On Fri, Jul 30, 2021 at 03:47:53PM -0400, Robert Haas wrote:
> On Fri, Jul 30, 2021 at 3:20 PM Bruce Momjian <[email protected]> wrote:
> > Uh, what do you suggest then? You wanted the years/months fixed, and
> > rounding at spill stop time makes sense, and fixes the problem.
>
> Hmm, maybe I misunderstood. Are you saying that you think the patch
> will fix cases like interval '-1.7 years 29.4 months' and interval
> '29.4 months -1.7 years' to produce the same answer without changing
> any other cases? I had the impression that you were proposing a bigger
Yes, tests from the oringal email:
SELECT interval '-1.7 years 29.4 months';
interval
----------------
9 mons 12 days
(1 row)
SELECT interval '29.4 months -1.7 years';
interval
----------------
9 mons 12 days
(1 row)
SELECT interval '-1.7 years' + interval '29.4 months';
?column?
----------------
9 mons 12 days
(1 row)
SELECT interval '29.4 months' + interval '-1.7 years';
?column?
----------------
9 mons 12 days
> change to the rules for converting fractional units to units of lower
> type, particularly because Tom called it an "API change".
The API change is to _round_ units greater than months to integeral
month values; we currently truncate. Changing the spill behavior has
been rejected.
> For some reason I can't apply the patch locally.
>
> [rhaas pgsql]$ patch -p1 < ~/Downloads/interval.diff
> (Stripping trailing CRs from patch.)
> patching file doc/src/sgml/datatype.sgml
> (Stripping trailing CRs from patch.)
> patching file src/backend/utils/adt/datetime.c
> patch: **** malformed patch at line 90: @@ -3601,7 +3597,7 @@
> DecodeISO8601Interval(char *str,
Uh, here is the patch again, in case that helps.
--
Bruce Momjian <[email protected]> https://momjian.us
EDB https://enterprisedb.com
If only the physical world exists, free will is an illusion.
diff --git a/doc/src/sgml/datatype.sgml b/doc/src/sgml/datatype.sgml
index 453115f942..50a2c8e5f1 100644
--- a/doc/src/sgml/datatype.sgml
+++ b/doc/src/sgml/datatype.sgml
@@ -2840,15 +2840,18 @@ P <optional> <replaceable>years</replaceable>-<replaceable>months</replaceable>-
</para>
<para>
- In the verbose input format, and in some fields of the more compact
- input formats, field values can have fractional parts; for example
- <literal>'1.5 week'</literal> or <literal>'01:02:03.45'</literal>. Such input is
- converted to the appropriate number of months, days, and seconds
- for storage. When this would result in a fractional number of
- months or days, the fraction is added to the lower-order fields
- using the conversion factors 1 month = 30 days and 1 day = 24 hours.
- For example, <literal>'1.5 month'</literal> becomes 1 month and 15 days.
- Only seconds will ever be shown as fractional on output.
+ Field values can have fractional parts: for example, <literal>'1.5
+ weeks'</literal> or <literal>'01:02:03.45'</literal>. However,
+ because interval internally stores only three integer units (months,
+ days, microseconds), fractional units must be spilled to smaller
+ units. Fractional parts of units greater than months is rounded to
+ be an integer number of months, e.g. <literal>'1.5 years'</literal>
+ becomes <literal>'1 year 6 mons'</literal>. Fractional parts of
+ weeks and days are computed to be an integer number of days and
+ microseconds, assuming 30 days per month and 24 hours per day, e.g.,
+ <literal>'1.75 months'</literal> becomes <literal>1 mon 22 days
+ 12:00:00</literal>. Only seconds will ever be shown as fractional
+ on output.
</para>
<para>
@@ -2892,10 +2895,10 @@ P <optional> <replaceable>years</replaceable>-<replaceable>months</replaceable>-
<para>
Internally <type>interval</type> values are stored as months, days,
- and seconds. This is done because the number of days in a month
+ and microseconds. This is done because the number of days in a month
varies, and a day can have 23 or 25 hours if a daylight savings
time adjustment is involved. The months and days fields are integers
- while the seconds field can store fractions. Because intervals are
+ while the microseconds field can store fractional seconds. Because intervals are
usually created from constant strings or <type>timestamp</type> subtraction,
this storage method works well in most cases, but can cause unexpected
results:
diff --git a/src/backend/utils/adt/datetime.c b/src/backend/utils/adt/datetime.c
index 54ae632de2..cb3fa85892 100644
--- a/src/backend/utils/adt/datetime.c
+++ b/src/backend/utils/adt/datetime.c
@@ -3306,29 +3306,25 @@ DecodeInterval(char **field, int *ftype, int nf, int range,
case DTK_YEAR:
tm->tm_year += val;
- if (fval != 0)
- tm->tm_mon += fval * MONTHS_PER_YEAR;
+ tm->tm_mon += rint(fval * MONTHS_PER_YEAR);
tmask = DTK_M(YEAR);
break;
case DTK_DECADE:
tm->tm_year += val * 10;
- if (fval != 0)
- tm->tm_mon += fval * MONTHS_PER_YEAR * 10;
+ tm->tm_mon += rint(fval * MONTHS_PER_YEAR * 10);
tmask = DTK_M(DECADE);
break;
case DTK_CENTURY:
tm->tm_year += val * 100;
- if (fval != 0)
- tm->tm_mon += fval * MONTHS_PER_YEAR * 100;
+ tm->tm_mon += rint(fval * MONTHS_PER_YEAR * 100);
tmask = DTK_M(CENTURY);
break;
case DTK_MILLENNIUM:
tm->tm_year += val * 1000;
- if (fval != 0)
- tm->tm_mon += fval * MONTHS_PER_YEAR * 1000;
+ tm->tm_mon += rint(fval * MONTHS_PER_YEAR * 1000);
tmask = DTK_M(MILLENNIUM);
break;
@@ -3565,7 +3561,7 @@ DecodeISO8601Interval(char *str,
{
case 'Y':
tm->tm_year += val;
- tm->tm_mon += (fval * MONTHS_PER_YEAR);
+ tm->tm_mon += rint(fval * MONTHS_PER_YEAR);
break;
case 'M':
tm->tm_mon += val;
@@ -3601,7 +3597,7 @@ DecodeISO8601Interval(char *str,
return DTERR_BAD_FORMAT;
tm->tm_year += val;
- tm->tm_mon += (fval * MONTHS_PER_YEAR);
+ tm->tm_mon += rint(fval * MONTHS_PER_YEAR);
if (unit == '\0')
return 0;
if (unit == 'T')
diff --git a/src/interfaces/ecpg/pgtypeslib/interval.c b/src/interfaces/ecpg/pgtypeslib/interval.c
index 02b3c47223..a7e530cb5d 100644
--- a/src/interfaces/ecpg/pgtypeslib/interval.c
+++ b/src/interfaces/ecpg/pgtypeslib/interval.c
@@ -155,7 +155,7 @@ DecodeISO8601Interval(char *str,
{
case 'Y':
tm->tm_year += val;
- tm->tm_mon += (fval * MONTHS_PER_YEAR);
+ tm->tm_mon += rint(fval * MONTHS_PER_YEAR);
break;
case 'M':
tm->tm_mon += val;
@@ -191,7 +191,7 @@ DecodeISO8601Interval(char *str,
return DTERR_BAD_FORMAT;
tm->tm_year += val;
- tm->tm_mon += (fval * MONTHS_PER_YEAR);
+ tm->tm_mon += rint(fval * MONTHS_PER_YEAR);
if (unit == '\0')
return 0;
if (unit == 'T')
@@ -528,29 +528,25 @@ DecodeInterval(char **field, int *ftype, int nf, /* int range, */
case DTK_YEAR:
tm->tm_year += val;
- if (fval != 0)
- tm->tm_mon += fval * MONTHS_PER_YEAR;
+ tm->tm_mon += rint(fval * MONTHS_PER_YEAR);
tmask = (fmask & DTK_M(YEAR)) ? 0 : DTK_M(YEAR);
break;
case DTK_DECADE:
tm->tm_year += val * 10;
- if (fval != 0)
- tm->tm_mon += fval * MONTHS_PER_YEAR * 10;
+ tm->tm_mon += rint(fval * MONTHS_PER_YEAR * 10);
tmask = (fmask & DTK_M(YEAR)) ? 0 : DTK_M(YEAR);
break;
case DTK_CENTURY:
tm->tm_year += val * 100;
- if (fval != 0)
- tm->tm_mon += fval * MONTHS_PER_YEAR * 100;
+ tm->tm_mon += rint(fval * MONTHS_PER_YEAR * 100);
tmask = (fmask & DTK_M(YEAR)) ? 0 : DTK_M(YEAR);
break;
case DTK_MILLENNIUM:
tm->tm_year += val * 1000;
- if (fval != 0)
- tm->tm_mon += fval * MONTHS_PER_YEAR * 1000;
+ tm->tm_mon += rint(fval * MONTHS_PER_YEAR * 1000);
tmask = (fmask & DTK_M(YEAR)) ? 0 : DTK_M(YEAR);
break;
