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postgres/src/backend/utils/adt/selfuncs.c
Bruce Momjian a033daf566 Commit to match discussed elog() changes. Only update is that LOG is 
now just below FATAL in server_min_messages.  Added more text to
highlight ordering difference between it and client_min_messages.

---------------------------------------------------------------------------

REALLYFATAL => PANIC
STOP => PANIC
New INFO level the prints to client by default
New LOG level the prints to server log by default
Cause VACUUM information to print only to the client
NOTICE => INFO where purely information messages are sent
DEBUG => LOG for purely server status messages
DEBUG removed, kept as backward compatible
DEBUG5, DEBUG4, DEBUG3, DEBUG2, DEBUG1 added
DebugLvl removed in favor of new DEBUG[1-5] symbols
New server_min_messages GUC parameter with values:
        DEBUG[5-1], INFO, NOTICE, ERROR, LOG, FATAL, PANIC
New client_min_messages GUC parameter with values:
        DEBUG[5-1], LOG, INFO, NOTICE, ERROR, FATAL, PANIC
Server startup now logged with LOG instead of DEBUG
Remove debug_level GUC parameter
elog() numbers now start at 10
Add test to print error message if older elog() values are passed to elog()
Bootstrap mode now has a -d that requires an argument, like postmaster
2002-03-02 21:39:36 +00:00

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/*-------------------------------------------------------------------------
*
* selfuncs.c
* Selectivity functions and index cost estimation functions for
* standard operators and index access methods.
*
* Selectivity routines are registered in the pg_operator catalog
* in the "oprrest" and "oprjoin" attributes.
*
* Index cost functions are registered in the pg_am catalog
* in the "amcostestimate" attribute.
*
* Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/utils/adt/selfuncs.c,v 1.105 2002/03/02 21:39:32 momjian Exp $
*
*-------------------------------------------------------------------------
*/
/*----------
* Operator selectivity estimation functions are called to estimate the
* selectivity of WHERE clauses whose top-level operator is their operator.
* We divide the problem into two cases:
* Restriction clause estimation: the clause involves vars of just
* one relation.
* Join clause estimation: the clause involves vars of multiple rels.
* Join selectivity estimation is far more difficult and usually less accurate
* than restriction estimation.
*
* When dealing with the inner scan of a nestloop join, we consider the
* join's joinclauses as restriction clauses for the inner relation, and
* treat vars of the outer relation as parameters (a/k/a constants of unknown
* values). So, restriction estimators need to be able to accept an argument
* telling which relation is to be treated as the variable.
*
* The call convention for a restriction estimator (oprrest function) is
*
* Selectivity oprrest (Query *root,
* Oid operator,
* List *args,
* int varRelid);
*
* root: general information about the query (rtable and RelOptInfo lists
* are particularly important for the estimator).
* operator: OID of the specific operator in question.
* args: argument list from the operator clause.
* varRelid: if not zero, the relid (rtable index) of the relation to
* be treated as the variable relation. May be zero if the args list
* is known to contain vars of only one relation.
*
* This is represented at the SQL level (in pg_proc) as
*
* float8 oprrest (opaque, oid, opaque, int4);
*
* The call convention for a join estimator (oprjoin function) is similar
* except that varRelid is not needed:
*
* Selectivity oprjoin (Query *root,
* Oid operator,
* List *args);
*
* float8 oprjoin (opaque, oid, opaque);
*----------
*/
#include "postgres.h"
#include <ctype.h>
#include <math.h>
#ifdef USE_LOCALE
#include <locale.h>
#endif
#include "access/heapam.h"
#include "catalog/catname.h"
#include "catalog/pg_operator.h"
#include "catalog/pg_proc.h"
#include "catalog/pg_statistic.h"
#include "catalog/pg_type.h"
#include "mb/pg_wchar.h"
#include "nodes/makefuncs.h"
#include "optimizer/clauses.h"
#include "optimizer/cost.h"
#include "optimizer/pathnode.h"
#include "optimizer/plancat.h"
#include "optimizer/prep.h"
#include "parser/parse_func.h"
#include "parser/parse_oper.h"
#include "parser/parsetree.h"
#include "utils/builtins.h"
#include "utils/date.h"
#include "utils/datum.h"
#include "utils/int8.h"
#include "utils/lsyscache.h"
#include "utils/selfuncs.h"
#include "utils/syscache.h"
/*
* Note: the default selectivity estimates are not chosen entirely at random.
* We want them to be small enough to ensure that indexscans will be used if
* available, for typical table densities of ~100 tuples/page. Thus, for
* example, 0.01 is not quite small enough, since that makes it appear that
* nearly all pages will be hit anyway. Also, since we sometimes estimate
* eqsel as 1/num_distinct, we probably want DEFAULT_NUM_DISTINCT to equal
* 1/DEFAULT_EQ_SEL.
*/
/* default selectivity estimate for equalities such as "A = b" */
#define DEFAULT_EQ_SEL 0.005
/* default selectivity estimate for inequalities such as "A < b" */
#define DEFAULT_INEQ_SEL (1.0 / 3.0)
/* default selectivity estimate for pattern-match operators such as LIKE */
#define DEFAULT_MATCH_SEL 0.005
/* default number of distinct values in a table */
#define DEFAULT_NUM_DISTINCT 200
/* default selectivity estimate for boolean and null test nodes */
#define DEFAULT_UNK_SEL 0.005
#define DEFAULT_NOT_UNK_SEL (1.0 - DEFAULT_UNK_SEL)
#define DEFAULT_BOOL_SEL 0.5
/*
* Clamp a computed probability estimate (which may suffer from roundoff or
* estimation errors) to valid range. Argument must be a float variable.
*/
#define CLAMP_PROBABILITY(p) \
do { \
if (p < 0.0) \
p = 0.0; \
else if (p > 1.0) \
p = 1.0; \
} while (0)
static bool get_var_maximum(Query *root, Var *var, Oid sortop, Datum *max);
static bool convert_to_scalar(Datum value, Oid valuetypid, double *scaledvalue,
Datum lobound, Datum hibound, Oid boundstypid,
double *scaledlobound, double *scaledhibound);
static double convert_numeric_to_scalar(Datum value, Oid typid);
static void convert_string_to_scalar(unsigned char *value,
double *scaledvalue,
unsigned char *lobound,
double *scaledlobound,
unsigned char *hibound,
double *scaledhibound);
static void convert_bytea_to_scalar(Datum value,
double *scaledvalue,
Datum lobound,
double *scaledlobound,
Datum hibound,
double *scaledhibound);
static double convert_one_string_to_scalar(unsigned char *value,
int rangelo, int rangehi);
static double convert_one_bytea_to_scalar(unsigned char *value, int valuelen,
int rangelo, int rangehi);
static unsigned char *convert_string_datum(Datum value, Oid typid);
static double convert_timevalue_to_scalar(Datum value, Oid typid);
static double get_att_numdistinct(Query *root, Var *var,
Form_pg_statistic stats);
static bool get_restriction_var(List *args, int varRelid,
Var **var, Node **other,
bool *varonleft);
static void get_join_vars(List *args, Var **var1, Var **var2);
static Selectivity prefix_selectivity(Query *root, Var *var, char *prefix);
static Selectivity pattern_selectivity(char *patt, Pattern_Type ptype);
static bool string_lessthan(const char *str1, const char *str2,
Oid datatype);
static Oid find_operator(const char *opname, Oid datatype);
static Datum string_to_datum(const char *str, Oid datatype);
static Const *string_to_const(const char *str, Oid datatype);
/*
* eqsel - Selectivity of "=" for any data types.
*
* Note: this routine is also used to estimate selectivity for some
* operators that are not "=" but have comparable selectivity behavior,
* such as "~=" (geometric approximate-match). Even for "=", we must
* keep in mind that the left and right datatypes may differ.
*/
Datum
eqsel(PG_FUNCTION_ARGS)
{
Query *root = (Query *) PG_GETARG_POINTER(0);
Oid operator = PG_GETARG_OID(1);
List *args = (List *) PG_GETARG_POINTER(2);
int varRelid = PG_GETARG_INT32(3);
Var *var;
Node *other;
bool varonleft;
Oid relid;
HeapTuple statsTuple;
Datum *values;
int nvalues;
float4 *numbers;
int nnumbers;
double selec;
/*
* If expression is not var = something or something = var for a
* simple var of a real relation (no subqueries, for now), then punt
* and return a default estimate.
*/
if (!get_restriction_var(args, varRelid,
&var, &other, &varonleft))
PG_RETURN_FLOAT8(DEFAULT_EQ_SEL);
relid = getrelid(var->varno, root->rtable);
if (relid == InvalidOid)
PG_RETURN_FLOAT8(DEFAULT_EQ_SEL);
/*
* If the something is a NULL constant, assume operator is strict and
* return zero, ie, operator will never return TRUE.
*/
if (IsA(other, Const) &&((Const *) other)->constisnull)
PG_RETURN_FLOAT8(0.0);
/* get stats for the attribute, if available */
statsTuple = SearchSysCache(STATRELATT,
ObjectIdGetDatum(relid),
Int16GetDatum(var->varattno),
0, 0);
if (HeapTupleIsValid(statsTuple))
{
Form_pg_statistic stats;
stats = (Form_pg_statistic) GETSTRUCT(statsTuple);
if (IsA(other, Const))
{
/* Var is being compared to a known non-null constant */
Datum constval = ((Const *) other)->constvalue;
bool match = false;
int i;
/*
* Is the constant "=" to any of the column's most common
* values? (Although the given operator may not really be
* "=", we will assume that seeing whether it returns TRUE is
* an appropriate test. If you don't like this, maybe you
* shouldn't be using eqsel for your operator...)
*/
if (get_attstatsslot(statsTuple, var->vartype, var->vartypmod,
STATISTIC_KIND_MCV, InvalidOid,
&values, &nvalues,
&numbers, &nnumbers))
{
FmgrInfo eqproc;
fmgr_info(get_opcode(operator), &eqproc);
for (i = 0; i < nvalues; i++)
{
/* be careful to apply operator right way 'round */
if (varonleft)
match = DatumGetBool(FunctionCall2(&eqproc,
values[i],
constval));
else
match = DatumGetBool(FunctionCall2(&eqproc,
constval,
values[i]));
if (match)
break;
}
}
else
{
/* no most-common-value info available */
values = NULL;
numbers = NULL;
i = nvalues = nnumbers = 0;
}
if (match)
{
/*
* Constant is "=" to this common value. We know
* selectivity exactly (or as exactly as VACUUM could
* calculate it, anyway).
*/
selec = numbers[i];
}
else
{
/*
* Comparison is against a constant that is neither NULL
* nor any of the common values. Its selectivity cannot
* be more than this:
*/
double sumcommon = 0.0;
double otherdistinct;
for (i = 0; i < nnumbers; i++)
sumcommon += numbers[i];
selec = 1.0 - sumcommon - stats->stanullfrac;
CLAMP_PROBABILITY(selec);
/*
* and in fact it's probably a good deal less. We
* approximate that all the not-common values share this
* remaining fraction equally, so we divide by the number
* of other distinct values.
*/
otherdistinct = get_att_numdistinct(root, var, stats)
- nnumbers;
if (otherdistinct > 1)
selec /= otherdistinct;
/*
* Another cross-check: selectivity shouldn't be estimated
* as more than the least common "most common value".
*/
if (nnumbers > 0 && selec > numbers[nnumbers - 1])
selec = numbers[nnumbers - 1];
}
free_attstatsslot(var->vartype, values, nvalues,
numbers, nnumbers);
}
else
{
double ndistinct;
/*
* Search is for a value that we do not know a priori, but we
* will assume it is not NULL. Estimate the selectivity as
* non-null fraction divided by number of distinct values, so
* that we get a result averaged over all possible values
* whether common or uncommon. (Essentially, we are assuming
* that the not-yet-known comparison value is equally likely
* to be any of the possible values, regardless of their
* frequency in the table. Is that a good idea?)
*/
selec = 1.0 - stats->stanullfrac;
ndistinct = get_att_numdistinct(root, var, stats);
if (ndistinct > 1)
selec /= ndistinct;
/*
* Cross-check: selectivity should never be estimated as more
* than the most common value's.
*/
if (get_attstatsslot(statsTuple, var->vartype, var->vartypmod,
STATISTIC_KIND_MCV, InvalidOid,
NULL, NULL,
&numbers, &nnumbers))
{
if (nnumbers > 0 && selec > numbers[0])
selec = numbers[0];
free_attstatsslot(var->vartype, NULL, 0, numbers, nnumbers);
}
}
ReleaseSysCache(statsTuple);
}
else
{
/*
* No VACUUM ANALYZE stats available, so make a guess using
* estimated number of distinct values and assuming they are
* equally common. (The guess is unlikely to be very good, but we
* do know a few special cases.)
*/
selec = 1.0 / get_att_numdistinct(root, var, NULL);
}
/* result should be in range, but make sure... */
CLAMP_PROBABILITY(selec);
PG_RETURN_FLOAT8((float8) selec);
}
/*
* neqsel - Selectivity of "!=" for any data types.
*
* This routine is also used for some operators that are not "!="
* but have comparable selectivity behavior. See above comments
* for eqsel().
*/
Datum
neqsel(PG_FUNCTION_ARGS)
{
Query *root = (Query *) PG_GETARG_POINTER(0);
Oid operator = PG_GETARG_OID(1);
List *args = (List *) PG_GETARG_POINTER(2);
int varRelid = PG_GETARG_INT32(3);
Oid eqop;
float8 result;
/*
* We want 1 - eqsel() where the equality operator is the one
* associated with this != operator, that is, its negator.
*/
eqop = get_negator(operator);
if (eqop)
{
result = DatumGetFloat8(DirectFunctionCall4(eqsel,
PointerGetDatum(root),
ObjectIdGetDatum(eqop),
PointerGetDatum(args),
Int32GetDatum(varRelid)));
}
else
{
/* Use default selectivity (should we raise an error instead?) */
result = DEFAULT_EQ_SEL;
}
result = 1.0 - result;
PG_RETURN_FLOAT8(result);
}
/*
* scalarineqsel - Selectivity of "<", "<=", ">", ">=" for scalars.
*
* This is the guts of both scalarltsel and scalargtsel. The caller has
* commuted the clause, if necessary, so that we can treat the Var as
* being on the left. The caller must also make sure that the other side
* of the clause is a non-null Const, and dissect same into a value and
* datatype.
*
* This routine works for any datatype (or pair of datatypes) known to
* convert_to_scalar(). If it is applied to some other datatype,
* it will return a default estimate.
*/
static double
scalarineqsel(Query *root, Oid operator, bool isgt,
Var *var, Datum constval, Oid consttype)
{
Oid relid;
HeapTuple statsTuple;
Form_pg_statistic stats;
FmgrInfo opproc;
Datum *values;
int nvalues;
float4 *numbers;
int nnumbers;
double mcv_selec,
hist_selec,
sumcommon;
double selec;
int i;
/*
* If expression is not var op something or something op var for a
* simple var of a real relation (no subqueries, for now), then punt
* and return a default estimate.
*/
relid = getrelid(var->varno, root->rtable);
if (relid == InvalidOid)
return DEFAULT_INEQ_SEL;
/* get stats for the attribute */
statsTuple = SearchSysCache(STATRELATT,
ObjectIdGetDatum(relid),
Int16GetDatum(var->varattno),
0, 0);
if (!HeapTupleIsValid(statsTuple))
{
/* no stats available, so default result */
return DEFAULT_INEQ_SEL;
}
stats = (Form_pg_statistic) GETSTRUCT(statsTuple);
fmgr_info(get_opcode(operator), &opproc);
/*
* If we have most-common-values info, add up the fractions of the MCV
* entries that satisfy MCV OP CONST. These fractions contribute
* directly to the result selectivity. Also add up the total fraction
* represented by MCV entries.
*/
mcv_selec = 0.0;
sumcommon = 0.0;
if (get_attstatsslot(statsTuple, var->vartype, var->vartypmod,
STATISTIC_KIND_MCV, InvalidOid,
&values, &nvalues,
&numbers, &nnumbers))
{
for (i = 0; i < nvalues; i++)
{
if (DatumGetBool(FunctionCall2(&opproc,
values[i],
constval)))
mcv_selec += numbers[i];
sumcommon += numbers[i];
}
free_attstatsslot(var->vartype, values, nvalues, numbers, nnumbers);
}
/*
* If there is a histogram, determine which bin the constant falls in,
* and compute the resulting contribution to selectivity.
*
* Someday, VACUUM might store more than one histogram per rel/att,
* corresponding to more than one possible sort ordering defined for
* the column type. However, to make that work we will need to figure
* out which staop to search for --- it's not necessarily the one we
* have at hand! (For example, we might have a '<=' operator rather
* than the '<' operator that will appear in staop.) For now, assume
* that whatever appears in pg_statistic is sorted the same way our
* operator sorts, or the reverse way if isgt is TRUE.
*/
hist_selec = 0.0;
if (get_attstatsslot(statsTuple, var->vartype, var->vartypmod,
STATISTIC_KIND_HISTOGRAM, InvalidOid,
&values, &nvalues,
NULL, NULL))
{
if (nvalues > 1)
{
double histfrac;
bool ltcmp;
ltcmp = DatumGetBool(FunctionCall2(&opproc,
values[0],
constval));
if (isgt)
ltcmp = !ltcmp;
if (!ltcmp)
{
/* Constant is below lower histogram boundary. */
histfrac = 0.0;
}
else
{
/*
* Scan to find proper location. This could be made
* faster by using a binary-search method, but it's
* probably not worth the trouble for typical histogram
* sizes.
*/
for (i = 1; i < nvalues; i++)
{
ltcmp = DatumGetBool(FunctionCall2(&opproc,
values[i],
constval));
if (isgt)
ltcmp = !ltcmp;
if (!ltcmp)
break;
}
if (i >= nvalues)
{
/* Constant is above upper histogram boundary. */
histfrac = 1.0;
}
else
{
double val,
high,
low;
double binfrac;
/*
* We have values[i-1] < constant < values[i].
*
* Convert the constant and the two nearest bin boundary
* values to a uniform comparison scale, and do a
* linear interpolation within this bin.
*/
if (convert_to_scalar(constval, consttype, &val,
values[i - 1], values[i],
var->vartype,
&low, &high))
{
if (high <= low)
{
/* cope if bin boundaries appear identical */
binfrac = 0.5;
}
else if (val <= low)
binfrac = 0.0;
else if (val >= high)
binfrac = 1.0;
else
{
binfrac = (val - low) / (high - low);
/*
* Watch out for the possibility that we got a
* NaN or Infinity from the division. This
* can happen despite the previous checks, if
* for example "low" is -Infinity.
*/
if (isnan(binfrac) ||
binfrac < 0.0 || binfrac > 1.0)
binfrac = 0.5;
}
}
else
{
/*
* Ideally we'd produce an error here, on the
* grounds that the given operator shouldn't have
* scalarXXsel registered as its selectivity func
* unless we can deal with its operand types. But
* currently, all manner of stuff is invoking
* scalarXXsel, so give a default estimate until
* that can be fixed.
*/
binfrac = 0.5;
}
/*
* Now, compute the overall selectivity across the
* values represented by the histogram. We have i-1
* full bins and binfrac partial bin below the
* constant.
*/
histfrac = (double) (i - 1) + binfrac;
histfrac /= (double) (nvalues - 1);
}
}
/*
* Now histfrac = fraction of histogram entries below the
* constant.
*
* Account for "<" vs ">"
*/
hist_selec = isgt ? (1.0 - histfrac) : histfrac;
/*
* The histogram boundaries are only approximate to begin
* with, and may well be out of date anyway. Therefore, don't
* believe extremely small or large selectivity estimates.
*/
if (hist_selec < 0.0001)
hist_selec = 0.0001;
else if (hist_selec > 0.9999)
hist_selec = 0.9999;
}
free_attstatsslot(var->vartype, values, nvalues, NULL, 0);
}
/*
* Now merge the results from the MCV and histogram calculations,
* realizing that the histogram covers only the non-null values that
* are not listed in MCV.
*/
selec = 1.0 - stats->stanullfrac - sumcommon;
if (hist_selec > 0.0)
selec *= hist_selec;
else
{
/*
* If no histogram but there are values not accounted for by MCV,
* arbitrarily assume half of them will match.
*/
selec *= 0.5;
}
selec += mcv_selec;
ReleaseSysCache(statsTuple);
/* result should be in range, but make sure... */
CLAMP_PROBABILITY(selec);
return selec;
}
/*
* scalarltsel - Selectivity of "<" (also "<=") for scalars.
*/
Datum
scalarltsel(PG_FUNCTION_ARGS)
{
Query *root = (Query *) PG_GETARG_POINTER(0);
Oid operator = PG_GETARG_OID(1);
List *args = (List *) PG_GETARG_POINTER(2);
int varRelid = PG_GETARG_INT32(3);
Var *var;
Node *other;
Datum constval;
Oid consttype;
bool varonleft;
bool isgt;
double selec;
/*
* If expression is not var op something or something op var for a
* simple var of a real relation (no subqueries, for now), then punt
* and return a default estimate.
*/
if (!get_restriction_var(args, varRelid,
&var, &other, &varonleft))
PG_RETURN_FLOAT8(DEFAULT_INEQ_SEL);
/*
* Can't do anything useful if the something is not a constant,
* either.
*/
if (!IsA(other, Const))
PG_RETURN_FLOAT8(DEFAULT_INEQ_SEL);
/*
* If the constant is NULL, assume operator is strict and return zero,
* ie, operator will never return TRUE.
*/
if (((Const *) other)->constisnull)
PG_RETURN_FLOAT8(0.0);
constval = ((Const *) other)->constvalue;
consttype = ((Const *) other)->consttype;
/*
* Force the var to be on the left to simplify logic in scalarineqsel.
*/
if (varonleft)
{
/* we have var < other */
isgt = false;
}
else
{
/* we have other < var, commute to make var > other */
operator = get_commutator(operator);
if (!operator)
{
/* Use default selectivity (should we raise an error instead?) */
PG_RETURN_FLOAT8(DEFAULT_INEQ_SEL);
}
isgt = true;
}
selec = scalarineqsel(root, operator, isgt, var, constval, consttype);
PG_RETURN_FLOAT8((float8) selec);
}
/*
* scalargtsel - Selectivity of ">" (also ">=") for integers.
*/
Datum
scalargtsel(PG_FUNCTION_ARGS)
{
Query *root = (Query *) PG_GETARG_POINTER(0);
Oid operator = PG_GETARG_OID(1);
List *args = (List *) PG_GETARG_POINTER(2);
int varRelid = PG_GETARG_INT32(3);
Var *var;
Node *other;
Datum constval;
Oid consttype;
bool varonleft;
bool isgt;
double selec;
/*
* If expression is not var op something or something op var for a
* simple var of a real relation (no subqueries, for now), then punt
* and return a default estimate.
*/
if (!get_restriction_var(args, varRelid,
&var, &other, &varonleft))
PG_RETURN_FLOAT8(DEFAULT_INEQ_SEL);
/*
* Can't do anything useful if the something is not a constant,
* either.
*/
if (!IsA(other, Const))
PG_RETURN_FLOAT8(DEFAULT_INEQ_SEL);
/*
* If the constant is NULL, assume operator is strict and return zero,
* ie, operator will never return TRUE.
*/
if (((Const *) other)->constisnull)
PG_RETURN_FLOAT8(0.0);
constval = ((Const *) other)->constvalue;
consttype = ((Const *) other)->consttype;
/*
* Force the var to be on the left to simplify logic in scalarineqsel.
*/
if (varonleft)
{
/* we have var > other */
isgt = true;
}
else
{
/* we have other > var, commute to make var < other */
operator = get_commutator(operator);
if (!operator)
{
/* Use default selectivity (should we raise an error instead?) */
PG_RETURN_FLOAT8(DEFAULT_INEQ_SEL);
}
isgt = false;
}
selec = scalarineqsel(root, operator, isgt, var, constval, consttype);
PG_RETURN_FLOAT8((float8) selec);
}
/*
* patternsel - Generic code for pattern-match selectivity.
*/
static double
patternsel(PG_FUNCTION_ARGS, Pattern_Type ptype)
{
Query *root = (Query *) PG_GETARG_POINTER(0);
#ifdef NOT_USED
Oid operator = PG_GETARG_OID(1);
#endif
List *args = (List *) PG_GETARG_POINTER(2);
int varRelid = PG_GETARG_INT32(3);
Var *var;
Node *other;
bool varonleft;
Oid relid;
Datum constval;
char *patt;
Pattern_Prefix_Status pstatus;
char *prefix;
char *rest;
double result;
/*
* If expression is not var op constant for a simple var of a real
* relation (no subqueries, for now), then punt and return a default
* estimate.
*/
if (!get_restriction_var(args, varRelid,
&var, &other, &varonleft))
return DEFAULT_MATCH_SEL;
if (!varonleft || !IsA(other, Const))
return DEFAULT_MATCH_SEL;
relid = getrelid(var->varno, root->rtable);
if (relid == InvalidOid)
return DEFAULT_MATCH_SEL;
/*
* If the constant is NULL, assume operator is strict and return zero,
* ie, operator will never return TRUE.
*/
if (((Const *) other)->constisnull)
return 0.0;
constval = ((Const *) other)->constvalue;
/* the right-hand const is type text for all supported operators */
Assert(((Const *) other)->consttype == TEXTOID);
patt = DatumGetCString(DirectFunctionCall1(textout, constval));
/* divide pattern into fixed prefix and remainder */
pstatus = pattern_fixed_prefix(patt, ptype, &prefix, &rest);
if (pstatus == Pattern_Prefix_Exact)
{
/*
* Pattern specifies an exact match, so pretend operator is '='
*/
Oid eqopr = find_operator("=", var->vartype);
Const *eqcon;
List *eqargs;
if (eqopr == InvalidOid)
elog(ERROR, "patternsel: no = operator for type %u",
var->vartype);
eqcon = string_to_const(prefix, var->vartype);
eqargs = makeList2(var, eqcon);
result = DatumGetFloat8(DirectFunctionCall4(eqsel,
PointerGetDatum(root),
ObjectIdGetDatum(eqopr),
PointerGetDatum(eqargs),
Int32GetDatum(varRelid)));
}
else
{
/*
* Not exact-match pattern. We estimate selectivity of the fixed
* prefix and remainder of pattern separately, then combine the
* two.
*/
Selectivity prefixsel;
Selectivity restsel;
Selectivity selec;
if (pstatus == Pattern_Prefix_Partial)
prefixsel = prefix_selectivity(root, var, prefix);
else
prefixsel = 1.0;
restsel = pattern_selectivity(rest, ptype);
selec = prefixsel * restsel;
/* result should be in range, but make sure... */
CLAMP_PROBABILITY(selec);
result = selec;
}
if (prefix)
pfree(prefix);
pfree(patt);
return result;
}
/*
* regexeqsel - Selectivity of regular-expression pattern match.
*/
Datum
regexeqsel(PG_FUNCTION_ARGS)
{
PG_RETURN_FLOAT8(patternsel(fcinfo, Pattern_Type_Regex));
}
/*
* icregexeqsel - Selectivity of case-insensitive regex match.
*/
Datum
icregexeqsel(PG_FUNCTION_ARGS)
{
PG_RETURN_FLOAT8(patternsel(fcinfo, Pattern_Type_Regex_IC));
}
/*
* likesel - Selectivity of LIKE pattern match.
*/
Datum
likesel(PG_FUNCTION_ARGS)
{
PG_RETURN_FLOAT8(patternsel(fcinfo, Pattern_Type_Like));
}
/*
* iclikesel - Selectivity of ILIKE pattern match.
*/
Datum
iclikesel(PG_FUNCTION_ARGS)
{
PG_RETURN_FLOAT8(patternsel(fcinfo, Pattern_Type_Like_IC));
}
/*
* regexnesel - Selectivity of regular-expression pattern non-match.
*/
Datum
regexnesel(PG_FUNCTION_ARGS)
{
double result;
result = patternsel(fcinfo, Pattern_Type_Regex);
result = 1.0 - result;
PG_RETURN_FLOAT8(result);
}
/*
* icregexnesel - Selectivity of case-insensitive regex non-match.
*/
Datum
icregexnesel(PG_FUNCTION_ARGS)
{
double result;
result = patternsel(fcinfo, Pattern_Type_Regex_IC);
result = 1.0 - result;
PG_RETURN_FLOAT8(result);
}
/*
* nlikesel - Selectivity of LIKE pattern non-match.
*/
Datum
nlikesel(PG_FUNCTION_ARGS)
{
double result;
result = patternsel(fcinfo, Pattern_Type_Like);
result = 1.0 - result;
PG_RETURN_FLOAT8(result);
}
/*
* icnlikesel - Selectivity of ILIKE pattern non-match.
*/
Datum
icnlikesel(PG_FUNCTION_ARGS)
{
double result;
result = patternsel(fcinfo, Pattern_Type_Like_IC);
result = 1.0 - result;
PG_RETURN_FLOAT8(result);
}
/*
* booltestsel - Selectivity of BooleanTest Node.
*/
Selectivity
booltestsel(Query *root, BooleanTest *clause, int varRelid)
{
Var *var;
Node *arg;
Oid relid;
HeapTuple statsTuple;
Datum *values;
int nvalues;
float4 *numbers;
int nnumbers;
double selec;
Assert(clause && IsA(clause, BooleanTest));
arg = (Node *) clause->arg;
/*
* Ignore any binary-compatible relabeling (probably unnecessary, but
* can't hurt)
*/
if (IsA(arg, RelabelType))
arg = ((RelabelType *) arg)->arg;
if (IsA(arg, Var) &&(varRelid == 0 || varRelid == ((Var *) arg)->varno))
var = (Var *) arg;
else
{
/*
* If argument is not a Var, we can't get statistics for it, but
* perhaps clause_selectivity can do something with it. We ignore
* the possibility of a NULL value when using clause_selectivity,
* and just assume the value is either TRUE or FALSE.
*/
switch (clause->booltesttype)
{
case IS_UNKNOWN:
selec = DEFAULT_UNK_SEL;
break;
case IS_NOT_UNKNOWN:
selec = DEFAULT_NOT_UNK_SEL;
break;
case IS_TRUE:
case IS_NOT_FALSE:
selec = (double) clause_selectivity(root, arg, varRelid);
break;
case IS_FALSE:
case IS_NOT_TRUE:
selec = 1.0 - (double) clause_selectivity(root, arg, varRelid);
break;
default:
elog(ERROR, "booltestsel: unexpected booltesttype %d",
(int) clause->booltesttype);
selec = 0.0; /* Keep compiler quiet */
break;
}
return (Selectivity) selec;
}
/* get stats for the attribute, if available */
relid = getrelid(var->varno, root->rtable);
if (relid == InvalidOid)
statsTuple = NULL;
else
statsTuple = SearchSysCache(STATRELATT,
ObjectIdGetDatum(relid),
Int16GetDatum(var->varattno),
0, 0);
if (HeapTupleIsValid(statsTuple))
{
Form_pg_statistic stats;
double freq_null;
stats = (Form_pg_statistic) GETSTRUCT(statsTuple);
freq_null = stats->stanullfrac;
if (get_attstatsslot(statsTuple, var->vartype, var->vartypmod,
STATISTIC_KIND_MCV, InvalidOid,
&values, &nvalues,
&numbers, &nnumbers)
&& nnumbers > 0)
{
double freq_true;
double freq_false;
/*
* Get first MCV frequency and derive frequency for true.
*/
if (DatumGetBool(values[0]))
freq_true = numbers[0];
else
freq_true = 1.0 - numbers[0] - freq_null;
/*
* Next derive freqency for false. Then use these as
* appropriate to derive frequency for each case.
*/
freq_false = 1.0 - freq_true - freq_null;
switch (clause->booltesttype)
{
case IS_UNKNOWN:
/* select only NULL values */
selec = freq_null;
break;
case IS_NOT_UNKNOWN:
/* select non-NULL values */
selec = 1.0 - freq_null;
break;
case IS_TRUE:
/* select only TRUE values */
selec = freq_true;
break;
case IS_NOT_TRUE:
/* select non-TRUE values */
selec = 1.0 - freq_true;
break;
case IS_FALSE:
/* select only FALSE values */
selec = freq_false;
break;
case IS_NOT_FALSE:
/* select non-FALSE values */
selec = 1.0 - freq_false;
break;
default:
elog(ERROR, "booltestsel: unexpected booltesttype %d",
(int) clause->booltesttype);
selec = 0.0; /* Keep compiler quiet */
break;
}
free_attstatsslot(var->vartype, values, nvalues,
numbers, nnumbers);
}
else
{
/*
* No most-common-value info available. Still have null
* fraction information, so use it for IS [NOT] UNKNOWN.
* Otherwise adjust for null fraction and assume an even split
* for boolean tests.
*/
switch (clause->booltesttype)
{
case IS_UNKNOWN:
/*
* Use freq_null directly.
*/
selec = freq_null;
break;
case IS_NOT_UNKNOWN:
/*
* Select not unknown (not null) values. Calculate
* from freq_null.
*/
selec = 1.0 - freq_null;
break;
case IS_TRUE:
case IS_NOT_TRUE:
case IS_FALSE:
case IS_NOT_FALSE:
selec = (1.0 - freq_null) / 2.0;
break;
default:
elog(ERROR, "booltestsel: unexpected booltesttype %d",
(int) clause->booltesttype);
selec = 0.0; /* Keep compiler quiet */
break;
}
}
ReleaseSysCache(statsTuple);
}
else
{
/*
* No VACUUM ANALYZE stats available, so use a default value.
* (Note: not much point in recursing to clause_selectivity here.)
*/
switch (clause->booltesttype)
{
case IS_UNKNOWN:
selec = DEFAULT_UNK_SEL;
break;
case IS_NOT_UNKNOWN:
selec = DEFAULT_NOT_UNK_SEL;
break;
case IS_TRUE:
case IS_NOT_TRUE:
case IS_FALSE:
case IS_NOT_FALSE:
selec = DEFAULT_BOOL_SEL;
break;
default:
elog(ERROR, "booltestsel: unexpected booltesttype %d",
(int) clause->booltesttype);
selec = 0.0; /* Keep compiler quiet */
break;
}
}
/* result should be in range, but make sure... */
CLAMP_PROBABILITY(selec);
return (Selectivity) selec;
}
/*
* nulltestsel - Selectivity of NullTest Node.
*/
Selectivity
nulltestsel(Query *root, NullTest *clause, int varRelid)
{
Var *var;
Node *arg;
Oid relid;
HeapTuple statsTuple;
double selec;
double defselec;
double freq_null;
Assert(clause && IsA(clause, NullTest));
switch (clause->nulltesttype)
{
case IS_NULL:
defselec = DEFAULT_UNK_SEL;
break;
case IS_NOT_NULL:
defselec = DEFAULT_NOT_UNK_SEL;
break;
default:
elog(ERROR, "nulltestsel: unexpected nulltesttype %d",
(int) clause->nulltesttype);
return (Selectivity) 0; /* keep compiler quiet */
}
arg = (Node *) clause->arg;
/*
* Ignore any binary-compatible relabeling
*/
if (IsA(arg, RelabelType))
arg = ((RelabelType *) arg)->arg;
if (IsA(arg, Var) &&(varRelid == 0 || varRelid == ((Var *) arg)->varno))
var = (Var *) arg;
else
{
/*
* punt if non-Var argument
*/
return (Selectivity) defselec;
}
relid = getrelid(var->varno, root->rtable);
if (relid == InvalidOid)
return (Selectivity) defselec;
/* get stats for the attribute, if available */
statsTuple = SearchSysCache(STATRELATT,
ObjectIdGetDatum(relid),
Int16GetDatum(var->varattno),
0, 0);
if (HeapTupleIsValid(statsTuple))
{
Form_pg_statistic stats;
stats = (Form_pg_statistic) GETSTRUCT(statsTuple);
freq_null = stats->stanullfrac;
switch (clause->nulltesttype)
{
case IS_NULL:
/*
* Use freq_null directly.
*/
selec = freq_null;
break;
case IS_NOT_NULL:
/*
* Select not unknown (not null) values. Calculate from
* freq_null.
*/
selec = 1.0 - freq_null;
break;
default:
elog(ERROR, "nulltestsel: unexpected nulltesttype %d",
(int) clause->nulltesttype);
return (Selectivity) 0; /* keep compiler quiet */
}
ReleaseSysCache(statsTuple);
}
else
{
/*
* No VACUUM ANALYZE stats available, so make a guess
*/
selec = defselec;
}
/* result should be in range, but make sure... */
CLAMP_PROBABILITY(selec);
return (Selectivity) selec;
}
/*
* eqjoinsel - Join selectivity of "="
*/
Datum
eqjoinsel(PG_FUNCTION_ARGS)
{
Query *root = (Query *) PG_GETARG_POINTER(0);
Oid operator = PG_GETARG_OID(1);
List *args = (List *) PG_GETARG_POINTER(2);
Var *var1;
Var *var2;
double selec;
get_join_vars(args, &var1, &var2);
if (var1 == NULL && var2 == NULL)
selec = DEFAULT_EQ_SEL;
else
{
HeapTuple statsTuple1 = NULL;
HeapTuple statsTuple2 = NULL;
Form_pg_statistic stats1 = NULL;
Form_pg_statistic stats2 = NULL;
double nd1 = DEFAULT_NUM_DISTINCT;
double nd2 = DEFAULT_NUM_DISTINCT;
bool have_mcvs1 = false;
Datum *values1 = NULL;
int nvalues1 = 0;
float4 *numbers1 = NULL;
int nnumbers1 = 0;
bool have_mcvs2 = false;
Datum *values2 = NULL;
int nvalues2 = 0;
float4 *numbers2 = NULL;
int nnumbers2 = 0;
if (var1 != NULL)
{
/* get stats for the attribute, if available */
Oid relid1 = getrelid(var1->varno, root->rtable);
if (relid1 != InvalidOid)
{
statsTuple1 = SearchSysCache(STATRELATT,
ObjectIdGetDatum(relid1),
Int16GetDatum(var1->varattno),
0, 0);
if (HeapTupleIsValid(statsTuple1))
{
stats1 = (Form_pg_statistic) GETSTRUCT(statsTuple1);
have_mcvs1 = get_attstatsslot(statsTuple1,
var1->vartype,
var1->vartypmod,
STATISTIC_KIND_MCV,
InvalidOid,
&values1, &nvalues1,
&numbers1, &nnumbers1);
}
nd1 = get_att_numdistinct(root, var1, stats1);
}
}
if (var2 != NULL)
{
/* get stats for the attribute, if available */
Oid relid2 = getrelid(var2->varno, root->rtable);
if (relid2 != InvalidOid)
{
statsTuple2 = SearchSysCache(STATRELATT,
ObjectIdGetDatum(relid2),
Int16GetDatum(var2->varattno),
0, 0);
if (HeapTupleIsValid(statsTuple2))
{
stats2 = (Form_pg_statistic) GETSTRUCT(statsTuple2);
have_mcvs2 = get_attstatsslot(statsTuple2,
var2->vartype,
var2->vartypmod,
STATISTIC_KIND_MCV,
InvalidOid,
&values2, &nvalues2,
&numbers2, &nnumbers2);
}
nd2 = get_att_numdistinct(root, var2, stats2);
}
}
if (have_mcvs1 && have_mcvs2)
{
/*
* We have most-common-value lists for both relations. Run
* through the lists to see which MCVs actually join to each
* other with the given operator. This allows us to determine
* the exact join selectivity for the portion of the relations
* represented by the MCV lists. We still have to estimate
* for the remaining population, but in a skewed distribution
* this gives us a big leg up in accuracy. For motivation see
* the analysis in Y. Ioannidis and S. Christodoulakis, "On
* the propagation of errors in the size of join results",
* Technical Report 1018, Computer Science Dept., University
* of Wisconsin, Madison, March 1991 (available from
* ftp.cs.wisc.edu).
*/
FmgrInfo eqproc;
bool *hasmatch1;
bool *hasmatch2;
double matchprodfreq,
matchfreq1,
matchfreq2,
unmatchfreq1,
unmatchfreq2,
otherfreq1,
otherfreq2,
totalsel1,
totalsel2;
int i,
nmatches;
fmgr_info(get_opcode(operator), &eqproc);
hasmatch1 = (bool *) palloc(nvalues1 * sizeof(bool));
memset(hasmatch1, 0, nvalues1 * sizeof(bool));
hasmatch2 = (bool *) palloc(nvalues2 * sizeof(bool));
memset(hasmatch2, 0, nvalues2 * sizeof(bool));
/*
* Note we assume that each MCV will match at most one member
* of the other MCV list. If the operator isn't really
* equality, there could be multiple matches --- but we don't
* look for them, both for speed and because the math wouldn't
* add up...
*/
matchprodfreq = 0.0;
nmatches = 0;
for (i = 0; i < nvalues1; i++)
{
int j;
for (j = 0; j < nvalues2; j++)
{
if (hasmatch2[j])
continue;
if (DatumGetBool(FunctionCall2(&eqproc,
values1[i],
values2[j])))
{
hasmatch1[i] = hasmatch2[j] = true;
matchprodfreq += numbers1[i] * numbers2[j];
nmatches++;
break;
}
}
}
CLAMP_PROBABILITY(matchprodfreq);
/* Sum up frequencies of matched and unmatched MCVs */
matchfreq1 = unmatchfreq1 = 0.0;
for (i = 0; i < nvalues1; i++)
{
if (hasmatch1[i])
matchfreq1 += numbers1[i];
else
unmatchfreq1 += numbers1[i];
}
CLAMP_PROBABILITY(matchfreq1);
CLAMP_PROBABILITY(unmatchfreq1);
matchfreq2 = unmatchfreq2 = 0.0;
for (i = 0; i < nvalues2; i++)
{
if (hasmatch2[i])
matchfreq2 += numbers2[i];
else
unmatchfreq2 += numbers2[i];
}
CLAMP_PROBABILITY(matchfreq2);
CLAMP_PROBABILITY(unmatchfreq2);
pfree(hasmatch1);
pfree(hasmatch2);
/*
* Compute total frequency of non-null values that are not in
* the MCV lists.
*/
otherfreq1 = 1.0 - stats1->stanullfrac - matchfreq1 - unmatchfreq1;
otherfreq2 = 1.0 - stats2->stanullfrac - matchfreq2 - unmatchfreq2;
CLAMP_PROBABILITY(otherfreq1);
CLAMP_PROBABILITY(otherfreq2);
/*
* We can estimate the total selectivity from the point of
* view of relation 1 as: the known selectivity for matched
* MCVs, plus unmatched MCVs that are assumed to match against
* random members of relation 2's non-MCV population, plus
* non-MCV values that are assumed to match against random
* members of relation 2's unmatched MCVs plus non-MCV values.
*/
totalsel1 = matchprodfreq;
if (nd2 > nvalues2)
totalsel1 += unmatchfreq1 * otherfreq2 / (nd2 - nvalues2);
if (nd2 > nmatches)
totalsel1 += otherfreq1 * (otherfreq2 + unmatchfreq2) /
(nd2 - nmatches);
/* Same estimate from the point of view of relation 2. */
totalsel2 = matchprodfreq;
if (nd1 > nvalues1)
totalsel2 += unmatchfreq2 * otherfreq1 / (nd1 - nvalues1);
if (nd1 > nmatches)
totalsel2 += otherfreq2 * (otherfreq1 + unmatchfreq1) /
(nd1 - nmatches);
/*
* Use the smaller of the two estimates. This can be
* justified in essentially the same terms as given below for
* the no-stats case: to a first approximation, we are
* estimating from the point of view of the relation with
* smaller nd.
*/
selec = (totalsel1 < totalsel2) ? totalsel1 : totalsel2;
}
else
{
/*
* We do not have MCV lists for both sides. Estimate the join
* selectivity as MIN(1/nd1, 1/nd2). This is plausible if we
* assume that the values are about equally distributed: a
* given tuple of rel1 will join to either 0 or N2/nd2 rows of
* rel2, so total join rows are at most N1*N2/nd2 giving a
* join selectivity of not more than 1/nd2. By the same logic
* it is not more than 1/nd1, so MIN(1/nd1, 1/nd2) is an upper
* bound. Using the MIN() means we estimate from the point of
* view of the relation with smaller nd (since the larger nd
* is determining the MIN). It is reasonable to assume that
* most tuples in this rel will have join partners, so the
* bound is probably reasonably tight and should be taken
* as-is.
*
* XXX Can we be smarter if we have an MCV list for just one
* side? It seems that if we assume equal distribution for the
* other side, we end up with the same answer anyway.
*/
if (nd1 > nd2)
selec = 1.0 / nd1;
else
selec = 1.0 / nd2;
}
if (have_mcvs1)
free_attstatsslot(var1->vartype, values1, nvalues1,
numbers1, nnumbers1);
if (have_mcvs2)
free_attstatsslot(var2->vartype, values2, nvalues2,
numbers2, nnumbers2);
if (HeapTupleIsValid(statsTuple1))
ReleaseSysCache(statsTuple1);
if (HeapTupleIsValid(statsTuple2))
ReleaseSysCache(statsTuple2);
}
CLAMP_PROBABILITY(selec);
PG_RETURN_FLOAT8((float8) selec);
}
/*
* neqjoinsel - Join selectivity of "!="
*/
Datum
neqjoinsel(PG_FUNCTION_ARGS)
{
Query *root = (Query *) PG_GETARG_POINTER(0);
Oid operator = PG_GETARG_OID(1);
List *args = (List *) PG_GETARG_POINTER(2);
Oid eqop;
float8 result;
/*
* We want 1 - eqjoinsel() where the equality operator is the one
* associated with this != operator, that is, its negator.
*/
eqop = get_negator(operator);
if (eqop)
{
result = DatumGetFloat8(DirectFunctionCall3(eqjoinsel,
PointerGetDatum(root),
ObjectIdGetDatum(eqop),
PointerGetDatum(args)));
}
else
{
/* Use default selectivity (should we raise an error instead?) */
result = DEFAULT_EQ_SEL;
}
result = 1.0 - result;
PG_RETURN_FLOAT8(result);
}
/*
* scalarltjoinsel - Join selectivity of "<" and "<=" for scalars
*/
Datum
scalarltjoinsel(PG_FUNCTION_ARGS)
{
PG_RETURN_FLOAT8(DEFAULT_INEQ_SEL);
}
/*
* scalargtjoinsel - Join selectivity of ">" and ">=" for scalars
*/
Datum
scalargtjoinsel(PG_FUNCTION_ARGS)
{
PG_RETURN_FLOAT8(DEFAULT_INEQ_SEL);
}
/*
* regexeqjoinsel - Join selectivity of regular-expression pattern match.
*/
Datum
regexeqjoinsel(PG_FUNCTION_ARGS)
{
PG_RETURN_FLOAT8(DEFAULT_MATCH_SEL);
}
/*
* icregexeqjoinsel - Join selectivity of case-insensitive regex match.
*/
Datum
icregexeqjoinsel(PG_FUNCTION_ARGS)
{
PG_RETURN_FLOAT8(DEFAULT_MATCH_SEL);
}
/*
* likejoinsel - Join selectivity of LIKE pattern match.
*/
Datum
likejoinsel(PG_FUNCTION_ARGS)
{
PG_RETURN_FLOAT8(DEFAULT_MATCH_SEL);
}
/*
* iclikejoinsel - Join selectivity of ILIKE pattern match.
*/
Datum
iclikejoinsel(PG_FUNCTION_ARGS)
{
PG_RETURN_FLOAT8(DEFAULT_MATCH_SEL);
}
/*
* regexnejoinsel - Join selectivity of regex non-match.
*/
Datum
regexnejoinsel(PG_FUNCTION_ARGS)
{
float8 result;
result = DatumGetFloat8(regexeqjoinsel(fcinfo));
result = 1.0 - result;
PG_RETURN_FLOAT8(result);
}
/*
* icregexnejoinsel - Join selectivity of case-insensitive regex non-match.
*/
Datum
icregexnejoinsel(PG_FUNCTION_ARGS)
{
float8 result;
result = DatumGetFloat8(icregexeqjoinsel(fcinfo));
result = 1.0 - result;
PG_RETURN_FLOAT8(result);
}
/*
* nlikejoinsel - Join selectivity of LIKE pattern non-match.
*/
Datum
nlikejoinsel(PG_FUNCTION_ARGS)
{
float8 result;
result = DatumGetFloat8(likejoinsel(fcinfo));
result = 1.0 - result;
PG_RETURN_FLOAT8(result);
}
/*
* icnlikejoinsel - Join selectivity of ILIKE pattern non-match.
*/
Datum
icnlikejoinsel(PG_FUNCTION_ARGS)
{
float8 result;
result = DatumGetFloat8(iclikejoinsel(fcinfo));
result = 1.0 - result;
PG_RETURN_FLOAT8(result);
}
/*
* mergejoinscansel - Scan selectivity of merge join.
*
* A merge join will stop as soon as it exhausts either input stream.
* Therefore, if we can estimate the ranges of both input variables,
* we can estimate how much of the input will actually be read. This
* can have a considerable impact on the cost when using indexscans.
*
* clause should be a clause already known to be mergejoinable.
*
* *leftscan is set to the fraction of the left-hand variable expected
* to be scanned (0 to 1), and similarly *rightscan for the right-hand
* variable.
*/
void
mergejoinscansel(Query *root, Node *clause,
Selectivity *leftscan,
Selectivity *rightscan)
{
Var *left,
*right;
Oid opno,
lsortop,
rsortop,
ltop,
gtop,
revltop;
Datum leftmax,
rightmax;
double selec;
/* Set default results if we can't figure anything out. */
*leftscan = *rightscan = 1.0;
/* Deconstruct the merge clause */
if (!is_opclause(clause))
return; /* shouldn't happen */
opno = ((Oper *) ((Expr *) clause)->oper)->opno;
left = get_leftop((Expr *) clause);
right = get_rightop((Expr *) clause);
if (!right)
return; /* shouldn't happen */
/* Can't do anything if inputs are not Vars */
if (!IsA(left, Var) ||!IsA(right, Var))
return;
/* Verify mergejoinability and get left and right "<" operators */
if (!op_mergejoinable(opno,
left->vartype,
right->vartype,
&lsortop,
&rsortop))
return; /* shouldn't happen */
/* Try to get maximum values of both vars */
if (!get_var_maximum(root, left, lsortop, &leftmax))
return; /* no max available from stats */
if (!get_var_maximum(root, right, rsortop, &rightmax))
return; /* no max available from stats */
/* Look up the "left < right" and "left > right" operators */
op_mergejoin_crossops(opno, &ltop, &gtop, NULL, NULL);
/* Look up the "right < left" operator */
revltop = get_commutator(gtop);
if (!OidIsValid(revltop))
return; /* shouldn't happen */
/*
* Now, the fraction of the left variable that will be scanned is the
* fraction that's <= the right-side maximum value. But only believe
* non-default estimates, else stick with our 1.0.
*/
selec = scalarineqsel(root, ltop, false, left,
rightmax, right->vartype);
if (selec != DEFAULT_INEQ_SEL)
*leftscan = selec;
/* And similarly for the right variable. */
selec = scalarineqsel(root, revltop, false, right,
leftmax, left->vartype);
if (selec != DEFAULT_INEQ_SEL)
*rightscan = selec;
/*
* Only one of the two fractions can really be less than 1.0; believe
* the smaller estimate and reset the other one to exactly 1.0.
*/
if (*leftscan > *rightscan)
*leftscan = 1.0;
else
*rightscan = 1.0;
}
/*
* get_var_maximum
* Estimate the maximum value of the specified variable.
* If successful, store value in *max and return TRUE.
* If no data available, return FALSE.
*
* sortop is the "<" comparison operator to use. (To extract the
* minimum instead of the maximum, just pass the ">" operator instead.)
*/
static bool
get_var_maximum(Query *root, Var *var, Oid sortop, Datum *max)
{
Datum tmax = 0;
bool have_max = false;
Oid relid;
HeapTuple statsTuple;
Form_pg_statistic stats;
int16 typLen;
bool typByVal;
Datum *values;
int nvalues;
int i;
relid = getrelid(var->varno, root->rtable);
if (relid == InvalidOid)
return false;
/* get stats for the attribute */
statsTuple = SearchSysCache(STATRELATT,
ObjectIdGetDatum(relid),
Int16GetDatum(var->varattno),
0, 0);
if (!HeapTupleIsValid(statsTuple))
{
/* no stats available, so default result */
return false;
}
stats = (Form_pg_statistic) GETSTRUCT(statsTuple);
get_typlenbyval(var->vartype, &typLen, &typByVal);
/*
* If there is a histogram, grab the last or first value as appropriate.
*
* If there is a histogram that is sorted with some other operator
* than the one we want, fail --- this suggests that there is data
* we can't use.
*/
if (get_attstatsslot(statsTuple, var->vartype, var->vartypmod,
STATISTIC_KIND_HISTOGRAM, sortop,
&values, &nvalues,
NULL, NULL))
{
if (nvalues > 0)
{
tmax = datumCopy(values[nvalues-1], typByVal, typLen);
have_max = true;
}
free_attstatsslot(var->vartype, values, nvalues, NULL, 0);
}
else
{
Oid rsortop = get_commutator(sortop);
if (OidIsValid(rsortop) &&
get_attstatsslot(statsTuple, var->vartype, var->vartypmod,
STATISTIC_KIND_HISTOGRAM, rsortop,
&values, &nvalues,
NULL, NULL))
{
if (nvalues > 0)
{
tmax = datumCopy(values[0], typByVal, typLen);
have_max = true;
}
free_attstatsslot(var->vartype, values, nvalues, NULL, 0);
}
else if (get_attstatsslot(statsTuple, var->vartype, var->vartypmod,
STATISTIC_KIND_HISTOGRAM, InvalidOid,
&values, &nvalues,
NULL, NULL))
{
free_attstatsslot(var->vartype, values, nvalues, NULL, 0);
ReleaseSysCache(statsTuple);
return false;
}
}
/*
* If we have most-common-values info, look for a large MCV. This
* is needed even if we also have a histogram, since the histogram
* excludes the MCVs. However, usually the MCVs will not be the
* extreme values, so avoid unnecessary data copying.
*/
if (get_attstatsslot(statsTuple, var->vartype, var->vartypmod,
STATISTIC_KIND_MCV, InvalidOid,
&values, &nvalues,
NULL, NULL))
{
bool large_mcv = false;
FmgrInfo opproc;
fmgr_info(get_opcode(sortop), &opproc);
for (i = 0; i < nvalues; i++)
{
if (!have_max)
{
tmax = values[i];
large_mcv = have_max = true;
}
else if (DatumGetBool(FunctionCall2(&opproc, tmax, values[i])))
{
tmax = values[i];
large_mcv = true;
}
}
if (large_mcv)
tmax = datumCopy(tmax, typByVal, typLen);
free_attstatsslot(var->vartype, values, nvalues, NULL, 0);
}
ReleaseSysCache(statsTuple);
*max = tmax;
return have_max;
}
/*
* convert_to_scalar
* Convert non-NULL values of the indicated types to the comparison
* scale needed by scalarltsel()/scalargtsel().
* Returns "true" if successful.
*
* XXX this routine is a hack: ideally we should look up the conversion
* subroutines in pg_type.
*
* All numeric datatypes are simply converted to their equivalent
* "double" values. (NUMERIC values that are outside the range of "double"
* are clamped to +/- HUGE_VAL.)
*
* String datatypes are converted by convert_string_to_scalar(),
* which is explained below. The reason why this routine deals with
* three values at a time, not just one, is that we need it for strings.
*
* The bytea datatype is just enough different from strings that it has
* to be treated separately.
*
* The several datatypes representing absolute times are all converted
* to Timestamp, which is actually a double, and then we just use that
* double value. Note this will give correct results even for the "special"
* values of Timestamp, since those are chosen to compare correctly;
* see timestamp_cmp.
*
* The several datatypes representing relative times (intervals) are all
* converted to measurements expressed in seconds.
*/
static bool
convert_to_scalar(Datum value, Oid valuetypid, double *scaledvalue,
Datum lobound, Datum hibound, Oid boundstypid,
double *scaledlobound, double *scaledhibound)
{
switch (valuetypid)
{
/*
* Built-in numeric types
*/
case BOOLOID:
case INT2OID:
case INT4OID:
case INT8OID:
case FLOAT4OID:
case FLOAT8OID:
case NUMERICOID:
case OIDOID:
case REGPROCOID:
*scaledvalue = convert_numeric_to_scalar(value, valuetypid);
*scaledlobound = convert_numeric_to_scalar(lobound, boundstypid);
*scaledhibound = convert_numeric_to_scalar(hibound, boundstypid);
return true;
/*
* Built-in string types
*/
case CHAROID:
case BPCHAROID:
case VARCHAROID:
case TEXTOID:
case NAMEOID:
{
unsigned char *valstr = convert_string_datum(value, valuetypid);
unsigned char *lostr = convert_string_datum(lobound, boundstypid);
unsigned char *histr = convert_string_datum(hibound, boundstypid);
convert_string_to_scalar(valstr, scaledvalue,
lostr, scaledlobound,
histr, scaledhibound);
pfree(valstr);
pfree(lostr);
pfree(histr);
return true;
}
/*
* Built-in bytea type
*/
case BYTEAOID:
{
convert_bytea_to_scalar(value, scaledvalue,
lobound, scaledlobound,
hibound, scaledhibound);
return true;
}
/*
* Built-in time types
*/
case TIMESTAMPOID:
case TIMESTAMPTZOID:
case ABSTIMEOID:
case DATEOID:
case INTERVALOID:
case RELTIMEOID:
case TINTERVALOID:
case TIMEOID:
case TIMETZOID:
*scaledvalue = convert_timevalue_to_scalar(value, valuetypid);
*scaledlobound = convert_timevalue_to_scalar(lobound, boundstypid);
*scaledhibound = convert_timevalue_to_scalar(hibound, boundstypid);
return true;
/*
* Built-in network types
*/
case INETOID:
case CIDROID:
case MACADDROID:
*scaledvalue = convert_network_to_scalar(value, valuetypid);
*scaledlobound = convert_network_to_scalar(lobound, boundstypid);
*scaledhibound = convert_network_to_scalar(hibound, boundstypid);
return true;
}
/* Don't know how to convert */
return false;
}
/*
* Do convert_to_scalar()'s work for any numeric data type.
*/
static double
convert_numeric_to_scalar(Datum value, Oid typid)
{
switch (typid)
{
case BOOLOID:
return (double) DatumGetBool(value);
case INT2OID:
return (double) DatumGetInt16(value);
case INT4OID:
return (double) DatumGetInt32(value);
case INT8OID:
return (double) DatumGetInt64(value);
case FLOAT4OID:
return (double) DatumGetFloat4(value);
case FLOAT8OID:
return (double) DatumGetFloat8(value);
case NUMERICOID:
/* Note: out-of-range values will be clamped to +-HUGE_VAL */
return (double)
DatumGetFloat8(DirectFunctionCall1(numeric_float8_no_overflow,
value));
case OIDOID:
case REGPROCOID:
/* we can treat OIDs as integers... */
return (double) DatumGetObjectId(value);
}
/*
* Can't get here unless someone tries to use scalarltsel/scalargtsel
* on an operator with one numeric and one non-numeric operand.
*/
elog(ERROR, "convert_numeric_to_scalar: unsupported type %u", typid);
return 0;
}
/*
* Do convert_to_scalar()'s work for any character-string data type.
*
* String datatypes are converted to a scale that ranges from 0 to 1,
* where we visualize the bytes of the string as fractional digits.
*
* We do not want the base to be 256, however, since that tends to
* generate inflated selectivity estimates; few databases will have
* occurrences of all 256 possible byte values at each position.
* Instead, use the smallest and largest byte values seen in the bounds
* as the estimated range for each byte, after some fudging to deal with
* the fact that we probably aren't going to see the full range that way.
*
* An additional refinement is that we discard any common prefix of the
* three strings before computing the scaled values. This allows us to
* "zoom in" when we encounter a narrow data range. An example is a phone
* number database where all the values begin with the same area code.
* (Actually, the bounds will be adjacent histogram-bin-boundary values,
* so this is more likely to happen than you might think.)
*/
static void
convert_string_to_scalar(unsigned char *value,
double *scaledvalue,
unsigned char *lobound,
double *scaledlobound,
unsigned char *hibound,
double *scaledhibound)
{
int rangelo,
rangehi;
unsigned char *sptr;
rangelo = rangehi = hibound[0];
for (sptr = lobound; *sptr; sptr++)
{
if (rangelo > *sptr)
rangelo = *sptr;
if (rangehi < *sptr)
rangehi = *sptr;
}
for (sptr = hibound; *sptr; sptr++)
{
if (rangelo > *sptr)
rangelo = *sptr;
if (rangehi < *sptr)
rangehi = *sptr;
}
/* If range includes any upper-case ASCII chars, make it include all */
if (rangelo <= 'Z' && rangehi >= 'A')
{
if (rangelo > 'A')
rangelo = 'A';
if (rangehi < 'Z')
rangehi = 'Z';
}
/* Ditto lower-case */
if (rangelo <= 'z' && rangehi >= 'a')
{
if (rangelo > 'a')
rangelo = 'a';
if (rangehi < 'z')
rangehi = 'z';
}
/* Ditto digits */
if (rangelo <= '9' && rangehi >= '0')
{
if (rangelo > '0')
rangelo = '0';
if (rangehi < '9')
rangehi = '9';
}
/*
* If range includes less than 10 chars, assume we have not got enough
* data, and make it include regular ASCII set.
*/
if (rangehi - rangelo < 9)
{
rangelo = ' ';
rangehi = 127;
}
/*
* Now strip any common prefix of the three strings.
*/
while (*lobound)
{
if (*lobound != *hibound || *lobound != *value)
break;
lobound++, hibound++, value++;
}
/*
* Now we can do the conversions.
*/
*scaledvalue = convert_one_string_to_scalar(value, rangelo, rangehi);
*scaledlobound = convert_one_string_to_scalar(lobound, rangelo, rangehi);
*scaledhibound = convert_one_string_to_scalar(hibound, rangelo, rangehi);
}
static double
convert_one_string_to_scalar(unsigned char *value, int rangelo, int rangehi)
{
int slen = strlen((char *) value);
double num,
denom,
base;
if (slen <= 0)
return 0.0; /* empty string has scalar value 0 */
/*
* Since base is at least 10, need not consider more than about 20
* chars
*/
if (slen > 20)
slen = 20;
/* Convert initial characters to fraction */
base = rangehi - rangelo + 1;
num = 0.0;
denom = base;
while (slen-- > 0)
{
int ch = *value++;
if (ch < rangelo)
ch = rangelo - 1;
else if (ch > rangehi)
ch = rangehi + 1;
num += ((double) (ch - rangelo)) / denom;
denom *= base;
}
return num;
}
/*
* Convert a string-type Datum into a palloc'd, null-terminated string.
*
* If USE_LOCALE is defined, we must pass the string through strxfrm()
* before continuing, so as to generate correct locale-specific results.
*/
static unsigned char *
convert_string_datum(Datum value, Oid typid)
{
char *val;
#ifdef USE_LOCALE
char *xfrmstr;
size_t xfrmsize;
size_t xfrmlen;
#endif
switch (typid)
{
case CHAROID:
val = (char *) palloc(2);
val[0] = DatumGetChar(value);
val[1] = '\0';
break;
case BPCHAROID:
case VARCHAROID:
case TEXTOID:
{
char *str = (char *) VARDATA(DatumGetPointer(value));
int strlength = VARSIZE(DatumGetPointer(value)) - VARHDRSZ;
val = (char *) palloc(strlength + 1);
memcpy(val, str, strlength);
val[strlength] = '\0';
break;
}
case NAMEOID:
{
NameData *nm = (NameData *) DatumGetPointer(value);
val = pstrdup(NameStr(*nm));
break;
}
default:
/*
* Can't get here unless someone tries to use scalarltsel on
* an operator with one string and one non-string operand.
*/
elog(ERROR, "convert_string_datum: unsupported type %u", typid);
return NULL;
}
#ifdef USE_LOCALE
/* Guess that transformed string is not much bigger than original */
xfrmsize = strlen(val) + 32; /* arbitrary pad value here... */
xfrmstr = (char *) palloc(xfrmsize);
xfrmlen = strxfrm(xfrmstr, val, xfrmsize);
if (xfrmlen >= xfrmsize)
{
/* Oops, didn't make it */
pfree(xfrmstr);
xfrmstr = (char *) palloc(xfrmlen + 1);
xfrmlen = strxfrm(xfrmstr, val, xfrmlen + 1);
}
pfree(val);
val = xfrmstr;
#endif
return (unsigned char *) val;
}
/*
* Do convert_to_scalar()'s work for any bytea data type.
*
* Very similar to convert_string_to_scalar except we can't assume
* null-termination and therefore pass explicit lengths around.
*
* Also, assumptions about likely "normal" ranges of characters have been
* removed - a data range of 0..255 is always used, for now. (Perhaps
* someday we will add information about actual byte data range to
* pg_statistic.)
*/
static void
convert_bytea_to_scalar(Datum value,
double *scaledvalue,
Datum lobound,
double *scaledlobound,
Datum hibound,
double *scaledhibound)
{
int rangelo,
rangehi,
valuelen = VARSIZE(DatumGetPointer(value)) - VARHDRSZ,
loboundlen = VARSIZE(DatumGetPointer(lobound)) - VARHDRSZ,
hiboundlen = VARSIZE(DatumGetPointer(hibound)) - VARHDRSZ,
i,
minlen;
unsigned char *valstr = (unsigned char *) VARDATA(DatumGetPointer(value)),
*lostr = (unsigned char *) VARDATA(DatumGetPointer(lobound)),
*histr = (unsigned char *) VARDATA(DatumGetPointer(hibound));
/*
* Assume bytea data is uniformly distributed across all byte values.
*/
rangelo = 0;
rangehi = 255;
/*
* Now strip any common prefix of the three strings.
*/
minlen = Min(Min(valuelen, loboundlen), hiboundlen);
for (i = 0; i < minlen; i++)
{
if (*lostr != *histr || *lostr != *valstr)
break;
lostr++, histr++, valstr++;
loboundlen--, hiboundlen--, valuelen--;
}
/*
* Now we can do the conversions.
*/
*scaledvalue = convert_one_bytea_to_scalar(valstr, valuelen, rangelo, rangehi);
*scaledlobound = convert_one_bytea_to_scalar(lostr, loboundlen, rangelo, rangehi);
*scaledhibound = convert_one_bytea_to_scalar(histr, hiboundlen, rangelo, rangehi);
}
static double
convert_one_bytea_to_scalar(unsigned char *value, int valuelen,
int rangelo, int rangehi)
{
double num,
denom,
base;
if (valuelen <= 0)
return 0.0; /* empty string has scalar value 0 */
/*
* Since base is 256, need not consider more than about 10 chars (even
* this many seems like overkill)
*/
if (valuelen > 10)
valuelen = 10;
/* Convert initial characters to fraction */
base = rangehi - rangelo + 1;
num = 0.0;
denom = base;
while (valuelen-- > 0)
{
int ch = *value++;
if (ch < rangelo)
ch = rangelo - 1;
else if (ch > rangehi)
ch = rangehi + 1;
num += ((double) (ch - rangelo)) / denom;
denom *= base;
}
return num;
}
/*
* Do convert_to_scalar()'s work for any timevalue data type.
*/
static double
convert_timevalue_to_scalar(Datum value, Oid typid)
{
switch (typid)
{
case TIMESTAMPOID:
return DatumGetTimestamp(value);
case TIMESTAMPTZOID:
return DatumGetTimestampTz(value);
case ABSTIMEOID:
return DatumGetTimestamp(DirectFunctionCall1(abstime_timestamp,
value));
case DATEOID:
return DatumGetTimestamp(DirectFunctionCall1(date_timestamp,
value));
case INTERVALOID:
{
Interval *interval = DatumGetIntervalP(value);
/*
* Convert the month part of Interval to days using
* assumed average month length of 365.25/12.0 days. Not
* too accurate, but plenty good enough for our purposes.
*/
return interval->time +
interval->month * (365.25 / 12.0 * 24.0 * 60.0 * 60.0);
}
case RELTIMEOID:
return DatumGetRelativeTime(value);
case TINTERVALOID:
{
TimeInterval interval = DatumGetTimeInterval(value);
if (interval->status != 0)
return interval->data[1] - interval->data[0];
return 0; /* for lack of a better idea */
}
case TIMEOID:
return DatumGetTimeADT(value);
case TIMETZOID:
{
TimeTzADT *timetz = DatumGetTimeTzADTP(value);
/* use GMT-equivalent time */
return (double) (timetz->time + timetz->zone);
}
}
/*
* Can't get here unless someone tries to use scalarltsel/scalargtsel
* on an operator with one timevalue and one non-timevalue operand.
*/
elog(ERROR, "convert_timevalue_to_scalar: unsupported type %u", typid);
return 0;
}
/*
* get_att_numdistinct
* Estimate the number of distinct values of an attribute.
*
* var: identifies the attribute to examine.
* stats: pg_statistic tuple for attribute, or NULL if not available.
*
* NB: be careful to produce an integral result, since callers may compare
* the result to exact integer counts.
*/
static double
get_att_numdistinct(Query *root, Var *var, Form_pg_statistic stats)
{
RelOptInfo *rel;
double ntuples;
/*
* Special-case boolean columns: presumably, two distinct values.
*
* Are there any other cases we should wire in special estimates for?
*/
if (var->vartype == BOOLOID)
return 2.0;
/*
* Otherwise we need to get the relation size.
*/
rel = find_base_rel(root, var->varno);
ntuples = rel->tuples;
if (ntuples <= 0.0)
return DEFAULT_NUM_DISTINCT; /* no data available; return a
* default */
/*
* Look to see if there is a unique index on the attribute. If so, we
* assume it's distinct, ignoring pg_statistic info which could be out
* of date.
*/
if (has_unique_index(rel, var->varattno))
return ntuples;
/*
* If ANALYZE determined a fixed or scaled estimate, use it.
*/
if (stats)
{
if (stats->stadistinct > 0.0)
return stats->stadistinct;
if (stats->stadistinct < 0.0)
return floor((-stats->stadistinct * ntuples) + 0.5);
}
/*
* ANALYZE does not compute stats for system attributes, but some of
* them can reasonably be assumed unique anyway.
*/
switch (var->varattno)
{
case ObjectIdAttributeNumber:
case SelfItemPointerAttributeNumber:
return ntuples;
case TableOidAttributeNumber:
return 1.0;
}
/*
* Estimate ndistinct = ntuples if the table is small, else use
* default.
*/
if (ntuples < DEFAULT_NUM_DISTINCT)
return ntuples;
return DEFAULT_NUM_DISTINCT;
}
/*
* get_restriction_var
* Examine the args of a restriction clause to see if it's of the
* form (var op something) or (something op var). If so, extract
* and return the var and the other argument.
*
* Inputs:
* args: clause argument list
* varRelid: see specs for restriction selectivity functions
*
* Outputs: (these are set only if TRUE is returned)
* *var: gets Var node
* *other: gets other clause argument
* *varonleft: set TRUE if var is on the left, FALSE if on the right
*
* Returns TRUE if a Var is identified, otherwise FALSE.
*/
static bool
get_restriction_var(List *args,
int varRelid,
Var **var,
Node **other,
bool *varonleft)
{
Node *left,
*right;
if (length(args) != 2)
return false;
left = (Node *) lfirst(args);
right = (Node *) lsecond(args);
/* Ignore any binary-compatible relabeling */
if (IsA(left, RelabelType))
left = ((RelabelType *) left)->arg;
if (IsA(right, RelabelType))
right = ((RelabelType *) right)->arg;
/* Look for the var */
if (IsA(left, Var) &&
(varRelid == 0 || varRelid == ((Var *) left)->varno))
{
*var = (Var *) left;
*other = right;
*varonleft = true;
}
else if (IsA(right, Var) &&
(varRelid == 0 || varRelid == ((Var *) right)->varno))
{
*var = (Var *) right;
*other = left;
*varonleft = false;
}
else
{
/* Duh, it's too complicated for me... */
return false;
}
return true;
}
/*
* get_join_vars
*
* Extract the two Vars from a join clause's argument list. Returns
* NULL for arguments that are not simple vars.
*/
static void
get_join_vars(List *args, Var **var1, Var **var2)
{
Node *left,
*right;
if (length(args) != 2)
{
*var1 = NULL;
*var2 = NULL;
return;
}
left = (Node *) lfirst(args);
right = (Node *) lsecond(args);
/* Ignore any binary-compatible relabeling */
if (IsA(left, RelabelType))
left = ((RelabelType *) left)->arg;
if (IsA(right, RelabelType))
right = ((RelabelType *) right)->arg;
if (IsA(left, Var))
*var1 = (Var *) left;
else
*var1 = NULL;
if (IsA(right, Var))
*var2 = (Var *) right;
else
*var2 = NULL;
}
/*-------------------------------------------------------------------------
*
* Pattern analysis functions
*
* These routines support analysis of LIKE and regular-expression patterns
* by the planner/optimizer. It's important that they agree with the
* regular-expression code in backend/regex/ and the LIKE code in
* backend/utils/adt/like.c.
*
* Note that the prefix-analysis functions are called from
* backend/optimizer/path/indxpath.c as well as from routines in this file.
*
*-------------------------------------------------------------------------
*/
/*
* Extract the fixed prefix, if any, for a pattern.
* *prefix is set to a palloc'd prefix string,
* or to NULL if no fixed prefix exists for the pattern.
* *rest is set to point to the remainder of the pattern after the
* portion describing the fixed prefix.
* The return value distinguishes no fixed prefix, a partial prefix,
* or an exact-match-only pattern.
*/
static Pattern_Prefix_Status
like_fixed_prefix(char *patt, bool case_insensitive,
char **prefix, char **rest)
{
char *match;
int pos,
match_pos;
*prefix = match = palloc(strlen(patt) + 1);
match_pos = 0;
for (pos = 0; patt[pos]; pos++)
{
/* % and _ are wildcard characters in LIKE */
if (patt[pos] == '%' ||
patt[pos] == '_')
break;
/* Backslash quotes the next character */
if (patt[pos] == '\\')
{
pos++;
if (patt[pos] == '\0')
break;
}
/*
* XXX I suspect isalpha() is not an adequately locale-sensitive
* test for characters that can vary under case folding?
*/
if (case_insensitive && isalpha((unsigned char) patt[pos]))
break;
/*
* NOTE: this code used to think that %% meant a literal %, but
* textlike() itself does not think that, and the SQL92 spec
* doesn't say any such thing either.
*/
match[match_pos++] = patt[pos];
}
match[match_pos] = '\0';
*rest = &patt[pos];
/* in LIKE, an empty pattern is an exact match! */
if (patt[pos] == '\0')
return Pattern_Prefix_Exact; /* reached end of pattern, so
* exact */
if (match_pos > 0)
return Pattern_Prefix_Partial;
pfree(match);
*prefix = NULL;
return Pattern_Prefix_None;
}
static Pattern_Prefix_Status
regex_fixed_prefix(char *patt, bool case_insensitive,
char **prefix, char **rest)
{
char *match;
int pos,
match_pos,
paren_depth;
/* Pattern must be anchored left */
if (patt[0] != '^')
{
*prefix = NULL;
*rest = patt;
return Pattern_Prefix_None;
}
/*
* If unquoted | is present at paren level 0 in pattern, then there
* are multiple alternatives for the start of the string.
*/
paren_depth = 0;
for (pos = 1; patt[pos]; pos++)
{
if (patt[pos] == '|' && paren_depth == 0)
{
*prefix = NULL;
*rest = patt;
return Pattern_Prefix_None;
}
else if (patt[pos] == '(')
paren_depth++;
else if (patt[pos] == ')' && paren_depth > 0)
paren_depth--;
else if (patt[pos] == '\\')
{
/* backslash quotes the next character */
pos++;
if (patt[pos] == '\0')
break;
}
}
/* OK, allocate space for pattern */
*prefix = match = palloc(strlen(patt) + 1);
match_pos = 0;
/* note start at pos 1 to skip leading ^ */
for (pos = 1; patt[pos]; pos++)
{
/*
* Check for characters that indicate multiple possible matches
* here. XXX I suspect isalpha() is not an adequately
* locale-sensitive test for characters that can vary under case
* folding?
*/
if (patt[pos] == '.' ||
patt[pos] == '(' ||
patt[pos] == '[' ||
patt[pos] == '$' ||
(case_insensitive && isalpha((unsigned char) patt[pos])))
break;
/*
* Check for quantifiers. Except for +, this means the preceding
* character is optional, so we must remove it from the prefix
* too!
*/
if (patt[pos] == '*' ||
patt[pos] == '?' ||
patt[pos] == '{')
{
if (match_pos > 0)
match_pos--;
pos--;
break;
}
if (patt[pos] == '+')
{
pos--;
break;
}
if (patt[pos] == '\\')
{
/* backslash quotes the next character */
pos++;
if (patt[pos] == '\0')
break;
}
match[match_pos++] = patt[pos];
}
match[match_pos] = '\0';
*rest = &patt[pos];
if (patt[pos] == '$' && patt[pos + 1] == '\0')
{
*rest = &patt[pos + 1];
return Pattern_Prefix_Exact; /* pattern specifies exact match */
}
if (match_pos > 0)
return Pattern_Prefix_Partial;
pfree(match);
*prefix = NULL;
return Pattern_Prefix_None;
}
Pattern_Prefix_Status
pattern_fixed_prefix(char *patt, Pattern_Type ptype,
char **prefix, char **rest)
{
Pattern_Prefix_Status result;
switch (ptype)
{
case Pattern_Type_Like:
result = like_fixed_prefix(patt, false, prefix, rest);
break;
case Pattern_Type_Like_IC:
result = like_fixed_prefix(patt, true, prefix, rest);
break;
case Pattern_Type_Regex:
result = regex_fixed_prefix(patt, false, prefix, rest);
break;
case Pattern_Type_Regex_IC:
result = regex_fixed_prefix(patt, true, prefix, rest);
break;
default:
elog(ERROR, "pattern_fixed_prefix: bogus ptype");
result = Pattern_Prefix_None; /* keep compiler quiet */
break;
}
return result;
}
/*
* Estimate the selectivity of a fixed prefix for a pattern match.
*
* A fixed prefix "foo" is estimated as the selectivity of the expression
* "var >= 'foo' AND var < 'fop'" (see also indxqual.c).
*
* XXX Note: we make use of the upper bound to estimate operator selectivity
* even if the locale is such that we cannot rely on the upper-bound string.
* The selectivity only needs to be approximately right anyway, so it seems
* more useful to use the upper-bound code than not.
*/
static Selectivity
prefix_selectivity(Query *root, Var *var, char *prefix)
{
Selectivity prefixsel;
Oid cmpopr;
Const *prefixcon;
List *cmpargs;
char *greaterstr;
cmpopr = find_operator(">=", var->vartype);
if (cmpopr == InvalidOid)
elog(ERROR, "prefix_selectivity: no >= operator for type %u",
var->vartype);
prefixcon = string_to_const(prefix, var->vartype);
cmpargs = makeList2(var, prefixcon);
/* Assume scalargtsel is appropriate for all supported types */
prefixsel = DatumGetFloat8(DirectFunctionCall4(scalargtsel,
PointerGetDatum(root),
ObjectIdGetDatum(cmpopr),
PointerGetDatum(cmpargs),
Int32GetDatum(0)));
/*-------
* If we can create a string larger than the prefix, say
* "x < greaterstr".
*-------
*/
greaterstr = make_greater_string(prefix, var->vartype);
if (greaterstr)
{
Selectivity topsel;
cmpopr = find_operator("<", var->vartype);
if (cmpopr == InvalidOid)
elog(ERROR, "prefix_selectivity: no < operator for type %u",
var->vartype);
prefixcon = string_to_const(greaterstr, var->vartype);
cmpargs = makeList2(var, prefixcon);
/* Assume scalarltsel is appropriate for all supported types */
topsel = DatumGetFloat8(DirectFunctionCall4(scalarltsel,
PointerGetDatum(root),
ObjectIdGetDatum(cmpopr),
PointerGetDatum(cmpargs),
Int32GetDatum(0)));
/*
* Merge the two selectivities in the same way as for a range
* query (see clauselist_selectivity()).
*/
prefixsel = topsel + prefixsel - 1.0;
/*
* A zero or slightly negative prefixsel 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 prefixsel is very negative, then we probably have
* default selectivity estimates on one or both sides of the
* range. In that case, insert a not-so-wildly-optimistic default
* estimate.
*/
if (prefixsel <= 0.0)
{
if (prefixsel < -0.01)
{
/*
* No data available --- use a default estimate that is
* small, but not real small.
*/
prefixsel = 0.005;
}
else
{
/*
* It's just roundoff error; use a small positive value
*/
prefixsel = 1.0e-10;
}
}
}
return prefixsel;
}
/*
* Estimate the selectivity of a pattern of the specified type.
* Note that any fixed prefix of the pattern will have been removed already.
*
* For now, we use a very simplistic approach: fixed characters reduce the
* selectivity a good deal, character ranges reduce it a little,
* wildcards (such as % for LIKE or .* for regex) increase it.
*/
#define FIXED_CHAR_SEL 0.04 /* about 1/25 */
#define CHAR_RANGE_SEL 0.25
#define ANY_CHAR_SEL 0.9 /* not 1, since it won't match
* end-of-string */
#define FULL_WILDCARD_SEL 5.0
#define PARTIAL_WILDCARD_SEL 2.0
static Selectivity
like_selectivity(char *patt, bool case_insensitive)
{
Selectivity sel = 1.0;
int pos;
/* Skip any leading %; it's already factored into initial sel */
pos = (*patt == '%') ? 1 : 0;
for (; patt[pos]; pos++)
{
/* % and _ are wildcard characters in LIKE */
if (patt[pos] == '%')
sel *= FULL_WILDCARD_SEL;
else if (patt[pos] == '_')
sel *= ANY_CHAR_SEL;
else if (patt[pos] == '\\')
{
/* Backslash quotes the next character */
pos++;
if (patt[pos] == '\0')
break;
sel *= FIXED_CHAR_SEL;
}
else
sel *= FIXED_CHAR_SEL;
}
/* Could get sel > 1 if multiple wildcards */
if (sel > 1.0)
sel = 1.0;
return sel;
}
static Selectivity
regex_selectivity_sub(char *patt, int pattlen, bool case_insensitive)
{
Selectivity sel = 1.0;
int paren_depth = 0;
int paren_pos = 0; /* dummy init to keep compiler quiet */
int pos;
for (pos = 0; pos < pattlen; pos++)
{
if (patt[pos] == '(')
{
if (paren_depth == 0)
paren_pos = pos; /* remember start of parenthesized item */
paren_depth++;
}
else if (patt[pos] == ')' && paren_depth > 0)
{
paren_depth--;
if (paren_depth == 0)
sel *= regex_selectivity_sub(patt + (paren_pos + 1),
pos - (paren_pos + 1),
case_insensitive);
}
else if (patt[pos] == '|' && paren_depth == 0)
{
/*
* If unquoted | is present at paren level 0 in pattern, we
* have multiple alternatives; sum their probabilities.
*/
sel += regex_selectivity_sub(patt + (pos + 1),
pattlen - (pos + 1),
case_insensitive);
break; /* rest of pattern is now processed */
}
else if (patt[pos] == '[')
{
bool negclass = false;
if (patt[++pos] == '^')
{
negclass = true;
pos++;
}
if (patt[pos] == ']') /* ']' at start of class is not
* special */
pos++;
while (pos < pattlen && patt[pos] != ']')
pos++;
if (paren_depth == 0)
sel *= (negclass ? (1.0 - CHAR_RANGE_SEL) : CHAR_RANGE_SEL);
}
else if (patt[pos] == '.')
{
if (paren_depth == 0)
sel *= ANY_CHAR_SEL;
}
else if (patt[pos] == '*' ||
patt[pos] == '?' ||
patt[pos] == '+')
{
/* Ought to be smarter about quantifiers... */
if (paren_depth == 0)
sel *= PARTIAL_WILDCARD_SEL;
}
else if (patt[pos] == '{')
{
while (pos < pattlen && patt[pos] != '}')
pos++;
if (paren_depth == 0)
sel *= PARTIAL_WILDCARD_SEL;
}
else if (patt[pos] == '\\')
{
/* backslash quotes the next character */
pos++;
if (pos >= pattlen)
break;
if (paren_depth == 0)
sel *= FIXED_CHAR_SEL;
}
else
{
if (paren_depth == 0)
sel *= FIXED_CHAR_SEL;
}
}
/* Could get sel > 1 if multiple wildcards */
if (sel > 1.0)
sel = 1.0;
return sel;
}
static Selectivity
regex_selectivity(char *patt, bool case_insensitive)
{
Selectivity sel;
int pattlen = strlen(patt);
/* If patt doesn't end with $, consider it to have a trailing wildcard */
if (pattlen > 0 && patt[pattlen - 1] == '$' &&
(pattlen == 1 || patt[pattlen - 2] != '\\'))
{
/* has trailing $ */
sel = regex_selectivity_sub(patt, pattlen - 1, case_insensitive);
}
else
{
/* no trailing $ */
sel = regex_selectivity_sub(patt, pattlen, case_insensitive);
sel *= FULL_WILDCARD_SEL;
if (sel > 1.0)
sel = 1.0;
}
return sel;
}
static Selectivity
pattern_selectivity(char *patt, Pattern_Type ptype)
{
Selectivity result;
switch (ptype)
{
case Pattern_Type_Like:
result = like_selectivity(patt, false);
break;
case Pattern_Type_Like_IC:
result = like_selectivity(patt, true);
break;
case Pattern_Type_Regex:
result = regex_selectivity(patt, false);
break;
case Pattern_Type_Regex_IC:
result = regex_selectivity(patt, true);
break;
default:
elog(ERROR, "pattern_selectivity: bogus ptype");
result = 1.0; /* keep compiler quiet */
break;
}
return result;
}
/*
* Test whether the database's LOCALE setting is safe for LIKE/regexp index
* optimization. The key requirement here is that given a prefix string,
* say "foo", we must be able to generate another string "fop" that is
* greater than all strings "foobar" starting with "foo". Unfortunately,
* many non-C locales have bizarre collation rules in which "fop" > "foo"
* is not sufficient to ensure "fop" > "foobar". Until we can come up
* with a more bulletproof way of generating the upper-bound string,
* disable the optimization in locales where it is not known to be safe.
*/
bool
locale_is_like_safe(void)
{
#ifdef USE_LOCALE
/* Cache result so we only have to compute it once */
static int result = -1;
char *localeptr;
if (result >= 0)
return (bool) result;
localeptr = setlocale(LC_COLLATE, NULL);
if (!localeptr)
elog(PANIC, "Invalid LC_COLLATE setting");
/*
* Currently we accept only "C" and "POSIX" (do any systems still
* return "POSIX"?). Which other locales allow safe optimization?
*/
if (strcmp(localeptr, "C") == 0)
result = true;
else if (strcmp(localeptr, "POSIX") == 0)
result = true;
else
result = false;
return (bool) result;
#else /* not USE_LOCALE */
return true; /* We must be in C locale, which is OK */
#endif /* USE_LOCALE */
}
/*
* Try to generate a string greater than the given string or any string it is
* a prefix of. If successful, return a palloc'd string; else return NULL.
*
* To work correctly in non-ASCII locales with weird collation orders,
* we cannot simply increment "foo" to "fop" --- we have to check whether
* we actually produced a string greater than the given one. If not,
* increment the righthand byte again and repeat. If we max out the righthand
* byte, truncate off the last character and start incrementing the next.
* For example, if "z" were the last character in the sort order, then we
* could produce "foo" as a string greater than "fonz".
*
* This could be rather slow in the worst case, but in most cases we won't
* have to try more than one or two strings before succeeding.
*
* XXX this is actually not sufficient, since it only copes with the case
* where individual characters collate in an order different from their
* numeric code assignments. It does not handle cases where there are
* cross-character effects, such as specially sorted digraphs, multiple
* sort passes, etc. For now, we just shut down the whole thing in locales
* that do such things :-(
*/
char *
make_greater_string(const char *str, Oid datatype)
{
char *workstr;
int len;
/*
* Make a modifiable copy, which will be our return value if
* successful
*/
workstr = pstrdup((char *) str);
while ((len = strlen(workstr)) > 0)
{
unsigned char *lastchar = (unsigned char *) (workstr + len - 1);
/*
* Try to generate a larger string by incrementing the last byte.
*/
while (*lastchar < (unsigned char) 255)
{
(*lastchar)++;
if (string_lessthan(str, workstr, datatype))
return workstr; /* Success! */
}
/*
* Truncate off the last character, which might be more than 1
* byte in MULTIBYTE case.
*/
#ifdef MULTIBYTE
len = pg_mbcliplen((const unsigned char *) workstr, len, len - 1);
workstr[len] = '\0';
#else
*lastchar = '\0';
#endif
}
/* Failed... */
pfree(workstr);
return NULL;
}
/*
* Test whether two strings are "<" according to the rules of the given
* datatype. We do this the hard way, ie, actually calling the type's
* "<" operator function, to ensure we get the right result...
*/
static bool
string_lessthan(const char *str1, const char *str2, Oid datatype)
{
Datum datum1 = string_to_datum(str1, datatype);
Datum datum2 = string_to_datum(str2, datatype);
bool result;
switch (datatype)
{
case TEXTOID:
result = DatumGetBool(DirectFunctionCall2(text_lt,
datum1, datum2));
break;
case BPCHAROID:
result = DatumGetBool(DirectFunctionCall2(bpcharlt,
datum1, datum2));
break;
case VARCHAROID:
result = DatumGetBool(DirectFunctionCall2(varcharlt,
datum1, datum2));
break;
case NAMEOID:
result = DatumGetBool(DirectFunctionCall2(namelt,
datum1, datum2));
break;
case BYTEAOID:
result = DatumGetBool(DirectFunctionCall2(bytealt,
datum1, datum2));
break;
default:
elog(ERROR, "string_lessthan: unexpected datatype %u", datatype);
result = false;
break;
}
pfree(DatumGetPointer(datum1));
pfree(DatumGetPointer(datum2));
return result;
}
/* See if there is a binary op of the given name for the given datatype */
static Oid
find_operator(const char *opname, Oid datatype)
{
return GetSysCacheOid(OPERNAME,
PointerGetDatum(opname),
ObjectIdGetDatum(datatype),
ObjectIdGetDatum(datatype),
CharGetDatum('b'));
}
/*
* Generate a Datum of the appropriate type from a C string.
* Note that all of the supported types are pass-by-ref, so the
* returned value should be pfree'd if no longer needed.
*/
static Datum
string_to_datum(const char *str, Oid datatype)
{
/*
* We cheat a little by assuming that textin() will do for bpchar and
* varchar constants too...
*/
if (datatype == NAMEOID)
return DirectFunctionCall1(namein, CStringGetDatum(str));
else
return DirectFunctionCall1(textin, CStringGetDatum(str));
}
/*
* Generate a Const node of the appropriate type from a C string.
*/
static Const *
string_to_const(const char *str, Oid datatype)
{
Datum conval = string_to_datum(str, datatype);
return makeConst(datatype, ((datatype == NAMEOID) ? NAMEDATALEN : -1),
conval, false, false, false, false);
}
/*-------------------------------------------------------------------------
*
* Index cost estimation functions
*
* genericcostestimate is a general-purpose estimator for use when we
* don't have any better idea about how to estimate. Index-type-specific
* knowledge can be incorporated in the type-specific routines.
*
*-------------------------------------------------------------------------
*/
static void
genericcostestimate(Query *root, RelOptInfo *rel,
IndexOptInfo *index, List *indexQuals,
Cost *indexStartupCost,
Cost *indexTotalCost,
Selectivity *indexSelectivity,
double *indexCorrelation)
{
double numIndexTuples;
double numIndexPages;
List *selectivityQuals = indexQuals;
/*
* If the index is partial, AND the index predicate with the
* explicitly given indexquals to produce a more accurate idea of the
* index restriction. This may produce redundant clauses, which we
* hope that cnfify and clauselist_selectivity will deal with
* intelligently.
*
* Note that index->indpred and indexQuals are both in implicit-AND form
* to start with, which we have to make explicit to hand to
* canonicalize_qual, and then we get back implicit-AND form again.
*/
if (index->indpred != NIL)
{
Expr *andedQuals;
andedQuals = make_ands_explicit(nconc(listCopy(index->indpred),
indexQuals));
selectivityQuals = canonicalize_qual(andedQuals, true);
}
/* Estimate the fraction of main-table tuples that will be visited */
*indexSelectivity = clauselist_selectivity(root, selectivityQuals,
lfirsti(rel->relids));
/*
* Estimate the number of tuples that will be visited. We do it in
* this rather peculiar-looking way in order to get the right answer
* for partial indexes. We can bound the number of tuples by the
* index size, in any case.
*/
numIndexTuples = *indexSelectivity * rel->tuples;
if (numIndexTuples > index->tuples)
numIndexTuples = index->tuples;
/*
* Always estimate at least one tuple is touched, even when
* indexSelectivity estimate is tiny.
*/
if (numIndexTuples < 1.0)
numIndexTuples = 1.0;
/*
* Estimate the number of index pages that will be retrieved.
*
* For all currently-supported index types, the first page of the index
* is a metadata page, and we should figure on fetching that plus a
* pro-rated fraction of the remaining pages.
*/
if (index->pages > 1 && index->tuples > 0)
{
numIndexPages = (numIndexTuples / index->tuples) * (index->pages - 1);
numIndexPages += 1; /* count the metapage too */
numIndexPages = ceil(numIndexPages);
}
else
numIndexPages = 1.0;
/*
* Compute the index access cost.
*
* Our generic assumption is that the index pages will be read
* sequentially, so they have cost 1.0 each, not random_page_cost.
* Also, we charge for evaluation of the indexquals at each index
* tuple. All the costs are assumed to be paid incrementally during
* the scan.
*/
*indexStartupCost = 0;
*indexTotalCost = numIndexPages +
(cpu_index_tuple_cost + cost_qual_eval(indexQuals)) * numIndexTuples;
/*
* Generic assumption about index correlation: there isn't any.
*/
*indexCorrelation = 0.0;
}
Datum
btcostestimate(PG_FUNCTION_ARGS)
{
Query *root = (Query *) PG_GETARG_POINTER(0);
RelOptInfo *rel = (RelOptInfo *) PG_GETARG_POINTER(1);
IndexOptInfo *index = (IndexOptInfo *) PG_GETARG_POINTER(2);
List *indexQuals = (List *) PG_GETARG_POINTER(3);
Cost *indexStartupCost = (Cost *) PG_GETARG_POINTER(4);
Cost *indexTotalCost = (Cost *) PG_GETARG_POINTER(5);
Selectivity *indexSelectivity = (Selectivity *) PG_GETARG_POINTER(6);
double *indexCorrelation = (double *) PG_GETARG_POINTER(7);
genericcostestimate(root, rel, index, indexQuals,
indexStartupCost, indexTotalCost,
indexSelectivity, indexCorrelation);
/*
* If it's a functional index, leave the default zero-correlation
* estimate in place. If not, and if we can get an estimate for the
* first variable's ordering correlation C from pg_statistic, estimate
* the index correlation as C / number-of-columns. (The idea here is
* that multiple columns dilute the importance of the first column's
* ordering, but don't negate it entirely.)
*/
if (index->indproc == InvalidOid)
{
Oid relid;
HeapTuple tuple;
relid = getrelid(lfirsti(rel->relids), root->rtable);
Assert(relid != InvalidOid);
tuple = SearchSysCache(STATRELATT,
ObjectIdGetDatum(relid),
Int16GetDatum(index->indexkeys[0]),
0, 0);
if (HeapTupleIsValid(tuple))
{
Oid typid;
int32 typmod;
float4 *numbers;
int nnumbers;
get_atttypetypmod(relid, index->indexkeys[0],
&typid, &typmod);
if (get_attstatsslot(tuple, typid, typmod,
STATISTIC_KIND_CORRELATION,
index->ordering[0],
NULL, NULL, &numbers, &nnumbers))
{
double varCorrelation;
int nKeys;
Assert(nnumbers == 1);
varCorrelation = numbers[0];
for (nKeys = 1; index->indexkeys[nKeys] != 0; nKeys++)
/* skip */ ;
*indexCorrelation = varCorrelation / nKeys;
free_attstatsslot(typid, NULL, 0, numbers, nnumbers);
}
ReleaseSysCache(tuple);
}
}
PG_RETURN_VOID();
}
Datum
rtcostestimate(PG_FUNCTION_ARGS)
{
Query *root = (Query *) PG_GETARG_POINTER(0);
RelOptInfo *rel = (RelOptInfo *) PG_GETARG_POINTER(1);
IndexOptInfo *index = (IndexOptInfo *) PG_GETARG_POINTER(2);
List *indexQuals = (List *) PG_GETARG_POINTER(3);
Cost *indexStartupCost = (Cost *) PG_GETARG_POINTER(4);
Cost *indexTotalCost = (Cost *) PG_GETARG_POINTER(5);
Selectivity *indexSelectivity = (Selectivity *) PG_GETARG_POINTER(6);
double *indexCorrelation = (double *) PG_GETARG_POINTER(7);
genericcostestimate(root, rel, index, indexQuals,
indexStartupCost, indexTotalCost,
indexSelectivity, indexCorrelation);
PG_RETURN_VOID();
}
Datum
hashcostestimate(PG_FUNCTION_ARGS)
{
Query *root = (Query *) PG_GETARG_POINTER(0);
RelOptInfo *rel = (RelOptInfo *) PG_GETARG_POINTER(1);
IndexOptInfo *index = (IndexOptInfo *) PG_GETARG_POINTER(2);
List *indexQuals = (List *) PG_GETARG_POINTER(3);
Cost *indexStartupCost = (Cost *) PG_GETARG_POINTER(4);
Cost *indexTotalCost = (Cost *) PG_GETARG_POINTER(5);
Selectivity *indexSelectivity = (Selectivity *) PG_GETARG_POINTER(6);
double *indexCorrelation = (double *) PG_GETARG_POINTER(7);
genericcostestimate(root, rel, index, indexQuals,
indexStartupCost, indexTotalCost,
indexSelectivity, indexCorrelation);
PG_RETURN_VOID();
}
Datum
gistcostestimate(PG_FUNCTION_ARGS)
{
Query *root = (Query *) PG_GETARG_POINTER(0);
RelOptInfo *rel = (RelOptInfo *) PG_GETARG_POINTER(1);
IndexOptInfo *index = (IndexOptInfo *) PG_GETARG_POINTER(2);
List *indexQuals = (List *) PG_GETARG_POINTER(3);
Cost *indexStartupCost = (Cost *) PG_GETARG_POINTER(4);
Cost *indexTotalCost = (Cost *) PG_GETARG_POINTER(5);
Selectivity *indexSelectivity = (Selectivity *) PG_GETARG_POINTER(6);
double *indexCorrelation = (double *) PG_GETARG_POINTER(7);
genericcostestimate(root, rel, index, indexQuals,
indexStartupCost, indexTotalCost,
indexSelectivity, indexCorrelation);
PG_RETURN_VOID();
}
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