Re: UUID query ignores characters 33 to n.... didn't know that!
When I first saw 4D’s requirement for unique indexes I was tempted to replace other ids in our databases with UUIDs in order to save space ... I quickly gave up on that idea. I just let 4D manage UUIDs to have unique IDs for backup and journalizing functions and I don’t assume anything regarding those fields and indexes. Paul > On 3 Sep 2018, at 21:07, Jim Labos - infobase via 4D_Tech > <4d_tech@lists.4d.com> wrote: > > Yes thanks, that is what I became aware of at that point. Previously UUID's > nature was not particularly interesting to me and so I thought of it as > Alpha numeric string. For comparison's sake a text will work but not as I > previously falsely assumed. > > This old dog can still learn! > > Cheers > > Jim Labos - infobase > > > > - > Jim Labos - infobase > -- > Sent from: http://4d.1045681.n5.nabble.com/4D-Tech-f1376241.html > ** > 4D Internet Users Group (4D iNUG) > Archive: http://lists.4d.com/archives.html > Options: https://lists.4d.com/mailman/options/4d_tech > Unsub: mailto:4d_tech-unsubscr...@lists.4d.com > ** ** 4D Internet Users Group (4D iNUG) Archive: http://lists.4d.com/archives.html Options: https://lists.4d.com/mailman/options/4d_tech Unsub: mailto:4d_tech-unsubscr...@lists.4d.com **
Re: UUID query ignores characters 33 to n.... didn't know that!
Yes thanks, that is what I became aware of at that point. Previously UUID's nature was not particularly interesting to me and so I thought of it as Alpha numeric string. For comparison's sake a text will work but not as I previously falsely assumed. This old dog can still learn! Cheers Jim Labos - infobase - Jim Labos - infobase -- Sent from: http://4d.1045681.n5.nabble.com/4D-Tech-f1376241.html ** 4D Internet Users Group (4D iNUG) Archive: http://lists.4d.com/archives.html Options: https://lists.4d.com/mailman/options/4d_tech Unsub: mailto:4d_tech-unsubscr...@lists.4d.com **
Re: UUID query ignores characters 33 to n.... didn't know that!
> Le 3 sept. 2018 à 00:45, Jim Labos - infobase via 4D_Tech
> <4d_tech@lists.4d.com> a écrit :
>
> [...]
>
> What do you all think? Is this a bug? An annoying gotcha? Did you already
> all know this and I am the only one who didn't?
QUERY([aTable];[aTable]longint=Num("123xxx")
We are not surprised that values = 123 are found. If you consider that 4D uuid
field is a 2^128 integer (scalar number), it's the same thing that happens to
your trailing "xxx" and those above.
BTW, I think that uuid fields with an alpha icon in structure it is a source of
confusion.
--
Arnaud de Montard
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Re: UUID query ignores characters 33 to n.... didn't know that!
it's not that "query ignores characters", it has more to do with how string-to-uuid conversion works. to understand how it works, create a UUID field, create a record, assign a value. e.g. CREATE RECORD([Table_1]) [Table_1]Field_2:="www" you will notice that Field_2 which is a UUID, evaluates as 7720202020202020202020202020 in the debugger. another example [Table_1]Field_2:="abcd" 61626364202020202020202020202020 but [Table_1]Field_2:="abcdabcdabcdabcdabcdabcdabcdabcd" ABCDABCDABCDABCDABCDABCDABCDABCD so if the string isn't a 32-digit hex, it is first transformed to look like one (UTF-8 character code, padding by spaces). then it is evaluates as integer (UUID). then it is converted back to string for display (hence the uppercase). ** 4D Internet Users Group (4D iNUG) Archive: http://lists.4d.com/archives.html Options: https://lists.4d.com/mailman/options/4d_tech Unsub: mailto:4d_tech-unsubscr...@lists.4d.com **
UUID query ignores characters 33 to n.... didn't know that!
Mac OS Yosemite, 4D v15.6 If I am querying a UUID field, I use a UUID var of course. However there is no UUID variable type so like everyone I use a text var. What I never noticed before as I didn't need to check, is that *if* the var itself contains the UUID in the first 32 characters but has extra characters after it then 4D still finds a match! So let's say the value in the UUID field's value is 607BFEA7CE2244EB9B00C2330E4E32F5 if my var $txt_UUID:="607BFEA7CE2244EB9B00C2330E4E32F5"+"xxx" Query([table1];[table1]UUID_FIELD=$txt_UUID) will still find the record. So in this case 607BFEA7CE2244EB9B00C2330E4E32F5"=607BFEA7CE2244EB9B00C2330E4E32F5xxx" I don't think this is a bug as 4D is using a special format for the UUID. However I falsely assumed that you needed an exact match for that type of query but it seems not. What do you all think? Is this a bug? An annoying gotcha? Did you already all know this and I am the only one who didn't? Cheers Jim Labos - infobase - Jim Labos - infobase -- Sent from: http://4d.1045681.n5.nabble.com/4D-Tech-f1376241.html ** 4D Internet Users Group (4D iNUG) Archive: http://lists.4d.com/archives.html Options: https://lists.4d.com/mailman/options/4d_tech Unsub: mailto:4d_tech-unsubscr...@lists.4d.com **
