Header And Logo
|
#include "postgres.h"#include "catalog/pg_operator.h"#include "nodes/makefuncs.h"#include "optimizer/clauses.h"#include "optimizer/cost.h"#include "optimizer/pathnode.h"#include "optimizer/plancat.h"#include "utils/fmgroids.h"#include "utils/lsyscache.h"#include "utils/selfuncs.h"
Go to the source code of this file.
Data Structures | |
| struct | RangeQueryClause |
Typedefs | |
| typedef struct RangeQueryClause | RangeQueryClause |
Functions | |
| static void | addRangeClause (RangeQueryClause **rqlist, Node *clause, bool varonleft, bool isLTsel, Selectivity s2) |
| Selectivity | clauselist_selectivity (PlannerInfo *root, List *clauses, int varRelid, JoinType jointype, SpecialJoinInfo *sjinfo) |
| static bool | bms_is_subset_singleton (const Bitmapset *s, int x) |
| static bool | treat_as_join_clause (Node *clause, RestrictInfo *rinfo, int varRelid, SpecialJoinInfo *sjinfo) |
| Selectivity | clause_selectivity (PlannerInfo *root, Node *clause, int varRelid, JoinType jointype, SpecialJoinInfo *sjinfo) |
| typedef struct RangeQueryClause RangeQueryClause |
| static void addRangeClause | ( | RangeQueryClause ** | rqlist, | |
| Node * | clause, | |||
| bool | varonleft, | |||
| bool | isLTsel, | |||
| Selectivity | s2 | |||
| ) | [static] |
Definition at line 287 of file clausesel.c.
References equal(), get_leftop(), get_rightop(), RangeQueryClause::have_hibound, RangeQueryClause::have_lobound, RangeQueryClause::hibound, RangeQueryClause::lobound, RangeQueryClause::next, palloc(), and RangeQueryClause::var.
Referenced by clauselist_selectivity().
{
RangeQueryClause *rqelem;
Node *var;
bool is_lobound;
if (varonleft)
{
var = get_leftop((Expr *) clause);
is_lobound = !isLTsel; /* x < something is high bound */
}
else
{
var = get_rightop((Expr *) clause);
is_lobound = isLTsel; /* something < x is low bound */
}
for (rqelem = *rqlist; rqelem; rqelem = rqelem->next)
{
/*
* We use full equal() here because the "var" might be a function of
* one or more attributes of the same relation...
*/
if (!equal(var, rqelem->var))
continue;
/* Found the right group to put this clause in */
if (is_lobound)
{
if (!rqelem->have_lobound)
{
rqelem->have_lobound = true;
rqelem->lobound = s2;
}
else
{
/*------
* We have found two similar clauses, such as
* x < y AND x < z.
* Keep only the more restrictive one.
*------
*/
if (rqelem->lobound > s2)
rqelem->lobound = s2;
}
}
else
{
if (!rqelem->have_hibound)
{
rqelem->have_hibound = true;
rqelem->hibound = s2;
}
else
{
/*------
* We have found two similar clauses, such as
* x > y AND x > z.
* Keep only the more restrictive one.
*------
*/
if (rqelem->hibound > s2)
rqelem->hibound = s2;
}
}
return;
}
/* No matching var found, so make a new clause-pair data structure */
rqelem = (RangeQueryClause *) palloc(sizeof(RangeQueryClause));
rqelem->var = var;
if (is_lobound)
{
rqelem->have_lobound = true;
rqelem->have_hibound = false;
rqelem->lobound = s2;
}
else
{
rqelem->have_lobound = false;
rqelem->have_hibound = true;
rqelem->hibound = s2;
}
rqelem->next = *rqlist;
*rqlist = rqelem;
}
Definition at line 385 of file clausesel.c.
References BMS_EMPTY_SET, bms_is_member(), bms_membership(), BMS_MULTIPLE, and BMS_SINGLETON.
Referenced by clause_selectivity().
{
switch (bms_membership(s))
{
case BMS_EMPTY_SET:
return true;
case BMS_SINGLETON:
return bms_is_member(x, s);
case BMS_MULTIPLE:
return false;
}
/* can't get here... */
return false;
}
| Selectivity clause_selectivity | ( | PlannerInfo * | root, | |
| Node * | clause, | |||
| int | varRelid, | |||
| JoinType | jointype, | |||
| SpecialJoinInfo * | sjinfo | |||
| ) |
Definition at line 484 of file clausesel.c.
References and_clause(), arg, OpExpr::args, bms_is_subset_singleton(), BooleanEqualOperator, booltestsel(), RestrictInfo::clause, RestrictInfo::clause_relids, clause_selectivity(), clauselist_selectivity(), Const::constisnull, Const::constvalue, CurrentOfExpr::cvarno, DatumGetBool, DEBUG4, elog, estimate_expression_value(), find_base_rel(), get_notclausearg(), OpExpr::inputcollid, InvalidOid, is_funcclause, is_opclause, IsA, JOIN_INNER, join_selectivity(), lfirst, list_make2, makeBoolConst(), RestrictInfo::norm_selec, not_clause(), NULL, nulltestsel(), OpExpr::opno, or_clause(), RestrictInfo::orclause, RestrictInfo::outer_selec, RestrictInfo::pseudoconstant, restriction_selectivity(), rowcomparesel(), s1, s2, scalararraysel(), treat_as_join_clause(), RelOptInfo::tuples, RangeQueryClause::var, Var::varlevelsup, and Var::varno.
Referenced by approx_tuple_count(), booltestsel(), clause_selectivity(), clauselist_selectivity(), and create_or_index_quals().
{
Selectivity s1 = 0.5; /* default for any unhandled clause type */
RestrictInfo *rinfo = NULL;
bool cacheable = false;
if (clause == NULL) /* can this still happen? */
return s1;
if (IsA(clause, RestrictInfo))
{
rinfo = (RestrictInfo *) clause;
/*
* If the clause is marked pseudoconstant, then it will be used as a
* gating qual and should not affect selectivity estimates; hence
* return 1.0. The only exception is that a constant FALSE may be
* taken as having selectivity 0.0, since it will surely mean no rows
* out of the plan. This case is simple enough that we need not
* bother caching the result.
*/
if (rinfo->pseudoconstant)
{
if (!IsA(rinfo->clause, Const))
return (Selectivity) 1.0;
}
/*
* If the clause is marked redundant, always return 1.0.
*/
if (rinfo->norm_selec > 1)
return (Selectivity) 1.0;
/*
* If possible, cache the result of the selectivity calculation for
* the clause. We can cache if varRelid is zero or the clause
* contains only vars of that relid --- otherwise varRelid will affect
* the result, so mustn't cache. Outer join quals might be examined
* with either their join's actual jointype or JOIN_INNER, so we need
* two cache variables to remember both cases. Note: we assume the
* result won't change if we are switching the input relations or
* considering a unique-ified case, so we only need one cache variable
* for all non-JOIN_INNER cases.
*/
if (varRelid == 0 ||
bms_is_subset_singleton(rinfo->clause_relids, varRelid))
{
/* Cacheable --- do we already have the result? */
if (jointype == JOIN_INNER)
{
if (rinfo->norm_selec >= 0)
return rinfo->norm_selec;
}
else
{
if (rinfo->outer_selec >= 0)
return rinfo->outer_selec;
}
cacheable = true;
}
/*
* Proceed with examination of contained clause. If the clause is an
* OR-clause, we want to look at the variant with sub-RestrictInfos,
* so that per-subclause selectivities can be cached.
*/
if (rinfo->orclause)
clause = (Node *) rinfo->orclause;
else
clause = (Node *) rinfo->clause;
}
if (IsA(clause, Var))
{
Var *var = (Var *) clause;
/*
* We probably shouldn't ever see an uplevel Var here, but if we do,
* return the default selectivity...
*/
if (var->varlevelsup == 0 &&
(varRelid == 0 || varRelid == (int) var->varno))
{
/*
* A Var at the top of a clause must be a bool Var. This is
* equivalent to the clause reln.attribute = 't', so we compute
* the selectivity as if that is what we have.
*/
s1 = restriction_selectivity(root,
BooleanEqualOperator,
list_make2(var,
makeBoolConst(true,
false)),
InvalidOid,
varRelid);
}
}
else if (IsA(clause, Const))
{
/* bool constant is pretty easy... */
Const *con = (Const *) clause;
s1 = con->constisnull ? 0.0 :
DatumGetBool(con->constvalue) ? 1.0 : 0.0;
}
else if (IsA(clause, Param))
{
/* see if we can replace the Param */
Node *subst = estimate_expression_value(root, clause);
if (IsA(subst, Const))
{
/* bool constant is pretty easy... */
Const *con = (Const *) subst;
s1 = con->constisnull ? 0.0 :
DatumGetBool(con->constvalue) ? 1.0 : 0.0;
}
else
{
/* XXX any way to do better than default? */
}
}
else if (not_clause(clause))
{
/* inverse of the selectivity of the underlying clause */
s1 = 1.0 - clause_selectivity(root,
(Node *) get_notclausearg((Expr *) clause),
varRelid,
jointype,
sjinfo);
}
else if (and_clause(clause))
{
/* share code with clauselist_selectivity() */
s1 = clauselist_selectivity(root,
((BoolExpr *) clause)->args,
varRelid,
jointype,
sjinfo);
}
else if (or_clause(clause))
{
/*
* Selectivities for an OR clause are computed as s1+s2 - s1*s2 to
* account for the probable overlap of selected tuple sets.
*
* XXX is this too conservative?
*/
ListCell *arg;
s1 = 0.0;
foreach(arg, ((BoolExpr *) clause)->args)
{
Selectivity s2 = clause_selectivity(root,
(Node *) lfirst(arg),
varRelid,
jointype,
sjinfo);
s1 = s1 + s2 - s1 * s2;
}
}
else if (is_opclause(clause) || IsA(clause, DistinctExpr))
{
OpExpr *opclause = (OpExpr *) clause;
Oid opno = opclause->opno;
if (treat_as_join_clause(clause, rinfo, varRelid, sjinfo))
{
/* Estimate selectivity for a join clause. */
s1 = join_selectivity(root, opno,
opclause->args,
opclause->inputcollid,
jointype,
sjinfo);
}
else
{
/* Estimate selectivity for a restriction clause. */
s1 = restriction_selectivity(root, opno,
opclause->args,
opclause->inputcollid,
varRelid);
}
/*
* DistinctExpr has the same representation as OpExpr, but the
* contained operator is "=" not "<>", so we must negate the result.
* This estimation method doesn't give the right behavior for nulls,
* but it's better than doing nothing.
*/
if (IsA(clause, DistinctExpr))
s1 = 1.0 - s1;
}
else if (is_funcclause(clause))
{
/*
* This is not an operator, so we guess at the selectivity. THIS IS A
* HACK TO GET V4 OUT THE DOOR. FUNCS SHOULD BE ABLE TO HAVE
* SELECTIVITIES THEMSELVES. -- JMH 7/9/92
*/
s1 = (Selectivity) 0.3333333;
}
#ifdef NOT_USED
else if (IsA(clause, SubPlan) ||
IsA(clause, AlternativeSubPlan))
{
/*
* Just for the moment! FIX ME! - vadim 02/04/98
*/
s1 = (Selectivity) 0.5;
}
#endif
else if (IsA(clause, ScalarArrayOpExpr))
{
/* Use node specific selectivity calculation function */
s1 = scalararraysel(root,
(ScalarArrayOpExpr *) clause,
treat_as_join_clause(clause, rinfo,
varRelid, sjinfo),
varRelid,
jointype,
sjinfo);
}
else if (IsA(clause, RowCompareExpr))
{
/* Use node specific selectivity calculation function */
s1 = rowcomparesel(root,
(RowCompareExpr *) clause,
varRelid,
jointype,
sjinfo);
}
else if (IsA(clause, NullTest))
{
/* Use node specific selectivity calculation function */
s1 = nulltestsel(root,
((NullTest *) clause)->nulltesttype,
(Node *) ((NullTest *) clause)->arg,
varRelid,
jointype,
sjinfo);
}
else if (IsA(clause, BooleanTest))
{
/* Use node specific selectivity calculation function */
s1 = booltestsel(root,
((BooleanTest *) clause)->booltesttype,
(Node *) ((BooleanTest *) clause)->arg,
varRelid,
jointype,
sjinfo);
}
else if (IsA(clause, CurrentOfExpr))
{
/* CURRENT OF selects at most one row of its table */
CurrentOfExpr *cexpr = (CurrentOfExpr *) clause;
RelOptInfo *crel = find_base_rel(root, cexpr->cvarno);
if (crel->tuples > 0)
s1 = 1.0 / crel->tuples;
}
else if (IsA(clause, RelabelType))
{
/* Not sure this case is needed, but it can't hurt */
s1 = clause_selectivity(root,
(Node *) ((RelabelType *) clause)->arg,
varRelid,
jointype,
sjinfo);
}
else if (IsA(clause, CoerceToDomain))
{
/* Not sure this case is needed, but it can't hurt */
s1 = clause_selectivity(root,
(Node *) ((CoerceToDomain *) clause)->arg,
varRelid,
jointype,
sjinfo);
}
/* Cache the result if possible */
if (cacheable)
{
if (jointype == JOIN_INNER)
rinfo->norm_selec = s1;
else
rinfo->outer_selec = s1;
}
#ifdef SELECTIVITY_DEBUG
elog(DEBUG4, "clause_selectivity: s1 %f", s1);
#endif /* SELECTIVITY_DEBUG */
return s1;
}
| Selectivity clauselist_selectivity | ( | PlannerInfo * | root, | |
| List * | clauses, | |||
| int | varRelid, | |||
| JoinType | jointype, | |||
| SpecialJoinInfo * | sjinfo | |||
| ) |
Definition at line 93 of file clausesel.c.
References addRangeClause(), OpExpr::args, bms_membership(), RestrictInfo::clause, RestrictInfo::clause_relids, clause_selectivity(), DEFAULT_INEQ_SEL, get_oprrest(), RangeQueryClause::have_hibound, RangeQueryClause::have_lobound, RangeQueryClause::hibound, IS_NULL, is_opclause, is_pseudo_constant_clause(), is_pseudo_constant_clause_relids(), IsA, RestrictInfo::left_relids, lfirst, linitial, list_length(), RangeQueryClause::lobound, lsecond, RangeQueryClause::next, NULL, nulltestsel(), NumRelids(), OpExpr::opno, pfree(), RestrictInfo::pseudoconstant, RestrictInfo::right_relids, s1, s2, and RangeQueryClause::var.
Referenced by btcostestimate(), calc_joinrel_size_estimate(), clause_selectivity(), compute_semi_anti_join_factors(), estimate_size(), genericcostestimate(), get_parameterized_baserel_size(), gincostestimate(), postgresGetForeignRelSize(), and set_baserel_size_estimates().
{
Selectivity s1 = 1.0;
RangeQueryClause *rqlist = NULL;
ListCell *l;
/*
* If there's exactly one clause, then no use in trying to match up pairs,
* so just go directly to clause_selectivity().
*/
if (list_length(clauses) == 1)
return clause_selectivity(root, (Node *) linitial(clauses),
varRelid, jointype, sjinfo);
/*
* Initial scan over clauses. Anything that doesn't look like a potential
* rangequery clause gets multiplied into s1 and forgotten. Anything that
* does gets inserted into an rqlist entry.
*/
foreach(l, clauses)
{
Node *clause = (Node *) lfirst(l);
RestrictInfo *rinfo;
Selectivity s2;
/* Always compute the selectivity using clause_selectivity */
s2 = clause_selectivity(root, clause, varRelid, jointype, sjinfo);
/*
* Check for being passed a RestrictInfo.
*
* If it's a pseudoconstant RestrictInfo, then s2 is either 1.0 or
* 0.0; just use that rather than looking for range pairs.
*/
if (IsA(clause, RestrictInfo))
{
rinfo = (RestrictInfo *) clause;
if (rinfo->pseudoconstant)
{
s1 = s1 * s2;
continue;
}
clause = (Node *) rinfo->clause;
}
else
rinfo = NULL;
/*
* See if it looks like a restriction clause with a pseudoconstant on
* one side. (Anything more complicated than that might not behave in
* the simple way we are expecting.) Most of the tests here can be
* done more efficiently with rinfo than without.
*/
if (is_opclause(clause) && list_length(((OpExpr *) clause)->args) == 2)
{
OpExpr *expr = (OpExpr *) clause;
bool varonleft = true;
bool ok;
if (rinfo)
{
ok = (bms_membership(rinfo->clause_relids) == BMS_SINGLETON) &&
(is_pseudo_constant_clause_relids(lsecond(expr->args),
rinfo->right_relids) ||
(varonleft = false,
is_pseudo_constant_clause_relids(linitial(expr->args),
rinfo->left_relids)));
}
else
{
ok = (NumRelids(clause) == 1) &&
(is_pseudo_constant_clause(lsecond(expr->args)) ||
(varonleft = false,
is_pseudo_constant_clause(linitial(expr->args))));
}
if (ok)
{
/*
* If it's not a "<" or ">" operator, just merge the
* selectivity in generically. But if it's the right oprrest,
* add the clause to rqlist for later processing.
*/
switch (get_oprrest(expr->opno))
{
case F_SCALARLTSEL:
addRangeClause(&rqlist, clause,
varonleft, true, s2);
break;
case F_SCALARGTSEL:
addRangeClause(&rqlist, clause,
varonleft, false, s2);
break;
default:
/* Just merge the selectivity in generically */
s1 = s1 * s2;
break;
}
continue; /* drop to loop bottom */
}
}
/* Not the right form, so treat it generically. */
s1 = s1 * s2;
}
/*
* Now scan the rangequery pair list.
*/
while (rqlist != NULL)
{
RangeQueryClause *rqnext;
if (rqlist->have_lobound && rqlist->have_hibound)
{
/* Successfully matched a pair of range clauses */
Selectivity s2;
/*
* Exact equality to the default value probably means the
* selectivity function punted. This is not airtight but should
* be good enough.
*/
if (rqlist->hibound == DEFAULT_INEQ_SEL ||
rqlist->lobound == DEFAULT_INEQ_SEL)
{
s2 = DEFAULT_RANGE_INEQ_SEL;
}
else
{
s2 = rqlist->hibound + rqlist->lobound - 1.0;
/* Adjust for double-exclusion of NULLs */
s2 += nulltestsel(root, IS_NULL, rqlist->var,
varRelid, jointype, sjinfo);
/*
* A zero or slightly negative s2 should be converted into a
* small positive value; we probably are dealing with a very
* tight range and got a bogus result due to roundoff errors.
* However, if s2 is very negative, then we probably have
* default selectivity estimates on one or both sides of the
* range that we failed to recognize above for some reason.
*/
if (s2 <= 0.0)
{
if (s2 < -0.01)
{
/*
* No data available --- use a default estimate that
* is small, but not real small.
*/
s2 = DEFAULT_RANGE_INEQ_SEL;
}
else
{
/*
* It's just roundoff error; use a small positive
* value
*/
s2 = 1.0e-10;
}
}
}
/* Merge in the selectivity of the pair of clauses */
s1 *= s2;
}
else
{
/* Only found one of a pair, merge it in generically */
if (rqlist->have_lobound)
s1 *= rqlist->lobound;
else
s1 *= rqlist->hibound;
}
/* release storage and advance */
rqnext = rqlist->next;
pfree(rqlist);
rqlist = rqnext;
}
return s1;
}
| static bool treat_as_join_clause | ( | Node * | clause, | |
| RestrictInfo * | rinfo, | |||
| int | varRelid, | |||
| SpecialJoinInfo * | sjinfo | |||
| ) | [inline, static] |
Definition at line 406 of file clausesel.c.
References bms_membership(), BMS_MULTIPLE, RestrictInfo::clause_relids, NULL, and NumRelids().
Referenced by clause_selectivity().
{
if (varRelid != 0)
{
/*
* Caller is forcing restriction mode (eg, because we are examining an
* inner indexscan qual).
*/
return false;
}
else if (sjinfo == NULL)
{
/*
* It must be a restriction clause, since it's being evaluated at a
* scan node.
*/
return false;
}
else
{
/*
* Otherwise, it's a join if there's more than one relation used. We
* can optimize this calculation if an rinfo was passed.
*
* XXX Since we know the clause is being evaluated at a join, the
* only way it could be single-relation is if it was delayed by outer
* joins. Although we can make use of the restriction qual estimators
* anyway, it seems likely that we ought to account for the
* probability of injected nulls somehow.
*/
if (rinfo)
return (bms_membership(rinfo->clause_relids) == BMS_MULTIPLE);
else
return (NumRelids(clause) > 1);
}
}
1.7.1