[CASSANDRA-11920] bloom_filter_fp_chance needs to be validated up front

• Type: Bug
• Status: Resolved
• Priority: Low
• Resolution: Fixed
• Fix Version/s: 2.2.7, 3.0.8, 3.8
• Component/s: Legacy/Local Write-Read Paths, Local/Startup and Shutdown
• Labels: lhf
• Severity: Low
• Assignee: Arindam Gupta
• Reporter: ADARSH KUMAR

Authors

Arindam Gupta

Reviewers

Tom Hobbs

• Tester: ADARSH KUMAR
• Created: 30/May/16 09:04
• Updated: 16/Apr/19 09:30
• Resolved: 21/Jun/16 16:17

Description

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.