Wednesday, 29 January 2020

Unpivoting Oracle APEX meta-data

There are APEX dictionary views for most of the data that represents the 'source' that is your APEX application meta-data.

Note: This post has beeen updated to reflect me not looking very hard, but I added a performance comparison... just because.

Today I found one place where I really wanted to run a query to find references to potential data - application substitution strings.

APEX Application Substitution Strings

And yes, I have a CSS rule to right-align those names, to make it easier to read.

I couldn't find any references in the APEX dictionary (correction, see below), so I looked in the Oracle data dictionary to find where it may live.
select * from all_tab_columns 
where column_name like 'SUB%03';
So not only are these stored in a place inaccessible to us mere-mortal developers, they are also stored in 20 sets of name/value columns - not rows.

This means if you have a dozen applications, with references in slightly different locations for each application, then string searches might be a pain.

Unpivot to the rescue!
select * from (
  select id app_id, alias, name -- key facts
      -- all the substitution stringz!
      ,substitution_string_01, substitution_value_01
      ,substitution_string_02, substitution_value_02
      ,substitution_string_03, substitution_value_03
      ,substitution_string_04, substitution_value_04
      ,substitution_string_05, substitution_value_05
      ,substitution_string_06, substitution_value_06
      ,substitution_string_07, substitution_value_07
      ,substitution_string_08, substitution_value_08
      ,substitution_string_09, substitution_value_09
      ,substitution_string_10, substitution_value_10
      ,substitution_string_11, substitution_value_11
      ,substitution_string_12, substitution_value_12
      ,substitution_string_13, substitution_value_13
      ,substitution_string_14, substitution_value_14
      ,substitution_string_15, substitution_value_15
      ,substitution_string_16, substitution_value_16
      ,substitution_string_17, substitution_value_17
      ,substitution_string_18, substitution_value_18
      ,substitution_string_19, substitution_value_19
      ,substitution_string_20, substitution_value_20
  from apex_190200.WWV_FLOWS -- direct from underlying view
)
unpivot (
(str, val) -- new columns
for rec in -- denoted by 
  ((substitution_string_01, substitution_value_01) as '01'
  ,(substitution_string_02, substitution_value_02) as '02'
  ,(substitution_string_03, substitution_value_03) as '03'
  ,(substitution_string_04, substitution_value_04) as '04'
  ,(substitution_string_05, substitution_value_05) as '05'
  ,(substitution_string_06, substitution_value_06) as '06'
  ,(substitution_string_07, substitution_value_07) as '07'
  ,(substitution_string_08, substitution_value_08) as '08'
  ,(substitution_string_09, substitution_value_09) as '09'
  ,(substitution_string_10, substitution_value_10) as '10'
  ,(substitution_string_11, substitution_value_11) as '11'
  ,(substitution_string_12, substitution_value_12) as '12'
  ,(substitution_string_13, substitution_value_13) as '13'
  ,(substitution_string_14, substitution_value_14) as '14'
  ,(substitution_string_15, substitution_value_15) as '15'
  ,(substitution_string_16, substitution_value_16) as '16'
  ,(substitution_string_17, substitution_value_17) as '17'
  ,(substitution_string_18, substitution_value_18) as '18'
  ,(substitution_string_19, substitution_value_19) as '19'
  ,(substitution_string_20, substitution_value_20) as '20'
  )
)
order by app_id, str 
This query transposes all the string/value columns into rows, each denonimated by the new "REC" column.

Note, this query can only be executed by those with the APEX Administrator Role, and if you want to have it within a view that could be executed by other schemas, then select access on wwv_flows is needed with grant option.

Columns unpivoted into rows

By placing the query in a view, I can now make queries like this to find any substitution strings in any applications that have date references.
select * from apx_app_sub_strings
where val like 'APP_DATE%';
Pretty neat, well at least as far as what I was trying to do.

This query may break in future versions, as it's based on an underlying, undocumented view.
I also think that once upon a time, there were fewer pairs.

Update: As the community quickly pointed out, I missed & forgot about a view already dedicated for such a task. I was too busy looking for a column number, when really I should have used APEX_APPLICATION_SUBSTITUTIONS.

I thought I'd see how 'they' solved the problem, and I was a little surprised to see a bunch of UNION statements.
SELECT ...
           f.substitution_string_18,
           f.substitution_value_18,
           f.substitution_string_19,
           f.substitution_value_19,
           f.substitution_string_20,
           f.substitution_value_20
      from wwv_flow_authorized auth,
           wwv_flows f
     where f.id = auth.application_id )
select workspace,
       workspace_display_name,
       application_id,
       application_name,
       substitution_string_01 as substitution_string,
       substitution_value_01  as substitution_value
  from substitution
where substitution_string_01 is not null
union all
select workspace,
       workspace_display_name,
       application_id,
       application_name,
       substitution_string_02 as substitution_string,
       substitution_value_02  as substitution_value
  from substitution
where substitution_string_02 is not null
union all...
After seeing this I couldn't help but run a brute for comparison, running both solutions x times.
iterations:5000
16.55 secs (.003310 secs per iteration) -- union all
 6.54 secs (.001308 secs per iteration) -- unpivot
I made sure the underlying join was the same, and I'm not all that surprised the unpivot did the job quicker.

4 comments:

Tony said...

I this not available in 19.2?

Select * from apex_application_substitutions where application_id=xxxx

AndrejGrlica said...
This comment has been removed by the author.
AndrejGrlica said...

Like Tony sad, you can fin that in "apex_application_substitutions"

Scott Wesley said...

Yup, somehow I missed that view - one I'm sure I've used in that past.

I'll update the post later... but my way is faster ;p