[RFC] Introduce uniqCombined64() to get sane results for cardinality > UINT_MAX#7222
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alexey-milovidov merged 4 commits intoClickHouse:masterfrom Oct 9, 2019
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…_MAX By default uniqCombined() uses 32-bit hash for all types except String, so this means that you cannot use uniqCombined() with i.e UInt64 and cardinality > UINT_MAX, although you can use uniqCombined(toString()) and this will lead to 64-bit hash, but will not have good performance. So uniqCombined64() had been introduced to fix this. Requires: ClickHouse#7213
| throw Exception( | ||
| "Parameter for aggregate function " + name + "is out or range: [12, 20].", ErrorCodes::ARGUMENT_OUT_OF_BOUND); | ||
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| "Parameter for aggregate function " + name + " is out or range: [12, 20].", ErrorCodes::ARGUMENT_OUT_OF_BOUND); |
alexey-milovidov
approved these changes
Oct 9, 2019
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Short description (up to few sentences):
Introduce uniqCombined64() to get sane results for cardinality > UINT_MAX
Detailed description (optional):
By default uniqCombined() uses 32-bit hash for all types except String,
so this means that you cannot use uniqCombined() with i.e UInt64 and
cardinality > UINT_MAX, although you can use uniqCombined(toString())
and this will lead to 64-bit hash, but will not have good performance.
Requires: #7213