[firebird-support] concurrency in firebird

['checkmail' check_m...@satron.de [firebird-support]]

Hello everybody,

 

I need to split an input string and import some data in tables, like this
(simplified) '123423453456'

In this case, the value 1 is 1234, value 2 = 2345. With a while loop the
values were inserted, if I get an error (value is not a integer), then I
will delete all records with this import-id. 

 

Now, value 1 should be add to an total counter, f. e. old value = 1, new
= 11234. If I get an error, I would like to return to the old value. Now I
have the following idea, I create a new column named tmp_insert an enter the
value to add. If all records were inserted without any errors, I can add the
new value to the total one and reset the column to 0. Now my question, how
handled firebird this with concurrency, if I call the stored procedure more
than once a time. Will ervery step worked to the end before the new call
runs? Can it be problematic? (column tmp_insert and add to the total value)

 

Thank you.

SV: [firebird-support] concurrency in firebird

[Svein Erling Tysvær svein.erling.tysv...@kreftregisteret.no [firebird-support]]

Hello everybody,

I need to split an input string and import some data in tables, like this 
(simplified) ‘123423453456’
In this case, the value 1 is 1234, value 2 = 2345. With a while loop the 
values were inserted, if I get an error (value is not a integer), then I will 
delete all records with this import-id.

Now, value 1 should be add to an total counter, f. e. old value = 1, new = 
11234. If I get an error, I would like to return to the old value. Now I have 
the following idea, 
I create a new column named tmp_insert an enter the value to add. If all 
records were inserted without any errors, I can add the new value to the total 
one and reset the column 
to 0. Now my question, how handled firebird this with concurrency, if I call 
the stored procedure more than once a time. Will ervery step worked to the end 
before the new call runs?
Can it be problematic? (column tmp_insert and add to the total value)

Having one record with a total value is almost the same as doing things serial 
rather than parallel, so avoid this if concurrency is an issue.

Rather than changing the value from 1 to 11234, insert a new record into 
the summation table with the value 1234. And rather than subtracting upon 
deletes, insert a new record with a negative value. To get the total value, 
query sum(TotalCounter) rather than just TotalCounter. 

Every once in a while (typically in a batch run during the night), do something 
like (I've added a group field, often you want to store more than one value - 
feel free to use a stored procedure rather than execute block).

EXECUTE BLOCK as
  declare variable SomeGroup integer;
  declare variable NewSum integer;
begin
  for select MyGroup, sum(TotalCounter)
  from MyTable
  group by MyGroup
  into :SomeGroup, :NewSum do
  begin
delete from MyTable
where MyGroup = :SomeGroup;
insert into MyTable(MyGroup, TotalCounter)
values(:SomeGroup, :NewSum);
  end
end

No need for any tmp_insert column.

HTH,
Set





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