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Support GROUPING SETS, CUBE and ROLLUP.

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This SQL standard functionality allows to aggregate data by different
GROUP BY clauses at once. Each grouping set returns rows with columns
grouped by in other sets set to NULL.

This could previously be achieved by doing each grouping as a separate
query, conjoined by UNION ALLs. Besides being considerably more concise,
grouping sets will in many cases be faster, requiring only one scan over
the underlying data.

The current implementation of grouping sets only supports using sorting
for input. Individual sets that share a sort order are computed in one
pass. If there are sets that don't share a sort order, additional sort &
aggregation steps are performed. These additional passes are sourced by
the previous sort step; thus avoiding repeated scans of the source data.

The code is structured in a way that adding support for purely using
hash aggregation or a mix of hashing and sorting is possible. Sorting
was chosen to be supported first, as it is the most generic method of
implementation.

Instead of, as in an earlier versions of the patch, representing the
chain of sort and aggregation steps as full blown planner and executor
nodes, all but the first sort are performed inside the aggregation node
itself. This avoids the need to do some unusual gymnastics to handle
having to return aggregated and non-aggregated tuples from underlying
nodes, as well as having to shut down underlying nodes early to limit
memory usage.  The optimizer still builds Sort/Agg node to describe each
phase, but they're not part of the plan tree, but instead additional
data for the aggregation node. They're a convenient and preexisting way
to describe aggregation and sorting.  The first (and possibly only) sort
step is still performed as a separate execution step. That retains
similarity with existing group by plans, makes rescans fairly simple,
avoids very deep plans (leading to slow explains) and easily allows to
avoid the sorting step if the underlying data is sorted by other means.

A somewhat ugly side of this patch is having to deal with a grammar
ambiguity between the new CUBE keyword and the cube extension/functions
named cube (and rollup). To avoid breaking existing deployments of the
cube extension it has not been renamed, neither has cube been made a
reserved keyword. Instead precedence hacking is used to make GROUP BY
cube(..) refer to the CUBE grouping sets feature, and not the function
cube(). To actually group by a function cube(), unlikely as that might
be, the function name has to be quoted.

Needs a catversion bump because stored rules may change.

Author: Andrew Gierth and Atri Sharma, with contributions from Andres Freund
Reviewed-By: Andres Freund, Noah Misch, Tom Lane, Svenne Krap, Tomas
    Vondra, Erik Rijkers, Marti Raudsepp, Pavel Stehule
Discussion: CAOeZVidmVRe2jU6aMk_5qkxnB7dfmPROzM7Ur8JPW5j8Y5X-Lw@mail.gmail.com
This commit is contained in:
Andres Freund
2015-05-16 03:40:59 +02:00
parent 6e4415c6aa
commit f3d3118532
63 changed files with 5255 additions and 618 deletions
Download Patch File Download Diff File Expand all files Collapse all files

723
src/backend/parser/parse_agg.c
View File

@ -42,7 +42,9 @@ typedef struct
{
ParseState *pstate;
Query *qry;
PlannerInfo *root;
List *groupClauses;
List *groupClauseCommonVars;
bool have_non_var_grouping;
List **func_grouped_rels;
int sublevels_up;
@ -56,11 +58,18 @@ static int check_agg_arguments(ParseState *pstate,
static bool check_agg_arguments_walker(Node *node,
check_agg_arguments_context *context);
static void check_ungrouped_columns(Node *node, ParseState *pstate, Query *qry,
List *groupClauses, bool have_non_var_grouping,
List *groupClauses, List *groupClauseVars,
bool have_non_var_grouping,
List **func_grouped_rels);
static bool check_ungrouped_columns_walker(Node *node,
check_ungrouped_columns_context *context);
static void finalize_grouping_exprs(Node *node, ParseState *pstate, Query *qry,
List *groupClauses, PlannerInfo *root,
bool have_non_var_grouping);
static bool finalize_grouping_exprs_walker(Node *node,
check_ungrouped_columns_context *context);
static void check_agglevels_and_constraints(ParseState *pstate,Node *expr);
static List *expand_groupingset_node(GroupingSet *gs);
/*
* transformAggregateCall -
@ -96,10 +105,7 @@ transformAggregateCall(ParseState *pstate, Aggref *agg,
List *tdistinct = NIL;
AttrNumber attno = 1;
int save_next_resno;
int min_varlevel;
ListCell *lc;
const char *err;
bool errkind;
if (AGGKIND_IS_ORDERED_SET(agg->aggkind))
{
@ -214,15 +220,97 @@ transformAggregateCall(ParseState *pstate, Aggref *agg,
agg->aggorder = torder;
agg->aggdistinct = tdistinct;
check_agglevels_and_constraints(pstate, (Node *) agg);
}
/*
* transformGroupingFunc
* Transform a GROUPING expression
*
* GROUPING() behaves very like an aggregate. Processing of levels and nesting
* is done as for aggregates. We set p_hasAggs for these expressions too.
*/
Node *
transformGroupingFunc(ParseState *pstate, GroupingFunc *p)
{
ListCell *lc;
List *args = p->args;
List *result_list = NIL;
GroupingFunc *result = makeNode(GroupingFunc);
if (list_length(args) > 31)
ereport(ERROR,
(errcode(ERRCODE_TOO_MANY_ARGUMENTS),
errmsg("GROUPING must have fewer than 32 arguments"),
parser_errposition(pstate, p->location)));
foreach(lc, args)
{
Node *current_result;
current_result = transformExpr(pstate, (Node*) lfirst(lc), pstate->p_expr_kind);
/* acceptability of expressions is checked later */
result_list = lappend(result_list, current_result);
}
result->args = result_list;
result->location = p->location;
check_agglevels_and_constraints(pstate, (Node *) result);
return (Node *) result;
}
/*
* Aggregate functions and grouping operations (which are combined in the spec
* as <set function specification>) are very similar with regard to level and
* nesting restrictions (though we allow a lot more things than the spec does).
* Centralise those restrictions here.
*/
static void
check_agglevels_and_constraints(ParseState *pstate, Node *expr)
{
List *directargs = NIL;
List *args = NIL;
Expr *filter = NULL;
int min_varlevel;
int location = -1;
Index *p_levelsup;
const char *err;
bool errkind;
bool isAgg = IsA(expr, Aggref);
if (isAgg)
{
Aggref *agg = (Aggref *) expr;
directargs = agg->aggdirectargs;
args = agg->args;
filter = agg->aggfilter;
location = agg->location;
p_levelsup = &agg->agglevelsup;
}
else
{
GroupingFunc *grp = (GroupingFunc *) expr;
args = grp->args;
location = grp->location;
p_levelsup = &grp->agglevelsup;
}
/*
* Check the arguments to compute the aggregate's level and detect
* improper nesting.
*/
min_varlevel = check_agg_arguments(pstate,
agg->aggdirectargs,
agg->args,
agg->aggfilter);
agg->agglevelsup = min_varlevel;
directargs,
args,
filter);
*p_levelsup = min_varlevel;
/* Mark the correct pstate level as having aggregates */
while (min_varlevel-- > 0)
@ -247,20 +335,32 @@ transformAggregateCall(ParseState *pstate, Aggref *agg,
Assert(false); /* can't happen */
break;
case EXPR_KIND_OTHER:
/* Accept aggregate here; caller must throw error if wanted */
/* Accept aggregate/grouping here; caller must throw error if wanted */
break;
case EXPR_KIND_JOIN_ON:
case EXPR_KIND_JOIN_USING:
err = _("aggregate functions are not allowed in JOIN conditions");
if (isAgg)
err = _("aggregate functions are not allowed in JOIN conditions");
else
err = _("grouping operations are not allowed in JOIN conditions");
break;
case EXPR_KIND_FROM_SUBSELECT:
/* Should only be possible in a LATERAL subquery */
Assert(pstate->p_lateral_active);
/* Aggregate scope rules make it worth being explicit here */
err = _("aggregate functions are not allowed in FROM clause of their own query level");
/* Aggregate/grouping scope rules make it worth being explicit here */
if (isAgg)
err = _("aggregate functions are not allowed in FROM clause of their own query level");
else
err = _("grouping operations are not allowed in FROM clause of their own query level");
break;
case EXPR_KIND_FROM_FUNCTION:
err = _("aggregate functions are not allowed in functions in FROM");
if (isAgg)
err = _("aggregate functions are not allowed in functions in FROM");
else
err = _("grouping operations are not allowed in functions in FROM");
break;
case EXPR_KIND_WHERE:
errkind = true;
@ -278,10 +378,18 @@ transformAggregateCall(ParseState *pstate, Aggref *agg,
/* okay */
break;
case EXPR_KIND_WINDOW_FRAME_RANGE:
err = _("aggregate functions are not allowed in window RANGE");
if (isAgg)
err = _("aggregate functions are not allowed in window RANGE");
else
err = _("grouping operations are not allowed in window RANGE");
break;
case EXPR_KIND_WINDOW_FRAME_ROWS:
err = _("aggregate functions are not allowed in window ROWS");
if (isAgg)
err = _("aggregate functions are not allowed in window ROWS");
else
err = _("grouping operations are not allowed in window ROWS");
break;
case EXPR_KIND_SELECT_TARGET:
/* okay */
@ -312,26 +420,55 @@ transformAggregateCall(ParseState *pstate, Aggref *agg,
break;
case EXPR_KIND_CHECK_CONSTRAINT:
case EXPR_KIND_DOMAIN_CHECK:
err = _("aggregate functions are not allowed in check constraints");
if (isAgg)
err = _("aggregate functions are not allowed in check constraints");
else
err = _("grouping operations are not allowed in check constraints");
break;
case EXPR_KIND_COLUMN_DEFAULT:
case EXPR_KIND_FUNCTION_DEFAULT:
err = _("aggregate functions are not allowed in DEFAULT expressions");
if (isAgg)
err = _("aggregate functions are not allowed in DEFAULT expressions");
else
err = _("grouping operations are not allowed in DEFAULT expressions");
break;
case EXPR_KIND_INDEX_EXPRESSION:
err = _("aggregate functions are not allowed in index expressions");
if (isAgg)
err = _("aggregate functions are not allowed in index expressions");
else
err = _("grouping operations are not allowed in index expressions");
break;
case EXPR_KIND_INDEX_PREDICATE:
err = _("aggregate functions are not allowed in index predicates");
if (isAgg)
err = _("aggregate functions are not allowed in index predicates");
else
err = _("grouping operations are not allowed in index predicates");
break;
case EXPR_KIND_ALTER_COL_TRANSFORM:
err = _("aggregate functions are not allowed in transform expressions");
if (isAgg)
err = _("aggregate functions are not allowed in transform expressions");
else
err = _("grouping operations are not allowed in transform expressions");
break;
case EXPR_KIND_EXECUTE_PARAMETER:
err = _("aggregate functions are not allowed in EXECUTE parameters");
if (isAgg)
err = _("aggregate functions are not allowed in EXECUTE parameters");
else
err = _("grouping operations are not allowed in EXECUTE parameters");
break;
case EXPR_KIND_TRIGGER_WHEN:
err = _("aggregate functions are not allowed in trigger WHEN conditions");
if (isAgg)
err = _("aggregate functions are not allowed in trigger WHEN conditions");
else
err = _("grouping operations are not allowed in trigger WHEN conditions");
break;
/*
@ -342,18 +479,28 @@ transformAggregateCall(ParseState *pstate, Aggref *agg,
* which is sane anyway.
*/
}
if (err)
ereport(ERROR,
(errcode(ERRCODE_GROUPING_ERROR),
errmsg_internal("%s", err),
parser_errposition(pstate, agg->location)));
parser_errposition(pstate, location)));
if (errkind)
{
if (isAgg)
/* translator: %s is name of a SQL construct, eg GROUP BY */
err = _("aggregate functions are not allowed in %s");
else
/* translator: %s is name of a SQL construct, eg GROUP BY */
err = _("grouping operations are not allowed in %s");
ereport(ERROR,
(errcode(ERRCODE_GROUPING_ERROR),
/* translator: %s is name of a SQL construct, eg GROUP BY */
errmsg("aggregate functions are not allowed in %s",
ParseExprKindName(pstate->p_expr_kind)),
parser_errposition(pstate, agg->location)));
errmsg_internal(err,
ParseExprKindName(pstate->p_expr_kind)),
parser_errposition(pstate, location)));
}
}
/*
@ -466,7 +613,6 @@ check_agg_arguments(ParseState *pstate,
locate_agg_of_level((Node *) directargs,
context.min_agglevel))));
}
return agglevel;
}
@ -507,6 +653,21 @@ check_agg_arguments_walker(Node *node,
/* no need to examine args of the inner aggregate */
return false;
}
if (IsA(node, GroupingFunc))
{
int agglevelsup = ((GroupingFunc *) node)->agglevelsup;
/* convert levelsup to frame of reference of original query */
agglevelsup -= context->sublevels_up;
/* ignore local aggs of subqueries */
if (agglevelsup >= 0)
{
if (context->min_agglevel < 0 ||
context->min_agglevel > agglevelsup)
context->min_agglevel = agglevelsup;
}
/* Continue and descend into subtree */
}
/* We can throw error on sight for a window function */
if (IsA(node, WindowFunc))
ereport(ERROR,
@ -527,6 +688,7 @@ check_agg_arguments_walker(Node *node,
context->sublevels_up--;
return result;
}
return expression_tree_walker(node,
check_agg_arguments_walker,
(void *) context);
@ -770,17 +932,66 @@ transformWindowFuncCall(ParseState *pstate, WindowFunc *wfunc,
void
parseCheckAggregates(ParseState *pstate, Query *qry)
{
List *gset_common = NIL;
List *groupClauses = NIL;
List *groupClauseCommonVars = NIL;
bool have_non_var_grouping;
List *func_grouped_rels = NIL;
ListCell *l;
bool hasJoinRTEs;
bool hasSelfRefRTEs;
PlannerInfo *root;
PlannerInfo *root = NULL;
Node *clause;
/* This should only be called if we found aggregates or grouping */
Assert(pstate->p_hasAggs || qry->groupClause || qry->havingQual);
Assert(pstate->p_hasAggs || qry->groupClause || qry->havingQual || qry->groupingSets);
/*
* If we have grouping sets, expand them and find the intersection of all
* sets.
*/
if (qry->groupingSets)
{
/*
* The limit of 4096 is arbitrary and exists simply to avoid resource
* issues from pathological constructs.
*/
List *gsets = expand_grouping_sets(qry->groupingSets, 4096);
if (!gsets)
ereport(ERROR,
(errcode(ERRCODE_STATEMENT_TOO_COMPLEX),
errmsg("too many grouping sets present (max 4096)"),
parser_errposition(pstate,
qry->groupClause
? exprLocation((Node *) qry->groupClause)
: exprLocation((Node *) qry->groupingSets))));
/*
* The intersection will often be empty, so help things along by
* seeding the intersect with the smallest set.
*/
gset_common = linitial(gsets);
if (gset_common)
{
for_each_cell(l, lnext(list_head(gsets)))
{
gset_common = list_intersection_int(gset_common, lfirst(l));
if (!gset_common)
break;
}
}
/*
* If there was only one grouping set in the expansion, AND if the
* groupClause is non-empty (meaning that the grouping set is not empty
* either), then we can ditch the grouping set and pretend we just had
* a normal GROUP BY.
*/
if (list_length(gsets) == 1 && qry->groupClause)
qry->groupingSets = NIL;
}
/*
* Scan the range table to see if there are JOIN or self-reference CTE
@ -800,15 +1011,19 @@ parseCheckAggregates(ParseState *pstate, Query *qry)
/*
* Build a list of the acceptable GROUP BY expressions for use by
* check_ungrouped_columns().
*
* We get the TLE, not just the expr, because GROUPING wants to know
* the sortgroupref.
*/
foreach(l, qry->groupClause)
{
SortGroupClause *grpcl = (SortGroupClause *) lfirst(l);
Node *expr;
TargetEntry *expr;
expr = get_sortgroupclause_expr(grpcl, qry->targetList);
expr = get_sortgroupclause_tle(grpcl, qry->targetList);
if (expr == NULL)
continue; /* probably cannot happen */
groupClauses = lcons(expr, groupClauses);
}
@ -830,21 +1045,28 @@ parseCheckAggregates(ParseState *pstate, Query *qry)
groupClauses = (List *) flatten_join_alias_vars(root,
(Node *) groupClauses);
}
else
root = NULL; /* keep compiler quiet */
/*
* Detect whether any of the grouping expressions aren't simple Vars; if
* they're all Vars then we don't have to work so hard in the recursive
* scans. (Note we have to flatten aliases before this.)
*
* Track Vars that are included in all grouping sets separately in
* groupClauseCommonVars, since these are the only ones we can use to check
* for functional dependencies.
*/
have_non_var_grouping = false;
foreach(l, groupClauses)
{
if (!IsA((Node *) lfirst(l), Var))
TargetEntry *tle = lfirst(l);
if (!IsA(tle->expr, Var))
{
have_non_var_grouping = true;
break;
}
else if (!qry->groupingSets ||
list_member_int(gset_common, tle->ressortgroupref))
{
groupClauseCommonVars = lappend(groupClauseCommonVars, tle->expr);
}
}
@ -855,19 +1077,30 @@ parseCheckAggregates(ParseState *pstate, Query *qry)
* this will also find ungrouped variables that came from ORDER BY and
* WINDOW clauses. For that matter, it's also going to examine the
* grouping expressions themselves --- but they'll all pass the test ...
*
* We also finalize GROUPING expressions, but for that we need to traverse
* the original (unflattened) clause in order to modify nodes.
*/
clause = (Node *) qry->targetList;
finalize_grouping_exprs(clause, pstate, qry,
groupClauses, root,
have_non_var_grouping);
if (hasJoinRTEs)
clause = flatten_join_alias_vars(root, clause);
check_ungrouped_columns(clause, pstate, qry,
groupClauses, have_non_var_grouping,
groupClauses, groupClauseCommonVars,
have_non_var_grouping,
&func_grouped_rels);
clause = (Node *) qry->havingQual;
finalize_grouping_exprs(clause, pstate, qry,
groupClauses, root,
have_non_var_grouping);
if (hasJoinRTEs)
clause = flatten_join_alias_vars(root, clause);
check_ungrouped_columns(clause, pstate, qry,
groupClauses, have_non_var_grouping,
groupClauses, groupClauseCommonVars,
have_non_var_grouping,
&func_grouped_rels);
/*
@ -904,14 +1137,17 @@ parseCheckAggregates(ParseState *pstate, Query *qry)
*/
static void
check_ungrouped_columns(Node *node, ParseState *pstate, Query *qry,
List *groupClauses, bool have_non_var_grouping,
List *groupClauses, List *groupClauseCommonVars,
bool have_non_var_grouping,
List **func_grouped_rels)
{
check_ungrouped_columns_context context;
context.pstate = pstate;
context.qry = qry;
context.root = NULL;
context.groupClauses = groupClauses;
context.groupClauseCommonVars = groupClauseCommonVars;
context.have_non_var_grouping = have_non_var_grouping;
context.func_grouped_rels = func_grouped_rels;
context.sublevels_up = 0;
@ -965,6 +1201,16 @@ check_ungrouped_columns_walker(Node *node,
return false;
}
if (IsA(node, GroupingFunc))
{
GroupingFunc *grp = (GroupingFunc *) node;
/* handled GroupingFunc separately, no need to recheck at this level */
if ((int) grp->agglevelsup >= context->sublevels_up)
return false;
}
/*
* If we have any GROUP BY items that are not simple Vars, check to see if
* subexpression as a whole matches any GROUP BY item. We need to do this
@ -976,7 +1222,9 @@ check_ungrouped_columns_walker(Node *node,
{
foreach(gl, context->groupClauses)
{
if (equal(node, lfirst(gl)))
TargetEntry *tle = lfirst(gl);
if (equal(node, tle->expr))
return false; /* acceptable, do not descend more */
}
}
@ -1003,7 +1251,7 @@ check_ungrouped_columns_walker(Node *node,
{
foreach(gl, context->groupClauses)
{
Var *gvar = (Var *) lfirst(gl);
Var *gvar = (Var *) ((TargetEntry *) lfirst(gl))->expr;
if (IsA(gvar, Var) &&
gvar->varno == var->varno &&
@ -1040,7 +1288,7 @@ check_ungrouped_columns_walker(Node *node,
if (check_functional_grouping(rte->relid,
var->varno,
0,
context->groupClauses,
context->groupClauseCommonVars,
&context->qry->constraintDeps))
{
*context->func_grouped_rels =
@ -1084,6 +1332,395 @@ check_ungrouped_columns_walker(Node *node,
(void *) context);
}
/*
* finalize_grouping_exprs -
* Scan the given expression tree for GROUPING() and related calls,
* and validate and process their arguments.
*
* This is split out from check_ungrouped_columns above because it needs
* to modify the nodes (which it does in-place, not via a mutator) while
* check_ungrouped_columns may see only a copy of the original thanks to
* flattening of join alias vars. So here, we flatten each individual
* GROUPING argument as we see it before comparing it.
*/
static void
finalize_grouping_exprs(Node *node, ParseState *pstate, Query *qry,
List *groupClauses, PlannerInfo *root,
bool have_non_var_grouping)
{
check_ungrouped_columns_context context;
context.pstate = pstate;
context.qry = qry;
context.root = root;
context.groupClauses = groupClauses;
context.groupClauseCommonVars = NIL;
context.have_non_var_grouping = have_non_var_grouping;
context.func_grouped_rels = NULL;
context.sublevels_up = 0;
context.in_agg_direct_args = false;
finalize_grouping_exprs_walker(node, &context);
}
static bool
finalize_grouping_exprs_walker(Node *node,
check_ungrouped_columns_context *context)
{
ListCell *gl;
if (node == NULL)
return false;
if (IsA(node, Const) ||
IsA(node, Param))
return false; /* constants are always acceptable */
if (IsA(node, Aggref))
{
Aggref *agg = (Aggref *) node;
if ((int) agg->agglevelsup == context->sublevels_up)
{
/*
* If we find an aggregate call of the original level, do not
* recurse into its normal arguments, ORDER BY arguments, or
* filter; GROUPING exprs of this level are not allowed there. But
* check direct arguments as though they weren't in an aggregate.
*/
bool result;
Assert(!context->in_agg_direct_args);
context->in_agg_direct_args = true;
result = finalize_grouping_exprs_walker((Node *) agg->aggdirectargs,
context);
context->in_agg_direct_args = false;
return result;
}
/*
* We can skip recursing into aggregates of higher levels altogether,
* since they could not possibly contain exprs of concern to us (see
* transformAggregateCall). We do need to look at aggregates of lower
* levels, however.
*/
if ((int) agg->agglevelsup > context->sublevels_up)
return false;
}
if (IsA(node, GroupingFunc))
{
GroupingFunc *grp = (GroupingFunc *) node;
/*
* We only need to check GroupingFunc nodes at the exact level to which
* they belong, since they cannot mix levels in arguments.
*/
if ((int) grp->agglevelsup == context->sublevels_up)
{
ListCell *lc;
List *ref_list = NIL;
foreach(lc, grp->args)
{
Node *expr = lfirst(lc);
Index ref = 0;
if (context->root)
expr = flatten_join_alias_vars(context->root, expr);
/*
* Each expression must match a grouping entry at the current
* query level. Unlike the general expression case, we don't
* allow functional dependencies or outer references.
*/
if (IsA(expr, Var))
{
Var *var = (Var *) expr;
if (var->varlevelsup == context->sublevels_up)
{
foreach(gl, context->groupClauses)
{
TargetEntry *tle = lfirst(gl);
Var *gvar = (Var *) tle->expr;
if (IsA(gvar, Var) &&
gvar->varno == var->varno &&
gvar->varattno == var->varattno &&
gvar->varlevelsup == 0)
{
ref = tle->ressortgroupref;
break;
}
}
}
}
else if (context->have_non_var_grouping &&
context->sublevels_up == 0)
{
foreach(gl, context->groupClauses)
{
TargetEntry *tle = lfirst(gl);
if (equal(expr, tle->expr))
{
ref = tle->ressortgroupref;
break;
}
}
}
if (ref == 0)
ereport(ERROR,
(errcode(ERRCODE_GROUPING_ERROR),
errmsg("arguments to GROUPING must be grouping expressions of the associated query level"),
parser_errposition(context->pstate,
exprLocation(expr))));
ref_list = lappend_int(ref_list, ref);
}
grp->refs = ref_list;
}
if ((int) grp->agglevelsup > context->sublevels_up)
return false;
}
if (IsA(node, Query))
{
/* Recurse into subselects */
bool result;
context->sublevels_up++;
result = query_tree_walker((Query *) node,
finalize_grouping_exprs_walker,
(void *) context,
0);
context->sublevels_up--;
return result;
}
return expression_tree_walker(node, finalize_grouping_exprs_walker,
(void *) context);
}
/*
* Given a GroupingSet node, expand it and return a list of lists.
*
* For EMPTY nodes, return a list of one empty list.
*
* For SIMPLE nodes, return a list of one list, which is the node content.
*
* For CUBE and ROLLUP nodes, return a list of the expansions.
*
* For SET nodes, recursively expand contained CUBE and ROLLUP.
*/
static List*
expand_groupingset_node(GroupingSet *gs)
{
List * result = NIL;
switch (gs->kind)
{
case GROUPING_SET_EMPTY:
result = list_make1(NIL);
break;
case GROUPING_SET_SIMPLE:
result = list_make1(gs->content);
break;
case GROUPING_SET_ROLLUP:
{
List *rollup_val = gs->content;
ListCell *lc;
int curgroup_size = list_length(gs->content);
while (curgroup_size > 0)
{
List *current_result = NIL;
int i = curgroup_size;
foreach(lc, rollup_val)
{
GroupingSet *gs_current = (GroupingSet *) lfirst(lc);
Assert(gs_current->kind == GROUPING_SET_SIMPLE);
current_result
= list_concat(current_result,
list_copy(gs_current->content));
/* If we are done with making the current group, break */
if (--i == 0)
break;
}
result = lappend(result, current_result);
--curgroup_size;
}
result = lappend(result, NIL);
}
break;
case GROUPING_SET_CUBE:
{
List *cube_list = gs->content;
int number_bits = list_length(cube_list);
uint32 num_sets;
uint32 i;
/* parser should cap this much lower */
Assert(number_bits < 31);
num_sets = (1U << number_bits);
for (i = 0; i < num_sets; i++)
{
List *current_result = NIL;
ListCell *lc;
uint32 mask = 1U;
foreach(lc, cube_list)
{
GroupingSet *gs_current = (GroupingSet *) lfirst(lc);
Assert(gs_current->kind == GROUPING_SET_SIMPLE);
if (mask & i)
{
current_result
= list_concat(current_result,
list_copy(gs_current->content));
}
mask <<= 1;
}
result = lappend(result, current_result);
}
}
break;
case GROUPING_SET_SETS:
{
ListCell *lc;
foreach(lc, gs->content)
{
List *current_result = expand_groupingset_node(lfirst(lc));
result = list_concat(result, current_result);
}
}
break;
}
return result;
}
static int
cmp_list_len_asc(const void *a, const void *b)
{
int la = list_length(*(List*const*)a);
int lb = list_length(*(List*const*)b);
return (la > lb) ? 1 : (la == lb) ? 0 : -1;
}
/*
* Expand a groupingSets clause to a flat list of grouping sets.
* The returned list is sorted by length, shortest sets first.
*
* This is mainly for the planner, but we use it here too to do
* some consistency checks.
*/
List *
expand_grouping_sets(List *groupingSets, int limit)
{
List *expanded_groups = NIL;
List *result = NIL;
double numsets = 1;
ListCell *lc;
if (groupingSets == NIL)
return NIL;
foreach(lc, groupingSets)
{
List *current_result = NIL;
GroupingSet *gs = lfirst(lc);
current_result = expand_groupingset_node(gs);
Assert(current_result != NIL);
numsets *= list_length(current_result);
if (limit >= 0 && numsets > limit)
return NIL;
expanded_groups = lappend(expanded_groups, current_result);
}
/*
* Do cartesian product between sublists of expanded_groups.
* While at it, remove any duplicate elements from individual
* grouping sets (we must NOT change the number of sets though)
*/
foreach(lc, (List *) linitial(expanded_groups))
{
result = lappend(result, list_union_int(NIL, (List *) lfirst(lc)));
}
for_each_cell(lc, lnext(list_head(expanded_groups)))
{
List *p = lfirst(lc);
List *new_result = NIL;
ListCell *lc2;
foreach(lc2, result)
{
List *q = lfirst(lc2);
ListCell *lc3;
foreach(lc3, p)
{
new_result = lappend(new_result,
list_union_int(q, (List *) lfirst(lc3)));
}
}
result = new_result;
}
if (list_length(result) > 1)
{
int result_len = list_length(result);
List **buf = palloc(sizeof(List*) * result_len);
List **ptr = buf;
foreach(lc, result)
{
*ptr++ = lfirst(lc);
}
qsort(buf, result_len, sizeof(List*), cmp_list_len_asc);
result = NIL;
ptr = buf;
while (result_len-- > 0)
result = lappend(result, *ptr++);
pfree(buf);
}
return result;
}
/*
* get_aggregate_argtypes
* Identify the specific datatypes passed to an aggregate call.