Обсуждение: Parameter types are inferred from context of first use only.
The following documentation comment has been logged on the website: Page: https://www.postgresql.org/docs/10/static/sql-prepare.html Description: Background can be found on the bugs list (pgsql-bug #15289). It was explained that when a prepared statement parameter needs to have its type inferred then, should the parameter be used more than once, only the first use is considered. (The example in that report is that the type of $1 can be inferred from "($1 = col) or ($1 is null)" but not from "($1 is null) or ($1 = col)".) The documentation as it stands says only that the parameter's type is inferred from the context in which it is used. The "first use only" proviso is not mentioned (hence "context" isn't so broad as to consist of all of the expressions in which the parameter appears).
On Mon, Jul 23, 2018 at 09:14:48AM +0000, PG Doc comments form wrote: > The following documentation comment has been logged on the website: > > Page: https://www.postgresql.org/docs/10/static/sql-prepare.html > Description: > > Background can be found on the bugs list (pgsql-bug #15289). It was > explained that when a prepared statement parameter needs to have its type > inferred then, should the parameter be used more than once, only the first > use is considered. (The example in that report is that the type of $1 can be > inferred from "($1 = col) or ($1 is null)" but not from "($1 is null) or ($1 > = col)".) > > The documentation as it stands says only that the parameter's type is > inferred from the context in which it is used. The "first use only" proviso > is not mentioned (hence "context" isn't so broad as to consist of all of the > expressions in which the parameter appears). I have developed the attached patch to cover what you found. -- Bruce Momjian <bruce@momjian.us> http://momjian.us EnterpriseDB http://enterprisedb.com + As you are, so once was I. As I am, so you will be. + + Ancient Roman grave inscription +
Вложения
On 2018-08-09 05:24, Bruce Momjian wrote: > On Mon, Jul 23, 2018 at 09:14:48AM +0000, PG Doc comments form wrote: >> The following documentation comment has been logged on the website: >> >> Page: https://www.postgresql.org/docs/10/static/sql-prepare.html >> Description: >> >> Background can be found on the bugs list (pgsql-bug #15289). It was >> explained that when a prepared statement parameter needs to have its type >> inferred then, should the parameter be used more than once, only the first >> use is considered. (The example in that report is that the type of $1 can be >> inferred from "($1 = col) or ($1 is null)" but not from "($1 is null) or ($1 >> = col)".) >> >> The documentation as it stands says only that the parameter's type is >> inferred from the context in which it is used. The "first use only" proviso >> is not mentioned (hence "context" isn't so broad as to consist of all of the >> expressions in which the parameter appears). > > I have developed the attached patch to cover what you found. > That says it for me. The third mention of context doesn't need anything because it's referring specifically to the (single) use of $2 in the example. I have to presume the type inference happens before any structural changes that might change the meaning of "first occurrence". Nick
On Thu, Aug 9, 2018 at 12:18:27PM +1200, Morgan Owens wrote: > On 2018-08-09 05:24, Bruce Momjian wrote: > >On Mon, Jul 23, 2018 at 09:14:48AM +0000, PG Doc comments form wrote: > >>The following documentation comment has been logged on the website: > >> > >>Page: https://www.postgresql.org/docs/10/static/sql-prepare.html > >>Description: > >> > >>Background can be found on the bugs list (pgsql-bug #15289). It was > >>explained that when a prepared statement parameter needs to have its type > >>inferred then, should the parameter be used more than once, only the first > >>use is considered. (The example in that report is that the type of $1 can be > >>inferred from "($1 = col) or ($1 is null)" but not from "($1 is null) or ($1 > >>= col)".) > >> > >>The documentation as it stands says only that the parameter's type is > >>inferred from the context in which it is used. The "first use only" proviso > >>is not mentioned (hence "context" isn't so broad as to consist of all of the > >>expressions in which the parameter appears). > > > >I have developed the attached patch to cover what you found. > > > > That says it for me. The third mention of context doesn't need anything > because it's referring specifically to the (single) use of $2 in the > example. I have to presume the type inference happens before any structural > changes that might change the meaning of "first occurrence". Great, patch applied through 9.3. I also changed "used" to "referenced": https://git.postgresql.org/pg/commitdiff/b284262e40424daa1c546ad76f365b31304d7944 -- Bruce Momjian <bruce@momjian.us> http://momjian.us EnterpriseDB http://enterprisedb.com + As you are, so once was I. As I am, so you will be. + + Ancient Roman grave inscription +
On Thu, Aug 9, 2018 at 10:14:33AM -0400, Bruce Momjian wrote: > On Thu, Aug 9, 2018 at 12:18:27PM +1200, Morgan Owens wrote: > > On 2018-08-09 05:24, Bruce Momjian wrote: > > >On Mon, Jul 23, 2018 at 09:14:48AM +0000, PG Doc comments form wrote: > > >>The following documentation comment has been logged on the website: > > >> > > >>Page: https://www.postgresql.org/docs/10/static/sql-prepare.html > > >>Description: > > >> > > >>Background can be found on the bugs list (pgsql-bug #15289). It was > > >>explained that when a prepared statement parameter needs to have its type > > >>inferred then, should the parameter be used more than once, only the first > > >>use is considered. (The example in that report is that the type of $1 can be > > >>inferred from "($1 = col) or ($1 is null)" but not from "($1 is null) or ($1 > > >>= col)".) > > >> > > >>The documentation as it stands says only that the parameter's type is > > >>inferred from the context in which it is used. The "first use only" proviso > > >>is not mentioned (hence "context" isn't so broad as to consist of all of the > > >>expressions in which the parameter appears). > > > > > >I have developed the attached patch to cover what you found. > > > > > > > That says it for me. The third mention of context doesn't need anything > > because it's referring specifically to the (single) use of $2 in the > > example. I have to presume the type inference happens before any structural > > changes that might change the meaning of "first occurrence". > > Great, patch applied through 9.3. I also changed "used" to > "referenced": > > https://git.postgresql.org/pg/commitdiff/b284262e40424daa1c546ad76f365b31304d7944 Sorry, reporting credit should have gone to Nick Farmer. -- Bruce Momjian <bruce@momjian.us> http://momjian.us EnterpriseDB http://enterprisedb.com + As you are, so once was I. As I am, so you will be. + + Ancient Roman grave inscription +