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https://issues.apache.org/jira/browse/CASSANDRA-3068?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13088972#comment-13088972
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Jonathan Ellis edited comment on CASSANDRA-3068 at 8/22/11 8:07 PM:
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count() is part of the SQL standard and should operate on rows as defined
there. Redefining it is gratuitously confusing to users ([1], [2]), and breaks
compatibility with Hive.
(I acknowledge my culpability in +1ing the idea in CASSANDRA-1704. I plead
temporary insanity since I'd obviously come to my senses by [1].)
Note that we do not need a replacement column-specific count function; the
"transposed" queries from CASSANDRA-2474 means you can count the columns in a
row with (normal row-based) count(), against the transposed row.
Additional note: count() is also odd in special-casing its return value in a
CqlResult.num field. "normal" behavior that JDBC, DBAPI, etc. expect would be
to return a CqlResult.rows with a single column named "count," and an int value
of the result. Let's fix this at the same time as long as we're going to bite
the incompatibility bullet.
[1]
http://cassandra-user-incubator-apache-org.3065146.n2.nabble.com/python-cql-driver-select-count-failed-td6410310.html
[2]
http://cassandra-user-incubator-apache-org.3065146.n2.nabble.com/CQL-COUNT-Not-Accurate-td6611854.html
was (Author: jbellis):
count() is part of the SQL standard and should operate on rows as defined
there. Redefining it is gratuitously confusing to users ([1], [2]), and breaks
compatibility with Hive.
(I acknowledge my culpability in +1ing the idea in CASSANDRA-1704. I plead
temporary insanity since I'd obviously come to my senses by [1].)
Note that we do not need a replacement column-specific count function; the
"transposed" queries from CASSANDRA-2 means you can count the columns in a row
with (normal row-based) count(), against the transposed row.
Additional note: count() is also odd in special-casing its return value in a
CqlResult.num field. "normal" behavior that JDBC, DBAPI, etc. expect would be
to return a CqlResult.rows with a single column named "count," and an int value
of the result. Let's fix this at the same time as long as we're going to bite
the incompatibility bullet.
[1]
http://cassandra-user-incubator-apache-org.3065146.n2.nabble.com/python-cql-driver-select-count-failed-td6410310.html
[2]
http://cassandra-user-incubator-apache-org.3065146.n2.nabble.com/CQL-COUNT-Not-Accurate-td6611854.html
> Fix count()
> -----------
>
> Key: CASSANDRA-3068
> URL: https://issues.apache.org/jira/browse/CASSANDRA-3068
> Project: Cassandra
> Issue Type: Sub-task
> Components: API, Core
> Reporter: Jonathan Ellis
> Fix For: 1.0
>
>
> count() has been broken since it was introduced in CASSANDRA-1704.
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