sqlparse
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andialbrecht
Performance improvement on str(tokenlist)
Thanks for the pr. The change you're suggesting has had the effect of changing the behavior of how the output is generated and as a consequence it changed the parsed output. Multiple tests are failing on this commit.
I'm currently going over the changes that would be needed to make the pr work, and its overall effects would net on a slower sqlparse as we would need to add multiple sections to update the value of the tokenlists since they are not updated after they are created.
Hi,
Thanks. I have a terribly long SQL (but simple, no nested queries, just a thousand result columns and many joins) and found it takes many seconds to parse it. Upon investigating by cProfile, I believe that is the hot spot. My change works on my example and cut the time spent to only 1/4.
Please let me know if I can help on something. I am new to sqlparse, just used a few minutes on reading the source code.
Sincerely, Adrian (righthandabacus)
On Tue, Aug 9, 2016 at 9:18 PM, Vik [email protected] wrote:
I'm currently going over the changes that would be needed to make the pr work, and its overall effects would net on a slower sqlparse as we would need to add multiple sections to update the value of the tokenlists since they are not updated after they are created.
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Sorry for the very late follow-up. Can you provide this example (or a similar one) to use as a benchmark.
Did you notice the delay during the parsing or when using any of the filters? (formatting, etc).
If its during the parsing phase, I think the issue is actually with this line that calls the function you listed multiple times. AFAIK TokenList.value is barely used, so we can probably replace it with a lazy evaluation and that may provide the speed-up you saw on your pull request.
I suspect the issue that this PR was attempting to be address was the same as reported in #621, and should be fully addressed by PR #710.
