FWD » Core Development » Database

05/09/2025

05:06 PM Feature #9976 (New): eliminating DMO usage in inter-program linkage

Greg Shah

04:17 PM Bug #9937: buffer argument with different DMO than the parameter

Please look at the test case from #9937-5.
As you can see we have pretty similar temp-table definitions in
<pr... Eduard Soltan

09:18 AM Bug #9937: buffer argument with different DMO than the parameter

> Alexandru, can you take a look, too, at 9937a? This touches the ArgumentProxy which IIRC was added by you.
I see... Alexandru Lungu

08:06 AM Bug #9937: buffer argument with different DMO than the parameter

Alexandru, can you take a look, too, at 9937a? This touches the @ArgumentProxy@ which IIRC was added by you. Constantin Asofiei

07:09 AM Bug #9937 (Review): buffer argument with different DMO than the parameter

Eduard Soltan

07:01 AM Bug #9937: buffer argument with different DMO than the parameter

Constantin Asofiei wrote:
> Just to double-check, please do the same in @ctest@, but with the @btt2 for tt2@ buffer ... Eduard Soltan

06:50 AM Bug #9937: buffer argument with different DMO than the parameter

Just to double-check, please do the same in @ctest@, but with the @btt2 for tt2@ buffer (which will not use the @buff... Constantin Asofiei

06:48 AM Bug #9937: buffer argument with different DMO than the parameter

Constantin Asofiei wrote:
> Are the tests in #9937-5 passing, plus what we discussed in previous notes (copy-temp-ta... Eduard Soltan

06:19 AM Bug #9937: buffer argument with different DMO than the parameter

Eduard, the approach is good and it should work; your reasoning is correct, the temp-tables need to be schema-compati... Constantin Asofiei

06:16 AM Bug #9937: buffer argument with different DMO than the parameter

Eduard Soltan wrote:
> Could you take just a quick look at 9937a, rev. 15889?
The only problem that we are facing... Eduard Soltan

06:03 AM Bug #9937: buffer argument with different DMO than the parameter

Could you take just a quick look at 9937a, rev. 15889? Eduard Soltan

04:58 AM Bug #9937: buffer argument with different DMO than the parameter

I checked and a single method will be created by the @ProxyAssembler@ for @Proxy3@ (@getF1@ and @setF1@), or any othe... Eduard Soltan

03:07 AM Bug #9937: buffer argument with different DMO than the parameter

Constantin Asofiei wrote:
> I don't think is OK to have methods from both Tt2_1 and TT1_1 DMO interfaces.
Then we... Eduard Soltan

02:55 AM Bug #9937: buffer argument with different DMO than the parameter

I don't think is OK to have methods from both Tt2_1 and TT1_1 DMO interfaces.
I don't think @Proxy3@ should be ret... Constantin Asofiei

02:47 AM Bug #9937: buffer argument with different DMO than the parameter

The proxy is a dynamic class created by @ProxyAssembler@ with the following structure:... Eduard Soltan

08:04 AM Bug #9950 (WIP): Upgrade the metadata schema to a newer version

I noticed the following changes in the currently supported meta files (from DDL PoV):
* 10 (mandatory) columns added... Ovidiu Maxiniuc

06:28 AM Bug #9318: Make record nursery visible on removeRecords

I've tested ETF conversion & runtime with 9318a and found no issues with the current implementation, I will rebase to... Dănuț Filimon

04:44 AM Feature #7504: Export data tool from FWD into .d files

Andrei, please commit whatever changes you've done for #7504 and introduce Lorian to this task. Alexandru Lungu

03:23 AM Bug #9914 (Test): Investigate why ListenerSet implementation is not properly working

Branch 9914a was merged into trunk as rev. 15893 and archived. Razvan-Nicolae Chichirau

02:58 AM Bug #9914 (Merge Pending): Investigate why ListenerSet implementation is not properly working

9914a can be merged after 5471a. Radu Apetrii

02:57 AM Bug #9914: Investigate why ListenerSet implementation is not properly working

Wonderful! I shall queue the branch up for merging. Radu Apetrii

02:51 AM Bug #9914: Investigate why ListenerSet implementation is not properly working

> * ask Danut to run unit tests and fwdtests for the application he is managing
No issues found ✅
Dănuț Filimon

02:15 AM Bug #9683: CompoundQuery is doing extra hydration attempts

Rebased on trunk rev 15891. Alexandru, could you please look at the last commits, I would like to move on with testin... Artur Școlnic

05/08/2025

09:14 AM Feature #9543: implement missing BUFFER attributes

Committed on 9543b, rev. 15892. Added support for AUTO-SYNCHRONIZE attribute. Eduard Soltan

06:24 AM Feature #9543: implement missing BUFFER attributes

Constantin Asofiei wrote:
> BTW, if buffer-copy fails validation, does synchronize still happen?
No. Eduard Soltan

06:23 AM Feature #9543: implement missing BUFFER attributes

Eduard Soltan wrote:
> Constantin Asofiei wrote:
> > Please also double-check the @ASSIGN@ statement if it trigger... Constantin Asofiei

06:09 AM Feature #9543: implement missing BUFFER attributes

Constantin Asofiei wrote:... Eduard Soltan

04:53 AM Feature #9543: implement missing BUFFER attributes

What happens if you do:... Constantin Asofiei

04:51 AM Feature #9543: implement missing BUFFER attributes

Constantin Asofiei wrote:
> Please also double-check the @ASSIGN@ statement if it triggers the synchronize or not. ... Eduard Soltan

04:39 AM Feature #9543: implement missing BUFFER attributes

Constantin Asofiei wrote:
> Please also double-check the @ASSIGN@ statement if it triggers the synchronize or not. ... Eduard Soltan

03:37 AM Feature #9543: implement missing BUFFER attributes

For @CAN-READ@ the only information I could find in the docs is:... Eduard Soltan

02:52 AM Feature #9543: implement missing BUFFER attributes

Constantin Asofiei wrote:
> Please also double-check the @ASSIGN@ statement if it triggers the synchronize or not. ... Eduard Soltan

02:32 AM Feature #9543: implement missing BUFFER attributes

Please also double-check the @ASSIGN@ statement if it triggers the synchronize or not. If the @ASSIGN@ part of @BUFF... Constantin Asofiei

01:48 AM Feature #9543: implement missing BUFFER attributes

I created some tests for @buffer-copy@ as a method and @buffer-copy@ statement.... Eduard Soltan

07:54 AM Bug #9318: Make record nursery visible on removeRecords

Rebased *9318a* to latest *trunk/15891*, the branch is now at revision *15895*. Dănuț Filimon

07:37 AM Bug #9914: Investigate why ListenerSet implementation is not properly working

> * ask Lorian to run harness
Harness passed ✅ Lorian Sandu

04:41 AM Bug #9914: Investigate why ListenerSet implementation is not properly working

> I will run unit tests and smoke tests of large customer application.
Everything is OK here. Alexandru Lungu

04:24 AM Bug #9914: Investigate why ListenerSet implementation is not properly working

* ChUI regression tests passed ✅
* Smoke-test for a large customer app passed ✅
* #9722 testing passed ✅
I think... Razvan-Nicolae Chichirau

05/07/2025

04:20 PM Feature #9831 (Internal Test): add admin API to set c3p0 configuration for individual tenant data...

> Meanwhile, I am putting the branch to the test using the the hotel, webGUI navigation and harness smoke-tests of a ... Ovidiu Maxiniuc

03:31 PM Feature #9831: add admin API to set c3p0 configuration for individual tenant databases

Ovidiu Maxiniuc wrote:
> Radu, please do a quick review when you have the time.
I think 9831a is alright. I don't s... Radu Apetrii

01:57 PM Feature #9831: add admin API to set c3p0 configuration for individual tenant databases

The @breakAfterAcquireFailure@ was removed from REST API and @landlord@ database.
The issues from note #9831-15 (th... Ovidiu Maxiniuc

09:26 AM Feature #9831: add admin API to set c3p0 configuration for individual tenant databases

Please remove @breakAfterAcquireFailure@ from the REST API, since we hard-code this setting to @true@ in the runtime. Eric Faulhaber

05:21 AM Feature #9831: add admin API to set c3p0 configuration for individual tenant databases

I looked at the changes in 9831a, and I can say quite confidently that functionally they are safe. I don't think they... Radu Apetrii

03:36 PM Bug #9914: Investigate why ListenerSet implementation is not properly working

ETF testing passed! Lorian Sandu

12:19 PM Feature #9543: implement missing BUFFER attributes

For @BUFFER-COPY@, if the destination buffer has no loaded record, then it CREATE's a record in that buffer. So, ple... Constantin Asofiei

12:16 PM Feature #9543: implement missing BUFFER attributes

Constantin Asofiei wrote:
> Also, are there cases when @auto-synchronize@ is disabled temporarily, like for @save-ro... Eduard Soltan

12:12 PM Feature #9543: implement missing BUFFER attributes

Constantin Asofiei wrote:
> Can this be described in short, the synchronize is automatically called when the buffer'... Eduard Soltan

12:10 PM Feature #9543: implement missing BUFFER attributes

Constantin Asofiei wrote:
> Can this be described in short, the synchronize is automatically called when the buffer'... Eduard Soltan

10:57 AM Feature #9543: implement missing BUFFER attributes

Also, are there cases when @auto-synchronize@ is disabled temporarily, like for @save-row-changes@ or @fill@ method c... Constantin Asofiei

10:56 AM Feature #9543: implement missing BUFFER attributes

Can this be described in short, the synchronize is automatically called when the buffer's record is either loaded, re... Constantin Asofiei

10:52 AM Feature #9543: implement missing BUFFER attributes

Created a few test cases for behaviour of @AUTO-SYNCHRONIZE@ attributes.... Eduard Soltan

10:11 AM Feature #9543: implement missing BUFFER attributes

OK, so we already support @SYNCHRONIZE@ method via @Buffer.querySynchronize@ - so looks like we just need to call it ... Constantin Asofiei

09:39 AM Feature #9543: implement missing BUFFER attributes

According to the docs for AUTO-SYNCHRONIZE attribute and a in a book *OpenEdge Development: ProDataSets* by John Sadd... Eduard Soltan

07:19 AM Feature #9543 (WIP): implement missing BUFFER attributes

Actually, this is back to WIP.
Eduard: did you get a chance to test how these attrs should behave at runtime? Constantin Asofiei

07:18 AM Feature #9543 (Test): implement missing BUFFER attributes

Constantin Asofiei

09:25 AM Bug #9969 (WIP): Parsing query string error with \r character.

Octavian Adrian Gavril

09:20 AM Bug #9969: Parsing query string error with \r character.

The escape sequences should include an additional '\' prefix. The current revision handles this only for '\u' within ... Octavian Adrian Gavril

08:53 AM Bug #9969: Parsing query string error with \r character.

Alexandru Lungu wrote:
> Eduard, is @'bc\r'@ right? Shouldn't it be @'bc~r'@ to actually generate the CR?
It is e... Eduard Soltan

08:51 AM Bug #9969: Parsing query string error with \r character.

Please also see #9967, which is somehow related to the escape char used under linux. Constantin Asofiei

08:48 AM Bug #9969: Parsing query string error with \r character.

Eduard, is @'bc\r'@ right? Shouldn't it be @'bc~r'@ to actually generate the CR? Alexandru Lungu

08:43 AM Bug #9969: Parsing query string error with \r character.

Our preprocessor/lexer strips @'\r'@ characters in a naive way that needs to be refined. Greg Shah

08:21 AM Bug #9969: Parsing query string error with \r character.

Alternatively this test case also reproduce the issues:... Eduard Soltan

08:06 AM Bug #9969: Parsing query string error with \r character.

... Eduard Soltan

08:02 AM Bug #9969 (WIP): Parsing query string error with \r character.

Eduard Soltan

08:20 AM Bug #9950: Upgrade the metadata schema to a newer version

Ovidiu, please get some preliminary changes in a branch, so we can patch 9457c and test FWD server startup. Constantin Asofiei

05:37 AM Bug #9937: buffer argument with different DMO than the parameter

I added my changes to 9937a rev. 15888.
When we have an ArgumentBuffer proxy, any direct field access (@btt1.getF1... Eduard Soltan

05/06/2025

10:07 AM Feature #9831: add admin API to set c3p0 configuration for individual tenant databases

Radu,
I rebased and did a quick review of my own code, this revealed some small issues which were fixed.
You can ... Ovidiu Maxiniuc

09:03 AM Feature #9831: add admin API to set c3p0 configuration for individual tenant databases

Ovidiu, is this ready to be reviewed? I see that it's been placed at 90%. Radu Apetrii

07:55 AM Feature #9831: add admin API to set c3p0 configuration for individual tenant databases

Added Radu as reviewer. Ovidiu Maxiniuc

07:37 AM Bug #9914 (Internal Test): Investigate why ListenerSet implementation is not properly working

I am OK with the changes in 9914a.
However, we will need some extensive testing with it, eventually across multiple ... Alexandru Lungu

07:26 AM Bug #9937: buffer argument with different DMO than the parameter

Constantin Asofiei wrote:
> Does this solve cases when the field is in an expression, copy-temp-table and others? B... Eduard Soltan

05:23 AM Bug #9937: buffer argument with different DMO than the parameter

Does this solve cases when the field is in an expression, copy-temp-table and others? Because @getDMOProxy();@ is us... Constantin Asofiei

05:21 AM Bug #9937: buffer argument with different DMO than the parameter

Constantin Asofiei wrote:
> I agree; but I'd like to solve this with the proxy, if possible; before committing to... Eduard Soltan

02:15 AM Bug #9937: buffer argument with different DMO than the parameter

Ovidiu Maxiniuc wrote:
> Yes, I am aware, as you quoted me, _"[...] which declare the @new shared@ tables and *simpl... Constantin Asofiei

07:10 AM Feature #7020: always use "expanded" extent fields

I have rebased 7020d to trunk revision 15884 and it's now at 15900. Stefanel Pezamosca

05/05/2025

04:19 PM Feature #7020 (Internal Test): always use "expanded" extent fields

Branch 7020c (now r15866) is rebased but does not seem to have changes from the last time I reviewed it (old r15824).... Ovidiu Maxiniuc

03:21 AM Feature #7020: always use "expanded" extent fields

Ovidiu, please provide a review for #7020-131. Alexandru Lungu

03:52 PM Bug #9937: buffer argument with different DMO than the parameter

Yes, I am aware, as you quoted me, _"[...] which declare the @new shared@ tables and *simple TT*."_ I was merely expr... Ovidiu Maxiniuc

01:48 PM Bug #9937: buffer argument with different DMO than the parameter

Ovidiu Maxiniuc wrote:
> So I think that would be the right implementation: to remove these attributes (like @xml-no... Constantin Asofiei

01:29 PM Bug #9937: buffer argument with different DMO than the parameter

I think we have discussed about an idea similar to Eduard's, some time ago.
Currently, the DMO of a @shared@ temp-... Ovidiu Maxiniuc

12:50 PM Bug #9937: buffer argument with different DMO than the parameter

Eduard Soltan wrote:
> Question: Since we established in #9763 that @xml-node-name@ is a property specific to the bu... Constantin Asofiei

12:32 PM Bug #9937 (WIP): buffer argument with different DMO than the parameter

Eduard Soltan

12:31 PM Bug #9937: buffer argument with different DMO than the parameter

I will let out some of my findings.
h3. Structure of tt1 after TemporaryBuffer.define
After the call in @FooTes... Eduard Soltan

04:04 AM Bug #9937: buffer argument with different DMO than the parameter

Eduard, I've tried something like this to create the proxy:... Constantin Asofiei

09:51 AM Bug #9965: Compound Query components not honoring the INCLUDE clause

... Lorian Sandu

09:44 AM Bug #9965 (New): Compound Query components not honoring the INCLUDE clause

Lorian Sandu

04/30/2025

02:15 PM Feature #9831: add admin API to set c3p0 configuration for individual tenant databases

Eric, please review.
I will rebase the branch since it is a bit behind the main trunk. Ovidiu Maxiniuc

02:33 AM Bug #9633: bulk delete for permanent tables

Rebased *9633a* with trunk revision *15878*, new revision is *15880*. Andrei Iacob

04/28/2025

04:51 PM Bug #9950: Upgrade the metadata schema to a newer version

One of the latest customer projects uses a newer schema (@standard.df@) of the _meta database than the one we have. I... Ovidiu Maxiniuc

04:36 PM Bug #9950 (Test): Upgrade the metadata schema to a newer version

Ovidiu Maxiniuc

07:32 AM Bug #9914: Investigate why ListenerSet implementation is not properly working

> Well, if the query is static, the scoping from #9914-14 would be correct! But the issue will still reproduce (?).
... Razvan-Nicolae Chichirau

04/25/2025

10:33 AM Bug #9907: LOOKUP seems to evaluate fast in WHERE clauses from the legacy code, but slow in FWD

I agree with #9907-3. But I am more interested to find out how 4GL is able to make this work fast. INDEXED-REPOSITION... Alexandru Lungu

10:22 AM Bug #9907: LOOKUP seems to evaluate fast in WHERE clauses from the legacy code, but slow in FWD

I've seen this task an I thought of something. This:... Stefanel Pezamosca

05:42 AM Bug #8044: Fix "Failed direct-access due to Error direct accessing for finding record by unique i...

Tomasz Domin wrote:
> Just to notify - I am still getting a lot of "Failed direct-access due to Error direct accessi... Dănuț Filimon

04/24/2025

08:19 AM Bug #9937: buffer argument with different DMO than the parameter

I've tested @DYNAMIC-INVOKE(.., BUFFER tt1)@ and runtime gets this @BUFFER parameter type not allowed for dynamic par... Constantin Asofiei

08:10 AM Bug #9937: buffer argument with different DMO than the parameter

In FWD, we create different DMO interfaces even if the schema matches, but the resource options, like @XML-NODE-NAME@... Constantin Asofiei

07:55 AM Bug #9937 (Test): buffer argument with different DMO than the parameter

Constantin Asofiei

06:52 AM Bug #9914: Investigate why ListenerSet implementation is not properly working

> No matter how many nested RUN statements we have in this testcase, we always end up trying to register the query at... Alexandru Lungu

06:09 AM Bug #9914: Investigate why ListenerSet implementation is not properly working

Experimented with @RUN custom.p@ from a @start.p@. Right before we should to add the query as a global listener, this... Razvan-Nicolae Chichirau

03:39 AM Bug #9914: Investigate why ListenerSet implementation is not properly working

> Anyway, it would be defined globally.
I am not sure that "globally" is right. It is within the scope of the exte... Alexandru Lungu

03:38 AM Bug #7364: Build a full test-suite for fast copy-temp-table

I extended the tests existent at @testcases/tests/table/TestCopyTempTable.cls@ as part of the work on #9397. These ar... Ioana-Cristina Prioteasa

03:15 AM Bug #7364: Build a full test-suite for fast copy-temp-table

Ioana, did you built a test-suite in your recent work for COPY-TEMP-TABLE construct? If so, is it based on plain proc... Alexandru Lungu

03:08 AM Bug #7403 (Closed): Copy-temp-table with replace-mode should replace already inserted records

Alexandru Lungu

02:48 AM Bug #7403: Copy-temp-table with replace-mode should replace already inserted records

Yes, thanks! Ioana-Cristina Prioteasa

04/23/2025

03:53 PM Feature #9831: add admin API to set c3p0 configuration for individual tenant databases

The default value for all of these is @null@ which means they will default to the c3p0 value of the default database.... Ovidiu Maxiniuc

03:22 PM Feature #9831: add admin API to set c3p0 configuration for individual tenant databases

Isn't @c3p0.break_on_fail@ always supposed to be @true@? I don't think we want customers to configure that. Greg Shah

03:00 PM Feature #9831 (Review): add admin API to set c3p0 configuration for individual tenant databases

The implementation is finished. I added the support even for @c3p0.break_on_fail@ which was recently added.
I've jus... Ovidiu Maxiniuc

02:11 PM Feature #9831: add admin API to set c3p0 configuration for individual tenant databases

Ovidiu, what is the status of this task? I did not do a full review, but I took a look at 9831a and the implementatio... Eric Faulhaber

11:04 AM Bug #9397 (Closed): Fix COPY-TEMP-TABLE issues

This can be closed. Alexandru Lungu

11:04 AM Bug #7403: Copy-temp-table with replace-mode should replace already inserted records

> #7403 is fixed by 9397a - FWD behavior aligns with progress with trunk rev.15627.
Ioana, does this mean that #74... Alexandru Lungu

11:00 AM Feature #7960 (Closed): Allow query logs to be collected in a H2 database

This can be closed now as the query logs seem to be accumulated well in H2. Alexandru Lungu

07:27 AM Bug #9914: Investigate why ListenerSet implementation is not properly working

After converting @start.p@ from #9914-6:... Razvan-Nicolae Chichirau

07:18 AM Bug #9914: Investigate why ListenerSet implementation is not properly working

I can't tell in #9914-5 where the buffer is defined. Alexandru Lungu

06:53 AM Bug #9914: Investigate why ListenerSet implementation is not properly working

> It looks like you are registering the query at the first nested scope and the buffer at the second nested scope.
... Razvan-Nicolae Chichirau

04:16 AM Bug #9914: Investigate why ListenerSet implementation is not properly working

> So, I don't think the problem comes from the unlinking of PreselectQuery after popping the procedure local scope, b... Alexandru Lungu

02:19 AM Bug #9914 (Review): Investigate why ListenerSet implementation is not properly working

Razvan-Nicolae Chichirau

02:19 AM Bug #9914 (WIP): Investigate why ListenerSet implementation is not properly working

Commited to *9914a/rev. 15868*.
Alex: Please review. Razvan-Nicolae Chichirau

04/22/2025

05:51 AM Bug #9914: Investigate why ListenerSet implementation is not properly working

Attached the original testcase.
There are 2 important phases while opening the query in @createWidgets@:
# Initia... Razvan-Nicolae Chichirau

02:36 AM Bug #9683: CompoundQuery is doing extra hydration attempts

Addressed a few formatting issues and rebased on trunk rev 15866. Artur Școlnic

04/17/2025

12:24 PM Feature #9093 (Closed): add protection for multi-tenant imports to optionally only import tables ...

Greg Shah

09:42 AM Bug #9914: Investigate why ListenerSet implementation is not properly working

Given this situation:... Razvan-Nicolae Chichirau

08:39 AM Bug #9914: Investigate why ListenerSet implementation is not properly working

Razvan-Nicolae Chichirau wrote:
> So, what we need to do is to replace the workaround of just combining all listener... Alexandru Lungu

08:29 AM Bug #9914: Investigate why ListenerSet implementation is not properly working

So, what we need to do is to replace the workaround of just combining all listeners sets and instead use the @Listene... Razvan-Nicolae Chichirau

08:18 AM Bug #9914: Investigate why ListenerSet implementation is not properly working

According to Eric, @ListenerSet@ from @ChangeBroker@ should have worked like a linked list which *references* other d... Alexandru Lungu

08:15 AM Bug #9914 (Test): Investigate why ListenerSet implementation is not properly working

Alexandru Lungu

09:40 AM Bug #9683 (Review): CompoundQuery is doing extra hydration attempts

I addressed the review and fixed a few bugs detected during testing, the code is in 9683a/15727. Artur Școlnic

04/16/2025

03:29 PM Feature #9093: add protection for multi-tenant imports to optionally only import tables that are ...

That is because #9875 was marked as a subtask of this one, which then blocks the direct setting of the %Done. Greg Shah

03:23 PM Feature #9093: add protection for multi-tenant imports to optionally only import tables that are ...

I wanted to, but for some unknown reasons to me, I cannot do it. I remember that I wanted to do it, but since *the co... Ovidiu Maxiniuc

02:54 PM Feature #9093: add protection for multi-tenant imports to optionally only import tables that are ...

Can we set Done to 100%? Greg Shah

04:23 AM Bug #9907: LOOKUP seems to evaluate fast in WHERE clauses from the legacy code, but slow in FWD

This is deferred work to understand the following pattern:... Alexandru Lungu

04:18 AM Bug #9907 (New): LOOKUP seems to evaluate fast in WHERE clauses from the legacy code, but slow in...

Alexandru Lungu

04/15/2025

06:29 PM Feature #9831: add admin API to set c3p0 configuration for individual tenant databases

To upgrade the @landlord@ database without re-creating it from scratch use:... Ovidiu Maxiniuc

06:26 PM Feature #9831 (WIP): add admin API to set c3p0 configuration for individual tenant databases

Rebased branch 9831a and added support for @c3p0.breakAfterAcquireFailure@ from #9736. A couple of fixes. Committed r... Ovidiu Maxiniuc

04/14/2025

07:36 AM Bug #9896: Record reference count should account for dirty records

h4. First problem
Dirty records are not accounted for the reference count, so that a dirty record referenced in tw... Alexandru Lungu

07:34 AM Bug #9896 (New): Record reference count should account for dirty records

Alexandru Lungu