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Commite80252d

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Add width_bucket(anyelement, anyarray).
This provides a convenient method of classifying input values into bucketsthat are not necessarily equal-width. It works on any sortable data type.The choice of function name is a bit debatable, perhaps, but showing thatthere's a relationship to the SQL standard's width_bucket() function seemsmore attractive than the other proposals.Petr Jelinek, reviewed by Pavel Stehule
1 parent220bb39 commite80252d

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7 files changed

+458
-12
lines changed

7 files changed

+458
-12
lines changed

‎doc/src/sgml/func.sgml

Lines changed: 24 additions & 9 deletions
Original file line numberDiff line numberDiff line change
@@ -901,25 +901,40 @@
901901
<indexterm>
902902
<primary>width_bucket</primary>
903903
</indexterm>
904-
<literal><function>width_bucket(<parameter>op</parameter> <type>numeric</type>, <parameter>b1</parameter> <type>numeric</type>, <parameter>b2</parameter> <type>numeric</type>, <parameter>count</parameter> <type>int</type>)</function></literal>
905-
</entry>
904+
<literal><function>width_bucket(<parameter>operand</parameter> <type>dp</type>, <parameter>b1</parameter> <type>dp</type>, <parameter>b2</parameter> <type>dp</type>, <parameter>count</parameter> <type>int</type>)</function></literal></entry>
906905
<entry><type>int</type></entry>
907-
<entry>return the bucket to which <parameter>operand</> would
908-
be assigned in an equidepth histogram with <parameter>count</>
909-
buckets, in the range <parameter>b1</> to <parameter>b2</></entry>
906+
<entry>return the bucket number to which <parameter>operand</> would
907+
be assigned in a histogram having <parameter>count</> equal-width
908+
buckets spanning the range <parameter>b1</> to <parameter>b2</>;
909+
returns <literal>0</> or <literal><parameter>count</>+1</literal> for
910+
an input outside the range</entry>
910911
<entry><literal>width_bucket(5.35, 0.024, 10.06, 5)</literal></entry>
911912
<entry><literal>3</literal></entry>
912913
</row>
913914

914915
<row>
915-
<entry><literal><function>width_bucket(<parameter>op</parameter> <type>dp</type>, <parameter>b1</parameter> <type>dp</type>, <parameter>b2</parameter> <type>dp</type>, <parameter>count</parameter> <type>int</type>)</function></literal></entry>
916+
<entry><literal><function>width_bucket(<parameter>operand</parameter> <type>numeric</type>, <parameter>b1</parameter> <type>numeric</type>, <parameter>b2</parameter> <type>numeric</type>, <parameter>count</parameter> <type>int</type>)</function></literal></entry>
916917
<entry><type>int</type></entry>
917-
<entry>return the bucket to which <parameter>operand</> would
918-
be assigned in an equidepth histogram with <parameter>count</>
919-
buckets, in the range <parameter>b1</> to <parameter>b2</></entry>
918+
<entry>return the bucket number to which <parameter>operand</> would
919+
be assigned in a histogram having <parameter>count</> equal-width
920+
buckets spanning the range <parameter>b1</> to <parameter>b2</>;
921+
returns <literal>0</> or <literal><parameter>count</>+1</literal> for
922+
an input outside the range</entry>
920923
<entry><literal>width_bucket(5.35, 0.024, 10.06, 5)</literal></entry>
921924
<entry><literal>3</literal></entry>
922925
</row>
926+
927+
<row>
928+
<entry><literal><function>width_bucket(<parameter>operand</parameter> <type>anyelement</type>, <parameter>thresholds</parameter> <type>anyarray</type>)</function></literal></entry>
929+
<entry><type>int</type></entry>
930+
<entry>return the bucket number to which <parameter>operand</> would
931+
be assigned given an array listing the lower bounds of the buckets;
932+
returns <literal>0</> for an input less than the first lower bound;
933+
the <parameter>thresholds</> array <emphasis>must be sorted</>,
934+
smallest first, or unexpected results will be obtained</entry>
935+
<entry><literal>width_bucket(now(), array['yesterday', 'today', 'tomorrow']::timestamptz[])</literal></entry>
936+
<entry><literal>2</literal></entry>
937+
</row>
923938
</tbody>
924939
</tgroup>
925940
</table>

‎src/backend/utils/adt/arrayfuncs.c

Lines changed: 243 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -15,8 +15,10 @@
1515
#include"postgres.h"
1616

1717
#include<ctype.h>
18+
#include<math.h>
1819

1920
#include"access/htup_details.h"
21+
#include"catalog/pg_type.h"
2022
#include"funcapi.h"
2123
#include"libpq/pqformat.h"
2224
#include"utils/array.h"
@@ -130,6 +132,15 @@ static ArrayType *array_replace_internal(ArrayType *array,
130132
Datumreplace,boolreplace_isnull,
131133
boolremove,Oidcollation,
132134
FunctionCallInfofcinfo);
135+
staticintwidth_bucket_array_float8(Datumoperand,ArrayType*thresholds);
136+
staticintwidth_bucket_array_fixed(Datumoperand,
137+
ArrayType*thresholds,
138+
Oidcollation,
139+
TypeCacheEntry*typentry);
140+
staticintwidth_bucket_array_variable(Datumoperand,
141+
ArrayType*thresholds,
142+
Oidcollation,
143+
TypeCacheEntry*typentry);
133144

134145

135146
/*
@@ -5502,3 +5513,235 @@ array_replace(PG_FUNCTION_ARGS)
55025513
fcinfo);
55035514
PG_RETURN_ARRAYTYPE_P(array);
55045515
}
5516+
5517+
/*
5518+
* Implements width_bucket(anyelement, anyarray).
5519+
*
5520+
* 'thresholds' is an array containing lower bound values for each bucket;
5521+
* these must be sorted from smallest to largest, or bogus results will be
5522+
* produced. If N thresholds are supplied, the output is from 0 to N:
5523+
* 0 is for inputs < first threshold, N is for inputs >= last threshold.
5524+
*/
5525+
Datum
5526+
width_bucket_array(PG_FUNCTION_ARGS)
5527+
{
5528+
Datumoperand=PG_GETARG_DATUM(0);
5529+
ArrayType*thresholds=PG_GETARG_ARRAYTYPE_P(1);
5530+
Oidcollation=PG_GET_COLLATION();
5531+
Oidelement_type=ARR_ELEMTYPE(thresholds);
5532+
intresult;
5533+
5534+
/* Check input */
5535+
if (ARR_NDIM(thresholds)>1)
5536+
ereport(ERROR,
5537+
(errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
5538+
errmsg("thresholds must be one-dimensional array")));
5539+
5540+
if (array_contains_nulls(thresholds))
5541+
ereport(ERROR,
5542+
(errcode(ERRCODE_NULL_VALUE_NOT_ALLOWED),
5543+
errmsg("thresholds array must not contain NULLs")));
5544+
5545+
/* We have a dedicated implementation for float8 data */
5546+
if (element_type==FLOAT8OID)
5547+
result=width_bucket_array_float8(operand,thresholds);
5548+
else
5549+
{
5550+
TypeCacheEntry*typentry;
5551+
5552+
/* Cache information about the input type */
5553+
typentry= (TypeCacheEntry*)fcinfo->flinfo->fn_extra;
5554+
if (typentry==NULL||
5555+
typentry->type_id!=element_type)
5556+
{
5557+
typentry=lookup_type_cache(element_type,
5558+
TYPECACHE_CMP_PROC_FINFO);
5559+
if (!OidIsValid(typentry->cmp_proc_finfo.fn_oid))
5560+
ereport(ERROR,
5561+
(errcode(ERRCODE_UNDEFINED_FUNCTION),
5562+
errmsg("could not identify a comparison function for type %s",
5563+
format_type_be(element_type))));
5564+
fcinfo->flinfo->fn_extra= (void*)typentry;
5565+
}
5566+
5567+
/*
5568+
* We have separate implementation paths for fixed- and variable-width
5569+
* types, since indexing the array is a lot cheaper in the first case.
5570+
*/
5571+
if (typentry->typlen>0)
5572+
result=width_bucket_array_fixed(operand,thresholds,
5573+
collation,typentry);
5574+
else
5575+
result=width_bucket_array_variable(operand,thresholds,
5576+
collation,typentry);
5577+
}
5578+
5579+
/* Avoid leaking memory when handed toasted input. */
5580+
PG_FREE_IF_COPY(thresholds,1);
5581+
5582+
PG_RETURN_INT32(result);
5583+
}
5584+
5585+
/*
5586+
* width_bucket_array for float8 data.
5587+
*/
5588+
staticint
5589+
width_bucket_array_float8(Datumoperand,ArrayType*thresholds)
5590+
{
5591+
float8op=DatumGetFloat8(operand);
5592+
float8*thresholds_data;
5593+
intleft;
5594+
intright;
5595+
5596+
/*
5597+
* Since we know the array contains no NULLs, we can just index it
5598+
* directly.
5599+
*/
5600+
thresholds_data= (float8*)ARR_DATA_PTR(thresholds);
5601+
5602+
left=0;
5603+
right=ArrayGetNItems(ARR_NDIM(thresholds),ARR_DIMS(thresholds));
5604+
5605+
/*
5606+
* If the probe value is a NaN, it's greater than or equal to all possible
5607+
* threshold values (including other NaNs), so we need not search. Note
5608+
* that this would give the same result as searching even if the array
5609+
* contains multiple NaNs (as long as they're correctly sorted), since the
5610+
* loop logic will find the rightmost of multiple equal threshold values.
5611+
*/
5612+
if (isnan(op))
5613+
returnright;
5614+
5615+
/* Find the bucket */
5616+
while (left<right)
5617+
{
5618+
intmid= (left+right) /2;
5619+
5620+
if (isnan(thresholds_data[mid])||op<thresholds_data[mid])
5621+
right=mid;
5622+
else
5623+
left=mid+1;
5624+
}
5625+
5626+
returnleft;
5627+
}
5628+
5629+
/*
5630+
* width_bucket_array for generic fixed-width data types.
5631+
*/
5632+
staticint
5633+
width_bucket_array_fixed(Datumoperand,
5634+
ArrayType*thresholds,
5635+
Oidcollation,
5636+
TypeCacheEntry*typentry)
5637+
{
5638+
char*thresholds_data;
5639+
inttyplen=typentry->typlen;
5640+
booltypbyval=typentry->typbyval;
5641+
FunctionCallInfoDatalocfcinfo;
5642+
intleft;
5643+
intright;
5644+
5645+
/*
5646+
* Since we know the array contains no NULLs, we can just index it
5647+
* directly.
5648+
*/
5649+
thresholds_data= (char*)ARR_DATA_PTR(thresholds);
5650+
5651+
InitFunctionCallInfoData(locfcinfo,&typentry->cmp_proc_finfo,2,
5652+
collation,NULL,NULL);
5653+
5654+
/* Find the bucket */
5655+
left=0;
5656+
right=ArrayGetNItems(ARR_NDIM(thresholds),ARR_DIMS(thresholds));
5657+
while (left<right)
5658+
{
5659+
intmid= (left+right) /2;
5660+
char*ptr;
5661+
int32cmpresult;
5662+
5663+
ptr=thresholds_data+mid*typlen;
5664+
5665+
locfcinfo.arg[0]=operand;
5666+
locfcinfo.arg[1]=fetch_att(ptr,typbyval,typlen);
5667+
locfcinfo.argnull[0]= false;
5668+
locfcinfo.argnull[1]= false;
5669+
locfcinfo.isnull= false;
5670+
5671+
cmpresult=DatumGetInt32(FunctionCallInvoke(&locfcinfo));
5672+
5673+
if (cmpresult<0)
5674+
right=mid;
5675+
else
5676+
left=mid+1;
5677+
}
5678+
5679+
returnleft;
5680+
}
5681+
5682+
/*
5683+
* width_bucket_array for generic variable-width data types.
5684+
*/
5685+
staticint
5686+
width_bucket_array_variable(Datumoperand,
5687+
ArrayType*thresholds,
5688+
Oidcollation,
5689+
TypeCacheEntry*typentry)
5690+
{
5691+
char*thresholds_data;
5692+
inttyplen=typentry->typlen;
5693+
booltypbyval=typentry->typbyval;
5694+
chartypalign=typentry->typalign;
5695+
FunctionCallInfoDatalocfcinfo;
5696+
intleft;
5697+
intright;
5698+
5699+
thresholds_data= (char*)ARR_DATA_PTR(thresholds);
5700+
5701+
InitFunctionCallInfoData(locfcinfo,&typentry->cmp_proc_finfo,2,
5702+
collation,NULL,NULL);
5703+
5704+
/* Find the bucket */
5705+
left=0;
5706+
right=ArrayGetNItems(ARR_NDIM(thresholds),ARR_DIMS(thresholds));
5707+
while (left<right)
5708+
{
5709+
intmid= (left+right) /2;
5710+
char*ptr;
5711+
inti;
5712+
int32cmpresult;
5713+
5714+
/* Locate mid'th array element by advancing from left element */
5715+
ptr=thresholds_data;
5716+
for (i=left;i<mid;i++)
5717+
{
5718+
ptr=att_addlength_pointer(ptr,typlen,ptr);
5719+
ptr= (char*)att_align_nominal(ptr,typalign);
5720+
}
5721+
5722+
locfcinfo.arg[0]=operand;
5723+
locfcinfo.arg[1]=fetch_att(ptr,typbyval,typlen);
5724+
locfcinfo.argnull[0]= false;
5725+
locfcinfo.argnull[1]= false;
5726+
locfcinfo.isnull= false;
5727+
5728+
cmpresult=DatumGetInt32(FunctionCallInvoke(&locfcinfo));
5729+
5730+
if (cmpresult<0)
5731+
right=mid;
5732+
else
5733+
{
5734+
left=mid+1;
5735+
5736+
/*
5737+
* Move the thresholds pointer to match new "left" index, so we
5738+
* don't have to seek over those elements again. This trick
5739+
* ensures we do only O(N) array indexing work, not O(N^2).
5740+
*/
5741+
ptr=att_addlength_pointer(ptr,typlen,ptr);
5742+
thresholds_data= (char*)att_align_nominal(ptr,typalign);
5743+
}
5744+
}
5745+
5746+
returnleft;
5747+
}

‎src/include/catalog/catversion.h

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -53,6 +53,6 @@
5353
*/
5454

5555
/*yyyymmddN */
56-
#defineCATALOG_VERSION_NO201408281
56+
#defineCATALOG_VERSION_NO201409091
5757

5858
#endif

‎src/include/catalog/pg_proc.h

Lines changed: 4 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -514,7 +514,7 @@ DATA(insert OID = 308 ( float84le PGNSP PGUID 12 1 0 0 0 f f f t t f i 2 0
514514
DATA(insertOID=309 (float84gtPGNSPPGUID121000fffttfi2016"701 700"_null__null__null__null_float84gt_null__null__null_ ));
515515
DATA(insertOID=310 (float84gePGNSPPGUID121000fffttfi2016"701 700"_null__null__null__null_float84ge_null__null__null_ ));
516516
DATA(insertOID=320 (width_bucketPGNSPPGUID121000fffftfi4023"701 701 701 23"_null__null__null__null_width_bucket_float8_null__null__null_ ));
517-
DESCR("bucket number of operand inequidepth histogram");
517+
DESCR("bucket number of operand inequal-width histogram");
518518

519519
DATA(insertOID=311 (float8PGNSPPGUID121000fffftfi10701"700"_null__null__null__null_ftod_null__null__null_ ));
520520
DESCR("convert float4 to float8");
@@ -885,6 +885,8 @@ DATA(insert OID = 2334 ( array_agg_finalfn PGNSP PGUID 12 1 0 0 0 f f f f f f
885885
DESCR("aggregate final function");
886886
DATA(insertOID=2335 (array_aggPGNSPPGUID121000tfffffi102277"2283"_null__null__null__null_aggregate_dummy_null__null__null_ ));
887887
DESCR("concatenate aggregate input into an array");
888+
DATA(insertOID=3218 (width_bucketPGNSPPGUID121000fffftfi2023"2283 2277"_null__null__null__null_width_bucket_array_null__null__null_ ));
889+
DESCR("bucket number of operand given a sorted array of bucket lower bounds");
888890
DATA(insertOID=3816 (array_typanalyzePGNSPPGUID121000fffftfs1016"2281"_null__null__null__null_array_typanalyze_null__null__null_ ));
889891
DESCR("array typanalyze");
890892
DATA(insertOID=3817 (arraycontselPGNSPPGUID121000fffftfs40701"2281 26 2281 23"_null__null__null__null_arraycontsel_null__null__null_ ));
@@ -2301,7 +2303,7 @@ DESCR("trunc(x/y)");
23012303
DATA(insertOID=1980 (numeric_div_truncPGNSPPGUID121000fffftfi201700"1700 1700"_null__null__null__null_numeric_div_trunc_null__null__null_ ));
23022304
DESCR("trunc(x/y)");
23032305
DATA(insertOID=2170 (width_bucketPGNSPPGUID121000fffftfi4023"1700 1700 1700 23"_null__null__null__null_width_bucket_numeric_null__null__null_ ));
2304-
DESCR("bucket number of operand inequidepth histogram");
2306+
DESCR("bucket number of operand inequal-width histogram");
23052307

23062308
DATA(insertOID=1747 (time_pl_intervalPGNSPPGUID121000fffftfi201083"1083 1186"_null__null__null__null_time_pl_interval_null__null__null_ ));
23072309
DATA(insertOID=1748 (time_mi_intervalPGNSPPGUID121000fffftfi201083"1083 1186"_null__null__null__null_time_mi_interval_null__null__null_ ));

‎src/include/utils/array.h

Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -214,6 +214,7 @@ extern Datum array_fill_with_lower_bounds(PG_FUNCTION_ARGS);
214214
externDatumarray_unnest(PG_FUNCTION_ARGS);
215215
externDatumarray_remove(PG_FUNCTION_ARGS);
216216
externDatumarray_replace(PG_FUNCTION_ARGS);
217+
externDatumwidth_bucket_array(PG_FUNCTION_ARGS);
217218

218219
externDatumarray_ref(ArrayType*array,intnSubscripts,int*indx,
219220
intarraytyplen,intelmlen,boolelmbyval,charelmalign,

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