Re: [Firebird-devel] BLOB_APPEND and NULL
On Thu, Aug 11, 2022, at 17:58, Vlad Khorsun wrote: >The answer is the same - for user convenience. When I want to append > something to the > already existing blob, I doesn't expect to destroy my blob just because > nothing is > appended to it. How is that different from `update foo set bar = bar || 'foo'` where `bar` is null? -- Mgr. Jiří Činčura https://www.tabsoverspaces.com/ Firebird-Devel mailing list, web interface at https://lists.sourceforge.net/lists/listinfo/firebird-devel
Re: [Firebird-devel] BLOB_APPEND and NULL
On Thu, Aug 11, 2022, at 18:56, Vlad Khorsun wrote: >I replied to Jiří who definitely read that discussion ;) But I read it like last week, completely, because I discovered it as part of reading RN. I wasn't in the discussion as it was unfolding. -- Mgr. Jiří Činčura https://www.tabsoverspaces.com/ Firebird-Devel mailing list, web interface at https://lists.sourceforge.net/lists/listinfo/firebird-devel
Re: [Firebird-devel] BLOB_APPEND and NULL
Em 11/08/2022 12:58, Vlad Khorsun escreveu:
11.08.2022 17:26, Mark Rotteveel wrote:
On 11-08-2022 16:21, Vlad Khorsun wrote:
11.08.2022 17:10, Mark Rotteveel wrote:
Why was this NULL behaviour chosen?
To make BLOB_APPEND more convenient for users.
I don't understand how using a different NULL behaviour then standard for
operations in SQL/Firebird is convenient.
There is no standard defined operation for appending blobs, afaik.
To me it sounds like something that will result in confusion because of the
difference with normal concatenation, but OK.
The BLOB_APPEND is not CONCATENATION, it is non-standard function with
custom semantics.
As well many of our system functions, and we choose to implement the
standard behavior on them.
This remember-me JavaScript:
> null + null
0
> 'null' + null
'nullnull'
The answer is the same - for user convenience. When I want to append
something to the
already existing blob, I doesn't expect to destroy my blob just because
nothing is
appended to it.
It's is inconsistent, and I do not see that as convenience.
Some user would think the convenience would be to treat it as strings
('null', 'NULL', 'Null').
Adriano
Firebird-Devel mailing list, web interface at
https://lists.sourceforge.net/lists/listinfo/firebird-devel
Re: [Firebird-devel] BLOB_APPEND and NULL
While I’m hardly entitled to a vote, it is almost impossible to find a use case where making a concatenation with a NULL a NULL is useful. NULL should be interpreted as “there ain’t nothing there” rather than a poison pill for other contexts. In Amorphous, concatenation of a NULL treats the NULL as an empty string, but then in Amorphous I am king and dictator. But, for the record, Ann and I disagree on this. On Thu, Aug 11, 2022 at 11:58 AM Vlad Khorsun wrote: > 11.08.2022 17:26, Mark Rotteveel wrote: > > On 11-08-2022 16:21, Vlad Khorsun wrote: > >> 11.08.2022 17:10, Mark Rotteveel wrote: > >>> Why was this NULL behaviour chosen? > >> > >>To make BLOB_APPEND more convenient for users. > > > > I don't understand how using a different NULL behaviour then standard > for operations in SQL/Firebird is convenient. > >There is no standard defined operation for appending blobs, afaik. > > > To me it sounds > > like something that will result in confusion because of the difference > with normal concatenation, but OK. > >The BLOB_APPEND is not CONCATENATION, it is non-standard function with > custom semantics. > > > I had hoped for something more solid, so I could add that as an > explanation when documenting it in the language reference. > >The answer is the same - for user convenience. When I want to append > something to the > already existing blob, I doesn't expect to destroy my blob just because > nothing is > appended to it. > > > PS You mailed this to me privately instead of to the list. > >Sorry, hope you are not suffer too much because of it ;) > > Regards, > Vlad > > > > Firebird-Devel mailing list, web interface at > https://lists.sourceforge.net/lists/listinfo/firebird-devel > -- Jim Starkey Firebird-Devel mailing list, web interface at https://lists.sourceforge.net/lists/listinfo/firebird-devel
Re: [Firebird-devel] BLOB_APPEND and NULL
11.08.2022 19:31, Mark Rotteveel wrote: On 11-08-2022 18:04, Vlad Khorsun wrote: 11.08.2022 17:46, Jiří Činčura wrote: I was thinking the same when reading the discussion on GH. There was a LOT of time to write something at that discussion. Nobody asked about NULL's there, while it was documented since a very beginning. Unfortunately I don't always have time or energy to monitor all GitHub updates, and there was no previous discussion on this list about BLOB_APPEND, so I simply had not noticed its existence before. I replied to Jiří who definitely read that discussion ;) It is always very sad to get such comments two month after the code was merged and release is almost out. Regards, Vlad Firebird-Devel mailing list, web interface at https://lists.sourceforge.net/lists/listinfo/firebird-devel
Re: [Firebird-devel] BLOB_APPEND and NULL
On 11-08-2022 18:09, Alex Peshkoff via Firebird-devel wrote: On 8/11/22 19:04, Vlad Khorsun wrote: So far I don't see it as mistake. +1 Function is anyway damned non-standard. And as soon as we have documented behavior - no problems at all. Time will tell. I think deviating NULL behaviour can lead to confusion, even if it is documented. In any case, I updated the language reference (I used the release notes as a starting point): https://www.firebirdsql.org/file/documentation/html/en/refdocs/fblangref40/firebird-40-language-reference.html#fblangref40-scalarfuncs-blob-append Mark -- Mark Rotteveel Firebird-Devel mailing list, web interface at https://lists.sourceforge.net/lists/listinfo/firebird-devel
Re: [Firebird-devel] BLOB_APPEND and NULL
On 11-08-2022 18:04, Vlad Khorsun wrote: 11.08.2022 17:46, Jiří Činčura wrote: I was thinking the same when reading the discussion on GH. There was a LOT of time to write something at that discussion. Nobody asked about NULL's there, while it was documented since a very beginning. Unfortunately I don't always have time or energy to monitor all GitHub updates, and there was no previous discussion on this list about BLOB_APPEND, so I simply had not noticed its existence before. Mark -- Mark Rotteveel Firebird-Devel mailing list, web interface at https://lists.sourceforge.net/lists/listinfo/firebird-devel
Re: [Firebird-devel] BLOB_APPEND and NULL
On 11-08-2022 17:58, Vlad Khorsun wrote: 11.08.2022 17:26, Mark Rotteveel wrote: On 11-08-2022 16:21, Vlad Khorsun wrote: 11.08.2022 17:10, Mark Rotteveel wrote: Why was this NULL behaviour chosen? To make BLOB_APPEND more convenient for users. I don't understand how using a different NULL behaviour then standard for operations in SQL/Firebird is convenient. There is no standard defined operation for appending blobs, afaik. I am talking about the general expectations raised by the SQL standard (and Firebird itself) regarding behaviour when faced with NULL, and that is, in general, that when one of the inputs of a function, operation, or other expression is NULL, the result is NULL. And given concatenation is defined for BLOBs in the standard, with the normal NULL behaviour, I would expect this appending to follow the same basic rules. To me it sounds like something that will result in confusion because of the difference with normal concatenation, but OK. The BLOB_APPEND is not CONCATENATION, it is non-standard function with custom semantics. It is a non-standard function that is intended to be used in places where you'd otherwise use concatenation. To me that means semantics of concatenation should be applied. Mark -- Mark Rotteveel Firebird-Devel mailing list, web interface at https://lists.sourceforge.net/lists/listinfo/firebird-devel
Re: [Firebird-devel] BLOB_APPEND and NULL
On 8/11/22 19:04, Vlad Khorsun wrote: So far I don't see it as mistake. +1 Function is anyway damned non-standard. And as soon as we have documented behavior - no problems at all. Firebird-Devel mailing list, web interface at https://lists.sourceforge.net/lists/listinfo/firebird-devel
Re: [Firebird-devel] BLOB_APPEND and returned SUB_TYPE
11.08.2022 17:40, Mark Rotteveel wrote: I noticed that BLOB_APPEND always returns a blob of SUB_TYPE TEXT, even if the first blob is binary or other type of blob. Is that expected? No, the intention was to use type\charset of first arg (if not NULL). I'll check and fix it, thanks. Regards, Vlad Firebird-Devel mailing list, web interface at https://lists.sourceforge.net/lists/listinfo/firebird-devel
Re: [Firebird-devel] BLOB_APPEND and NULL
11.08.2022 17:46, Jiří Činčura wrote: I was thinking the same when reading the discussion on GH. There was a LOT of time to write something at that discussion. Nobody asked about NULL's there, while it was documented since a very beginning. I believe it's not late to make correction (hey, we all make mistakes) and have consistent behavior. So far I don't see it as mistake. Regards, Vlad Firebird-Devel mailing list, web interface at https://lists.sourceforge.net/lists/listinfo/firebird-devel
Re: [Firebird-devel] BLOB_APPEND and NULL
11.08.2022 17:26, Mark Rotteveel wrote: On 11-08-2022 16:21, Vlad Khorsun wrote: 11.08.2022 17:10, Mark Rotteveel wrote: Why was this NULL behaviour chosen? To make BLOB_APPEND more convenient for users. I don't understand how using a different NULL behaviour then standard for operations in SQL/Firebird is convenient. There is no standard defined operation for appending blobs, afaik. To me it sounds like something that will result in confusion because of the difference with normal concatenation, but OK. The BLOB_APPEND is not CONCATENATION, it is non-standard function with custom semantics. I had hoped for something more solid, so I could add that as an explanation when documenting it in the language reference. The answer is the same - for user convenience. When I want to append something to the already existing blob, I doesn't expect to destroy my blob just because nothing is appended to it. PS You mailed this to me privately instead of to the list. Sorry, hope you are not suffer too much because of it ;) Regards, Vlad Firebird-Devel mailing list, web interface at https://lists.sourceforge.net/lists/listinfo/firebird-devel
Re: [Firebird-devel] BLOB_APPEND and NULL
+1 András Feladó: Jiří Činčura Elküldve: 2022. augusztus 11. 16:46 Címzett: For discussion among Firebird Developers Tárgy: Re: [Firebird-devel] BLOB_APPEND and NULL I was thinking the same when reading the discussion on GH. I believe it's not late to make correction (hey, we all make mistakes) and have consistent behavior. -- Mgr. Jiří Činčura https://www.tabsoverspaces.com/ Firebird-Devel mailing list, web interface at https://lists.sourceforge.net/lists/listinfo/firebird-devel Firebird-Devel mailing list, web interface at https://lists.sourceforge.net/lists/listinfo/firebird-devel
Re: [Firebird-devel] BLOB_APPEND and NULL
I was thinking the same when reading the discussion on GH. I believe it's not late to make correction (hey, we all make mistakes) and have consistent behavior. -- Mgr. Jiří Činčura https://www.tabsoverspaces.com/ Firebird-Devel mailing list, web interface at https://lists.sourceforge.net/lists/listinfo/firebird-devel
[Firebird-devel] BLOB_APPEND and returned SUB_TYPE
I noticed that BLOB_APPEND always returns a blob of SUB_TYPE TEXT, even if the first blob is binary or other type of blob. Is that expected? Mark -- Mark Rotteveel Firebird-Devel mailing list, web interface at https://lists.sourceforge.net/lists/listinfo/firebird-devel
Re: [Firebird-devel] BLOB_APPEND and NULL
On 11-08-2022 16:21, Vlad Khorsun wrote: 11.08.2022 17:10, Mark Rotteveel wrote: Why was this NULL behaviour chosen? To make BLOB_APPEND more convenient for users. I don't understand how using a different NULL behaviour then standard for operations in SQL/Firebird is convenient. To me it sounds like something that will result in confusion because of the difference with normal concatenation, but OK. I had hoped for something more solid, so I could add that as an explanation when documenting it in the language reference. PS You mailed this to me privately instead of to the list. -- Mark Rotteveel Firebird-Devel mailing list, web interface at https://lists.sourceforge.net/lists/listinfo/firebird-devel
[Firebird-devel] BLOB_APPEND and NULL
The new BLOB_APPEND function has a NULL behaviour that is not consistent
with the normal NULL behaviour. Using NULL in BLOB_APPEND behaves as an
empty string, while the normal behaviour for functions and operations
involving NULL is to result in NULL.
For example, normal concatenation:
select cast(null as blob sub_type text) || cast('a' as blob sub_type
text) || cast(null as blob sub_type text) || cast('b' as blob sub_type
text) from rdb$database;
results in NULL, while BLOB_APPEND:
select blob_append(null, 'a', null, 'b') from rdb$database;
results in 'ab'.
If the "normal" NULL-behaviour had been used, it would be possible to
easily rewrite normal concatenation involving blobs to BLOB_APPEND, but
now that requires careful consideration. In addition, this closes an
avenue for the engine to - at some point in the future, as an engine
optimization - rewrite concatenation to BLOB_APPEND internally.
Why was this NULL behaviour chosen?
Mark
--
Mark Rotteveel
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