@ -15,7 +15,7 @@
*
*
* IDENTIFICATION
* $ PostgreSQL : pgsql / src / backend / utils / adt / selfuncs . c , v 1.181 2005 / 06 / 10 22 : 25 : 36 tgl Exp $
* $ PostgreSQL : pgsql / src / backend / utils / adt / selfuncs . c , v 1.182 2005 / 06 / 13 23 : 14 : 48 tgl Exp $
*
* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
*/
@ -4195,18 +4195,23 @@ string_to_bytea_const(const char *str, size_t str_len)
* don ' t have any better idea about how to estimate . Index - type - specific
* knowledge can be incorporated in the type - specific routines .
*
* One bit of index - type - specific knowledge we can relatively easily use
* in genericcostestimate is the estimate of the number of index tuples
* visited . If numIndexTuples is not 0 then it is used as the estimate ,
* otherwise we compute a generic estimate .
*
* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
*/
static void
genericcostestimate ( PlannerInfo * root ,
IndexOptInfo * index , List * indexQuals ,
double numIndexTuples ,
Cost * indexStartupCost ,
Cost * indexTotalCost ,
Selectivity * indexSelectivity ,
double * indexCorrelation )
{
double numIndexTuples ;
double numIndexPages ;
QualCost index_qual_cost ;
double qual_op_cost ;
@ -4254,20 +4259,20 @@ genericcostestimate(PlannerInfo *root,
JOIN_INNER ) ;
/*
* 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 .
* If caller didn ' t give us an estimate , estimate the number of index
* tuples that will be visited . We do it in this rather peculiar - looking
* way in order to get the right answer for partial indexes .
*/
numIndexTuples = * indexSelectivity * index - > rel - > tuples ;
if ( numIndexTuples > index - > tuples )
numIndexTuples = index - > tuples ;
if ( numIndexTuples < = 0.0 )
numIndexTuples = * indexSelectivity * index - > rel - > tuples ;
/*
* Always estimate at least one tuple is touched , even when
* We can bound the number of tuples by the index size in any case .
* Also , always estimate at least one tuple is touched , even when
* indexSelectivity estimate is tiny .
*/
if ( numIndexTuples > index - > tuples )
numIndexTuples = index - > tuples ;
if ( numIndexTuples < 1.0 )
numIndexTuples = 1.0 ;
@ -4337,8 +4342,95 @@ btcostestimate(PG_FUNCTION_ARGS)
Oid relid ;
AttrNumber colnum ;
HeapTuple tuple ;
double numIndexTuples ;
List * indexBoundQuals ;
int indexcol ;
bool eqQualHere ;
ListCell * l ;
/*
* For a btree scan , only leading ' = ' quals plus inequality quals
* for the immediately next attribute contribute to index selectivity
* ( these are the " boundary quals " that determine the starting and
* stopping points of the index scan ) . Additional quals can suppress
* visits to the heap , so it ' s OK to count them in indexSelectivity ,
* but they should not count for estimating numIndexTuples . So we must
* examine the given indexQuals to find out which ones count as boundary
* quals . We rely on the knowledge that they are given in index column
* order .
*/
indexBoundQuals = NIL ;
indexcol = 0 ;
eqQualHere = false ;
foreach ( l , indexQuals )
{
RestrictInfo * rinfo = ( RestrictInfo * ) lfirst ( l ) ;
Expr * clause ;
Oid clause_op ;
int op_strategy ;
Assert ( IsA ( rinfo , RestrictInfo ) ) ;
clause = rinfo - > clause ;
Assert ( IsA ( clause , OpExpr ) ) ;
clause_op = ( ( OpExpr * ) clause ) - > opno ;
if ( match_index_to_operand ( get_leftop ( clause ) , indexcol , index ) )
{
/* clause_op is correct */
}
else if ( match_index_to_operand ( get_rightop ( clause ) , indexcol , index ) )
{
/* Must flip operator to get the opclass member */
clause_op = get_commutator ( clause_op ) ;
}
else
{
/* Must be past the end of quals for indexcol, try next */
if ( ! eqQualHere )
break ; /* done if no '=' qual for indexcol */
indexcol + + ;
eqQualHere = false ;
if ( match_index_to_operand ( get_leftop ( clause ) , indexcol , index ) )
{
/* clause_op is correct */
}
else if ( match_index_to_operand ( get_rightop ( clause ) ,
indexcol , index ) )
{
/* Must flip operator to get the opclass member */
clause_op = get_commutator ( clause_op ) ;
}
else
{
/* No quals for new indexcol, so we are done */
break ;
}
}
op_strategy = get_op_opclass_strategy ( clause_op ,
index - > classlist [ indexcol ] ) ;
Assert ( op_strategy ! = 0 ) ; /* not a member of opclass?? */
if ( op_strategy = = BTEqualStrategyNumber )
eqQualHere = true ;
indexBoundQuals = lappend ( indexBoundQuals , rinfo ) ;
}
/*
* If index is unique and we found an ' = ' clause for each column ,
* we can just assume numIndexTuples = 1 and skip the expensive
* clauselist_selectivity calculations .
*/
if ( index - > unique & & indexcol = = index - > ncolumns - 1 & & eqQualHere )
numIndexTuples = 1.0 ;
else
{
Selectivity btreeSelectivity ;
btreeSelectivity = clauselist_selectivity ( root , indexBoundQuals ,
index - > rel - > relid ,
JOIN_INNER ) ;
numIndexTuples = btreeSelectivity * index - > rel - > tuples ;
}
genericcostestimate ( root , index , indexQuals ,
genericcostestimate ( root , index , indexQuals , numIndexTuples ,
indexStartupCost , indexTotalCost ,
indexSelectivity , indexCorrelation ) ;
@ -4414,7 +4506,7 @@ rtcostestimate(PG_FUNCTION_ARGS)
Selectivity * indexSelectivity = ( Selectivity * ) PG_GETARG_POINTER ( 5 ) ;
double * indexCorrelation = ( double * ) PG_GETARG_POINTER ( 6 ) ;
genericcostestimate ( root , index , indexQuals ,
genericcostestimate ( root , index , indexQuals , 0.0 ,
indexStartupCost , indexTotalCost ,
indexSelectivity , indexCorrelation ) ;
@ -4432,7 +4524,7 @@ hashcostestimate(PG_FUNCTION_ARGS)
Selectivity * indexSelectivity = ( Selectivity * ) PG_GETARG_POINTER ( 5 ) ;
double * indexCorrelation = ( double * ) PG_GETARG_POINTER ( 6 ) ;
genericcostestimate ( root , index , indexQuals ,
genericcostestimate ( root , index , indexQuals , 0.0 ,
indexStartupCost , indexTotalCost ,
indexSelectivity , indexCorrelation ) ;
@ -4450,7 +4542,7 @@ gistcostestimate(PG_FUNCTION_ARGS)
Selectivity * indexSelectivity = ( Selectivity * ) PG_GETARG_POINTER ( 5 ) ;
double * indexCorrelation = ( double * ) PG_GETARG_POINTER ( 6 ) ;
genericcostestimate ( root , index , indexQuals ,
genericcostestimate ( root , index , indexQuals , 0.0 ,
indexStartupCost , indexTotalCost ,
indexSelectivity , indexCorrelation ) ;
Tom Lane
21 years ago