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I have occasionally been struck by extremely bad performance when it comes to the OCL Collect operator. | I have occasionally been struck by extremely bad performance when it comes to the OCL Collect operator. | ||
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Consider this expression: | Consider this expression: | ||
Sequence{0..7000}->collect(a| vCollectionDetails.add(Detail.Create)) | Sequence{0..7000}->collect(a| vCollectionDetails.add(Detail.Create)) | ||
My intention is to create 7000 Detail-objects and put them in the variable <code>vCollectionDetails</code> that has type Collection(Detail). | My intention is to create 7000 Detail-objects and put them in the variable <code>'''<span class="col-black">vCollectionDetails</span>'''</code> that has type Collection(Detail). | ||
But this expression is extremely slow. | But this expression is extremely slow. | ||
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The main reason for the slowness is that Collect actually builds a result of all the results of the inner expression. In our case, this is a List of Lists; List of 1 detail, List of 2 details, List of 3 details...List of 6990 details etc. This is a heavy operation as 7000 thousand lists must be created and filled with 7000*7000/2 objects - I am not interested in that result. I only used the Collect operator as a convenient way to act on each. | The main reason for the slowness is that Collect actually builds a result of all the results of the inner expression. In our case, this is a List of Lists; List of 1 detail, List of 2 details, List of 3 details...List of 6990 details etc. This is a heavy operation as 7000 thousand lists must be created and filled with 7000*7000/2 objects - I am not interested in that result. I only used the Collect operator as a convenient way to act on each. | ||
Look at [[OCLOperators foreach|foreach]] for a solution or to avoid returning the list. Instead, return something simple like this: | Look at [[Documentation:OCLOperators foreach|foreach]] for a solution or to avoid returning the list. Instead, return something simple like this: | ||
Sequence{0..7000}->collect(a| vCollectionDetails.add(Detail.Create);0) | Sequence{0..7000}->collect(a| vCollectionDetails.add(Detail.Create);0) | ||
In this case, the collect operator returns 1 list with 7000 zeros - much faster than 24 million references to 7000 Detail objects. | In this case, the collect operator returns 1 list with 7000 zeros - much faster than 24 million references to 7000 Detail objects. | ||
[[Category:OCL]] | [[Category:OCL]] | ||
{{Edited|July|12|2025}} | |||
Latest revision as of 05:46, 11 February 2025
I have occasionally been struck by extremely bad performance when it comes to the OCL Collect operator.
After debugging, I concluded that the expression used was wrong compared to my intended usage and need.
Consider this expression:
Sequence{0..7000}->collect(a| vCollectionDetails.add(Detail.Create))
My intention is to create 7000 Detail-objects and put them in the variable vCollectionDetails that has type Collection(Detail).
But this expression is extremely slow.
The main reason for the slowness is that Collect actually builds a result of all the results of the inner expression. In our case, this is a List of Lists; List of 1 detail, List of 2 details, List of 3 details...List of 6990 details etc. This is a heavy operation as 7000 thousand lists must be created and filled with 7000*7000/2 objects - I am not interested in that result. I only used the Collect operator as a convenient way to act on each.
Look at foreach for a solution or to avoid returning the list. Instead, return something simple like this:
Sequence{0..7000}->collect(a| vCollectionDetails.add(Detail.Create);0)
In this case, the collect operator returns 1 list with 7000 zeros - much faster than 24 million references to 7000 Detail objects.