Skip to content

Commit 9717353

Browse files
deanrasheeddeanrasheed
committed
Add a planner support function for numeric generate_series().
This allows the planner to estimate the number of rows returned by generate_series(numeric, numeric[, numeric]), when the input values can be estimated at plan time. Song Jinzhou, reviewed by Dean Rasheed and David Rowley. Discussion: https://postgr.es/m/tencent_F43E7F4DD50EF5986D1051DE8DE547910206%40qq.com Discussion: https://postgr.es/m/tencent_1F6D5B9A1545E02FD7D0EE508DFD056DE50A%40qq.com
1 parent 3315235 commit 9717353

File tree

5 files changed

+232
-3
lines changed

5 files changed

+232
-3
lines changed

‎src/backend/utils/adt/numeric.c

Lines changed: 121 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -34,6 +34,7 @@
3434
#include "miscadmin.h"
3535
#include "nodes/nodeFuncs.h"
3636
#include "nodes/supportnodes.h"
37+
#include "optimizer/optimizer.h"
3738
#include "utils/array.h"
3839
#include "utils/builtins.h"
3940
#include "utils/float.h"
@@ -1827,6 +1828,126 @@ generate_series_step_numeric(PG_FUNCTION_ARGS)
18271828
SRF_RETURN_DONE(funcctx);
18281829
}
18291830

1831+
/*
1832+
* Planner support function for generate_series(numeric, numeric [, numeric])
1833+
*/
1834+
Datum
1835+
generate_series_numeric_support(PG_FUNCTION_ARGS)
1836+
{
1837+
Node *rawreq = (Node *) PG_GETARG_POINTER(0);
1838+
Node *ret = NULL;
1839+
1840+
if (IsA(rawreq, SupportRequestRows))
1841+
{
1842+
/* Try to estimate the number of rows returned */
1843+
SupportRequestRows *req = (SupportRequestRows *) rawreq;
1844+
1845+
if (is_funcclause(req->node)) /* be paranoid */
1846+
{
1847+
List *args = ((FuncExpr *) req->node)->args;
1848+
Node *arg1,
1849+
*arg2,
1850+
*arg3;
1851+
1852+
/* We can use estimated argument values here */
1853+
arg1 = estimate_expression_value(req->root, linitial(args));
1854+
arg2 = estimate_expression_value(req->root, lsecond(args));
1855+
if (list_length(args) >= 3)
1856+
arg3 = estimate_expression_value(req->root, lthird(args));
1857+
else
1858+
arg3 = NULL;
1859+
1860+
/*
1861+
* If any argument is constant NULL, we can safely assume that
1862+
* zero rows are returned. Otherwise, if they're all non-NULL
1863+
* constants, we can calculate the number of rows that will be
1864+
* returned.
1865+
*/
1866+
if ((IsA(arg1, Const) &&
1867+
((Const *) arg1)->constisnull) ||
1868+
(IsA(arg2, Const) &&
1869+
((Const *) arg2)->constisnull) ||
1870+
(arg3 != NULL && IsA(arg3, Const) &&
1871+
((Const *) arg3)->constisnull))
1872+
{
1873+
req->rows = 0;
1874+
ret = (Node *) req;
1875+
}
1876+
else if (IsA(arg1, Const) &&
1877+
IsA(arg2, Const) &&
1878+
(arg3 == NULL || IsA(arg3, Const)))
1879+
{
1880+
Numeric start_num;
1881+
Numeric stop_num;
1882+
NumericVar step = const_one;
1883+
1884+
/*
1885+
* If any argument is NaN or infinity, generate_series() will
1886+
* error out, so we needn't produce an estimate.
1887+
*/
1888+
start_num = DatumGetNumeric(((Const *) arg1)->constvalue);
1889+
stop_num = DatumGetNumeric(((Const *) arg2)->constvalue);
1890+
1891+
if (NUMERIC_IS_SPECIAL(start_num) ||
1892+
NUMERIC_IS_SPECIAL(stop_num))
1893+
PG_RETURN_POINTER(NULL);
1894+
1895+
if (arg3)
1896+
{
1897+
Numeric step_num;
1898+
1899+
step_num = DatumGetNumeric(((Const *) arg3)->constvalue);
1900+
1901+
if (NUMERIC_IS_SPECIAL(step_num))
1902+
PG_RETURN_POINTER(NULL);
1903+
1904+
init_var_from_num(step_num, &step);
1905+
}
1906+
1907+
/*
1908+
* The number of rows that will be returned is given by
1909+
* floor((stop - start) / step) + 1, if the sign of step
1910+
* matches the sign of stop - start. Otherwise, no rows will
1911+
* be returned.
1912+
*/
1913+
if (cmp_var(&step, &const_zero) != 0)
1914+
{
1915+
NumericVar start;
1916+
NumericVar stop;
1917+
NumericVar res;
1918+
1919+
init_var_from_num(start_num, &start);
1920+
init_var_from_num(stop_num, &stop);
1921+
1922+
init_var(&res);
1923+
sub_var(&stop, &start, &res);
1924+
1925+
if (step.sign != res.sign)
1926+
{
1927+
/* no rows will be returned */
1928+
req->rows = 0;
1929+
ret = (Node *) req;
1930+
}
1931+
else
1932+
{
1933+
if (arg3)
1934+
div_var(&res, &step, &res, 0, false, false);
1935+
else
1936+
trunc_var(&res, 0); /* step = 1 */
1937+
1938+
req->rows = numericvar_to_double_no_overflow(&res) + 1;
1939+
ret = (Node *) req;
1940+
}
1941+
1942+
free_var(&res);
1943+
}
1944+
}
1945+
}
1946+
}
1947+
1948+
PG_RETURN_POINTER(ret);
1949+
}
1950+
18301951

18311952
/*
18321953
* Implements the numeric version of the width_bucket() function

‎src/include/catalog/catversion.h

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -57,6 +57,6 @@
5757
*/
5858

5959
/* yyyymmddN */
60-
#define CATALOG_VERSION_NO 202411111
60+
#define CATALOG_VERSION_NO 202412021
6161

6262
#endif

‎src/include/catalog/pg_proc.dat

Lines changed: 7 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -8464,13 +8464,18 @@
84648464
proname => 'generate_series_int8_support', prorettype => 'internal',
84658465
proargtypes => 'internal', prosrc => 'generate_series_int8_support' },
84668466
{ oid => '3259', descr => 'non-persistent series generator',
8467-
proname => 'generate_series', prorows => '1000', proretset => 't',
8467+
proname => 'generate_series', prorows => '1000',
8468+
prosupport => 'generate_series_numeric_support', proretset => 't',
84688469
prorettype => 'numeric', proargtypes => 'numeric numeric numeric',
84698470
prosrc => 'generate_series_step_numeric' },
84708471
{ oid => '3260', descr => 'non-persistent series generator',
8471-
proname => 'generate_series', prorows => '1000', proretset => 't',
8472+
proname => 'generate_series', prorows => '1000',
8473+
prosupport => 'generate_series_numeric_support', proretset => 't',
84728474
prorettype => 'numeric', proargtypes => 'numeric numeric',
84738475
prosrc => 'generate_series_numeric' },
8476+
{ oid => '8405', descr => 'planner support for generate_series',
8477+
proname => 'generate_series_numeric_support', prorettype => 'internal',
8478+
proargtypes => 'internal', prosrc => 'generate_series_numeric_support' },
84748479
{ oid => '938', descr => 'non-persistent series generator',
84758480
proname => 'generate_series', prorows => '1000',
84768481
prosupport => 'generate_series_timestamp_support', proretset => 't',

‎src/test/regress/expected/misc_functions.out

Lines changed: 65 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -712,6 +712,71 @@ false, true, false, true);
712712
-- the support function.
713713
SELECT * FROM generate_series(TIMESTAMPTZ '2024-02-01', TIMESTAMPTZ '2024-03-01', INTERVAL '0 day') g(s);
714714
ERROR: step size cannot equal zero
715+
--
716+
-- Test the SupportRequestRows support function for generate_series_numeric()
717+
--
718+
-- Ensure the row estimate matches the actual rows
719+
SELECT explain_mask_costs($$
720+
SELECT * FROM generate_series(1.0, 25.0) g(s);$$,
721+
true, true, false, true);
722+
explain_mask_costs
723+
------------------------------------------------------------------------------------------
724+
Function Scan on generate_series g (cost=N..N rows=25 width=N) (actual rows=25 loops=1)
725+
(1 row)
726+
727+
-- As above but with non-default step
728+
SELECT explain_mask_costs($$
729+
SELECT * FROM generate_series(1.0, 25.0, 2.0) g(s);$$,
730+
true, true, false, true);
731+
explain_mask_costs
732+
------------------------------------------------------------------------------------------
733+
Function Scan on generate_series g (cost=N..N rows=13 width=N) (actual rows=13 loops=1)
734+
(1 row)
735+
736+
-- Ensure the estimates match when step is decreasing
737+
SELECT explain_mask_costs($$
738+
SELECT * FROM generate_series(25.0, 1.0, -1.0) g(s);$$,
739+
true, true, false, true);
740+
explain_mask_costs
741+
------------------------------------------------------------------------------------------
742+
Function Scan on generate_series g (cost=N..N rows=25 width=N) (actual rows=25 loops=1)
743+
(1 row)
744+
745+
-- Ensure an empty range estimates 1 row
746+
SELECT explain_mask_costs($$
747+
SELECT * FROM generate_series(25.0, 1.0, 1.0) g(s);$$,
748+
true, true, false, true);
749+
explain_mask_costs
750+
----------------------------------------------------------------------------------------
751+
Function Scan on generate_series g (cost=N..N rows=1 width=N) (actual rows=0 loops=1)
752+
(1 row)
753+
754+
-- Ensure we get the default row estimate for error cases (infinity/NaN values
755+
-- and zero step size)
756+
SELECT explain_mask_costs($$
757+
SELECT * FROM generate_series('-infinity'::NUMERIC, 'infinity'::NUMERIC, 1.0) g(s);$$,
758+
false, true, false, true);
759+
explain_mask_costs
760+
-------------------------------------------------------------------
761+
Function Scan on generate_series g (cost=N..N rows=1000 width=N)
762+
(1 row)
763+
764+
SELECT explain_mask_costs($$
765+
SELECT * FROM generate_series(1.0, 25.0, 'NaN'::NUMERIC) g(s);$$,
766+
false, true, false, true);
767+
explain_mask_costs
768+
-------------------------------------------------------------------
769+
Function Scan on generate_series g (cost=N..N rows=1000 width=N)
770+
(1 row)
771+
772+
SELECT explain_mask_costs($$
773+
SELECT * FROM generate_series(25.0, 2.0, 0.0) g(s);$$,
774+
false, true, false, true);
775+
explain_mask_costs
776+
-------------------------------------------------------------------
777+
Function Scan on generate_series g (cost=N..N rows=1000 width=N)
778+
(1 row)
779+
715780
-- Test functions for control data
716781
SELECT count(*) > 0 AS ok FROM pg_control_checkpoint();
717782
ok

‎src/test/regress/sql/misc_functions.sql

Lines changed: 38 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -311,6 +311,44 @@ false, true, false, true);
311311
-- the support function.
312312
SELECT * FROM generate_series(TIMESTAMPTZ '2024-02-01', TIMESTAMPTZ '2024-03-01', INTERVAL '0 day') g(s);
313313

314+
--
315+
-- Test the SupportRequestRows support function for generate_series_numeric()
316+
--
317+
318+
-- Ensure the row estimate matches the actual rows
319+
SELECT explain_mask_costs($$
320+
SELECT * FROM generate_series(1.0, 25.0) g(s);$$,
321+
true, true, false, true);
322+
323+
-- As above but with non-default step
324+
SELECT explain_mask_costs($$
325+
SELECT * FROM generate_series(1.0, 25.0, 2.0) g(s);$$,
326+
true, true, false, true);
327+
328+
-- Ensure the estimates match when step is decreasing
329+
SELECT explain_mask_costs($$
330+
SELECT * FROM generate_series(25.0, 1.0, -1.0) g(s);$$,
331+
true, true, false, true);
332+
333+
-- Ensure an empty range estimates 1 row
334+
SELECT explain_mask_costs($$
335+
SELECT * FROM generate_series(25.0, 1.0, 1.0) g(s);$$,
336+
true, true, false, true);
337+
338+
-- Ensure we get the default row estimate for error cases (infinity/NaN values
339+
-- and zero step size)
340+
SELECT explain_mask_costs($$
341+
SELECT * FROM generate_series('-infinity'::NUMERIC, 'infinity'::NUMERIC, 1.0) g(s);$$,
342+
false, true, false, true);
343+
344+
SELECT explain_mask_costs($$
345+
SELECT * FROM generate_series(1.0, 25.0, 'NaN'::NUMERIC) g(s);$$,
346+
false, true, false, true);
347+
348+
SELECT explain_mask_costs($$
349+
SELECT * FROM generate_series(25.0, 2.0, 0.0) g(s);$$,
350+
false, true, false, true);
351+
314352
-- Test functions for control data
315353
SELECT count(*) > 0 AS ok FROM pg_control_checkpoint();
316354
SELECT count(*) > 0 AS ok FROM pg_control_init();

0 commit comments

Comments
 (0)
pFad - Phonifier reborn

Pfad - The Proxy pFad of © 2024 Garber Painting. All rights reserved.

Note: This service is not intended for secure transactions such as banking, social media, email, or purchasing. Use at your own risk. We assume no liability whatsoever for broken pages.


Alternative Proxies:

Alternative Proxy

pFad Proxy

pFad v3 Proxy

pFad v4 Proxy