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mirror of https://github.com/postgres/postgres.git synced 2025-11-03 09:13:20 +03:00

Another round of planner/optimizer work. This is just restructuring and

code cleanup; no major improvements yet.  However, EXPLAIN does produce
more intuitive outputs for nested loops with indexscans now...
This commit is contained in:
Tom Lane
2000-01-09 00:26:47 +00:00
parent 69d4299e3e
commit 166b5c1def
35 changed files with 1239 additions and 1448 deletions

View File

@@ -9,7 +9,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/optimizer/plan/createplan.c,v 1.77 1999/11/23 20:06:57 momjian Exp $
* $Header: /cvsroot/pgsql/src/backend/optimizer/plan/createplan.c,v 1.78 2000/01/09 00:26:34 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -22,6 +22,7 @@
#include "optimizer/clauses.h"
#include "optimizer/cost.h"
#include "optimizer/internal.h"
#include "optimizer/paths.h"
#include "optimizer/planmain.h"
#include "optimizer/restrictinfo.h"
#include "optimizer/tlist.h"
@@ -31,12 +32,12 @@
static List *switch_outer(List *clauses);
static int set_tlist_sort_info(List *tlist, List *pathkeys);
static Scan *create_scan_node(Path *best_path, List *tlist);
static Join *create_join_node(JoinPath *best_path, List *tlist);
static Scan *create_scan_node(Query *root, Path *best_path, List *tlist);
static Join *create_join_node(Query *root, JoinPath *best_path, List *tlist);
static SeqScan *create_seqscan_node(Path *best_path, List *tlist,
List *scan_clauses);
static IndexScan *create_indexscan_node(IndexPath *best_path, List *tlist,
List *scan_clauses);
static IndexScan *create_indexscan_node(Query *root, IndexPath *best_path,
List *tlist, List *scan_clauses);
static TidScan *create_tidscan_node(TidPath *best_path, List *tlist,
List *scan_clauses);
static NestLoop *create_nestloop_node(NestPath *best_path, List *tlist,
@@ -49,10 +50,11 @@ static HashJoin *create_hashjoin_node(HashPath *best_path, List *tlist,
List *clauses, Plan *outer_node, List *outer_tlist,
Plan *inner_node, List *inner_tlist);
static List *fix_indxqual_references(List *indexquals, IndexPath *index_path);
static List *fix_indxqual_sublist(List *indexqual, IndexPath *index_path,
Form_pg_index index);
static Node *fix_indxqual_operand(Node *node, IndexPath *index_path,
static List *fix_indxqual_sublist(List *indexqual, int baserelid, Oid relam,
Form_pg_index index);
static Node *fix_indxqual_operand(Node *node, int baserelid,
Form_pg_index index,
Oid *opclass);
static IndexScan *make_indexscan(List *qptlist, List *qpqual, Index scanrelid,
List *indxid, List *indxqual, List *indxqualorig);
static TidScan *make_tidscan(List *qptlist, List *qpqual, Index scanrelid,
@@ -66,7 +68,8 @@ static MergeJoin *make_mergejoin(List *tlist, List *qpqual,
List *mergeclauses, Plan *righttree, Plan *lefttree);
static Material *make_material(List *tlist, Oid nonameid, Plan *lefttree,
int keycount);
static void copy_costsize(Plan *dest, Plan *src);
static void copy_path_costsize(Plan *dest, Path *src);
static void copy_plan_costsize(Plan *dest, Plan *src);
/*
* create_plan
@@ -84,46 +87,31 @@ static void copy_costsize(Plan *dest, Plan *src);
* Returns the access plan.
*/
Plan *
create_plan(Path *best_path)
create_plan(Query *root, Path *best_path)
{
List *tlist;
List *tlist = best_path->parent->targetlist;
Plan *plan_node = (Plan *) NULL;
RelOptInfo *parent_rel;
int size;
int width;
int pages;
int tuples;
parent_rel = best_path->parent;
tlist = parent_rel->targetlist;
size = parent_rel->size;
width = parent_rel->width;
pages = parent_rel->pages;
tuples = parent_rel->tuples;
switch (best_path->pathtype)
{
case T_IndexScan:
case T_SeqScan:
case T_TidScan:
plan_node = (Plan *) create_scan_node(best_path, tlist);
plan_node = (Plan *) create_scan_node(root, best_path, tlist);
break;
case T_HashJoin:
case T_MergeJoin:
case T_NestLoop:
plan_node = (Plan *) create_join_node((JoinPath *) best_path, tlist);
plan_node = (Plan *) create_join_node(root,
(JoinPath *) best_path,
tlist);
break;
default:
/* do nothing */
elog(ERROR, "create_plan: unknown pathtype %d",
best_path->pathtype);
break;
}
plan_node->plan_size = size;
plan_node->plan_width = width;
if (pages == 0)
pages = 1;
plan_node->plan_tupperpage = tuples / pages;
#ifdef NOT_USED /* fix xfunc */
/* sort clauses by cost/(1-selectivity) -- JMH 2/26/92 */
if (XfuncMode != XFUNC_OFF)
@@ -149,9 +137,8 @@ create_plan(Path *best_path)
* Returns the scan node.
*/
static Scan *
create_scan_node(Path *best_path, List *tlist)
create_scan_node(Query *root, Path *best_path, List *tlist)
{
Scan *node = NULL;
List *scan_clauses;
@@ -168,7 +155,8 @@ create_scan_node(Path *best_path, List *tlist)
break;
case T_IndexScan:
node = (Scan *) create_indexscan_node((IndexPath *) best_path,
node = (Scan *) create_indexscan_node(root,
(IndexPath *) best_path,
tlist,
scan_clauses);
break;
@@ -199,7 +187,7 @@ create_scan_node(Path *best_path, List *tlist)
* Returns the join node.
*/
static Join *
create_join_node(JoinPath *best_path, List *tlist)
create_join_node(Query *root, JoinPath *best_path, List *tlist)
{
Plan *outer_node;
List *outer_tlist;
@@ -208,13 +196,13 @@ create_join_node(JoinPath *best_path, List *tlist)
List *clauses;
Join *retval = NULL;
outer_node = create_plan((Path *) best_path->outerjoinpath);
outer_node = create_plan(root, best_path->outerjoinpath);
outer_tlist = outer_node->targetlist;
inner_node = create_plan((Path *) best_path->innerjoinpath);
inner_node = create_plan(root, best_path->innerjoinpath);
inner_tlist = inner_node->targetlist;
clauses = get_actual_clauses(best_path->pathinfo);
clauses = get_actual_clauses(best_path->path.parent->restrictinfo);
switch (best_path->path.pathtype)
{
@@ -280,20 +268,19 @@ create_join_node(JoinPath *best_path, List *tlist)
static SeqScan *
create_seqscan_node(Path *best_path, List *tlist, List *scan_clauses)
{
SeqScan *scan_node = (SeqScan *) NULL;
Index scan_relid = -1;
List *temp;
SeqScan *scan_node;
Index scan_relid;
temp = best_path->parent->relids;
/* there should be exactly one base rel involved... */
Assert(length(temp) == 1);
scan_relid = (Index) lfirsti(temp);
Assert(length(best_path->parent->relids) == 1);
scan_relid = (Index) lfirsti(best_path->parent->relids);
scan_node = make_seqscan(tlist,
scan_clauses,
scan_relid);
scan_node->plan.cost = best_path->path_cost;
copy_path_costsize(&scan_node->plan, best_path);
return scan_node;
}
@@ -312,7 +299,8 @@ create_seqscan_node(Path *best_path, List *tlist, List *scan_clauses)
* scan.
*/
static IndexScan *
create_indexscan_node(IndexPath *best_path,
create_indexscan_node(Query *root,
IndexPath *best_path,
List *tlist,
List *scan_clauses)
{
@@ -322,11 +310,12 @@ create_indexscan_node(IndexPath *best_path,
List *ixid;
IndexScan *scan_node;
bool lossy = false;
double plan_rows;
/* there should be exactly one base rel involved... */
Assert(length(best_path->path.parent->relids) == 1);
/* check and see if any of the indices are lossy */
/* check to see if any of the indices are lossy */
foreach(ixid, best_path->indexid)
{
HeapTuple indexTuple;
@@ -354,44 +343,72 @@ create_indexscan_node(IndexPath *best_path,
*
* Since the indexquals were generated from the restriction clauses
* given by scan_clauses, there will normally be some duplications
* between the lists. Get rid of the duplicates, then add back if lossy.
* between the lists. We get rid of the duplicates, then add back
* if lossy.
*
* If this indexscan is a nestloop-join inner indexscan (as indicated
* by having nonempty joinrelids), then it uses indexqual conditions
* that are not part of the relation's restriction clauses. The rows
* estimate stored in the relation's RelOptInfo will be an overestimate
* because it did not take these extra conditions into account. So,
* in this case we recompute the selectivity of the whole scan ---
* considering both indexqual and qpqual --- rather than using the
* RelOptInfo's rows value. Since clausesel.c assumes it's working on
* minimized (no duplicates) expressions, we have to do that while we
* have the duplicate-free qpqual available.
*/
plan_rows = best_path->path.parent->rows; /* OK unless nestloop inner */
if (length(indxqual) > 1)
{
/*
* Build an expression representation of the indexqual, expanding
* the implicit OR and AND semantics of the first- and second-level
* lists. XXX Is it really necessary to do a deep copy here?
* lists.
*/
List *orclauses = NIL;
List *orclause;
Expr *indxqual_expr;
foreach(orclause, indxqual)
{
orclauses = lappend(orclauses,
make_ands_explicit((List *) copyObject(lfirst(orclause))));
}
make_ands_explicit(lfirst(orclause)));
indxqual_expr = make_orclause(orclauses);
/* this set_difference is almost certainly a waste of time... */
qpqual = set_difference(scan_clauses,
lcons(indxqual_expr, NIL));
if (best_path->joinrelids)
{
/* recompute output row estimate using all available quals */
plan_rows = best_path->path.parent->tuples *
clauselist_selec(root, lcons(indxqual_expr, qpqual));
}
if (lossy)
qpqual = lappend(qpqual, indxqual_expr);
qpqual = lappend(qpqual, copyObject(indxqual_expr));
}
else if (indxqual != NIL)
{
/* Here, we can simply treat the first sublist as an independent
* set of qual expressions, since there is no top-level OR behavior.
*/
qpqual = set_difference(scan_clauses, lfirst(indxqual));
List *indxqual_list = lfirst(indxqual);
qpqual = set_difference(scan_clauses, indxqual_list);
if (best_path->joinrelids)
{
/* recompute output row estimate using all available quals */
plan_rows = best_path->path.parent->tuples *
clauselist_selec(root, nconc(listCopy(indxqual_list), qpqual));
}
if (lossy)
qpqual = nconc(qpqual, (List *) copyObject(lfirst(indxqual)));
qpqual = nconc(qpqual, (List *) copyObject(indxqual_list));
}
else
qpqual = NIL;
qpqual = scan_clauses;
/* The executor needs a copy with the indexkey on the left of each clause
* and with index attr numbers substituted for table ones.
@@ -405,7 +422,8 @@ create_indexscan_node(IndexPath *best_path,
fixed_indxqual,
indxqual);
scan_node->scan.plan.cost = best_path->path.path_cost;
copy_path_costsize(&scan_node->scan.plan, &best_path->path);
scan_node->scan.plan.plan_rows = plan_rows;
return scan_node;
}
@@ -416,11 +434,11 @@ make_tidscan(List *qptlist,
Index scanrelid,
List *tideval)
{
TidScan *node = makeNode(TidScan);
TidScan *node = makeNode(TidScan);
Plan *plan = &node->scan.plan;
plan->cost = 0;
plan->plan_size = 0;
plan->plan_rows = 0;
plan->plan_width = 0;
plan->state = (EState *) NULL;
plan->targetlist = qptlist;
@@ -428,7 +446,7 @@ make_tidscan(List *qptlist,
plan->lefttree = NULL;
plan->righttree = NULL;
node->scan.scanrelid = scanrelid;
node->tideval = copyObject(tideval);
node->tideval = copyObject(tideval); /* XXX do we really need a copy? */
node->needRescan = false;
node->scan.scanstate = (CommonScanState *) NULL;
@@ -443,25 +461,23 @@ make_tidscan(List *qptlist,
static TidScan *
create_tidscan_node(TidPath *best_path, List *tlist, List *scan_clauses)
{
TidScan *scan_node = (TidScan *) NULL;
Index scan_relid = -1;
List *temp;
TidScan *scan_node;
Index scan_relid;
/* there should be exactly one base rel involved... */
Assert(length(best_path->path.parent->relids) == 1);
scan_relid = (Index) lfirsti(best_path->path.parent->relids);
temp = best_path->path.parent->relids;
if (temp == NULL)
elog(ERROR, "scanrelid is empty");
else if (length(temp) != 1)
return scan_node;
else
scan_relid = (Index) lfirsti(temp);
scan_node = make_tidscan(tlist,
scan_clauses,
scan_relid,
best_path->tideval);
scan_clauses,
scan_relid,
best_path->tideval);
if (best_path->unjoined_relids)
scan_node->needRescan = true;
scan_node->scan.plan.cost = best_path->path.path_cost;
copy_path_costsize(&scan_node->scan.plan, &best_path->path);
return scan_node;
}
@@ -581,7 +597,7 @@ create_nestloop_node(NestPath *best_path,
outer_node,
inner_node);
join_node->join.cost = best_path->path.path_cost;
copy_path_costsize(&join_node->join, &best_path->path);
return join_node;
}
@@ -639,7 +655,7 @@ create_mergejoin_node(MergePath *best_path,
inner_node,
outer_node);
join_node->join.cost = best_path->jpath.path.path_cost;
copy_path_costsize(&join_node->join, &best_path->jpath.path);
return join_node;
}
@@ -699,7 +715,7 @@ create_hashjoin_node(HashPath *best_path,
outer_node,
(Plan *) hash_node);
join_node->join.cost = best_path->jpath.path.path_cost;
copy_path_costsize(&join_node->join, &best_path->jpath.path);
return join_node;
}
@@ -713,10 +729,18 @@ create_hashjoin_node(HashPath *best_path,
/*
* fix_indxqual_references
* Adjust indexqual clauses to refer to index attributes instead of the
* attributes of the original relation. Also, commute clauses if needed
* to put the indexkey on the left. (Someday the executor might not need
* that, but for now it does.)
* Adjust indexqual clauses to the form the executor's indexqual
* machinery needs.
*
* We have three tasks here:
* * Var nodes representing index keys must have varattno equal to the
* index's attribute number, not the attribute number in the original rel.
* * indxpath.c may have selected an index that is binary-compatible with
* the actual expression operator, but not the same; we must replace the
* expression's operator with the binary-compatible equivalent operator
* that the index will recognize.
* * If the index key is on the right, commute the clause to put it on the
* left. (Someday the executor might not need this, but for now it does.)
*
* This code used to be entirely bogus for multi-index scans. Now it keeps
* track of which index applies to each subgroup of index qual clauses...
@@ -729,6 +753,7 @@ static List *
fix_indxqual_references(List *indexquals, IndexPath *index_path)
{
List *fixed_quals = NIL;
int baserelid = lfirsti(index_path->path.parent->relids);
List *indexids = index_path->indexid;
List *i;
@@ -737,19 +762,31 @@ fix_indxqual_references(List *indexquals, IndexPath *index_path)
List *indexqual = lfirst(i);
Oid indexid = lfirsti(indexids);
HeapTuple indexTuple;
Oid relam;
Form_pg_index index;
/* Get the relam from the index's pg_class entry */
indexTuple = SearchSysCacheTuple(RELOID,
ObjectIdGetDatum(indexid),
0, 0, 0);
if (!HeapTupleIsValid(indexTuple))
elog(ERROR, "fix_indxqual_references: index %u not found in pg_class",
indexid);
relam = ((Form_pg_class) GETSTRUCT(indexTuple))->relam;
/* Need the index's pg_index entry for other stuff */
indexTuple = SearchSysCacheTuple(INDEXRELID,
ObjectIdGetDatum(indexid),
0, 0, 0);
if (!HeapTupleIsValid(indexTuple))
elog(ERROR, "fix_indxqual_references: index %u not found",
elog(ERROR, "fix_indxqual_references: index %u not found in pg_index",
indexid);
index = (Form_pg_index) GETSTRUCT(indexTuple);
fixed_quals = lappend(fixed_quals,
fix_indxqual_sublist(indexqual,
index_path,
baserelid,
relam,
index));
indexids = lnext(indexids);
@@ -761,11 +798,11 @@ fix_indxqual_references(List *indexquals, IndexPath *index_path)
* Fix the sublist of indexquals to be used in a particular scan.
*
* For each qual clause, commute if needed to put the indexkey operand on the
* left, and then change its varno. We do not need to change the other side
* of the clause.
* left, and then change its varno. (We do not need to change the other side
* of the clause.) Also change the operator if necessary.
*/
static List *
fix_indxqual_sublist(List *indexqual, IndexPath *index_path,
fix_indxqual_sublist(List *indexqual, int baserelid, Oid relam,
Form_pg_index index)
{
List *fixed_qual = NIL;
@@ -779,6 +816,8 @@ fix_indxqual_sublist(List *indexqual, IndexPath *index_path,
Datum constval;
int flag;
Expr *newclause;
Oid opclass,
newopno;
if (!is_opclause((Node *) clause) ||
length(clause->args) != 2)
@@ -788,8 +827,7 @@ fix_indxqual_sublist(List *indexqual, IndexPath *index_path,
*
* get_relattval sets flag&SEL_RIGHT if the indexkey is on the LEFT.
*/
get_relattval((Node *) clause,
lfirsti(index_path->path.parent->relids),
get_relattval((Node *) clause, baserelid,
&relid, &attno, &constval, &flag);
/* Copy enough structure to allow commuting and replacing an operand
@@ -802,10 +840,27 @@ fix_indxqual_sublist(List *indexqual, IndexPath *index_path,
if ((flag & SEL_RIGHT) == 0)
CommuteClause(newclause);
/* Now, change the indexkey operand as needed. */
/* Now, determine which index attribute this is,
* change the indexkey operand as needed,
* and get the index opclass.
*/
lfirst(newclause->args) = fix_indxqual_operand(lfirst(newclause->args),
index_path,
index);
baserelid,
index,
&opclass);
/* Substitute the appropriate operator if the expression operator
* is merely binary-compatible with the index. This shouldn't fail,
* since indxpath.c found it before...
*/
newopno = indexable_operator(newclause, opclass, relam, true);
if (newopno == InvalidOid)
elog(ERROR, "fix_indxqual_sublist: failed to find substitute op");
if (newopno != ((Oper *) newclause->oper)->opno)
{
newclause->oper = (Node *) copyObject(newclause->oper);
((Oper *) newclause->oper)->opno = newopno;
}
fixed_qual = lappend(fixed_qual, newclause);
}
@@ -813,12 +868,12 @@ fix_indxqual_sublist(List *indexqual, IndexPath *index_path,
}
static Node *
fix_indxqual_operand(Node *node, IndexPath *index_path,
Form_pg_index index)
fix_indxqual_operand(Node *node, int baserelid, Form_pg_index index,
Oid *opclass)
{
if (IsA(node, Var))
{
if (((Var *) node)->varno == lfirsti(index_path->path.parent->relids))
if (((Var *) node)->varno == baserelid)
{
int varatt = ((Var *) node)->varattno;
int pos;
@@ -829,6 +884,7 @@ fix_indxqual_operand(Node *node, IndexPath *index_path,
{
Node *newnode = copyObject(node);
((Var *) newnode)->varattno = pos + 1;
*opclass = index->indclass[pos];
return newnode;
}
}
@@ -851,6 +907,9 @@ fix_indxqual_operand(Node *node, IndexPath *index_path,
* misbehaves...)
*/
/* indclass[0] is the only class of a functional index */
*opclass = index->indclass[0];
/* return the unmodified node */
return node;
}
@@ -963,24 +1022,45 @@ set_tlist_sort_info(List *tlist, List *pathkeys)
return keysassigned;
}
/*
* Copy cost and size info from a Path node to the Plan node created from it.
* The executor won't use this info, but it's needed by EXPLAIN.
*/
static void
copy_path_costsize(Plan *dest, Path *src)
{
if (src)
{
dest->cost = src->path_cost;
dest->plan_rows = src->parent->rows;
dest->plan_width = src->parent->width;
}
else
{
dest->cost = 0;
dest->plan_rows = 0;
dest->plan_width = 0;
}
}
/*
* Copy cost and size info from a lower plan node to an inserted node.
* This is not critical, since the decisions have already been made,
* but it helps produce more reasonable-looking EXPLAIN output.
*/
static void
copy_costsize(Plan *dest, Plan *src)
copy_plan_costsize(Plan *dest, Plan *src)
{
if (src)
{
dest->cost = src->cost;
dest->plan_size = src->plan_size;
dest->plan_rows = src->plan_rows;
dest->plan_width = src->plan_width;
}
else
{
dest->cost = 0;
dest->plan_size = 0;
dest->plan_rows = 0;
dest->plan_width = 0;
}
}
@@ -1042,7 +1122,7 @@ make_seqscan(List *qptlist,
SeqScan *node = makeNode(SeqScan);
Plan *plan = &node->plan;
copy_costsize(plan, NULL);
copy_plan_costsize(plan, NULL);
plan->state = (EState *) NULL;
plan->targetlist = qptlist;
plan->qual = qpqual;
@@ -1065,7 +1145,7 @@ make_indexscan(List *qptlist,
IndexScan *node = makeNode(IndexScan);
Plan *plan = &node->scan.plan;
copy_costsize(plan, NULL);
copy_plan_costsize(plan, NULL);
plan->state = (EState *) NULL;
plan->targetlist = qptlist;
plan->qual = qpqual;
@@ -1140,7 +1220,7 @@ make_hash(List *tlist, Var *hashkey, Plan *lefttree)
Hash *node = makeNode(Hash);
Plan *plan = &node->plan;
copy_costsize(plan, lefttree);
copy_plan_costsize(plan, lefttree);
plan->state = (EState *) NULL;
plan->targetlist = tlist;
plan->qual = NULL;
@@ -1183,8 +1263,8 @@ make_sort(List *tlist, Oid nonameid, Plan *lefttree, int keycount)
Sort *node = makeNode(Sort);
Plan *plan = &node->plan;
copy_costsize(plan, lefttree);
plan->cost += cost_sort(NULL, plan->plan_size, plan->plan_width);
copy_plan_costsize(plan, lefttree);
plan->cost += cost_sort(NIL, plan->plan_rows, plan->plan_width);
plan->state = (EState *) NULL;
plan->targetlist = tlist;
plan->qual = NIL;
@@ -1205,7 +1285,7 @@ make_material(List *tlist,
Material *node = makeNode(Material);
Plan *plan = &node->plan;
copy_costsize(plan, lefttree);
copy_plan_costsize(plan, lefttree);
plan->state = (EState *) NULL;
plan->targetlist = tlist;
plan->qual = NIL;
@@ -1222,7 +1302,7 @@ make_agg(List *tlist, Plan *lefttree)
{
Agg *node = makeNode(Agg);
copy_costsize(&node->plan, lefttree);
copy_plan_costsize(&node->plan, lefttree);
node->plan.state = (EState *) NULL;
node->plan.qual = NULL;
node->plan.targetlist = tlist;
@@ -1241,7 +1321,7 @@ make_group(List *tlist,
{
Group *node = makeNode(Group);
copy_costsize(&node->plan, lefttree);
copy_plan_costsize(&node->plan, lefttree);
node->plan.state = (EState *) NULL;
node->plan.qual = NULL;
node->plan.targetlist = tlist;
@@ -1266,7 +1346,7 @@ make_unique(List *tlist, Plan *lefttree, char *uniqueAttr)
Unique *node = makeNode(Unique);
Plan *plan = &node->plan;
copy_costsize(plan, lefttree);
copy_plan_costsize(plan, lefttree);
plan->state = (EState *) NULL;
plan->targetlist = tlist;
plan->qual = NIL;
@@ -1292,7 +1372,7 @@ make_result(List *tlist,
#ifdef NOT_USED
tlist = generate_fjoin(tlist);
#endif
copy_costsize(plan, subplan);
copy_plan_costsize(plan, subplan);
plan->state = (EState *) NULL;
plan->targetlist = tlist;
plan->qual = NIL;