ exprLocation(n)));
+ }
+ else if (IsA(n, GroupingSet))
+ {
+ GroupingSet *gset2 = (GroupingSet *) lfirst(gl);
+
+ content = lappend(content, transformGroupingSet(flatresult,
+ pstate, gset2,
+ targetlist, sortClause,
+ exprKind, useSQL99, false));
+ }
+ else
+ {
+ Index ref = transformGroupClauseExpr(flatresult,
+ NULL,
+ pstate,
+ n,
+ targetlist,
+ sortClause,
+ exprKind,
+ useSQL99,
+ false);
+
+ content = lappend(content, makeGroupingSet(GROUPING_SET_SIMPLE,
+ list_make1_int(ref),
+ exprLocation(n)));
+ }
+ }
+
+ /* Arbitrarily cap the size of CUBE, which has exponential growth */
+ if (gset->kind == GROUPING_SET_CUBE)
+ {
+ if (list_length(content) > 12)
+ ereport(ERROR,
+ (errcode(ERRCODE_TOO_MANY_COLUMNS),
+ errmsg("CUBE is limited to 12 elements"),
+ parser_errposition(pstate, gset->location)));
+ }
+
+ return (Node *) makeGroupingSet(gset->kind, content, gset->location);
+}
+
+
+/*
+ * transformGroupClause -
+ * transform a GROUP BY clause
+ *
+ * GROUP BY items will be added to the targetlist (as resjunk columns)
+ * if not already present, so the targetlist must be passed by reference.
+ *
+ * This is also used for window PARTITION BY clauses (which act almost the
+ * same, but are always interpreted per SQL99 rules).
+ *
+ * Grouping sets make this a lot more complex than it was. Our goal here is
+ * twofold: we make a flat list of SortGroupClause nodes referencing each
+ * distinct expression used for grouping, with those expressions added to the
+ * targetlist if needed. At the same time, we build the groupingSets tree,
+ * which stores only ressortgrouprefs as integer lists inside GroupingSet nodes
+ * (possibly nested, but limited in depth: a GROUPING_SET_SETS node can contain
+ * nested SIMPLE, CUBE or ROLLUP nodes, but not more sets - we flatten that
+ * out; while CUBE and ROLLUP can contain only SIMPLE nodes).
+ *
+ * We skip much of the hard work if there are no grouping sets.
+ *
+ * One subtlety is that the groupClause list can end up empty while the
+ * groupingSets list is not; this happens if there are only empty grouping
+ * sets, or an explicit GROUP BY (). This has the same effect as specifying
+ * aggregates or a HAVING clause with no GROUP BY; the output is one row per
+ * grouping set even if the input is empty.
+ *
+ * Returns the transformed (flat) groupClause.
+ *
+ * pstate ParseState
+ * grouplist clause to transform
+ * groupingSets reference to list to contain the grouping set tree
+ * targetlist reference to TargetEntry list
+ * sortClause ORDER BY clause (SortGroupClause nodes)
+ * exprKind expression kind
+ * useSQL99 SQL99 rather than SQL92 syntax
+ */
+List *
+transformGroupClause(ParseState *pstate, List *grouplist, List **groupingSets,
+ List **targetlist, List *sortClause,
+ ParseExprKind exprKind, bool useSQL99)
+{
+ List *result = NIL;
+ List *flat_grouplist;
+ List *gsets = NIL;
+ ListCell *gl;
+ bool hasGroupingSets = false;
+ Bitmapset *seen_local = NULL;
+
+ /*
+ * Recursively flatten implicit RowExprs. (Technically this is only
+ * needed for GROUP BY, per the syntax rules for grouping sets, but
+ * we do it anyway.)
+ */
+ flat_grouplist = (List *) flatten_grouping_sets((Node *) grouplist,
+ true,
+ &hasGroupingSets);
+
+ /*
+ * If the list is now empty, but hasGroupingSets is true, it's because
+ * we elided redundant empty grouping sets. Restore a single empty
+ * grouping set to leave a canonical form: GROUP BY ()
+ */
+
+ if (flat_grouplist == NIL && hasGroupingSets)
+ {
+ flat_grouplist = list_make1(makeGroupingSet(GROUPING_SET_EMPTY,
+ NIL,
+ exprLocation((Node *) grouplist)));
+ }
+
+ foreach(gl, flat_grouplist)
+ {
+ Node *gexpr = (Node *) lfirst(gl);
+
+ if (IsA(gexpr, GroupingSet))
+ {
+ GroupingSet *gset = (GroupingSet *) gexpr;
+
+ switch (gset->kind)
+ {
+ case GROUPING_SET_EMPTY:
+ gsets = lappend(gsets, gset);
+ break;
+ case GROUPING_SET_SIMPLE:
+ /* can't happen */
+ Assert(false);
+ break;
+ case GROUPING_SET_SETS:
+ case GROUPING_SET_CUBE:
+ case GROUPING_SET_ROLLUP:
+ gsets = lappend(gsets,
+ transformGroupingSet(&result,
+ pstate, gset,
+ targetlist, sortClause,
+ exprKind, useSQL99, true));
break;
- }
}
}
+ else
+ {
+ Index ref = transformGroupClauseExpr(&result, seen_local,
+ pstate, gexpr,
+ targetlist, sortClause,
+ exprKind, useSQL99, true);
- /*
- * If no match in ORDER BY, just add it to the result using default
- * sort/group semantics.
- */
- if (!found)
- result = addTargetToGroupList(pstate, tle,
- result, *targetlist,
- exprLocation(gexpr),
- true);
+ if (ref > 0)
+ {
+ seen_local = bms_add_member(seen_local, ref);
+ if (hasGroupingSets)
+ gsets = lappend(gsets,
+ makeGroupingSet(GROUPING_SET_SIMPLE,
+ list_make1_int(ref),
+ exprLocation(gexpr)));
+ }
+ }
}
+ /* parser should prevent this */
+ Assert(gsets == NIL || groupingSets != NULL);
+
+ if (groupingSets)
+ *groupingSets = gsets;
+
return result;
}
@@ -1903,6 +2318,7 @@ transformWindowDefinitions(ParseState *pstate,
true /* force SQL99 rules */ );
partitionClause = transformGroupClause(pstate,
windef->partitionClause,
+ NULL,
targetlist,
orderClause,
EXPR_KIND_WINDOW_PARTITION,
generated by cgit v1.2.3 (git 2.25.1) at 2025-05-23 09:48:51 +0000