refactor(taps): Change SQLStream.schema into a cached property
#1745
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Schema is called at least once per record and does not change within a stream, so it should be cached for performance benefits.
``` @Property @lru_cache() ``` is a backwards compatible version of functools.cached_property for Python 3.7 https://stackoverflow.com/questions/4037481/caching-class-attributes-in-python
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edgarrmondragon
changed the title
SQLStream.schema into a cached property
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@mjsqu can you fix the failing mypy check? Some of the conversation in python/mypy#5107 (comment) might be helpful. Thanks! |
mypy checks fail because the schema return type is lru_cache: ``` singer_sdk/streams/sql.py:82: error: Signature of "schema" incompatible with supertype "Stream" [override] singer_sdk/streams/sql.py:154: error: Argument "schema" to "get_selected_schema" has incompatible type "_lru_cache_wrapper[Dict[Any, Any]]"; expected "Dict[Any, Any]" [arg-type] Found 2 errors in 1 file (checked 59 source files) ``` The update should pass over the `_lru_cache_wrapper` type and return a `Dict` as expected
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- Remove `lru_cache` - Set `_cached_schema` up as a class variable to hold the schema for each stream - Check for presence of `self._cached_schema` on the stream
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Codecov Report
@@ Coverage Diff @@
## main #1745 +/- ##
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Coverage 85.47% 85.48%
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Files 59 59
Lines 4888 4891 +3
Branches 802 803 +1
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+ Hits 4178 4181 +3
Misses 510 510
Partials 200 200
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Thanks for the inspiration @qbatten Done a quick test in https://github.com/mjsqu/tap-db2/blob/feature/meltano_sdk/tap_db2/client.py - still getting the speed benefit |
edgarrmondragon
changed the title
SQLStream.schema into a cached propertySQLStream.schema into a cached property
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Schema is called at least once per record and does not change within a stream, so it should be cached for performance benefits.
https://app.slack.com/client/TFG99TU9K/C013Z450LCD/thread/C013Z450LCD-1685703921.187269
📚 Documentation preview 📚: https://meltano-sdk--1745.org.readthedocs.build/en/1745/