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Implement approx_distinct for CHAR type #11101

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arhimondr merged 1 commit into from
Jul 20, 2018
Merged

Implement approx_distinct for CHAR type #11101

arhimondr merged 1 commit into from
Jul 20, 2018

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@arhimondr arhimondr commented Jul 20, 2018

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@arhimondr arhimondr requested a review from jessesleeping July 20, 2018 17:01
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arhimondr commented Jul 20, 2018 •
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Note: this implementation follows existing EQUALS semantics. abc is considered different than abc (abc[space] != abc[space][space]). It is consistent with current count(DISTINCT c_char) semantics.

@arhimondr arhimondr requested a review from sopel39 July 20, 2018 17:12
@arhimondr arhimondr mentioned this pull request Jul 20, 2018
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jessesleeping
jessesleeping approved these changes Jul 20, 2018
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LGTM

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findepi commented Jul 20, 2018

abc[space] != abc[space][space]

this are values of different types: char(4) and char(5) respectively

if you meant internal representation, then note that trailing spaces are strictly forbidden in internal representation

findepi
findepi approved these changes Jul 20, 2018
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presto-tests/src/main/java/com/facebook/presto/tests/AbstractTestAggregations.java
assertQuery("SELECT approx_distinct(CAST(custkey AS VARCHAR), 0.023) FROM orders", "SELECT 1036");

// test char
assertQuery("SELECT approx_distinct(CAST(CAST(custkey AS VARCHAR) AS CHAR(20))) FROM orders", "SELECT 1036");
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@findepi findepi Jul 20, 2018

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i guess CAST(custkey AS CHAR(20)) is not enough?

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@arhimondr arhimondr Jul 20, 2018

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No, there is no direct cast operator

@arhimondr arhimondr merged commit 2036070 into prestodb:master Jul 20, 2018
@arhimondr arhimondr deleted the approx-distinct-char branch August 2, 2018 15:20
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@jessesleeping jessesleeping jessesleeping approved these changes

@sopel39 sopel39 Awaiting requested review from sopel39

+1 more reviewer

@findepi findepi findepi approved these changes

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