Improved performance when decoding the entire set of rows with streamable JSON formats #253
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mshustov
reviewed
Mar 29, 2024
| @@ -40,9 +40,9 @@ describe('[Web] SELECT streaming', () => { | |||
| it('should consume a text response only once', async () => { | |||
| const rs = await client.query({ | |||
| query: 'SELECT * FROM system.numbers LIMIT 1', | |||
| format: 'TabSeparated', | |||
| format: 'JSONEachRow', | |||
There was a problem hiding this comment.
can't call JSON on TabSeparated.
mshustov
approved these changes
Mar 29, 2024
The |
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Unless JIT optimizes it out (it does not), it's at least one extra full pass, worst case two. |
slvrtrn
added a commit
that referenced
this pull request
Mar 29, 2024
1.0.0 * Add support for URL parameters parsing (#232) * Infer ResultSet type hints based on DataFormat (#238) * Add SharedMergeTree Cloud tests, remove Node 16 from the CI, and add Node 21 (#234) * Add pathname config option, revert read-only switch/default settings (#251) * Improved performance when decoding the entire set of rows with streamable JSON formats (#253) * Bump dev dependencies, update internal module resolution (#248)
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Summary
Improved performance when decoding the entire set of rows with streamable JSON formats (such as
JSONEachRoworJSONCompactEachRow) by calling theResultSet.json()method. Depending on the dataset, it's between 10-15% (like cell_towers) and 40% (with large rows and very long strings) less execution time. NB: The actual streaming performance when consuming theResultSet.stream()(which was fast) hasn't changed. Only theResultSet.json()method used a suboptimal stream processing in some instances, and nowResultSet.json()just consumes the same stream transformer provided by theResultSet.stream()method.Before:
After:
Removed the outdated
decodefunction.Updated exported types and doc entries for DataFormat.
Fixed weird flakiness in expect-type assertions