Datamart breaks when existing table is enhanced

[smpa01]

I have deployed a datamart and queried tables from different sources (sql, sharepoint, api).

However, if I try to enhnace any table by changing the code in PQ window (while being mindful of keeping the number of the column same as well as the order of the column), and load it back to datamart, the datamart breaks, meaning following element breaks

Data source credentials

Loading data- I expect to see 50k+ rows here, which does not happen.

Can someone from MS please advise what is going on here?

Also, I can query the AZURE SQL tables, but the query execution has some flaws. A super optimized query that executes in 1 second, takes 7 minutes on a subsequest execution. Why is that? How can I access/improve these severs myself?

Datamart will be a game changer without these flaws and I need to know all these things beforehand so that I don't tangle myself with prod reports feeding from a datamart that is stale.

[v-yetao1-msft]

Hi @smpa01 

You mentioned that you enhnaced any table by changing the code in PQ window , can you explain it in detail ? I don't quite understand what you mean, maybe you can show your actions through screenshots or videos?

Best Regards,
Community Support Team _ Ailsa Tao

[smpa01]

@v-yetao1-msft  I queried a table from sql server and set it up in the datamart.

Let's suppose that the following query was used when it was set up for the first time

select
      col1
      ,col2
      ,col3
from
    fact1 a 
outer apply (select * from dim1 b.....where)
where (predicate)
and exists (predicate) 
     

After a couple of days, I received an enhancement req from ops so that the query now becomes

select
      col1
      ,col2
      ,col3
from
    fact1 a 
outer apply (select * from dim1 b.....where)
where (predicate)
and exists (predicate) 
     
union all

select
      col1
      ,col2
      ,col3
from
    fact2 a 
outer apply (select * from dim2 b.....where)
where (predicate) and ..... and ...... and.....
and exists (predicate) 

Whenever I update/enhance/ my query I am facing challenges like this.