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> After all that about numbering centuries and millenia correctly,
> why does CVS tip still give me > > regression=# select extract(century from now()); > date_part > ----------- > 20 > (1 row) > [ ... looks in code ... ] > > Apparently it's because you fixed only timestamp_part, and not > timestamptz_part. I'm not too sure about what timestamp_trunc or > timestamptz_trunc should do, but they may be wrong as well. Sigh... as usual, what is not tested does not work:-( > Could we have a more complete patch? Please find a submission attached. I hope it really fixes all decade, century and millenium issues for extract and *_trunc functions on interval and other timestamp types. If someone could check that the results are reasonnable, it would be great. I indeed overlooked the fact that there were two functions. The patch fixes the code so that both variants agree. I added comments to interval extractions, because it relies on the C division to have a negative remainder: -7/10 = 0 and remains -7. As for *_trunc functions, I have chosen to put the first year of the century or millennium: -100, 1, 101... 1001 2001 etc. Indeed, I don't think it would make sense to put 2000 (last year of the 2nd millennium) for rounding all years of the third millenium. I also fixed the code so that all decades last 10 years and decade 199 means the 1990's. I have added some tests that are relevant to deal with tricky cases. The formula may be simplified, but all these cases must pass. Please keep them. Fabien Coelho
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-12
lines changed

3 files changed

+256
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lines changed

‎src/backend/utils/adt/timestamp.c

Lines changed: 73 additions & 12 deletions
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
*
99
*
1010
* IDENTIFICATION
11-
* $PostgreSQL: pgsql/src/backend/utils/adt/timestamp.c,v 1.109 2004/06/03 17:57:09 tgl Exp $
11+
* $PostgreSQL: pgsql/src/backend/utils/adt/timestamp.c,v 1.110 2004/08/20 03:45:13 momjian Exp $
1212
*
1313
*-------------------------------------------------------------------------
1414
*/
@@ -2727,11 +2727,26 @@ timestamp_trunc(PG_FUNCTION_ARGS)
27272727
fsec = 0;
27282728
break;
27292729
case DTK_MILLENNIUM:
2730-
tm->tm_year = (tm->tm_year / 1000) * 1000;
2730+
/* see comments in timestamptz_trunc */
2731+
if (tm->tm_year > 0)
2732+
tm->tm_year = ((tm->tm_year+999) / 1000) * 1000 - 999;
2733+
else
2734+
tm->tm_year = - ((999 - (tm->tm_year-1))/1000) * 1000 + 1;
27312735
case DTK_CENTURY:
2732-
tm->tm_year = (tm->tm_year / 100) * 100;
2736+
/* see comments in timestamptz_trunc */
2737+
if (tm->tm_year > 0)
2738+
tm->tm_year = ((tm->tm_year+99) / 100) * 100 - 99;
2739+
else
2740+
tm->tm_year = - ((99 - (tm->tm_year-1))/100) * 100 + 1;
27332741
case DTK_DECADE:
2734-
tm->tm_year = (tm->tm_year / 10) * 10;
2742+
/* see comments in timestamptz_trunc */
2743+
if (val != DTK_MILLENNIUM && val != DTK_CENTURY)
2744+
{
2745+
if (tm->tm_year > 0)
2746+
tm->tm_year = (tm->tm_year / 10) * 10;
2747+
else
2748+
tm->tm_year = - ((8-(tm->tm_year-1)) / 10) * 10;
2749+
}
27352750
case DTK_YEAR:
27362751
tm->tm_mon = 1;
27372752
case DTK_QUARTER:
@@ -2830,12 +2845,33 @@ timestamptz_trunc(PG_FUNCTION_ARGS)
28302845
tm->tm_sec = 0;
28312846
fsec = 0;
28322847
break;
2848+
/* one may consider DTK_THOUSAND and DTK_HUNDRED... */
28332849
case DTK_MILLENNIUM:
2834-
tm->tm_year = (tm->tm_year / 1000) * 1000;
2850+
/* truncating to the millennium? what is this supposed to mean?
2851+
* let us put the first year of the millennium...
2852+
* i.e. -1000, 1, 1001, 2001...
2853+
*/
2854+
if (tm->tm_year > 0)
2855+
tm->tm_year = ((tm->tm_year+999) / 1000) * 1000 - 999;
2856+
else
2857+
tm->tm_year = - ((999 - (tm->tm_year-1))/1000) * 1000 + 1;
28352858
case DTK_CENTURY:
2836-
tm->tm_year = (tm->tm_year / 100) * 100;
2859+
/* truncating to the century? as above: -100, 1, 101... */
2860+
if (tm->tm_year > 0)
2861+
tm->tm_year = ((tm->tm_year+99) / 100) * 100 - 99 ;
2862+
else
2863+
tm->tm_year = - ((99 - (tm->tm_year-1))/100) * 100 + 1;
28372864
case DTK_DECADE:
2838-
tm->tm_year = (tm->tm_year / 10) * 10;
2865+
/* truncating to the decade? first year of the decade.
2866+
* must not be applied if year was truncated before!
2867+
*/
2868+
if (val != DTK_MILLENNIUM && val != DTK_CENTURY)
2869+
{
2870+
if (tm->tm_year > 0)
2871+
tm->tm_year = (tm->tm_year / 10) * 10;
2872+
else
2873+
tm->tm_year = - ((8-(tm->tm_year-1)) / 10) * 10;
2874+
}
28392875
case DTK_YEAR:
28402876
tm->tm_mon = 1;
28412877
case DTK_QUARTER:
@@ -2923,10 +2959,13 @@ interval_trunc(PG_FUNCTION_ARGS)
29232959
switch (val)
29242960
{
29252961
case DTK_MILLENNIUM:
2962+
/* caution: C division may have negative remainder */
29262963
tm->tm_year = (tm->tm_year / 1000) * 1000;
29272964
case DTK_CENTURY:
2965+
/* caution: C division may have negative remainder */
29282966
tm->tm_year = (tm->tm_year / 100) * 100;
29292967
case DTK_DECADE:
2968+
/* caution: C division may have negative remainder */
29302969
tm->tm_year = (tm->tm_year / 10) * 10;
29312970
case DTK_YEAR:
29322971
tm->tm_mon = 0;
@@ -3221,7 +3260,14 @@ timestamp_part(PG_FUNCTION_ARGS)
32213260
break;
32223261

32233262
case DTK_DECADE:
3224-
result = (tm->tm_year / 10);
3263+
/* what is a decade wrt dates?
3264+
* let us assume that decade 199 is 1990 thru 1999...
3265+
* decade 0 starts on year 1 BC, and -1 is 11 BC thru 2 BC...
3266+
*/
3267+
if (tm->tm_year>=0)
3268+
result = (tm->tm_year / 10);
3269+
else
3270+
result = -((8-(tm->tm_year-1)) / 10);
32253271
break;
32263272

32273273
case DTK_CENTURY:
@@ -3232,7 +3278,7 @@ timestamp_part(PG_FUNCTION_ARGS)
32323278
if (tm->tm_year > 0)
32333279
result = ((tm->tm_year+99) / 100);
32343280
else
3235-
/* caution: C division may yave negative remainder */
3281+
/* caution: C division may have negative remainder */
32363282
result = - ((99 - (tm->tm_year-1))/100);
32373283
break;
32383284

@@ -3445,15 +3491,27 @@ timestamptz_part(PG_FUNCTION_ARGS)
34453491
break;
34463492

34473493
case DTK_DECADE:
3448-
result = (tm->tm_year / 10);
3494+
/* see comments in timestamp_part */
3495+
if (tm->tm_year>0)
3496+
result = (tm->tm_year / 10);
3497+
else
3498+
result = - ((8-(tm->tm_year-1)) / 10);
34493499
break;
34503500

34513501
case DTK_CENTURY:
3452-
result = (tm->tm_year / 100);
3502+
/* see comments in timestamp_part */
3503+
if (tm->tm_year > 0)
3504+
result = ((tm->tm_year+99) / 100);
3505+
else
3506+
result = - ((99 - (tm->tm_year-1))/100);
34533507
break;
34543508

34553509
case DTK_MILLENNIUM:
3456-
result = (tm->tm_year / 1000);
3510+
/* see comments in timestamp_part */
3511+
if (tm->tm_year > 0)
3512+
result = ((tm->tm_year+999) / 1000);
3513+
else
3514+
result = - ((999 - (tm->tm_year-1))/1000);
34573515
break;
34583516

34593517
case DTK_JULIAN:
@@ -3606,14 +3664,17 @@ interval_part(PG_FUNCTION_ARGS)
36063664
break;
36073665

36083666
case DTK_DECADE:
3667+
/* caution: C division may have negative remainder */
36093668
result = (tm->tm_year / 10);
36103669
break;
36113670

36123671
case DTK_CENTURY:
3672+
/* caution: C division may have negative remainder */
36133673
result = (tm->tm_year / 100);
36143674
break;
36153675

36163676
case DTK_MILLENNIUM:
3677+
/* caution: C division may have negative remainder */
36173678
result = (tm->tm_year / 1000);
36183679
break;
36193680

‎src/test/regress/expected/date.out

Lines changed: 149 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -930,3 +930,152 @@ SELECT EXTRACT(MILLENNIUM FROM CURRENT_DATE); -- 3
930930
3
931931
(1 row)
932932

933+
--
934+
-- decade
935+
--
936+
SELECT EXTRACT(DECADE FROM DATE '1994-12-25'); -- 199
937+
date_part
938+
-----------
939+
199
940+
(1 row)
941+
942+
SELECT EXTRACT(DECADE FROM DATE '0010-01-01'); -- 1
943+
date_part
944+
-----------
945+
1
946+
(1 row)
947+
948+
SELECT EXTRACT(DECADE FROM DATE '0009-12-31'); -- 0
949+
date_part
950+
-----------
951+
0
952+
(1 row)
953+
954+
SELECT EXTRACT(DECADE FROM DATE '0001-01-01 BC'); -- 0
955+
date_part
956+
-----------
957+
0
958+
(1 row)
959+
960+
SELECT EXTRACT(DECADE FROM DATE '0002-12-31 BC'); -- -1
961+
date_part
962+
-----------
963+
-1
964+
(1 row)
965+
966+
SELECT EXTRACT(DECADE FROM DATE '0011-01-01 BC'); -- -1
967+
date_part
968+
-----------
969+
-1
970+
(1 row)
971+
972+
SELECT EXTRACT(DECADE FROM DATE '0012-12-31 BC'); -- -2
973+
date_part
974+
-----------
975+
-2
976+
(1 row)
977+
978+
--
979+
-- some other types:
980+
--
981+
-- on a timestamp.
982+
SELECT EXTRACT(CENTURY FROM NOW())>=21 AS True; -- true
983+
true
984+
------
985+
t
986+
(1 row)
987+
988+
SELECT EXTRACT(CENTURY FROM TIMESTAMP '1970-03-20 04:30:00.00000'); -- 20
989+
date_part
990+
-----------
991+
20
992+
(1 row)
993+
994+
-- on an interval
995+
SELECT EXTRACT(CENTURY FROM INTERVAL '100 y'); -- 1
996+
date_part
997+
-----------
998+
1
999+
(1 row)
1000+
1001+
SELECT EXTRACT(CENTURY FROM INTERVAL '99 y'); -- 0
1002+
date_part
1003+
-----------
1004+
0
1005+
(1 row)
1006+
1007+
SELECT EXTRACT(CENTURY FROM INTERVAL '-99 y'); -- 0
1008+
date_part
1009+
-----------
1010+
0
1011+
(1 row)
1012+
1013+
SELECT EXTRACT(CENTURY FROM INTERVAL '-100 y'); -- -1
1014+
date_part
1015+
-----------
1016+
-1
1017+
(1 row)
1018+
1019+
--
1020+
-- test trunc function!
1021+
--
1022+
SELECT DATE_TRUNC('MILLENNIUM', TIMESTAMP '1970-03-20 04:30:00.00000'); -- 1001
1023+
date_trunc
1024+
--------------------------
1025+
Thu Jan 01 00:00:00 1001
1026+
(1 row)
1027+
1028+
SELECT DATE_TRUNC('MILLENNIUM', DATE '1970-03-20'); -- 1001-01-01
1029+
date_trunc
1030+
------------------------------
1031+
Thu Jan 01 00:00:00 1001 PST
1032+
(1 row)
1033+
1034+
SELECT DATE_TRUNC('CENTURY', TIMESTAMP '1970-03-20 04:30:00.00000'); -- 1901
1035+
date_trunc
1036+
--------------------------
1037+
Tue Jan 01 00:00:00 1901
1038+
(1 row)
1039+
1040+
SELECT DATE_TRUNC('CENTURY', DATE '1970-03-20'); -- 1901
1041+
date_trunc
1042+
------------------------------
1043+
Tue Jan 01 00:00:00 1901 PST
1044+
(1 row)
1045+
1046+
SELECT DATE_TRUNC('CENTURY', DATE '2004-08-10'); -- 2001-01-01
1047+
date_trunc
1048+
------------------------------
1049+
Mon Jan 01 00:00:00 2001 PST
1050+
(1 row)
1051+
1052+
SELECT DATE_TRUNC('CENTURY', DATE '0002-02-04'); -- 0001-01-01
1053+
date_trunc
1054+
------------------------------
1055+
Mon Jan 01 00:00:00 0001 PST
1056+
(1 row)
1057+
1058+
SELECT DATE_TRUNC('CENTURY', DATE '0055-08-10 BC'); -- 0100-01-01 BC
1059+
date_trunc
1060+
---------------------------------
1061+
Tue Jan 01 00:00:00 0100 PST BC
1062+
(1 row)
1063+
1064+
SELECT DATE_TRUNC('DECADE', DATE '1993-12-25'); -- 1990-01-01
1065+
date_trunc
1066+
------------------------------
1067+
Mon Jan 01 00:00:00 1990 PST
1068+
(1 row)
1069+
1070+
SELECT DATE_TRUNC('DECADE', DATE '0004-12-25'); -- 0001-01-01 BC
1071+
date_trunc
1072+
---------------------------------
1073+
Sat Jan 01 00:00:00 0001 PST BC
1074+
(1 row)
1075+
1076+
SELECT DATE_TRUNC('DECADE', DATE '0002-12-31 BC'); -- 0011-01-01 BC
1077+
date_trunc
1078+
---------------------------------
1079+
Mon Jan 01 00:00:00 0011 PST BC
1080+
(1 row)
1081+

‎src/test/regress/sql/date.sql

Lines changed: 34 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -235,3 +235,37 @@ SELECT EXTRACT(MILLENNIUM FROM DATE '2000-12-31'); -- 2
235235
SELECT EXTRACT(MILLENNIUM FROM DATE '2001-01-01'); -- 3
236236
-- next test to be fixed on the turn of the next millennium;-)
237237
SELECT EXTRACT(MILLENNIUM FROM CURRENT_DATE); -- 3
238+
--
239+
-- decade
240+
--
241+
SELECT EXTRACT(DECADE FROM DATE '1994-12-25'); -- 199
242+
SELECT EXTRACT(DECADE FROM DATE '0010-01-01'); -- 1
243+
SELECT EXTRACT(DECADE FROM DATE '0009-12-31'); -- 0
244+
SELECT EXTRACT(DECADE FROM DATE '0001-01-01 BC'); -- 0
245+
SELECT EXTRACT(DECADE FROM DATE '0002-12-31 BC'); -- -1
246+
SELECT EXTRACT(DECADE FROM DATE '0011-01-01 BC'); -- -1
247+
SELECT EXTRACT(DECADE FROM DATE '0012-12-31 BC'); -- -2
248+
--
249+
-- some other types:
250+
--
251+
-- on a timestamp.
252+
SELECT EXTRACT(CENTURY FROM NOW())>=21 AS True; -- true
253+
SELECT EXTRACT(CENTURY FROM TIMESTAMP '1970-03-20 04:30:00.00000'); -- 20
254+
-- on an interval
255+
SELECT EXTRACT(CENTURY FROM INTERVAL '100 y'); -- 1
256+
SELECT EXTRACT(CENTURY FROM INTERVAL '99 y'); -- 0
257+
SELECT EXTRACT(CENTURY FROM INTERVAL '-99 y'); -- 0
258+
SELECT EXTRACT(CENTURY FROM INTERVAL '-100 y'); -- -1
259+
--
260+
-- test trunc function!
261+
--
262+
SELECT DATE_TRUNC('MILLENNIUM', TIMESTAMP '1970-03-20 04:30:00.00000'); -- 1001
263+
SELECT DATE_TRUNC('MILLENNIUM', DATE '1970-03-20'); -- 1001-01-01
264+
SELECT DATE_TRUNC('CENTURY', TIMESTAMP '1970-03-20 04:30:00.00000'); -- 1901
265+
SELECT DATE_TRUNC('CENTURY', DATE '1970-03-20'); -- 1901
266+
SELECT DATE_TRUNC('CENTURY', DATE '2004-08-10'); -- 2001-01-01
267+
SELECT DATE_TRUNC('CENTURY', DATE '0002-02-04'); -- 0001-01-01
268+
SELECT DATE_TRUNC('CENTURY', DATE '0055-08-10 BC'); -- 0100-01-01 BC
269+
SELECT DATE_TRUNC('DECADE', DATE '1993-12-25'); -- 1990-01-01
270+
SELECT DATE_TRUNC('DECADE', DATE '0004-12-25'); -- 0001-01-01 BC
271+
SELECT DATE_TRUNC('DECADE', DATE '0002-12-31 BC'); -- 0011-01-01 BC

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