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First step in fixing selectivity-estimation code. eqsel and
neqsel now behave as per my suggestions in pghackers a few days ago. selectivity for < > <= >= should work OK for integral types as well, but still need work for nonintegral types. Since these routines have never actually executed before :-(, this may result in some significant changes in the optimizer's choices of execution plans. Let me know if you see any serious misbehavior. CAUTION: THESE CHANGES REQUIRE INITDB. pg_statistic table has changed.
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5 files changed

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-199
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5 files changed

+535
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‎src/backend/commands/vacuum.c

Lines changed: 46 additions & 22 deletions
Original file line numberDiff line numberDiff line change
@@ -7,7 +7,7 @@
77
*
88
*
99
* IDENTIFICATION
10-
* $Header: /cvsroot/pgsql/src/backend/commands/vacuum.c,v 1.115 1999/07/19 07:07:20 momjian Exp $
10+
* $Header: /cvsroot/pgsql/src/backend/commands/vacuum.c,v 1.116 1999/08/01 04:54:24 tgl Exp $
1111
*
1212
*-------------------------------------------------------------------------
1313
*/
@@ -78,7 +78,7 @@ static void vc_vacpage(Page page, VPageDescr vpd);
7878
static void vc_vaconeind(VPageList vpl, Relation indrel, int num_tuples, int keep_tuples);
7979
static void vc_scanoneind(Relation indrel, int num_tuples);
8080
static void vc_attrstats(Relation onerel, VRelStats *vacrelstats, HeapTuple tuple);
81-
static void vc_bucketcpy(Form_pg_attribute attr, Datum value, Datum *bucket, int16 *bucket_len);
81+
static void vc_bucketcpy(Form_pg_attribute attr, Datum value, Datum *bucket, int *bucket_len);
8282
static void vc_updstats(Oid relid, int num_pages, int num_tuples, bool hasindex, VRelStats *vacrelstats);
8383
static void vc_delhilowstats(Oid relid, int attcnt, int *attnums);
8484
static VPageDescr vc_tidreapped(ItemPointer itemptr, VPageList vpl);
@@ -473,9 +473,13 @@ vc_vacone(Oid relid, bool analyze, List *va_cols)
473473
{
474474
pgopform = (Form_pg_operator) GETSTRUCT(func_operator);
475475
fmgr_info(pgopform->oprcode, &(stats->f_cmplt));
476+
stats->op_cmplt = oprid(func_operator);
476477
}
477478
else
479+
{
478480
stats->f_cmplt.fn_addr = NULL;
481+
stats->op_cmplt = InvalidOid;
482+
}
479483

480484
func_operator = oper(">", stats->attr->atttypid, stats->attr->atttypid, true);
481485
if (func_operator != NULL)
@@ -2200,8 +2204,8 @@ vc_attrstats(Relation onerel, VRelStats *vacrelstats, HeapTuple tuple)
22002204
{
22012205
swapDatum(stats->guess1, stats->guess2);
22022206
swapInt(stats->guess1_len, stats->guess2_len);
2203-
stats->guess1_cnt = stats->guess2_hits;
22042207
swapLong(stats->guess1_hits, stats->guess2_hits);
2208+
stats->guess1_cnt = stats->guess1_hits;
22052209
}
22062210
if (stats->guess1_cnt > stats->best_cnt)
22072211
{
@@ -2227,7 +2231,7 @@ vc_attrstats(Relation onerel, VRelStats *vacrelstats, HeapTuple tuple)
22272231
*
22282232
*/
22292233
static void
2230-
vc_bucketcpy(Form_pg_attribute attr, Datum value, Datum *bucket, int16 *bucket_len)
2234+
vc_bucketcpy(Form_pg_attribute attr, Datum value, Datum *bucket, int *bucket_len)
22312235
{
22322236
if (attr->attbyval && attr->attlen != -1)
22332237
*bucket = value;
@@ -2340,13 +2344,14 @@ vc_updstats(Oid relid, int num_pages, int num_tuples, bool hasindex, VRelStats *
23402344
selratio = 0;
23412345
else if (VacAttrStatsLtGtValid(stats) && stats->min_cnt + stats->max_cnt == stats->nonnull_cnt)
23422346
{
2347+
/* exact result when there are just 1 or 2 values... */
23432348
double min_cnt_d = stats->min_cnt,
23442349
max_cnt_d = stats->max_cnt,
23452350
null_cnt_d = stats->null_cnt,
2346-
nonnullcnt_d = stats->nonnull_cnt; /* prevent overflow */
2351+
nonnull_cnt_d = stats->nonnull_cnt; /* prevent overflow */
23472352

23482353
selratio = (min_cnt_d * min_cnt_d + max_cnt_d * max_cnt_d + null_cnt_d * null_cnt_d) /
2349-
(nonnullcnt_d + null_cnt_d) / (nonnullcnt_d + null_cnt_d);
2354+
(nonnull_cnt_d + null_cnt_d) / (nonnull_cnt_d + null_cnt_d);
23502355
}
23512356
else
23522357
{
@@ -2359,7 +2364,9 @@ vc_updstats(Oid relid, int num_pages, int num_tuples, bool hasindex, VRelStats *
23592364
*/
23602365
selratio = (most * most + 0.20 * most * (total - most)) / total / total;
23612366
}
2362-
if (selratio > 1.0)
2367+
if (selratio < 0.0)
2368+
selratio = 0.0;
2369+
else if (selratio > 1.0)
23632370
selratio = 1.0;
23642371
attp->attdisbursion = selratio;
23652372

@@ -2375,13 +2382,22 @@ vc_updstats(Oid relid, int num_pages, int num_tuples, bool hasindex, VRelStats *
23752382
* doing system relations, especially pg_statistic is a
23762383
* problem
23772384
*/
2378-
if (VacAttrStatsLtGtValid(stats) && stats->initialized /* &&
2379-
* !IsSystemRelationName(
2380-
*
2381-
pgcform->relname.data) */ )
2385+
if (VacAttrStatsLtGtValid(stats) && stats->initialized
2386+
/* && !IsSystemRelationName(pgcform->relname.data)
2387+
*/ )
23822388
{
2389+
float32data nullratio;
2390+
float32data bestratio;
23832391
FmgrInfo out_function;
23842392
char *out_string;
2393+
double best_cnt_d = stats->best_cnt,
2394+
null_cnt_d = stats->null_cnt,
2395+
nonnull_cnt_d = stats->nonnull_cnt; /* prevent overflow */
2396+
2397+
nullratio = null_cnt_d / (nonnull_cnt_d + null_cnt_d);
2398+
bestratio = best_cnt_d / (nonnull_cnt_d + null_cnt_d);
2399+
2400+
fmgr_info(stats->outfunc, &out_function);
23852401

23862402
for (i = 0; i < Natts_pg_statistic; ++i)
23872403
nulls[i] = ' ';
@@ -2391,26 +2407,34 @@ vc_updstats(Oid relid, int num_pages, int num_tuples, bool hasindex, VRelStats *
23912407
* ----------------
23922408
*/
23932409
i = 0;
2394-
values[i++] = (Datum) relid; /* 1 */
2395-
values[i++] = (Datum) attp->attnum; /* 2 */
2396-
values[i++] = (Datum) InvalidOid; /* 3 */
2397-
fmgr_info(stats->outfunc, &out_function);
2398-
out_string = (*fmgr_faddr(&out_function)) (stats->min, stats->attr->atttypid);
2399-
values[i++] = (Datum) fmgr(F_TEXTIN, out_string);
2410+
values[i++] = (Datum) relid; /* starelid */
2411+
values[i++] = (Datum) attp->attnum; /* staattnum */
2412+
values[i++] = (Datum) stats->op_cmplt; /* staop */
2413+
/* hack: this code knows float4 is pass-by-ref */
2414+
values[i++] = PointerGetDatum(&nullratio); /* stanullfrac */
2415+
values[i++] = PointerGetDatum(&bestratio); /* stacommonfrac */
2416+
out_string = (*fmgr_faddr(&out_function)) (stats->best, stats->attr->atttypid, stats->attr->atttypmod);
2417+
values[i++] = PointerGetDatum(textin(out_string)); /* stacommonval */
24002418
pfree(out_string);
2401-
out_string = (char *) (*fmgr_faddr(&out_function)) (stats->max, stats->attr->atttypid);
2402-
values[i++] = (Datum) fmgr(F_TEXTIN, out_string);
2419+
out_string = (*fmgr_faddr(&out_function)) (stats->min, stats->attr->atttypid, stats->attr->atttypmod);
2420+
values[i++] = PointerGetDatum(textin(out_string)); /* staloval */
2421+
pfree(out_string);
2422+
out_string = (char *) (*fmgr_faddr(&out_function)) (stats->max, stats->attr->atttypid, stats->attr->atttypmod);
2423+
values[i++] = PointerGetDatum(textin(out_string)); /* stahival */
24032424
pfree(out_string);
24042425

24052426
stup = heap_formtuple(sd->rd_att, values, nulls);
24062427

24072428
/* ----------------
2408-
* insert the tuple in the relation and get the tuple's oid.
2429+
* insert the tuple in the relation.
24092430
* ----------------
24102431
*/
24112432
heap_insert(sd, stup);
2412-
pfree(DatumGetPointer(values[3]));
2413-
pfree(DatumGetPointer(values[4]));
2433+
2434+
/* release allocated space */
2435+
pfree(DatumGetPointer(values[Anum_pg_statistic_stacommonval-1]));
2436+
pfree(DatumGetPointer(values[Anum_pg_statistic_staloval-1]));
2437+
pfree(DatumGetPointer(values[Anum_pg_statistic_stahival-1]));
24142438
pfree(stup);
24152439
}
24162440
}

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