[
https://issues.apache.org/jira/browse/CASSANDRA-9224?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14546049#comment-14546049
]
Tyler Hobbs commented on CASSANDRA-9224:
----------------------------------------
What version of python are you running the tests with? With 2.7.6, I get the
problem that I mentioned in the description about using high precision values.
Here's what I get for output on the dtest:
{noformat}
part | id | val1 | val2
------+----+---------------------------+-----------------------
+ | 1 | 5.999999999999999e-08 | 5.99999978589949e-08
+ | 2 | 6e-07 | 6.000000212225132e-07
+ | 3 | 6e-06 | 6.000000212225132e-06
+ | 4 | 6e-05 | 5.999999848427e-05
+ | 5 | 0.0006 | 0.00060000002849847
+ | 6 | 0.006 | 0.00600000005215406
+ | 7 | 0.06 | 0.05999999865889549
+ | 8 | 0.59999999999999998 | 0.60000002384185791
+ | 9 | 6 | 6
+ | 10 | 6 | 6
+ | 11 | 6 | 6
+ | 12 | 6 | 6
+ | 13 | 6 | 6
+ | 14 | 6 | 6
+ | 15 | 6.0999999999999996 | 6.0999999046325684
+ | 16 | 6.1200000000000001 | 6.119999885559082
+ | 17 | 6.1230000000000002 | 6.1230001449584961
+ | 18 | 6.1234000000000002 | 6.1234002113342285
+ | 19 | 6.1234500000000001 | 6.1234498023986816
+ | 20 | 6.1234539999999997 | 6.1234540939331055
+ | 21 | 6.1234549999999999 | 6.1234550476074219
+ | 22 | 6.123456 | 6.1234560012817383
+ | 23 | 6.1234564999999996 | 6.1234564781188965
+ | 24 | 6.1234555000000004 | 6.1234555244445801
+ | 25 | 6.1234555500000001 | 6.1234555244445801
+ | 26 | 6.1234555555555499 | 6.1234555244445801
+ | 27 | 16.1234499999999983 | 16.1234493255615234
+ | 28 | 116.1234500000000054 | 116.1234512329101562
+ | 29 | 1116.123450000000048 | 1116.1234130859375
+ | 30 | 11116.1234499999991385 | 11116.123046875
+ | 31 | 111116.1234499999991385 | 111116.125
+ | 32 | 1111116.1234500000718981 | 1111116.125
+ | 33 | 11111116.1234499998390675 | 11111116
{noformat}
A few other comments on the patch:
* Use one space after '#' for comments in python
* Python supports conditionals like {{if -4 <= exponent < float_precision:}}
* In 2.1, the patch needs an import of {{sys}} in cql3handling.py
* The dtest should use {{\@since('2.1')}}
Overall, very nice job on the tests! Thank you for taking the time to write
those.
> Figure out a better default float precision rule for cqlsh
> ----------------------------------------------------------
>
> Key: CASSANDRA-9224
> URL: https://issues.apache.org/jira/browse/CASSANDRA-9224
> Project: Cassandra
> Issue Type: Improvement
> Components: Tools
> Reporter: Tyler Hobbs
> Assignee: Stefania
> Labels: cqlsh
> Fix For: 3.x, 2.1.x, 2.2.x
>
>
> We currently use a {{DEFAULT_FLOAT_PRECISION}} of 5 in cqlsh with formatting
> {{'%.*g' % (float_precision, val)}}. In practice, this is way too low. For
> example, 12345.5 will show up as 123456. Since the float precision is used
> for cqlsh's COPY TO, it's particularly important that we maintain as much
> precision as is practical by default.
> There are some other tricky considerations, though. If the precision is too
> high, python will do something like this:
> {noformat}
> > '%.25g' % (12345.5555555555555555,)
> '12345.55555555555474711582'
> {noformat}
> That's not terrible, but it would be nice to avoid if we can.
--
This message was sent by Atlassian JIRA
(v6.3.4#6332)
