*
*
* IDENTIFICATION
- * $Header: /cvsroot/pgsql/src/backend/optimizer/plan/planner.c,v 1.47 1999/04/19 01:43:11 tgl Exp $
+ * $Header: /cvsroot/pgsql/src/backend/optimizer/plan/planner.c,v 1.48 1999/05/03 00:38:43 tgl Exp $
*
*-------------------------------------------------------------------------
*/
#include "access/genam.h"
#include "parser/parse_oper.h"
+static List *make_subplanTargetList(Query *parse, List *tlist,
+ AttrNumber **groupColIdx);
+static Plan *make_groupplan(List *group_tlist, bool tuplePerGroup,
+ List *groupClause, AttrNumber *grpColIdx,
+ Plan *subplan);
static bool need_sortplan(List *sortcls, Plan *plan);
static Plan *make_sortplan(List *tlist, List *sortcls, Plan *plannode);
-extern Plan *make_groupPlan(List **tlist, bool tuplePerGroup,
- List *groupClause, Plan *subplan);
/*****************************************************************************
*
union_planner(Query *parse)
{
List *tlist = parse->targetList;
-
- /***S*H***/
- /* copy the original tlist, we will need the original one
- * for the AGG node later on */
- List *new_tlist = new_unsorted_tlist(tlist);
-
List *rangetable = parse->rtable;
-
Plan *result_plan = (Plan *) NULL;
-
+ AttrNumber *groupColIdx = NULL;
Index rt_index;
if (parse->unionClause)
else
{
List **vpm = NULL;
+ List *sub_tlist;
- /*
- * If there is a HAVING clause, make sure all vars referenced in it
- * are included in the target list for query_planner().
- */
- if (parse->havingQual)
- new_tlist = check_having_qual_for_vars(parse->havingQual, new_tlist);
-
- new_tlist = preprocess_targetlist(new_tlist,
- parse->commandType,
- parse->resultRelation,
- parse->rtable);
+ /* Preprocess targetlist in case we are inside an INSERT/UPDATE. */
+ tlist = preprocess_targetlist(tlist,
+ parse->commandType,
+ parse->resultRelation,
+ parse->rtable);
- /* FOR UPDATE ... */
+ /* Add row-mark targets for UPDATE
+ * (should this be done in preprocess_targetlist?)
+ */
if (parse->rowMark != NULL)
{
List *l;
- TargetEntry *ctid;
- Resdom *resdom;
- Var *var;
- char *resname;
foreach (l, parse->rowMark)
{
- if (!(((RowMark*)lfirst(l))->info & ROW_MARK_FOR_UPDATE))
+ RowMark *rowmark = (RowMark*) lfirst(l);
+ TargetEntry *ctid;
+ Resdom *resdom;
+ Var *var;
+ char *resname;
+
+ if (!(rowmark->info & ROW_MARK_FOR_UPDATE))
continue;
resname = (char*) palloc(32);
- sprintf(resname, "ctid%u", ((RowMark*)lfirst(l))->rti);
- resdom = makeResdom(length(new_tlist) + 1,
+ sprintf(resname, "ctid%u", rowmark->rti);
+ resdom = makeResdom(length(tlist) + 1,
TIDOID,
-1,
resname,
0,
1);
- var = makeVar(((RowMark*)lfirst(l))->rti, -1, TIDOID,
- -1, 0, ((RowMark*)lfirst(l))->rti, -1);
+ var = makeVar(rowmark->rti, -1, TIDOID,
+ -1, 0, rowmark->rti, -1);
ctid = makeTargetEntry(resdom, (Node *) var);
- new_tlist = lappend(new_tlist, ctid);
+ tlist = lappend(tlist, ctid);
}
}
-
- /* Here starts the original (pre having) code */
- tlist = preprocess_targetlist(tlist,
- parse->commandType,
- parse->resultRelation,
- parse->rtable);
-
+
+ /* Generate appropriate target list for subplan; may be different
+ * from tlist if grouping or aggregation is needed.
+ */
+ sub_tlist = make_subplanTargetList(parse, tlist, &groupColIdx);
+
+ /* Generate the (sub) plan */
if (parse->rtable != NULL)
{
vpm = (List **) palloc(length(parse->rtable) * sizeof(List *));
}
PlannerVarParam = lcons(vpm, PlannerVarParam);
result_plan = query_planner(parse,
- parse->commandType,
- new_tlist,
- (List *) parse->qual);
+ parse->commandType,
+ sub_tlist,
+ (List *) parse->qual);
PlannerVarParam = lnext(PlannerVarParam);
if (vpm != NULL)
pfree(vpm);
if (parse->groupClause)
{
bool tuplePerGroup;
+ List *group_tlist;
/*
- * decide whether how many tuples per group the Group node needs
+ * Decide whether how many tuples per group the Group node needs
* to return. (Needs only one tuple per group if no aggregate is
* present. Otherwise, need every tuple from the group to do the
- * aggregation.)
+ * aggregation.) Note tuplePerGroup is named backwards :-(
*/
tuplePerGroup = parse->hasAggs;
- /***S*H***/
- /* Use 'new_tlist' instead of 'tlist' */
- result_plan = make_groupPlan(&new_tlist,
- tuplePerGroup,
- parse->groupClause,
- result_plan);
+ /* If there are aggregates then the Group node should just return
+ * the same (simplified) tlist as the subplan, which we indicate
+ * to make_groupplan by passing NIL. If there are no aggregates
+ * then the Group node had better compute the final tlist.
+ */
+ group_tlist = parse->hasAggs ? NIL : tlist;
+
+ result_plan = make_groupplan(group_tlist,
+ tuplePerGroup,
+ parse->groupClause,
+ groupColIdx,
+ result_plan);
}
/*
*/
if (parse->hasAggs)
{
- /* Use 'tlist' not 'new_tlist' as target list because we
- * don't want the additional attributes used for the havingQual
- * (see above) to show up in the result
- */
result_plan = (Plan *) make_agg(tlist, result_plan);
/* HAVING clause, if any, becomes qual of the Agg node */
*/
if (! set_agg_tlist_references((Agg *) result_plan))
elog(ERROR, "SELECT/HAVING requires aggregates to be valid");
+
+ /*
+ * Check that we actually found some aggregates, else executor
+ * will die unpleasantly. (The rewrite module currently has bugs
+ * that allow hasAggs to be incorrectly set 'true' sometimes.
+ * It's not easy to recover here, since we've already made decisions
+ * assuming there will be an Agg node.)
+ */
+ if (((Agg *) result_plan)->aggs == NIL)
+ elog(ERROR, "union_planner: query is marked hasAggs, but I don't see any");
}
/*
}
+/*---------------
+ * make_subplanTargetList
+ * Generate appropriate target lists when grouping is required.
+ *
+ * When union_planner inserts Aggregate and/or Group/Sort plan nodes above
+ * the result of query_planner, we typically need to pass a different
+ * target list to query_planner than the outer plan nodes should have.
+ * This routine generates the correct target list for the subplan, and
+ * if necessary modifies the target list for the inserted nodes as well.
+ *
+ * The initial target list passed from the parser already contains entries
+ * for all ORDER BY and GROUP BY expressions, but it will not have entries
+ * for variables used only in HAVING clauses; so we need to add those
+ * variables to the subplan target list. Also, if we are doing either
+ * grouping or aggregation, we flatten all expressions except GROUP BY items
+ * into their component variables; the other expressions will be computed by
+ * the inserted nodes rather than by the subplan. For example,
+ * given a query like
+ * SELECT a+b,SUM(c+d) FROM table GROUP BY a+b;
+ * we want to pass this targetlist to the subplan:
+ * a+b,c,d
+ * where the a+b target will be used by the Sort/Group steps, and the
+ * c and d targets will be needed to compute the aggregate results.
+ *
+ * 'parse' is the query being processed.
+ * 'tlist' is the query's target list. CAUTION: list elements may be
+ * modified by this routine!
+ * 'groupColIdx' receives an array of column numbers for the GROUP BY
+ * expressions (if there are any) in the subplan's target list.
+ *
+ * The result is the targetlist to be passed to the subplan. Also,
+ * the parent tlist is modified so that any nontrivial targetlist items that
+ * exactly match GROUP BY items are replaced by simple Var nodes referencing
+ * those outputs of the subplan. This avoids redundant recalculations in
+ * cases like
+ * SELECT a+1, ... GROUP BY a+1
+ * Note, however, that other varnodes in the parent's targetlist (and
+ * havingQual, if any) will still need to be updated to refer to outputs
+ * of the subplan. This routine is quite large enough already, so we do
+ * that later.
+ *---------------
+ */
+static List *
+make_subplanTargetList(Query *parse,
+ List *tlist,
+ AttrNumber **groupColIdx)
+{
+ List *sub_tlist;
+ List *prnt_tlist;
+ List *sl,
+ *gl;
+ List *glc = NIL;
+ List *extravars = NIL;
+ int numCols;
+ AttrNumber *grpColIdx = NULL;
+ int next_resno = 1;
+
+ *groupColIdx = NULL;
+
+ /* If we're not grouping or aggregating, nothing to do here;
+ * query_planner should receive the unmodified target list.
+ */
+ if (!parse->hasAggs && !parse->groupClause && !parse->havingQual)
+ return tlist;
+
+ /* If grouping, make a working copy of groupClause list (which we use
+ * just to verify that we found all the groupClause items in tlist).
+ * Also allocate space to remember where the group columns are in the
+ * subplan tlist.
+ */
+ numCols = length(parse->groupClause);
+ if (numCols > 0)
+ {
+ glc = listCopy(parse->groupClause);
+ grpColIdx = (AttrNumber *) palloc(sizeof(AttrNumber) * numCols);
+ *groupColIdx = grpColIdx;
+ }
+
+ sub_tlist = new_unsorted_tlist(tlist); /* make a modifiable copy */
+
+ /*
+ * Step 1: build grpColIdx by finding targetlist items that match
+ * GroupBy entries. If there are aggregates, remove non-GroupBy items
+ * from sub_tlist, and reset its resnos accordingly. When we leave an
+ * expression in the subplan tlist, modify the parent tlist to copy the
+ * value from the subplan output rather than re-evaluating it.
+ */
+ prnt_tlist = tlist; /* scans parent tlist in sync with sl */
+ foreach(sl, sub_tlist)
+ {
+ TargetEntry *te = (TargetEntry *) lfirst(sl);
+ TargetEntry *parentte = (TargetEntry *) lfirst(prnt_tlist);
+ Resdom *resdom = te->resdom;
+ bool keepInSubPlan = true;
+ bool foundGroupClause = false;
+ int keyno = 0;
+
+ foreach(gl, parse->groupClause)
+ {
+ GroupClause *grpcl = (GroupClause *) lfirst(gl);
+
+ keyno++; /* sort key # for this GroupClause */
+ /* Is it safe to use just resno to match tlist and glist items?? */
+ if (grpcl->entry->resdom->resno == resdom->resno)
+ {
+ /* Found a matching groupclause; record info for sorting */
+ foundGroupClause = true;
+ resdom->reskey = keyno;
+ resdom->reskeyop = get_opcode(grpcl->grpOpoid);
+ grpColIdx[keyno - 1] = next_resno;
+ /* Remove groupclause from our list of unmatched groupclauses.
+ * NB: this depends on having used a shallow listCopy() above.
+ */
+ glc = lremove((void*) grpcl, glc);
+ break;
+ }
+ }
+
+ if (! foundGroupClause)
+ {
+ /*
+ * Non-GroupBy entry: remove it from subplan if there are
+ * aggregates in query - it will be evaluated by Aggregate plan.
+ * But do not remove simple-Var entries; we'd just have to add
+ * them back anyway, and we risk confusing INSERT/UPDATE.
+ */
+ if (parse->hasAggs && ! IsA(te->expr, Var))
+ keepInSubPlan = false;
+ }
+
+ if (keepInSubPlan)
+ {
+ /* Assign new sequential resnos to subplan tlist items */
+ resdom->resno = next_resno++;
+ if (! IsA(parentte->expr, Var))
+ {
+ /* Since the item is being computed in the subplan,
+ * we can just make a Var node to reference it in the
+ * outer plan, rather than recomputing it there.
+ * Note we use varnoold = -1 as a flag to let
+ * replace_vars_with_subplan_refs know it needn't change
+ * this Var node.
+ * If it's only a Var anyway, we leave it alone for now;
+ * replace_vars_with_subplan_refs will fix it later.
+ */
+ parentte->expr = (Node *) makeVar(1, resdom->resno,
+ resdom->restype,
+ resdom->restypmod,
+ 0, -1, resdom->resno);
+ }
+ }
+ else
+ {
+ /* Remove this tlist item from the subplan, but remember the
+ * vars it needs. The outer tlist item probably needs changes,
+ * but that will happen later.
+ */
+ sub_tlist = lremove(te, sub_tlist);
+ extravars = nconc(extravars, pull_var_clause(te->expr));
+ }
+
+ prnt_tlist = lnext(prnt_tlist);
+ }
+
+ /* We should have found all the GROUP BY clauses in the tlist. */
+ if (length(glc) != 0)
+ elog(ERROR, "make_subplanTargetList: GROUP BY attribute not found in target list");
+
+ /*
+ * Add subplan targets for any variables needed by removed tlist entries
+ * that aren't otherwise mentioned in the subplan target list.
+ * We'll also need targets for any variables seen only in HAVING.
+ */
+ extravars = nconc(extravars, pull_var_clause(parse->havingQual));
+
+ foreach(gl, extravars)
+ {
+ Var *v = (Var *) lfirst(gl);
+
+ if (tlist_member(v, sub_tlist) == NULL)
+ {
+ sub_tlist = lappend(sub_tlist,
+ create_tl_element(v, next_resno));
+ next_resno++;
+ }
+ }
+
+ return sub_tlist;
+}
+
+static Plan *
+make_groupplan(List *group_tlist,
+ bool tuplePerGroup,
+ List *groupClause,
+ AttrNumber *grpColIdx,
+ Plan *subplan)
+{
+ List *sort_tlist;
+ List *sl;
+ Sort *sortplan;
+ Group *grpplan;
+ int numCols = length(groupClause);
+
+ /*
+ * Make the targetlist for the Sort node; it always just references
+ * each of the corresponding target items of the subplan. We need to
+ * ensure that simple Vars in the subplan's target list are recognizable
+ * by replace_vars_with_subplan_refs when it's applied to the Sort/Group
+ * target list, so copy up their varnoold/varoattno.
+ */
+ sort_tlist = NIL;
+ foreach(sl, subplan->targetlist)
+ {
+ TargetEntry *te = (TargetEntry *) lfirst(sl);
+ Resdom *resdom = te->resdom;
+ Var *newvar;
+
+ if (IsA(te->expr, Var))
+ {
+ Var *subvar = (Var *) te->expr;
+ newvar = makeVar(1, resdom->resno,
+ resdom->restype, resdom->restypmod,
+ 0, subvar->varnoold, subvar->varoattno);
+ }
+ else
+ {
+ newvar = makeVar(1, resdom->resno,
+ resdom->restype, resdom->restypmod,
+ 0, -1, resdom->resno);
+ }
+
+ sort_tlist = lappend(sort_tlist,
+ makeTargetEntry((Resdom *) copyObject(resdom),
+ (Node *) newvar));
+ }
+
+ /*
+ * Make the Sort node
+ */
+ sortplan = make_sort(sort_tlist,
+ _NONAME_RELATION_ID_,
+ subplan,
+ numCols);
+ sortplan->plan.cost = subplan->cost; /* XXX assume no cost */
+
+ /*
+ * If the caller gave us a target list, use it after fixing the variables.
+ * If not, we need the same sort of "repeater" tlist as for the Sort node.
+ */
+ if (group_tlist)
+ {
+ group_tlist = copyObject(group_tlist); /* necessary?? */
+ replace_tlist_with_subplan_refs(group_tlist,
+ (Index) 0,
+ subplan->targetlist);
+ }
+ else
+ {
+ group_tlist = copyObject(sort_tlist);
+ }
+
+ /*
+ * Make the Group node
+ */
+ grpplan = make_group(group_tlist, tuplePerGroup, numCols,
+ grpColIdx, sortplan);
+
+ return (Plan *) grpplan;
+}
+
/*
* make_sortplan
* Returns a sortplan which is basically a SORT node attached to the
* the final query in the function. We do some ad-hoc define-time
* type checking here to be sure that the user is returning the
* type he claims.
+ *
+ * XXX Why is this function in this module?
*/
void
pg_checkretval(Oid rettype, QueryTreeList *queryTreeList)
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