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Posted to commits@cassandra.apache.org by "Daniel Fiala (JIRA)" <ji...@apache.org> on 2018/01/17 10:24:00 UTC
[jira] [Updated] (CASSANDRA-14170) Loss of digits when doing CAST
from varint/bigint to decimal
[ https://issues.apache.org/jira/browse/CASSANDRA-14170?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Daniel Fiala updated CASSANDRA-14170:
-------------------------------------
Description:
Cast functions from numeric types to decimal type are implemented as conversion to double first and then from double to decimal: [https://github.com/apache/cassandra/compare/trunk...blerer:10310-3.0#diff-6aa4a8f76df6c30c5bb4026b8c9251eeR80].
This can cause loss of digits for big values stored in varint or bigint. It is probably unexpected because decimal can store such values precisely.
Examples:
{{cqlsh> CREATE TABLE cast_bigint_test(k int PRIMARY KEY, bigint_clmn bigint);}}
{{cqlsh> INSERT INTO cast_bigint_test(k, decimal_clmn) VALUES(2, 9223372036854775807);}}
{{cqlsh> SELECT CAST(bigint_clmn AS decimal) FROM cast_bigint_test;}}
{{cast(bigint_clmn as decimal)}}
{{------------------------------}}
{{9.223372036854776E+18}}
{{(1 rows)}}
{{cqlsh> CREATE TABLE cast_varint_test (k int PRIMARY KEY, varint_clmn varint);}}
{{cqlsh> INSERT INTO cast_varint_test(k, varint_clmn) values(2, 1234567890123456789);}}
{{cqlsh> SELECT CAST(varint_clmn AS decimal) FROM cast_varint_test;}}
{{cast(varint_clmn as decimal)}}
{{------------------------------}}
1.23456789012345677E+18
{{(1 rows)}}
was:
Cast functions from numeric types to decimal type are implemented as conversion to double first and then from double to decimal: [https://github.com/apache/cassandra/compare/trunk...blerer:10310-3.0#diff-6aa4a8f76df6c30c5bb4026b8c9251eeR80].
This can cause loss of digits for big values stored in varint or bigint. It is probably unexpected because decimal can store such values precisely.
Examples:
{{cqlsh> CREATE TABLE cast_bigint_test(k int PRIMARY KEY, bigint_clmn bigint);}}
{{cqlsh> INSERT INTO cast_bigint_test(k, decimal_clmn) VALUES(2, 9223372036854775807);}}
{{cqlsh> SELECT CAST(bigint_clmn AS decimal) FROM cast_bigint_test;}}
{{cast(bigint_clmn as decimal)}}
{{------------------------------}}
{{9.223372036854776E+18}}
{{(1 rows)}}
{{cqlsh> CREATE TABLE cast_varint_test (k int PRIMARY KEY, varint_clmn varint);}}
{{cqlsh> INSERT INTO cast_varint_test(k, varint_clmn) values(2, 1234567890123456789);}}
{{cqlsh> SELECT CAST(varint_clmn AS decimal) FROM cast_varint_test;}}
{{cast(varint_clmn as decimal)}}
{{------------------------------}}
{{ 1.23456789012345677E+18}}
{{(1 rows)}}
> Loss of digits when doing CAST from varint/bigint to decimal
> ------------------------------------------------------------
>
> Key: CASSANDRA-14170
> URL: https://issues.apache.org/jira/browse/CASSANDRA-14170
> Project: Cassandra
> Issue Type: Bug
> Environment: Tested with Cassandra 3.11.1 but this issue is present since the implementation of cast functions.
> Reporter: Daniel Fiala
> Priority: Minor
>
> Cast functions from numeric types to decimal type are implemented as conversion to double first and then from double to decimal: [https://github.com/apache/cassandra/compare/trunk...blerer:10310-3.0#diff-6aa4a8f76df6c30c5bb4026b8c9251eeR80].
> This can cause loss of digits for big values stored in varint or bigint. It is probably unexpected because decimal can store such values precisely.
> Examples:
> {{cqlsh> CREATE TABLE cast_bigint_test(k int PRIMARY KEY, bigint_clmn bigint);}}
> {{cqlsh> INSERT INTO cast_bigint_test(k, decimal_clmn) VALUES(2, 9223372036854775807);}}
> {{cqlsh> SELECT CAST(bigint_clmn AS decimal) FROM cast_bigint_test;}}
> {{cast(bigint_clmn as decimal)}}
> {{------------------------------}}
> {{9.223372036854776E+18}}
> {{(1 rows)}}
> {{cqlsh> CREATE TABLE cast_varint_test (k int PRIMARY KEY, varint_clmn varint);}}
> {{cqlsh> INSERT INTO cast_varint_test(k, varint_clmn) values(2, 1234567890123456789);}}
> {{cqlsh> SELECT CAST(varint_clmn AS decimal) FROM cast_varint_test;}}
> {{cast(varint_clmn as decimal)}}
> {{------------------------------}}
> 1.23456789012345677E+18
> {{(1 rows)}}
>
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