*
*
* IDENTIFICATION
- * $Header: /cvsroot/pgsql/src/backend/commands/vacuum.c,v 1.115 1999/07/19 07:07:20 momjian Exp $
+ * $Header: /cvsroot/pgsql/src/backend/commands/vacuum.c,v 1.116 1999/08/01 04:54:24 tgl Exp $
*
*-------------------------------------------------------------------------
*/
static void vc_vaconeind(VPageList vpl, Relation indrel, int num_tuples, int keep_tuples);
static void vc_scanoneind(Relation indrel, int num_tuples);
static void vc_attrstats(Relation onerel, VRelStats *vacrelstats, HeapTuple tuple);
-static void vc_bucketcpy(Form_pg_attribute attr, Datum value, Datum *bucket, int16 *bucket_len);
+static void vc_bucketcpy(Form_pg_attribute attr, Datum value, Datum *bucket, int *bucket_len);
static void vc_updstats(Oid relid, int num_pages, int num_tuples, bool hasindex, VRelStats *vacrelstats);
static void vc_delhilowstats(Oid relid, int attcnt, int *attnums);
static VPageDescr vc_tidreapped(ItemPointer itemptr, VPageList vpl);
{
pgopform = (Form_pg_operator) GETSTRUCT(func_operator);
fmgr_info(pgopform->oprcode, &(stats->f_cmplt));
+ stats->op_cmplt = oprid(func_operator);
}
else
+ {
stats->f_cmplt.fn_addr = NULL;
+ stats->op_cmplt = InvalidOid;
+ }
func_operator = oper(">", stats->attr->atttypid, stats->attr->atttypid, true);
if (func_operator != NULL)
{
swapDatum(stats->guess1, stats->guess2);
swapInt(stats->guess1_len, stats->guess2_len);
- stats->guess1_cnt = stats->guess2_hits;
swapLong(stats->guess1_hits, stats->guess2_hits);
+ stats->guess1_cnt = stats->guess1_hits;
}
if (stats->guess1_cnt > stats->best_cnt)
{
*
*/
static void
-vc_bucketcpy(Form_pg_attribute attr, Datum value, Datum *bucket, int16 *bucket_len)
+vc_bucketcpy(Form_pg_attribute attr, Datum value, Datum *bucket, int *bucket_len)
{
if (attr->attbyval && attr->attlen != -1)
*bucket = value;
selratio = 0;
else if (VacAttrStatsLtGtValid(stats) && stats->min_cnt + stats->max_cnt == stats->nonnull_cnt)
{
+ /* exact result when there are just 1 or 2 values... */
double min_cnt_d = stats->min_cnt,
max_cnt_d = stats->max_cnt,
null_cnt_d = stats->null_cnt,
- nonnullcnt_d = stats->nonnull_cnt; /* prevent overflow */
+ nonnull_cnt_d = stats->nonnull_cnt; /* prevent overflow */
selratio = (min_cnt_d * min_cnt_d + max_cnt_d * max_cnt_d + null_cnt_d * null_cnt_d) /
- (nonnullcnt_d + null_cnt_d) / (nonnullcnt_d + null_cnt_d);
+ (nonnull_cnt_d + null_cnt_d) / (nonnull_cnt_d + null_cnt_d);
}
else
{
*/
selratio = (most * most + 0.20 * most * (total - most)) / total / total;
}
- if (selratio > 1.0)
+ if (selratio < 0.0)
+ selratio = 0.0;
+ else if (selratio > 1.0)
selratio = 1.0;
attp->attdisbursion = selratio;
* doing system relations, especially pg_statistic is a
* problem
*/
- if (VacAttrStatsLtGtValid(stats) && stats->initialized /* &&
- * !IsSystemRelationName(
- *
- pgcform->relname.data) */ )
+ if (VacAttrStatsLtGtValid(stats) && stats->initialized
+ /* && !IsSystemRelationName(pgcform->relname.data)
+ */ )
{
+ float32data nullratio;
+ float32data bestratio;
FmgrInfo out_function;
char *out_string;
+ double best_cnt_d = stats->best_cnt,
+ null_cnt_d = stats->null_cnt,
+ nonnull_cnt_d = stats->nonnull_cnt; /* prevent overflow */
+
+ nullratio = null_cnt_d / (nonnull_cnt_d + null_cnt_d);
+ bestratio = best_cnt_d / (nonnull_cnt_d + null_cnt_d);
+
+ fmgr_info(stats->outfunc, &out_function);
for (i = 0; i < Natts_pg_statistic; ++i)
nulls[i] = ' ';
* ----------------
*/
i = 0;
- values[i++] = (Datum) relid; /* 1 */
- values[i++] = (Datum) attp->attnum; /* 2 */
- values[i++] = (Datum) InvalidOid; /* 3 */
- fmgr_info(stats->outfunc, &out_function);
- out_string = (*fmgr_faddr(&out_function)) (stats->min, stats->attr->atttypid);
- values[i++] = (Datum) fmgr(F_TEXTIN, out_string);
+ values[i++] = (Datum) relid; /* starelid */
+ values[i++] = (Datum) attp->attnum; /* staattnum */
+ values[i++] = (Datum) stats->op_cmplt; /* staop */
+ /* hack: this code knows float4 is pass-by-ref */
+ values[i++] = PointerGetDatum(&nullratio); /* stanullfrac */
+ values[i++] = PointerGetDatum(&bestratio); /* stacommonfrac */
+ out_string = (*fmgr_faddr(&out_function)) (stats->best, stats->attr->atttypid, stats->attr->atttypmod);
+ values[i++] = PointerGetDatum(textin(out_string)); /* stacommonval */
pfree(out_string);
- out_string = (char *) (*fmgr_faddr(&out_function)) (stats->max, stats->attr->atttypid);
- values[i++] = (Datum) fmgr(F_TEXTIN, out_string);
+ out_string = (*fmgr_faddr(&out_function)) (stats->min, stats->attr->atttypid, stats->attr->atttypmod);
+ values[i++] = PointerGetDatum(textin(out_string)); /* staloval */
+ pfree(out_string);
+ out_string = (char *) (*fmgr_faddr(&out_function)) (stats->max, stats->attr->atttypid, stats->attr->atttypmod);
+ values[i++] = PointerGetDatum(textin(out_string)); /* stahival */
pfree(out_string);
stup = heap_formtuple(sd->rd_att, values, nulls);
/* ----------------
- * insert the tuple in the relation and get the tuple's oid.
+ * insert the tuple in the relation.
* ----------------
*/
heap_insert(sd, stup);
- pfree(DatumGetPointer(values[3]));
- pfree(DatumGetPointer(values[4]));
+
+ /* release allocated space */
+ pfree(DatumGetPointer(values[Anum_pg_statistic_stacommonval-1]));
+ pfree(DatumGetPointer(values[Anum_pg_statistic_staloval-1]));
+ pfree(DatumGetPointer(values[Anum_pg_statistic_stahival-1]));
pfree(stup);
}
}
* These routines are registered in the operator catalog in the
* "oprrest" and "oprjoin" attributes.
*
- * XXX check all the functions--I suspect them to be 1-based.
- *
* Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
- * $Header: /cvsroot/pgsql/src/backend/utils/adt/selfuncs.c,v 1.35 1999/07/17 20:17:59 momjian Exp $
+ * $Header: /cvsroot/pgsql/src/backend/utils/adt/selfuncs.c,v 1.36 1999/08/01 04:54:22 tgl Exp $
*
*-------------------------------------------------------------------------
*/
#include "access/heapam.h"
#include "catalog/catname.h"
+#include "catalog/pg_operator.h"
#include "catalog/pg_statistic.h"
+#include "catalog/pg_type.h"
+#include "parser/parse_oper.h"
#include "utils/builtins.h"
#include "utils/lsyscache.h"
#include "utils/syscache.h"
/* N is not a valid var/constant or relation id */
#define NONVALUE(N) ((N) == -1)
-/*
- * generalize the test for functional index selectivity request
- */
-#define FunctionalSelectivity(nIndKeys,attNum) (attNum==InvalidAttrNumber)
+/* are we looking at a functional index selectivity request? */
+#define FunctionalSelectivity(nIndKeys,attNum) ((attNum)==InvalidAttrNumber)
-static float32data getattdisbursion(Oid relid, AttrNumber attnum);
-static void gethilokey(Oid relid, AttrNumber attnum, Oid opid,
- char **high, char **low);
+/* default selectivity estimate for inequalities such as "A < b" */
+#define DEFAULT_INEQ_SEL (1.0 / 3.0)
+
+static void getattproperties(Oid relid, AttrNumber attnum,
+ Oid *typid,
+ int *typlen,
+ bool *typbyval,
+ int32 *typmod);
+static bool getattstatistics(Oid relid, AttrNumber attnum,
+ Oid typid, int32 typmod,
+ double *nullfrac,
+ double *commonfrac,
+ Datum *commonval,
+ Datum *loval,
+ Datum *hival);
+static double getattdisbursion(Oid relid, AttrNumber attnum);
/*
- * eqsel - Selectivity of "=" for any data type.
+ * eqsel - Selectivity of "=" for any data types.
*/
float64
eqsel(Oid opid,
Oid relid,
AttrNumber attno,
- char *value,
+ Datum value,
int32 flag)
{
float64 result;
if (NONVALUE(attno) || NONVALUE(relid))
*result = 0.1;
else
- *result = (float64data) getattdisbursion(relid, (int) attno);
+ {
+ Oid typid;
+ int typlen;
+ bool typbyval;
+ int32 typmod;
+ double nullfrac;
+ double commonfrac;
+ Datum commonval;
+ double selec;
+
+ /* get info about the attribute */
+ getattproperties(relid, attno,
+ &typid, &typlen, &typbyval, &typmod);
+
+ if (getattstatistics(relid, attno, typid, typmod,
+ &nullfrac, &commonfrac, &commonval,
+ NULL, NULL))
+ {
+ if (flag & SEL_CONSTANT)
+ {
+ /* Is the constant the same as the most common value? */
+ HeapTuple oprtuple;
+ Oid ltype,
+ rtype;
+ Operator func_operator;
+ bool mostcommon = false;
+
+ /* get left and right datatypes of the operator */
+ oprtuple = get_operator_tuple(opid);
+ if (! HeapTupleIsValid(oprtuple))
+ elog(ERROR, "eqsel: no tuple for operator %u", opid);
+ ltype = ((Form_pg_operator) GETSTRUCT(oprtuple))->oprleft;
+ rtype = ((Form_pg_operator) GETSTRUCT(oprtuple))->oprright;
+
+ /* and find appropriate equality operator (no, it ain't
+ * necessarily opid itself...)
+ */
+ func_operator = oper("=", ltype, rtype, true);
+
+ if (func_operator != NULL)
+ {
+ RegProcedure eqproc = ((Form_pg_operator) GETSTRUCT(func_operator))->oprcode;
+ if (flag & SEL_RIGHT) /* given value on the right? */
+ mostcommon = (bool)
+ DatumGetUInt8(fmgr(eqproc, commonval, value));
+ else
+ mostcommon = (bool)
+ DatumGetUInt8(fmgr(eqproc, value, commonval));
+ }
+
+ if (mostcommon)
+ {
+ /* Search is for the most common value. We know the
+ * selectivity exactly (or as exactly as VACUUM could
+ * calculate it, anyway).
+ */
+ selec = commonfrac;
+ }
+ else
+ {
+ /* Comparison is against a constant that is neither the
+ * most common value nor null. Its selectivity cannot
+ * be more than this:
+ */
+ selec = 1.0 - commonfrac - nullfrac;
+ if (selec > commonfrac)
+ selec = commonfrac;
+ /* and in fact it's probably less, so apply a fudge
+ * factor.
+ */
+ selec *= 0.5;
+ }
+ }
+ else
+ {
+ /* Search is for a value that we do not know a priori,
+ * but we will assume it is not NULL. Selectivity
+ * cannot be more than this:
+ */
+ selec = 1.0 - nullfrac;
+ if (selec > commonfrac)
+ selec = commonfrac;
+ /* and in fact it's probably less, so apply a fudge
+ * factor.
+ */
+ selec *= 0.5;
+ }
+
+ /* result should be in range, but make sure... */
+ if (selec < 0.0)
+ selec = 0.0;
+ else if (selec > 1.0)
+ selec = 1.0;
+
+ if (! typbyval)
+ pfree(DatumGetPointer(commonval));
+ }
+ else
+ {
+ /* No VACUUM ANALYZE stats available, so make a guess using
+ * the disbursion stat (if we have that, which is unlikely...)
+ */
+ selec = getattdisbursion(relid, attno);
+ }
+
+ *result = (float64data) selec;
+ }
return result;
}
/*
- * neqsel - Selectivity of "!=" for any data type.
+ * neqsel - Selectivity of "!=" for any data types.
*/
float64
neqsel(Oid opid,
Oid relid,
AttrNumber attno,
- char *value,
+ Datum value,
int32 flag)
{
float64 result;
}
/*
- * intltsel - Selectivity of "<" for integers.
+ * intltsel - Selectivity of "<" (also "<=") for integers.
* Should work for both longs and shorts.
*/
float64
intltsel(Oid opid,
Oid relid,
AttrNumber attno,
- int32 value,
+ Datum value,
int32 flag)
{
float64 result;
- char *highchar,
- *lowchar;
- long val,
- high,
- low,
- top,
- bottom;
result = (float64) palloc(sizeof(float64data));
- if (NONVALUE(attno) || NONVALUE(relid))
- *result = 1.0 / 3;
+ if (! (flag & SEL_CONSTANT) || NONVALUE(attno) || NONVALUE(relid))
+ *result = DEFAULT_INEQ_SEL;
else
{
- /* XXX val = atol(value); */
- val = value;
- gethilokey(relid, (int) attno, opid, &highchar, &lowchar);
- if (*highchar == 'n' || *lowchar == 'n')
+ HeapTuple oprtuple;
+ Oid ltype,
+ rtype;
+ Oid typid;
+ int typlen;
+ bool typbyval;
+ int32 typmod;
+ Datum hival,
+ loval;
+ long val,
+ high,
+ low,
+ numerator,
+ denominator;
+
+ /* get left and right datatypes of the operator */
+ oprtuple = get_operator_tuple(opid);
+ if (! HeapTupleIsValid(oprtuple))
+ elog(ERROR, "intltsel: no tuple for operator %u", opid);
+ ltype = ((Form_pg_operator) GETSTRUCT(oprtuple))->oprleft;
+ rtype = ((Form_pg_operator) GETSTRUCT(oprtuple))->oprright;
+
+ /*
+ * TEMPORARY HACK: this code is currently getting called for
+ * a bunch of non-integral types. Give a default estimate if
+ * either side is not pass-by-val. Need better solution.
+ */
+ if (! get_typbyval(ltype) || ! get_typbyval(rtype))
{
- *result = 1.0 / 3.0;
+ *result = DEFAULT_INEQ_SEL;
return result;
}
- high = atol(highchar);
- low = atol(lowchar);
- if ((flag & SEL_RIGHT && val < low) ||
- (!(flag & SEL_RIGHT) && val > high))
+
+ /* Deduce type of the constant, and convert to uniform "long" format.
+ * Note that constant might well be a different type than attribute.
+ * XXX this ought to use a type-specific "convert to double" op.
+ */
+ typid = (flag & SEL_RIGHT) ? rtype : ltype;
+ switch (get_typlen(typid))
{
- float32data nvals;
+ case 1:
+ val = (long) DatumGetUInt8(value);
+ break;
+ case 2:
+ val = (long) DatumGetInt16(value);
+ break;
+ case 4:
+ val = (long) DatumGetInt32(value);
+ break;
+ default:
+ elog(ERROR, "intltsel: unsupported type %u", typid);
+ *result = DEFAULT_INEQ_SEL;
+ return result;
+ }
- nvals = getattdisbursion(relid, (int) attno);
- if (nvals == 0)
- *result = 1.0 / 3.0;
- else
- {
- *result = 3.0 * (float64data) nvals;
- if (*result > 1.0)
- *result = 1;
- }
+ /* Now get info about the attribute */
+ getattproperties(relid, attno,
+ &typid, &typlen, &typbyval, &typmod);
+
+ if (! getattstatistics(relid, attno, typid, typmod,
+ NULL, NULL, NULL,
+ &loval, &hival))
+ {
+ *result = DEFAULT_INEQ_SEL;
+ return result;
+ }
+ /*
+ * Convert loval/hival to common "long int" representation.
+ */
+ switch (typlen)
+ {
+ case 1:
+ low = (long) DatumGetUInt8(loval);
+ high = (long) DatumGetUInt8(hival);
+ break;
+ case 2:
+ low = (long) DatumGetInt16(loval);
+ high = (long) DatumGetInt16(hival);
+ break;
+ case 4:
+ low = (long) DatumGetInt32(loval);
+ high = (long) DatumGetInt32(hival);
+ break;
+ default:
+ elog(ERROR, "intltsel: unsupported type %u", typid);
+ *result = DEFAULT_INEQ_SEL;
+ return result;
+ }
+ if (val < low || val > high)
+ {
+ /* If given value is outside the statistical range,
+ * assume we have out-of-date stats and return a default guess.
+ * We could return a small or large value if we trusted the stats
+ * more. XXX change this eventually.
+ */
+ *result = DEFAULT_INEQ_SEL;
}
else
{
- bottom = high - low;
- if (bottom == 0)
- ++bottom;
+ denominator = high - low;
+ if (denominator <= 0)
+ denominator = 1;
if (flag & SEL_RIGHT)
- top = val - low;
+ numerator = val - low;
else
- top = high - val;
- if (top > bottom)
+ numerator = high - val;
+ if (numerator <= 0) /* never return a zero estimate! */
+ numerator = 1;
+ if (numerator >= denominator)
*result = 1.0;
else
- {
- if (top == 0)
- ++top;
- *result = ((1.0 * top) / bottom);
- }
+ *result = (double) numerator / (double) denominator;
+ }
+ if (! typbyval)
+ {
+ pfree(DatumGetPointer(hival));
+ pfree(DatumGetPointer(loval));
}
}
return result;
}
/*
- * intgtsel - Selectivity of ">" for integers.
+ * intgtsel - Selectivity of ">" (also ">=") for integers.
* Should work for both longs and shorts.
*/
float64
intgtsel(Oid opid,
Oid relid,
AttrNumber attno,
- int32 value,
+ Datum value,
int32 flag)
{
float64 result;
- int notflag;
- if (flag & 0)
- notflag = flag & ~SEL_RIGHT;
- else
- notflag = flag | SEL_RIGHT;
- result = intltsel(opid, relid, attno, value, (int32) notflag);
+ /* Compute selectivity of "<", then invert --- but only if we
+ * were able to produce a non-default estimate.
+ */
+ result = intltsel(opid, relid, attno, value, flag);
+ if (*result != DEFAULT_INEQ_SEL)
+ *result = 1.0 - *result;
return result;
}
AttrNumber attno2)
{
float64 result;
- float32data num1,
+ float64data num1,
num2,
max;
*result = 0.1;
else
{
- num1 = getattdisbursion(relid1, (int) attno1);
- num2 = getattdisbursion(relid2, (int) attno2);
+ num1 = getattdisbursion(relid1, attno1);
+ num2 = getattdisbursion(relid2, attno2);
max = (num1 > num2) ? num1 : num2;
- if (max == 0)
+ if (max <= 0)
*result = 1.0;
else
- *result = (float64data) max;
+ *result = max;
}
return result;
}
}
/*
- * intltjoinsel - Join selectivity of "<"
+ * intltjoinsel - Join selectivity of "<" and "<="
*/
float64
intltjoinsel(Oid opid,
float64 result;
result = (float64) palloc(sizeof(float64data));
- *result = 1.0 / 3.0;
+ *result = DEFAULT_INEQ_SEL;
return result;
}
/*
- * intgtjoinsel - Join selectivity of ">"
+ * intgtjoinsel - Join selectivity of ">" and ">="
*/
float64
intgtjoinsel(Oid opid,
float64 result;
result = (float64) palloc(sizeof(float64data));
- *result = 1.0 / 3.0;
+ *result = DEFAULT_INEQ_SEL;
return result;
}
/*
- * getattdisbursion - Retrieves the number of values within an attribute.
- *
- * Note:
- * getattdisbursion and gethilokey both currently use keyed
- * relation scans and amgetattr. Alternatively,
- * the relation scan could be non-keyed and the tuple
- * returned could be cast (struct X *) tuple + tuple->t_hoff.
- * The first method is good for testing the implementation,
- * but the second may ultimately be faster?!? In any case,
- * using the cast instead of amgetattr would be
- * more efficient. However, the cast will not work
- * for gethilokey which accesses stahikey in struct statistic.
+ * getattproperties
+ * Retrieve pg_attribute properties for an attribute,
+ * including type OID, type len, type byval flag, typmod.
*/
-static float32data
-getattdisbursion(Oid relid, AttrNumber attnum)
+static void
+getattproperties(Oid relid, AttrNumber attnum,
+ Oid *typid, int *typlen, bool *typbyval, int32 *typmod)
{
HeapTuple atp;
- float32data nvals;
- int32 ntuples;
+ Form_pg_attribute att_tup;
atp = SearchSysCacheTuple(ATTNUM,
ObjectIdGetDatum(relid),
Int16GetDatum(attnum),
0, 0);
- if (!HeapTupleIsValid(atp))
- {
- elog(ERROR, "getattdisbursion: no attribute tuple %u %d",
- relid, attnum);
- return 0;
- }
- nvals = ((Form_pg_attribute) GETSTRUCT(atp))->attdisbursion;
- if (nvals > 0)
- return nvals;
-
- atp = SearchSysCacheTuple(RELOID,
- ObjectIdGetDatum(relid),
- 0, 0, 0);
-
- /*
- * XXX -- use number of tuples as number of distinctive values just
- * for now, in case number of distinctive values is not cached
- */
- if (!HeapTupleIsValid(atp))
- {
- elog(ERROR, "getattdisbursion: no relation tuple %u", relid);
- return 0;
- }
- ntuples = ((Form_pg_class) GETSTRUCT(atp))->reltuples;
- /* Look above how nvals is used. - vadim 04/09/97 */
- if (ntuples > 0)
- nvals = 1.0 / ntuples;
-
- return nvals;
+ if (! HeapTupleIsValid(atp))
+ elog(ERROR, "getattproperties: no attribute tuple %u %d",
+ relid, (int) attnum);
+ att_tup = (Form_pg_attribute) GETSTRUCT(atp);
+
+ *typid = att_tup->atttypid;
+ *typlen = att_tup->attlen;
+ *typbyval = att_tup->attbyval;
+ *typmod = att_tup->atttypmod;
}
/*
- * gethilokey - Returns a pointer to strings containing
- * the high and low keys within an attribute.
+ * getattstatistics
+ * Retrieve the pg_statistic data for an attribute.
+ * Returns 'false' if no stats are available.
+ *
+ * Inputs:
+ * 'relid' and 'attnum' are the relation and attribute number.
+ * 'typid' and 'typmod' are the type and typmod of the column,
+ * which the caller must already have looked up.
*
- * Currently returns "0", and "0" in high and low if the statistic
- * catalog does not contain the proper tuple. Eventually, the
- * statistic demon should have the tuple maintained, and it should
- * elog() if the tuple is missing.
+ * Outputs:
+ * The available stats are nullfrac, commonfrac, commonval, loval, hival.
+ * The caller need not retrieve all five --- pass NULL pointers for the
+ * unwanted values.
*
- * XXX Question: is this worth sticking in the catalog caches,
- * or will this get invalidated too often?
+ * commonval, loval, hival are returned as Datums holding the internal
+ * representation of the values. (Note that these should be pfree'd
+ * after use if the data type is not by-value.)
+ *
+ * XXX currently, this does a linear search of pg_statistic because there
+ * is no index nor syscache for pg_statistic. FIX THIS!
*/
-static void
-gethilokey(Oid relid,
- AttrNumber attnum,
- Oid opid,
- char **high,
- char **low)
+static bool
+getattstatistics(Oid relid, AttrNumber attnum, Oid typid, int32 typmod,
+ double *nullfrac,
+ double *commonfrac,
+ Datum *commonval,
+ Datum *loval,
+ Datum *hival)
{
Relation rel;
HeapScanDesc scan;
- static ScanKeyData key[3] = {
+ static ScanKeyData key[2] = {
{0, Anum_pg_statistic_starelid, F_OIDEQ, {0, 0, F_OIDEQ}},
- {0, Anum_pg_statistic_staattnum, F_INT2EQ, {0, 0, F_INT2EQ}},
- {0, Anum_pg_statistic_staop, F_OIDEQ, {0, 0, F_OIDEQ}}
+ {0, Anum_pg_statistic_staattnum, F_INT2EQ, {0, 0, F_INT2EQ}}
};
bool isnull;
HeapTuple tuple;
+ HeapTuple typeTuple;
+ FmgrInfo inputproc;
rel = heap_openr(StatisticRelationName);
key[0].sk_argument = ObjectIdGetDatum(relid);
key[1].sk_argument = Int16GetDatum((int16) attnum);
- key[2].sk_argument = ObjectIdGetDatum(opid);
- scan = heap_beginscan(rel, 0, SnapshotNow, 3, key);
+
+ scan = heap_beginscan(rel, 0, SnapshotNow, 2, key);
tuple = heap_getnext(scan, 0);
if (!HeapTupleIsValid(tuple))
{
- *high = "n";
- *low = "n";
+ /* no such stats entry */
+ heap_endscan(scan);
+ heap_close(rel);
+ return false;
+ }
- /*
- * XXX elog(ERROR, "gethilokey: statistic tuple not
- * found");
- */
- return;
+ /* We assume that there will only be one entry in pg_statistic
+ * for the given rel/att. Someday, VACUUM might store more than one...
+ */
+ if (nullfrac)
+ *nullfrac = ((Form_pg_statistic) GETSTRUCT(tuple))->stanullfrac;
+ if (commonfrac)
+ *commonfrac = ((Form_pg_statistic) GETSTRUCT(tuple))->stacommonfrac;
+
+ /* Get the type input proc for the column datatype */
+ typeTuple = SearchSysCacheTuple(TYPOID,
+ ObjectIdGetDatum(typid),
+ 0, 0, 0);
+ if (! HeapTupleIsValid(typeTuple))
+ elog(ERROR, "getattstatistics: Cache lookup failed for type %u",
+ typid);
+ fmgr_info(((Form_pg_type) GETSTRUCT(typeTuple))->typinput, &inputproc);
+
+ /* Values are variable-length fields, so cannot access as struct fields.
+ * Must do it the hard way with heap_getattr.
+ */
+ if (commonval)
+ {
+ text *val = (text *) heap_getattr(tuple,
+ Anum_pg_statistic_stacommonval,
+ RelationGetDescr(rel),
+ &isnull);
+ if (isnull)
+ {
+ elog(DEBUG, "getattstatistics: stacommonval is null");
+ *commonval = PointerGetDatum(NULL);
+ }
+ else
+ {
+ char *strval = textout(val);
+ *commonval = (Datum)
+ (*fmgr_faddr(&inputproc)) (strval, typid, typmod);
+ pfree(strval);
+ }
}
- *high = textout((struct varlena *)
- heap_getattr(tuple,
- Anum_pg_statistic_stahikey,
- RelationGetDescr(rel),
- &isnull));
- if (isnull)
- elog(DEBUG, "gethilokey: high key is null");
- *low = textout((struct varlena *)
- heap_getattr(tuple,
- Anum_pg_statistic_stalokey,
- RelationGetDescr(rel),
- &isnull));
- if (isnull)
- elog(DEBUG, "gethilokey: low key is null");
+
+ if (loval)
+ {
+ text *val = (text *) heap_getattr(tuple,
+ Anum_pg_statistic_staloval,
+ RelationGetDescr(rel),
+ &isnull);
+ if (isnull)
+ {
+ elog(DEBUG, "getattstatistics: staloval is null");
+ *loval = PointerGetDatum(NULL);
+ }
+ else
+ {
+ char *strval = textout(val);
+ *loval = (Datum)
+ (*fmgr_faddr(&inputproc)) (strval, typid, typmod);
+ pfree(strval);
+ }
+ }
+
+ if (hival)
+ {
+ text *val = (text *) heap_getattr(tuple,
+ Anum_pg_statistic_stahival,
+ RelationGetDescr(rel),
+ &isnull);
+ if (isnull)
+ {
+ elog(DEBUG, "getattstatistics: stahival is null");
+ *hival = PointerGetDatum(NULL);
+ }
+ else
+ {
+ char *strval = textout(val);
+ *hival = (Datum)
+ (*fmgr_faddr(&inputproc)) (strval, typid, typmod);
+ pfree(strval);
+ }
+ }
+
heap_endscan(scan);
heap_close(rel);
+ return true;
+}
+
+/*
+ * getattdisbursion
+ * Retrieve the disbursion statistic for an attribute,
+ * or produce an estimate if no info is available.
+ */
+static double
+getattdisbursion(Oid relid, AttrNumber attnum)
+{
+ HeapTuple atp;
+ double disbursion;
+ int32 ntuples;
+
+ atp = SearchSysCacheTuple(ATTNUM,
+ ObjectIdGetDatum(relid),
+ Int16GetDatum(attnum),
+ 0, 0);
+ if (!HeapTupleIsValid(atp))
+ {
+ /* this should not happen */
+ elog(ERROR, "getattdisbursion: no attribute tuple %u %d",
+ relid, attnum);
+ return 0.1;
+ }
+
+ disbursion = ((Form_pg_attribute) GETSTRUCT(atp))->attdisbursion;
+ if (disbursion > 0.0)
+ return disbursion;
+
+ /* VACUUM ANALYZE has not stored a disbursion statistic for us.
+ * Produce an estimate = 1/numtuples. This may produce
+ * unreasonably small estimates for large tables, so limit
+ * the estimate to no less than 0.01.
+ */
+ atp = SearchSysCacheTuple(RELOID,
+ ObjectIdGetDatum(relid),
+ 0, 0, 0);
+ if (!HeapTupleIsValid(atp))
+ {
+ /* this should not happen */
+ elog(ERROR, "getattdisbursion: no relation tuple %u", relid);
+ return 0.1;
+ }
+
+ ntuples = ((Form_pg_class) GETSTRUCT(atp))->reltuples;
+
+ if (ntuples > 0)
+ disbursion = 1.0 / (double) ntuples;
+
+ if (disbursion < 0.01)
+ disbursion = 0.01;
+
+ return disbursion;
}
float64
projects / postgresql / commitdiff