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https://issues.apache.org/jira/browse/CASSANDRA-11920?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15339015#comment-15339015
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Arindam Gupta commented on CASSANDRA-11920:
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Thanks Tyler Hobbs for your help. Please let me know if any further actions
required from my side.
One additional question : Do we need to change documentation also reflecting
this change?
> bloom_filter_fp_chance needs to be validated up front
> -----------------------------------------------------
>
> Key: CASSANDRA-11920
> URL: https://issues.apache.org/jira/browse/CASSANDRA-11920
> Project: Cassandra
> Issue Type: Bug
> Components: Lifecycle, Local Write-Read Paths
> Reporter: ADARSH KUMAR
> Assignee: Arindam Gupta
> Priority: Minor
> Labels: lhf
> Attachments: 11920-3.0.txt
>
>
> Hi,
> I was doing some bench-marking on bloom_filter_fp_chance values. Everything
> worked fine for values .01(default for STCS), .001, .0001. But when I set
> bloom_filter_fp_chance = .00001 i observed following behaviour:
> 1). Reads and writes looked normal from cqlsh.
> 2). SSttables are never created.
> 3). It just creates two files (*-Data.db and *-index.db) of size 0kb.
> 4). nodetool flush does not work and produce following exception:
> java.lang.UnsupportedOperationException: Unable to satisfy 1.0E-5 with 20
> buckets per element
> at
> org.apache.cassandra.utils.BloomCalculations.computeBloomSpec(BloomCalculations.java:150)
> .....
> I checked BloomCalculations class and following lines are responsible for
> this exception:
> if (maxFalsePosProb < probs[maxBucketsPerElement][maxK]) {
> throw new UnsupportedOperationException(String.format("Unable to
> satisfy %s with %s buckets per element",
> maxFalsePosProb,
> maxBucketsPerElement));
> }
> From the code it looks like a hard coaded validation (unless we can change
> the nuber of buckets).
> So, if this validation is hard coaded then why it is even allowed to set such
> value of bloom_fileter_fp_chance, that can prevent ssTable generation?
> Please correct this issue.
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