[client-v2] Fixes handling empty results while using reader #1845
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Paultagoras
reviewed
Sep 30, 2024
| @@ -148,11 +151,16 @@ public <T> T readValue(String colName) { | |||
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| @Override | |||
| public boolean hasNext() { | |||
| if (initialState) { | |||
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Is it possible to have no results? IE can we be sure it SHOULD always be true?
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Yes, it is possible to have no results: empty dataset or completely no data in a response body.
Both cases are handled. The initialState is changed once any bytes are read from input stream).
Paultagoras
approved these changes
Sep 30, 2024
chernser
changed the title
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Summary
BinaryFormatReader implementation is stateful and hold current record to be accessible before calling
next(). Data is provided as stream and because of this reason handlinghasNext()is complex because reader should read data upfront without affect current own position to avoid skipping records.This PR fixes detecting if no data is present in data stream.
Note
There are two cases of empty result:
SELECT 1 LIMIT 0- has no result data but has column name and typeCREATE TABLE test- has nothing at all, so readers that expect schema before data should also handle it correctly.Closes #1788
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