parser: lowercase timespans in extract #59598
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The `extract` builtin is kind of weird - it is actually supported by the parser and not an ordinary builtin function that people can call without parser support. As such, we can normalize its inputs right in the parser. The benefit of this is that, later, we are going to unconditionally ToLower() the string arguments to extract - which costs an allocation. So we can do this normalization up front to save a bunch of allocations in queries that run `extract` over a lot of data rows. Release note (performance improvement): improve the allocation performance of workloads that use the `EXTRACT` builtin.
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otan
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Jan 31, 2021
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Touches #19965. Confirmed that this (relatively silly) PR gets rid of the allocations in the experiment listed in #19965 (comment)
The
extractbuiltin is kind of weird - it is actually supported by theparser and not an ordinary builtin function that people can call without
parser support. As such, we can normalize its inputs right in the
parser.
The benefit of this is that, later, we are going to unconditionally
ToLower() the string arguments to extract - which costs an allocation.
So we can do this normalization up front to save a bunch of allocations
in queries that run
extractover a lot of data rows.Release note (performance improvement): improve the allocation
performance of workloads that use the
EXTRACTbuiltin.