Re: Incomplete or misleading explanation of the data types formathematical operators
От | Bruce Momjian |
---|---|
Тема | Re: Incomplete or misleading explanation of the data types formathematical operators |
Дата | |
Msg-id | 20200331224449.GI17676@momjian.us обсуждение исходный текст |
Ответ на | Re: Incomplete or misleading explanation of the data types formathematical operators (Bruce Momjian <bruce@momjian.us>) |
Список | pgsql-docs |
Patch applied through 9.5, thanks. --------------------------------------------------------------------------- On Sat, Mar 21, 2020 at 10:31:32AM -0400, Bruce Momjian wrote: > On Thu, Mar 5, 2020 at 08:03:19PM -0700, Sergei Agalakov wrote: > > On 3/5/2020 7:29 PM, Bruce Momjian wrote: > > > On Wed, Jan 29, 2020 at 07:35:18PM +0000, PG Doc comments form wrote: > > > > Multiplication preserves data type, exponentiation silently converts bigint > > > > to double, but preserves numeric data type, square root silently converts > > > > both int and numeric types to double. > > > > The best would be to explain this behaivior of operators like it was done > > > > for mathematical functions. > > > Uh, how does this relate to bitwise operators? Why would we mention > > > type changes for things like exponentiation in the bitwise operator > > > documentation section? > > > > > This chapter is named "Mathematical Functions and Operators". The table 9.4. > > is named "Mathematical Operators". I don't see on this page any section > > "Bitwise operators" so I don't really understand your complaint. > > How do you understand the phrase "The bitwise operators work only on > > integral data types, whereas the others are available for all numeric data > > types. " in the context of the table "Mathematical Operators"? > > I understand it that all other mathematical operators except bitwise > > operators do exist for all numeric data type. > > In what place by your opinion documentation should describe that some > > mathematical operators exist only for some numeric data types but not > > others? > > I have given examples of such operators - exponentiation and square root > > aren't defined for all numeric data types and do hidden conversion of the > > data types. > > Ah, I see what you are saying now --- there are operators listed above > that are not supported by all numeric data types, so "the others are > available for all numeric data types" is false. I think the text was > written because non-integer calls to bit-wise functions _fail_, rather > than being silently converted: > > SELECT 1::float4 | 1; > ERROR: operator does not exist: real | integer > LINE 1: SELECT 1::float4 | 1; > ^ > HINT: No operator matches the given name and argument types. You might > need to add explicit type casts. > > but I see your point. I guess we could change the word "available" to > "silently converted", but it seems best to just remove that phrase. > Documentation patch attached. > > -- > Bruce Momjian <bruce@momjian.us> https://momjian.us > EnterpriseDB https://enterprisedb.com > > + As you are, so once was I. As I am, so you will be. + > + Ancient Roman grave inscription + > diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml > index 464a48ed6a..e1d70c251d 100644 > --- a/doc/src/sgml/func.sgml > +++ b/doc/src/sgml/func.sgml > @@ -732,9 +732,8 @@ > </table> > > <para> > - The bitwise operators work only on integral data types, whereas > - the others are available for all numeric data types. The bitwise > - operators are also available for the bit > + The bitwise operators work only on integral data types, and are also > + available for the bit > string types <type>bit</type> and <type>bit varying</type>, as > shown in <xref linkend="functions-bit-string-op-table"/>. > </para> -- Bruce Momjian <bruce@momjian.us> https://momjian.us EnterpriseDB https://enterprisedb.com + As you are, so once was I. As I am, so you will be. + + Ancient Roman grave inscription +
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