Обсуждение: [PATCH] Supporting +-Infinity values by to_timestamp(float8)
Hello, Hackers! I worked on a patch[1] allows "EXTRACT(epoch FROM +-Inf::timestamp[tz])" to return "+-Inf::float8". There is an opposite function "to_timestamp(float8)" which now defined as: SELECT ('epoch'::timestamptz + $1 * '1 second'::interval) Since intervals do not support infinity values, it is impossible to do something like: SELECT to_timestamp('infinity'::float8); ... which is not good. Supporting of such converting is in the TODO list[2] (by "converting between infinity timestamp and float8"). Proposed patch implements it. There is an other patch in the CF[3] 2016-03 implements checking of timestamp[tz] for being in allowed range. Since it is wise to set (fix) the upper boundary of timestamp[tz]s, I've included the file "src/include/datatype/timestamp.h" from there to check that an input value and a result are in the allowed range. There is no changes in a documentation because allowed range is the same as officially supported[4] (i.e. until 294277 AD). [1]http://git.postgresql.org/pg/commitdiff/647d87c56ab6da70adb753c08d7cdf7ee905ea8a [2]https://wiki.postgresql.org/wiki/Todo#Dates_and_Times [3]https://commitfest.postgresql.org/9/540/ [4]http://www.postgresql.org/docs/devel/static/datatype-datetime.html -- Best regards, Vitaly Burovoy
Вложения
Added to the CF 2016-03: https://commitfest.postgresql.org/9/546/ -- Best regards, Vitaly Burovoy
On 2/26/16, Vitaly Burovoy <vitaly.burovoy@gmail.com> wrote: > Proposed patch implements it. I'm sorry, I forgot to leave a note for reviewers and committers: This patch requires CATALOG_VERSION_NO be bumped. Since pg_proc.h entry has changed, it is important to check and run regress tests on a new cluster (as if CATALOG_VERSION_NO was bumped). -- Best regards, Vitaly Burovoy
27.02.2016 09:57, Vitaly Burovoy:<br /><blockquote cite="mid:CAKOSWN=qbbnF_oRue4rfsMmWb+7wkBN6fq5XNHgt5vR0TiAA5g@mail.gmail.com"type="cite"><pre wrap="">Hello, Hackers! I worked on a patch[1] allows "EXTRACT(epoch FROM +-Inf::timestamp[tz])" to return "+-Inf::float8". There is an opposite function "to_timestamp(float8)" which now defined as: SELECT ('epoch'::timestamptz + $1 * '1 second'::interval) </pre></blockquote><br /> Hi, <br /> thank you for the patches.<br /> Could you explain, whether they depend on each other?<br/><br /><blockquote cite="mid:CAKOSWN=qbbnF_oRue4rfsMmWb+7wkBN6fq5XNHgt5vR0TiAA5g@mail.gmail.com" type="cite"><prewrap="">Since intervals do not support infinity values, it is impossible to do something like: SELECT to_timestamp('infinity'::float8); ... which is not good. Supporting of such converting is in the TODO list[2] (by "converting between infinity timestamp and float8"). </pre></blockquote><br /> You mention intervals here, and TODO item definitely says about 'infinity' interval,<br /> whilepatch and all the following discussion concerns to timestamps.<br /> Is it a typo or I misunderstood something important?<br /> I assumed that following query will work, but it isn't. Could you clarify that?<br /> select to_timestamp('infinity'::interval);<br/><br /><blockquote cite="mid:CAKOSWN=qbbnF_oRue4rfsMmWb+7wkBN6fq5XNHgt5vR0TiAA5g@mail.gmail.com"type="cite"><pre wrap="">Proposed patch implementsit. There is an other patch in the CF[3] 2016-03 implements checking of timestamp[tz] for being in allowed range. Since it is wise to set (fix) the upper boundary of timestamp[tz]s, I've included the file "src/include/datatype/timestamp.h" from there to check that an input value and a result are in the allowed range. There is no changes in a documentation because allowed range is the same as officially supported[4] (i.e. until 294277 AD). </pre></blockquote><br /> I think that you should update documentation. At least description of epoch on this page:<br /><ahref="http://www.postgresql.org/docs/devel/static/functions-datetime.html"><a class="moz-txt-link-freetext" href="http://www.postgresql.org/docs/devel/static/functions-datetime.html">http://www.postgresql.org/docs/devel/static/functions-datetime.html</a></a><br /><p>Hereis how you can convert an epoch value back to a time stamp:<pre class="SCREEN">SELECT TIMESTAMP WITH TIME ZONE 'epoch'+ 982384720.12 * INTERVAL '1 second'; </pre><p>(The <code class="FUNCTION">to_timestamp</code> function encapsulates the above conversion.)<br /> More thoughtsabout the patch:<br /><br /> 1. When I copy value from hints for min and max values (see examples below), it worksfine for min, while max still leads to error.<br /> It comes from the check "if (seconds >= epoch_ubound)". I wonder,whether you should change hint message? <br /><br /> select to_timestamp(-210866803200.000000);<br /> to_timestamp <br /> ---------------------------------<br /> 4714-11-24 02:30:17+02:30:17 BC<br /> (1 row)<br /><br/><br /> select to_timestamp(9224318016000.000000);<br /> ERROR: UNIX epoch out of range: "9224318016000.000000"<br/> HINT: Maximal UNIX epoch value is "9224318016000.000000"<br /><br /> 2. There is a comment aboutJULIAN_MAXYEAR inaccuracy in timestamp.h:<br /><br /> * IS_VALID_JULIAN checks the minimum date exactly, but is a bitsloppy<br /> * about the maximum, since it's far enough out to not be especially<br /> * interesting.<br /><br /> Maybeyou can expand it?<br /> - Is JULIAN_MAXYEAR4STAMPS helps to avoid overflow in all possible cases?<br /> - Why do weneed to hold both definitions? I suppose, it's a matter of backward compatibility, isn't it?<br /><br /> 3. (nitpicking)I don't sure about "4STAMPS" suffix. "4" is nice abbreviation, but it seems slightly confusing to me.<br /><preclass="moz-signature" cols="72">-- Anastasia Lubennikova Postgres Professional: <a class="moz-txt-link-freetext" href="http://www.postgrespro.com">http://www.postgrespro.com</a> The Russian Postgres Company</pre>
On 3/4/16, Anastasia Lubennikova <a.lubennikova@postgrespro.ru> wrote: > 27.02.2016 09:57, Vitaly Burovoy: >> Hello, Hackers! >> >> I worked on a patch[1] allows "EXTRACT(epoch FROM >> +-Inf::timestamp[tz])" to return "+-Inf::float8". >> There is an opposite function "to_timestamp(float8)" which now defined >> as: >> SELECT ('epoch'::timestamptz + $1 * '1 second'::interval) > > Hi, > thank you for the patches. Thank you for the review. > Could you explain, whether they depend on each other? Only logically. They reverse each other: postgres=# SELECT v, to_timestamp(v), extract(epoch FROM to_timestamp(v)) FROM postgres-# unnest(ARRAY['+inf', '-inf', 0, 65536, 982384720.12]::float8[]) v; v | to_timestamp | date_part --------------+---------------------------+-------------- Infinity | infinity | Infinity -Infinity| -infinity | -Infinity 0 | 1970-01-01 00:00:00+00 | 0 65536 |1970-01-01 18:12:16+00 | 65536982384720.12 | 2001-02-17 04:38:40.12+00 | 982384720.12 (5 rows) >> Since intervals do not support infinity values, it is impossible to do >> something like: >> >> SELECT to_timestamp('infinity'::float8); >> >> ... which is not good. >> >> Supporting of such converting is in the TODO list[2] (by "converting >> between infinity timestamp and float8"). > > You mention intervals here, and TODO item definitely says about > 'infinity' interval, Yes, it is in the same block. But I wanted to point to the link "converting between infinity timestamp and float8". There are two-way conversion examples. > while patch and all the following discussion concerns to timestamps. > Is it a typo or I misunderstood something important? It is just a reason why I rewrote it as an internal function. I asked whether to just rewrite the function "pg_catalog.to_timestamp(float8)" as an internal one or to add support of infinite intervals. Tom Lane answered[5] "you should stay away from infinite intervals". So I left intervals as is. > I assumed that following query will work, but it isn't. Could you > clarify that? > select to_timestamp('infinity'::interval); It is not hard. There is no logical way to convert interval (e.g. "5minutes") to a timestamp (or date). There never was a function "to_timestamp(interval)" and never will be. postgres=# select to_timestamp('5min'::interval); ERROR: function to_timestamp(interval) does not exist LINE 1: select to_timestamp('1min'::interval); ^ HINT: No function matches the given name and argument types. You might need to add explicit type casts. >> Proposed patch implements it. >> >> There is an other patch in the CF[3] 2016-03 implements checking of >> timestamp[tz] for being in allowed range. Since it is wise to set >> (fix) the upper boundary of timestamp[tz]s, I've included the file >> "src/include/datatype/timestamp.h" from there to check that an input >> value and a result are in the allowed range. >> >> There is no changes in a documentation because allowed range is the >> same as officially supported[4] (i.e. until 294277 AD). > > I think that you should update documentation. At least description of > epoch on this page: > http://www.postgresql.org/docs/devel/static/functions-datetime.html Thank you very much for pointing where it is located (I saw only "to_timestamp(TEXT, TEXT)"). I'll think how to update it. > More thoughts about the patch: > > 1. When I copy value from hints for min and max values (see examples > below), it works fine for min, while max still leads to error. > It comes from the check "if (seconds >= epoch_ubound)". I wonder, > whether you should change hint message? > > select to_timestamp(-210866803200.000000); > to_timestamp > --------------------------------- > 4714-11-24 02:30:17+02:30:17 BC > (1 row) > > > select to_timestamp(9224318016000.000000); > ERROR: UNIX epoch out of range: "9224318016000.000000" > HINT: Maximal UNIX epoch value is "9224318016000.000000" I agree, it is a little confusing. Do you (or anyone) know how to construct a condensed phrase that it is an exclusive upper bound of an allowed UNIX epoch range? > 2. There is a comment about JULIAN_MAXYEAR inaccuracy in timestamp.h: > > * IS_VALID_JULIAN checks the minimum date exactly, but is a bit sloppy > * about the maximum, since it's far enough out to not be especially > * interesting. It is just about the accuracy to the day for a lower bound, and to the year (not to a day) for an upper bound. > Maybe you can expand it? > - Is JULIAN_MAXYEAR4STAMPS helps to avoid overflow in all possible cases? > - Why do we need to hold both definitions? I suppose, it's a matter of > backward compatibility, isn't it? Yes. I tried to be less invasive from the point of view of endusers. They can be sure if they follow the documentation they won't get into trouble. > 3. (nitpicking) I don't sure about "4STAMPS" suffix. "4" is nice > abbreviation, but it seems slightly confusing to me. It doesn't matter for me what it is called, it is short enough and reflects a type on which it is applied. What would the best name be for it? [5]http://www.postgresql.org/message-id/21367.1447046745@sss.pgh.pa.us -- Best regards, Vitaly Burovoy
On 3/4/16 2:56 PM, Vitaly Burovoy wrote: > On 3/4/16, Anastasia Lubennikova <a.lubennikova@postgrespro.ru> wrote: > >> I think that you should update documentation. At least description of >> epoch on this page: >> http://www.postgresql.org/docs/devel/static/functions-datetime.html > > Thank you very much for pointing where it is located (I saw only > "to_timestamp(TEXT, TEXT)"). > I'll think how to update it. Vitaly, have you decided how to update this yet? >> 3. (nitpicking) I don't sure about "4STAMPS" suffix. "4" is nice >> abbreviation, but it seems slightly confusing to me. > > It doesn't matter for me what it is called, it is short enough and > reflects a type on which it is applied. > What would the best name be for it? Anastasia, any suggestions for a better name, or just leave it as is? I'm not in favor of the "4", either. I think I would prefer JULIAN_MAXYEAR_STAMP. -- -David david@pgmasters.net
15.03.2016 22:28, David Steele: > On 3/4/16 2:56 PM, Vitaly Burovoy wrote: > >> On 3/4/16, Anastasia Lubennikova <a.lubennikova@postgrespro.ru> wrote: >> >>> I think that you should update documentation. At least description of >>> epoch on this page: >>> http://www.postgresql.org/docs/devel/static/functions-datetime.html >> Thank you very much for pointing where it is located (I saw only >> "to_timestamp(TEXT, TEXT)"). >> I'll think how to update it. > Vitaly, have you decided how to update this yet? > >>> 3. (nitpicking) I don't sure about "4STAMPS" suffix. "4" is nice >>> abbreviation, but it seems slightly confusing to me. >> It doesn't matter for me what it is called, it is short enough and >> reflects a type on which it is applied. >> What would the best name be for it? > Anastasia, any suggestions for a better name, or just leave it as is? > > I'm not in favor of the "4", either. I think I would prefer > JULIAN_MAXYEAR_STAMP. > This point is related to another patch https://commitfest.postgresql.org/9/540/. And added to this patch just for compatibility. If Tom wouldn't change the name of the macros there, I don't see any reasons why should we do it in this patch. -- Anastasia Lubennikova Postgres Professional: http://www.postgrespro.com The Russian Postgres Company
On 2016-03-15, David Steele <david@pgmasters.net> wrote: > On 3/4/16 2:56 PM, Vitaly Burovoy wrote: >> On 3/4/16, Anastasia Lubennikova <a.lubennikova@postgrespro.ru> wrote: >> >>> I think that you should update documentation. At least description of >>> epoch on this page: >>> http://www.postgresql.org/docs/devel/static/functions-datetime.html >> >> Thank you very much for pointing where it is located (I saw only >> "to_timestamp(TEXT, TEXT)"). >> I'll think how to update it. > > Vitaly, have you decided how to update this yet? Yes, there are three versions: * remove mentioning how to get timestamptz from UNIX stamp; * leave a note how to get timestamptz and add a note that such encapsulation existed prior to 9.6; * replace to the proposed current behavior (without interval). I decided to implement the third case (but a result there has a time zone which can be different, so the result can be not exactly same for a concrete user). If a committer decides to do somehow else, he is free to choose one from the list above or to do something else. >>> 3. (nitpicking) I don't sure about "4STAMPS" suffix. "4" is nice >>> abbreviation, but it seems slightly confusing to me. >> >> It doesn't matter for me what it is called, it is short enough and >> reflects a type on which it is applied. >> What would the best name be for it? > > Anastasia, any suggestions for a better name, or just leave it as is? > > I'm not in favor of the "4", either. I think I would prefer > JULIAN_MAXYEAR_STAMP. It turns out that Tom has changed almost one third of timestamp.h and now the constant has a name "TIMESTAMP_END_JULIAN". I've rebased the patch to the current master (5db5146) and changed it according to the new timestamp.h. Now it passes both versions (integer and float timestamps). I deleted test for the upper boundary for integer timestamps, changed a little comments. I decided to delete hints about minimum and maximum allowed values because no one type has such hint. Please find attached a new version of the patch. -- Best regards, Vitaly Burovoy
Вложения
Anastasia Lubennikova <a.lubennikova@postgrespro.ru> writes: > 15.03.2016 22:28, David Steele: >> I'm not in favor of the "4", either. I think I would prefer >> JULIAN_MAXYEAR_STAMP. > This point is related to another patch > https://commitfest.postgresql.org/9/540/. > And added to this patch just for compatibility. > If Tom wouldn't change the name of the macros there, I don't see any > reasons why should we do it in this patch. Yeah, I didn't like the "4STAMPS" terminology at all. It ended up being moot for that patch, because the answer eventually turned out to be that we needed to decouple the Julian-date boundaries from the datatype boundaries altogether. But I would've renamed those macros to something else if they'd stayed. regards, tom lane
17.03.2016 06:27, Vitaly Burovoy: > On 2016-03-15, David Steele <david@pgmasters.net> wrote: >> On 3/4/16 2:56 PM, Vitaly Burovoy wrote: >>> On 3/4/16, Anastasia Lubennikova <a.lubennikova@postgrespro.ru> wrote: >>> >>>> I think that you should update documentation. At least description of >>>> epoch on this page: >>>> http://www.postgresql.org/docs/devel/static/functions-datetime.html >>> Thank you very much for pointing where it is located (I saw only >>> "to_timestamp(TEXT, TEXT)"). >>> I'll think how to update it. >> Vitaly, have you decided how to update this yet? > Yes, there are three versions: > * remove mentioning how to get timestamptz from UNIX stamp; > * leave a note how to get timestamptz and add a note that such > encapsulation existed prior to 9.6; > * replace to the proposed current behavior (without interval). > > I decided to implement the third case (but a result there has a time > zone which can be different, so the result can be not exactly same for > a concrete user). If a committer decides to do somehow else, he is > free to choose one from the list above or to do something else. > >>>> 3. (nitpicking) I don't sure about "4STAMPS" suffix. "4" is nice >>>> abbreviation, but it seems slightly confusing to me. >>> It doesn't matter for me what it is called, it is short enough and >>> reflects a type on which it is applied. >>> What would the best name be for it? >> Anastasia, any suggestions for a better name, or just leave it as is? >> >> I'm not in favor of the "4", either. I think I would prefer >> JULIAN_MAXYEAR_STAMP. > It turns out that Tom has changed almost one third of timestamp.h and > now the constant has a name "TIMESTAMP_END_JULIAN". > > I've rebased the patch to the current master (5db5146) and changed it > according to the new timestamp.h. > > Now it passes both versions (integer and float timestamps). > I deleted test for the upper boundary for integer timestamps, changed > a little comments. > > I decided to delete hints about minimum and maximum allowed values > because no one type has such hint. > > Please find attached a new version of the patch. > I think, I should write something as a reviewer. I read the patch again and I don't see any issues with it. It applies to the master and works as expected. So I'll mark it as "Ready for committer" -- Anastasia Lubennikova Postgres Professional: http://www.postgrespro.com The Russian Postgres Company
Anastasia Lubennikova <a.lubennikova@postgrespro.ru> writes: > 17.03.2016 06:27, Vitaly Burovoy: >> Please find attached a new version of the patch. > I think, I should write something as a reviewer. > I read the patch again and I don't see any issues with it. > It applies to the master and works as expected. So I'll mark it as > "Ready for committer" Pushed with minor adjustments. regards, tom lane
On 3/29/16, Tom Lane <tgl@sss.pgh.pa.us> wrote: > Pushed with minor adjustments. > > regards, tom lane > Thank you very much! -- Best regards, Vitaly Burovoy