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Commit8787bc8

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committed
After further thought about support for gathering stats on functional
indexes, it seems like we ought to put another layer of indirectionbetween the compute_stats functions and the actual data storage. Thiswould allow us to compute the values on-the-fly, for example.
1 parent1a46523 commit8787bc8

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2 files changed

+81
-52
lines changed

2 files changed

+81
-52
lines changed

‎src/backend/commands/analyze.c‎

Lines changed: 61 additions & 40 deletions
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
*
99
*
1010
* IDENTIFICATION
11-
* $PostgreSQL: pgsql/src/backend/commands/analyze.c,v 1.68 2004/02/12 23:41:02 tgl Exp $
11+
* $PostgreSQL: pgsql/src/backend/commands/analyze.c,v 1.69 2004/02/13 06:39:49 tgl Exp $
1212
*
1313
*-------------------------------------------------------------------------
1414
*/
@@ -52,6 +52,7 @@ static double init_selection_state(int n);
5252
staticdoubleselect_next_random_record(doublet,intn,double*stateptr);
5353
staticintcompare_rows(constvoid*a,constvoid*b);
5454
staticvoidupdate_attstats(Oidrelid,intnatts,VacAttrStats**vacattrstats);
55+
staticDatumstd_fetch_func(VacAttrStatsPstats,intrownum,bool*isNull);
5556

5657
staticboolstd_typanalyze(VacAttrStats*stats);
5758

@@ -259,12 +260,14 @@ analyze_rel(Oid relid, VacuumStmt *vacstmt)
259260
old_context=MemoryContextSwitchTo(col_context);
260261
for (i=0;i<attr_cnt;i++)
261262
{
262-
(*vacattrstats[i]->compute_stats) (vacattrstats[i],
263-
vacattrstats[i]->tupattnum,
264-
onerel->rd_att,
265-
totalrows,
266-
rows,
267-
numrows);
263+
VacAttrStats*stats=vacattrstats[i];
264+
265+
stats->rows=rows;
266+
stats->tupDesc=onerel->rd_att;
267+
(*stats->compute_stats) (stats,
268+
std_fetch_func,
269+
numrows,
270+
totalrows);
268271
MemoryContextResetAndDeleteChildren(col_context);
269272
}
270273
MemoryContextSwitchTo(old_context);
@@ -861,6 +864,22 @@ update_attstats(Oid relid, int natts, VacAttrStats **vacattrstats)
861864
heap_close(sd,RowExclusiveLock);
862865
}
863866

867+
/*
868+
* Standard fetch function for use by compute_stats subroutines.
869+
*
870+
* This exists to provide some insulation between compute_stats routines
871+
* and the actual storage of the sample data.
872+
*/
873+
staticDatum
874+
std_fetch_func(VacAttrStatsPstats,intrownum,bool*isNull)
875+
{
876+
intattnum=stats->tupattnum;
877+
HeapTupletuple=stats->rows[rownum];
878+
TupleDesctupDesc=stats->tupDesc;
879+
880+
returnheap_getattr(tuple,attnum,tupDesc,isNull);
881+
}
882+
864883

865884
/*==========================================================================
866885
*
@@ -915,12 +934,14 @@ static SortFunctionKind datumCmpFnKind;
915934
staticint*datumCmpTupnoLink;
916935

917936

918-
staticvoidcompute_minimal_stats(VacAttrStats*stats,intattnum,
919-
TupleDesctupDesc,doubletotalrows,
920-
HeapTuple*rows,intnumrows);
921-
staticvoidcompute_scalar_stats(VacAttrStats*stats,intattnum,
922-
TupleDesctupDesc,doubletotalrows,
923-
HeapTuple*rows,intnumrows);
937+
staticvoidcompute_minimal_stats(VacAttrStatsPstats,
938+
AnalyzeAttrFetchFuncfetchfunc,
939+
intsamplerows,
940+
doubletotalrows);
941+
staticvoidcompute_scalar_stats(VacAttrStatsPstats,
942+
AnalyzeAttrFetchFuncfetchfunc,
943+
intsamplerows,
944+
doubletotalrows);
924945
staticintcompare_scalars(constvoid*a,constvoid*b);
925946
staticintcompare_mcvs(constvoid*a,constvoid*b);
926947

@@ -1024,9 +1045,10 @@ std_typanalyze(VacAttrStats *stats)
10241045
*depend mainly on the length of the list we are willing to keep.
10251046
*/
10261047
staticvoid
1027-
compute_minimal_stats(VacAttrStats*stats,intattnum,
1028-
TupleDesctupDesc,doubletotalrows,
1029-
HeapTuple*rows,intnumrows)
1048+
compute_minimal_stats(VacAttrStatsPstats,
1049+
AnalyzeAttrFetchFuncfetchfunc,
1050+
intsamplerows,
1051+
doubletotalrows)
10301052
{
10311053
inti;
10321054
intnull_cnt=0;
@@ -1061,9 +1083,8 @@ compute_minimal_stats(VacAttrStats *stats, int attnum,
10611083

10621084
fmgr_info(mystats->eqfunc,&f_cmpeq);
10631085

1064-
for (i=0;i<numrows;i++)
1086+
for (i=0;i<samplerows;i++)
10651087
{
1066-
HeapTupletuple=rows[i];
10671088
Datumvalue;
10681089
boolisnull;
10691090
boolmatch;
@@ -1072,7 +1093,7 @@ compute_minimal_stats(VacAttrStats *stats, int attnum,
10721093

10731094
vacuum_delay_point();
10741095

1075-
value=heap_getattr(tuple,attnum,tupDesc,&isnull);
1096+
value=fetchfunc(stats,i,&isnull);
10761097

10771098
/* Check for null/nonnull */
10781099
if (isnull)
@@ -1166,7 +1187,7 @@ compute_minimal_stats(VacAttrStats *stats, int attnum,
11661187

11671188
stats->stats_valid= true;
11681189
/* Do the simple null-frac and width stats */
1169-
stats->stanullfrac= (double)null_cnt / (double)numrows;
1190+
stats->stanullfrac= (double)null_cnt / (double)samplerows;
11701191
if (is_varwidth)
11711192
stats->stawidth=total_width / (double)nonnull_cnt;
11721193
else
@@ -1222,10 +1243,10 @@ compute_minimal_stats(VacAttrStats *stats, int attnum,
12221243
denom,
12231244
stadistinct;
12241245

1225-
numer= (double)numrows*(double)d;
1246+
numer= (double)samplerows*(double)d;
12261247

1227-
denom= (double) (numrows-f1)+
1228-
(double)f1*(double)numrows /totalrows;
1248+
denom= (double) (samplerows-f1)+
1249+
(double)f1*(double)samplerows /totalrows;
12291250

12301251
stadistinct=numer /denom;
12311252
/* Clamp to sane range in case of roundoff error */
@@ -1270,7 +1291,7 @@ compute_minimal_stats(VacAttrStats *stats, int attnum,
12701291
if (ndistinct<0)
12711292
ndistinct=-ndistinct*totalrows;
12721293
/* estimate # of occurrences in sample of a typical value */
1273-
avgcount= (double)numrows /ndistinct;
1294+
avgcount= (double)samplerows /ndistinct;
12741295
/* set minimum threshold count to store a value */
12751296
mincount=avgcount*1.25;
12761297
if (mincount<2)
@@ -1303,7 +1324,7 @@ compute_minimal_stats(VacAttrStats *stats, int attnum,
13031324
mcv_values[i]=datumCopy(track[i].value,
13041325
stats->attr->attbyval,
13051326
stats->attr->attlen);
1306-
mcv_freqs[i]= (double)track[i].count / (double)numrows;
1327+
mcv_freqs[i]= (double)track[i].count / (double)samplerows;
13071328
}
13081329
MemoryContextSwitchTo(old_context);
13091330

@@ -1333,9 +1354,10 @@ compute_minimal_stats(VacAttrStats *stats, int attnum,
13331354
*data values into order.
13341355
*/
13351356
staticvoid
1336-
compute_scalar_stats(VacAttrStats*stats,intattnum,
1337-
TupleDesctupDesc,doubletotalrows,
1338-
HeapTuple*rows,intnumrows)
1357+
compute_scalar_stats(VacAttrStatsPstats,
1358+
AnalyzeAttrFetchFuncfetchfunc,
1359+
intsamplerows,
1360+
doubletotalrows)
13391361
{
13401362
inti;
13411363
intnull_cnt=0;
@@ -1359,23 +1381,22 @@ compute_scalar_stats(VacAttrStats *stats, int attnum,
13591381
intnum_bins=stats->attr->attstattarget;
13601382
StdAnalyzeData*mystats= (StdAnalyzeData*)stats->extra_data;
13611383

1362-
values= (ScalarItem*)palloc(numrows*sizeof(ScalarItem));
1363-
tupnoLink= (int*)palloc(numrows*sizeof(int));
1384+
values= (ScalarItem*)palloc(samplerows*sizeof(ScalarItem));
1385+
tupnoLink= (int*)palloc(samplerows*sizeof(int));
13641386
track= (ScalarMCVItem*)palloc(num_mcv*sizeof(ScalarMCVItem));
13651387

13661388
SelectSortFunction(mystats->ltopr,&cmpFn,&cmpFnKind);
13671389
fmgr_info(cmpFn,&f_cmpfn);
13681390

13691391
/* Initial scan to find sortable values */
1370-
for (i=0;i<numrows;i++)
1392+
for (i=0;i<samplerows;i++)
13711393
{
1372-
HeapTupletuple=rows[i];
13731394
Datumvalue;
13741395
boolisnull;
13751396

13761397
vacuum_delay_point();
13771398

1378-
value=heap_getattr(tuple,attnum,tupDesc,&isnull);
1399+
value=fetchfunc(stats,i,&isnull);
13791400

13801401
/* Check for null/nonnull */
13811402
if (isnull)
@@ -1505,7 +1526,7 @@ compute_scalar_stats(VacAttrStats *stats, int attnum,
15051526

15061527
stats->stats_valid= true;
15071528
/* Do the simple null-frac and width stats */
1508-
stats->stanullfrac= (double)null_cnt / (double)numrows;
1529+
stats->stanullfrac= (double)null_cnt / (double)samplerows;
15091530
if (is_varwidth)
15101531
stats->stawidth=total_width / (double)nonnull_cnt;
15111532
else
@@ -1546,10 +1567,10 @@ compute_scalar_stats(VacAttrStats *stats, int attnum,
15461567
denom,
15471568
stadistinct;
15481569

1549-
numer= (double)numrows*(double)d;
1570+
numer= (double)samplerows*(double)d;
15501571

1551-
denom= (double) (numrows-f1)+
1552-
(double)f1*(double)numrows /totalrows;
1572+
denom= (double) (samplerows-f1)+
1573+
(double)f1*(double)samplerows /totalrows;
15531574

15541575
stadistinct=numer /denom;
15551576
/* Clamp to sane range in case of roundoff error */
@@ -1599,13 +1620,13 @@ compute_scalar_stats(VacAttrStats *stats, int attnum,
15991620
if (ndistinct<0)
16001621
ndistinct=-ndistinct*totalrows;
16011622
/* estimate # of occurrences in sample of a typical value */
1602-
avgcount= (double)numrows /ndistinct;
1623+
avgcount= (double)samplerows /ndistinct;
16031624
/* set minimum threshold count to store a value */
16041625
mincount=avgcount*1.25;
16051626
if (mincount<2)
16061627
mincount=2;
16071628
/* don't let threshold exceed 1/K, however */
1608-
maxmincount= (double)numrows / (double)num_bins;
1629+
maxmincount= (double)samplerows / (double)num_bins;
16091630
if (mincount>maxmincount)
16101631
mincount=maxmincount;
16111632
if (num_mcv>track_cnt)
@@ -1636,7 +1657,7 @@ compute_scalar_stats(VacAttrStats *stats, int attnum,
16361657
mcv_values[i]=datumCopy(values[track[i].first].value,
16371658
stats->attr->attbyval,
16381659
stats->attr->attlen);
1639-
mcv_freqs[i]= (double)track[i].count / (double)numrows;
1660+
mcv_freqs[i]= (double)track[i].count / (double)samplerows;
16401661
}
16411662
MemoryContextSwitchTo(old_context);
16421663

‎src/include/commands/vacuum.h‎

Lines changed: 20 additions & 12 deletions
Original file line numberDiff line numberDiff line change
@@ -7,7 +7,7 @@
77
* Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group
88
* Portions Copyright (c) 1994, Regents of the University of California
99
*
10-
* $PostgreSQL: pgsql/src/include/commands/vacuum.h,v 1.49 2004/02/12 23:41:04 tgl Exp $
10+
* $PostgreSQL: pgsql/src/include/commands/vacuum.h,v 1.50 2004/02/13 06:39:49 tgl Exp $
1111
*
1212
*-------------------------------------------------------------------------
1313
*/
@@ -40,18 +40,18 @@
4040
* and must return TRUE to continue analysis, FALSE to skip analysis of this
4141
* column. In the TRUE case it must set the compute_stats and minrows fields,
4242
* and can optionally set extra_data to pass additional info to compute_stats.
43+
* minrows is its request for the minimum number of sample rows to be gathered
44+
* (but note this request might not be honored, eg if there are fewer rows
45+
* than that in the table).
4346
*
4447
* The compute_stats routine will be called after sample rows have been
4548
* gathered. Aside from this struct, it is passed:
46-
*attnum: attribute number within the supplied tuples
47-
*tupDesc: tuple descriptor for the supplied tuples
49+
*fetchfunc: a function for accessing the column values from the
50+
* sample rows
51+
*samplerows: the number of sample tuples
4852
*totalrows: estimated total number of rows in relation
49-
*rows: an array of the sample tuples
50-
*numrows: the number of sample tuples
51-
* Note that the passed attnum and tupDesc could possibly be different from
52-
* what one would expect by looking at the pg_attribute row. It is important
53-
* to use these values for extracting attribute values from the given rows
54-
* (and not for any other purpose).
53+
* The fetchfunc may be called with rownum running from 0 to samplerows-1.
54+
* It returns a Datum and an isNull flag.
5555
*
5656
* compute_stats should set stats_valid TRUE if it is able to compute
5757
* any useful statistics. If it does, the remainder of the struct holds
@@ -60,6 +60,11 @@
6060
* be CurrentMemoryContext when compute_stats is called.
6161
*----------
6262
*/
63+
typedefstructVacAttrStats*VacAttrStatsP;
64+
65+
typedefDatum (*AnalyzeAttrFetchFunc) (VacAttrStatsPstats,intrownum,
66+
bool*isNull);
67+
6368
typedefstructVacAttrStats
6469
{
6570
/*
@@ -74,9 +79,10 @@ typedef struct VacAttrStats
7479
* These fields must be filled in by the typanalyze routine,
7580
* unless it returns FALSE.
7681
*/
77-
void (*compute_stats) (structVacAttrStats*stats,intattnum,
78-
TupleDesctupDesc,doubletotalrows,
79-
HeapTuple*rows,intnumrows);
82+
void (*compute_stats) (VacAttrStatsPstats,
83+
AnalyzeAttrFetchFuncfetchfunc,
84+
intsamplerows,
85+
doubletotalrows);
8086
intminrows;/* Minimum # of rows wanted for stats */
8187
void*extra_data;/* for extra type-specific data */
8288

@@ -100,6 +106,8 @@ typedef struct VacAttrStats
100106
* be looked at by type-specific functions.
101107
*/
102108
inttupattnum;/* attribute number within tuples */
109+
HeapTuple*rows;/* access info for fetch function */
110+
TupleDesctupDesc;
103111
}VacAttrStats;
104112

105113

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