I see the sstablemetadata tool as far back as 1.2.19 (in tools/bin).
Sean Durity From: Anishek Agarwal [mailto:anis...@gmail.com] Sent: Tuesday, February 23, 2016 3:37 AM To: user@cassandra.apache.org Subject: Re: High Bloom filter false ratio Looks like that sstablemetadata is available in 2.2 , we are on 2.0.x do you know anything that will work on 2.0.x On Tue, Feb 23, 2016 at 1:48 PM, Anishek Agarwal <anis...@gmail.com<mailto:anis...@gmail.com>> wrote: Thanks Jeff, Awesome will look at the tools and JMX endpoint. our settings are below originated from the jira you posted above as the base. we are running on 48 core machines with 2 SSD disks of 800 GB each . MAX_HEAP_SIZE="6G" HEAP_NEWSIZE="4G" JVM_OPTS="$JVM_OPTS -XX:+UseParNewGC" JVM_OPTS="$JVM_OPTS -XX:+UseConcMarkSweepGC" JVM_OPTS="$JVM_OPTS -XX:+CMSParallelRemarkEnabled" JVM_OPTS="$JVM_OPTS -XX:SurvivorRatio=6" JVM_OPTS="$JVM_OPTS -XX:MaxTenuringThreshold=4" JVM_OPTS="$JVM_OPTS -XX:CMSInitiatingOccupancyFraction=70" JVM_OPTS="$JVM_OPTS -XX:+UseCMSInitiatingOccupancyOnly" JVM_OPTS="$JVM_OPTS -XX:+UseTLAB" JVM_OPTS="$JVM_OPTS -XX:MaxPermSize=256m" JVM_OPTS="$JVM_OPTS -XX:+AggressiveOpts" JVM_OPTS="$JVM_OPTS -XX:+UseCompressedOops" JVM_OPTS="$JVM_OPTS -XX:+CMSScavengeBeforeRemark" JVM_OPTS="$JVM_OPTS -XX:ConcGCThreads=48" JVM_OPTS="$JVM_OPTS -XX:ParallelGCThreads=48" JVM_OPTS="$JVM_OPTS -XX:-ExplicitGCInvokesConcurrent" JVM_OPTS="$JVM_OPTS -XX:+UnlockDiagnosticVMOptions" JVM_OPTS="$JVM_OPTS -XX:+UseGCTaskAffinity" JVM_OPTS="$JVM_OPTS -XX:+BindGCTaskThreadsToCPUs" # earlier value 131072 JVM_OPTS="$JVM_OPTS -XX:ParGCCardsPerStrideChunk=32678" JVM_OPTS="$JVM_OPTS -XX:CMSScheduleRemarkEdenSizeThreshold=104857600" JVM_OPTS="$JVM_OPTS -XX:CMSRescanMultiple=32678" JVM_OPTS="$JVM_OPTS -XX:CMSConcMarkMultiple=32678" On Tue, Feb 23, 2016 at 1:06 PM, Jeff Jirsa <jeff.ji...@crowdstrike.com<mailto:jeff.ji...@crowdstrike.com>> wrote: There exists a JMX endpoint called forceUserDefinedCompaction that takes a comma separated list of sstables to compact together. There also exists a tool called sstablemetadata (may be in a ‘cassandra-tools’ package separate from whatever package you used to install cassandra, or in the tools/ directory of your binary package). Using sstablemetadata, you can look at the maxTimestamp for each table, and the ‘Estimated droppable tombstones’. Using those two fields, you could, very easily, write a script that gives you a list of sstables that you could feed to forceUserDefinedCompaction to join together to eliminate leftover waste. Your long ParNew times may be fixable by increasing the new gen size of your heap – the general guidance in cassandra-env.sh is out of date, you may want to reference CASSANDRA-8150 for “newer” advice ( http://issues.apache.org/jira/browse/CASSANDRA-8150 ) - Jeff From: Anishek Agarwal Reply-To: "user@cassandra.apache.org<mailto:user@cassandra.apache.org>" Date: Monday, February 22, 2016 at 8:33 PM To: "user@cassandra.apache.org<mailto:user@cassandra.apache.org>" Subject: Re: High Bloom filter false ratio Hey Jeff, Thanks for the clarification, I did not explain my self clearly, the max_stable_age_days is set to 30 days and the ttl on every insert is set to 30 days also by default. gc_grace_seconds is 0, so i would think the sstable as a whole would be deleted. Because of the problems mentioned by at 1) above it looks like, there might be cases where the table just lies around since no compaction is happening on it and even though everything is expired it would still not be deleted? for 3) the average read is pretty good, though the throughput doesn't seem to be that great, when no repair is running we get GCIns > 200ms every couple of hours once, otherwise its every 10-20 mins INFO [ScheduledTasks:1] 2016-02-23 05:15:03,070 GCInspector.java (line 116) GC for ParNew: 205 ms for 1 collections, 1712439128 used; max is 7784628224 INFO [ScheduledTasks:1] 2016-02-23 08:30:47,709 GCInspector.java (line 116) GC for ParNew: 242 ms for 1 collections, 1819126928 used; max is 7784628224 INFO [ScheduledTasks:1] 2016-02-23 09:09:55,085 GCInspector.java (line 116) GC for ParNew: 374 ms for 1 collections, 1829660304 used; max is 7784628224 INFO [ScheduledTasks:1] 2016-02-23 09:11:21,245 GCInspector.java (line 116) GC for ParNew: 419 ms for 1 collections, 2309875224 used; max is 7784628224 INFO [ScheduledTasks:1] 2016-02-23 09:35:50,717 GCInspector.java (line 116) GC for ParNew: 231 ms for 1 collections, 2515325328 used; max is 7784628224 INFO [ScheduledTasks:1] 2016-02-23 09:38:47,194 GCInspector.java (line 116) GC for ParNew: 252 ms for 1 collections, 1724241952 used; max is 7784628224 our reading patterns are dependent on BF to work efficiently as we do a lot of reads for keys that may not exists because its time series and we segregate data based on hourly boundary from epoch. hey Christoper, yes every row in the stable that should have been deleted has "d" in that column. Also the key for one of the row is as "key": "0008000000000cdd5edd000008000000000006251000" how do i get it back to normal readable format to get the (long,long) -- composite partition key back? Looks like i have to force a major compaction to delete a lot of data ? are there any other solutions ? thanks anishek On Mon, Feb 22, 2016 at 11:21 PM, Jeff Jirsa <jeff.ji...@crowdstrike.com<mailto:jeff.ji...@crowdstrike.com>> wrote: 1) getFullyExpiredSSTables in 2.0 isn’t as thorough as many expect, so it’s very likely that some sstables stick around longer than you expect. 2) max_sstable_age_days tells cassandra when to stop compacting that file, not when to delete it. 3) You can change the window size using both the base_time_seconds parameter and max_sstable_age_days parameter (use the former to set the size of the first window, and the latter to determine how long before you stop compacting that window). It’s somewhat non-intuitive. Your read latencies actually look pretty reasonable, are you sure you’re not simply hitting GC pauses that cause your queries to run longer than you expect? Do you have graphs of GC time (first derivative of total gc time is common for tools like graphite), or do you see ‘gcinspector’ in your logs indicating pauses > 200ms? From: Anishek Agarwal Reply-To: "user@cassandra.apache.org<mailto:user@cassandra.apache.org>" Date: Sunday, February 21, 2016 at 11:13 PM To: "user@cassandra.apache.org<mailto:user@cassandra.apache.org>" Subject: Re: High Bloom filter false ratio Hey guys, Just did some more digging ... looks like DTCS is not removing old data completely, I used sstable2json for one such table and saw old data there. we have a value of 30 for max_stable_age_days for the table. One of the columns showed data as :["2015-12-10 11\\:03+0530:", "56690ea2", 1449725602552000, "d"] what is the meaning of "d" in the last IS_MARKED_FOR_DELETE column ? I see data from 10 dec 2015 still there, looks like there are a few issues with DTCS, Operationally what choices do i have to rectify this, We are on version 2.0.15. thanks anishek On Mon, Feb 22, 2016 at 10:23 AM, Anishek Agarwal <anis...@gmail.com<mailto:anis...@gmail.com>> wrote: We are using DTCS have a 30 day window for them before they are cleaned up. I don't think with DTCS we can do anything about table sizing. Please do let me know if there are other ideas. On Sat, Feb 20, 2016 at 12:51 AM, Jaydeep Chovatia <chovatia.jayd...@gmail.com<mailto:chovatia.jayd...@gmail.com>> wrote: To me following three looks on higher side: SSTable count: 1289 In order to reduce SSTable count see if you are compacting of not (If using STCS). Is it possible to change this to LCS? Number of keys (estimate): 345137664 (345M partition keys) I don't have any suggestion about reducing this unless you partition your data. Bloom filter space used, bytes: 493777336 (400MB is huge) If number of keys are reduced then this will automatically reduce bloom filter size I believe. Jaydeep On Thu, Feb 18, 2016 at 7:52 PM, Anishek Agarwal <anis...@gmail.com<mailto:anis...@gmail.com>> wrote: Hey all, @Jaydeep here is the cfstats output from one node. Read Count: 1721134722 Read Latency: 0.04268825050756254 ms. Write Count: 56743880 Write Latency: 0.014650376727851532 ms. Pending Tasks: 0 Table: user_stay_points SSTable count: 1289 Space used (live), bytes: 122141272262 Space used (total), bytes: 224227850870 Off heap memory used (total), bytes: 653827528 SSTable Compression Ratio: 0.4959736121441446 Number of keys (estimate): 345137664 Memtable cell count: 339034 Memtable data size, bytes: 106558314 Memtable switch count: 3266 Local read count: 1721134803 Local read latency: 0.048 ms Local write count: 56743898 Local write latency: 0.018 ms Pending tasks: 0 Bloom filter false positives: 40664437 Bloom filter false ratio: 0.69058 Bloom filter space used, bytes: 493777336 Bloom filter off heap memory used, bytes: 493767024 Index summary off heap memory used, bytes: 91677192 Compression metadata off heap memory used, bytes: 68383312 Compacted partition minimum bytes: 104 Compacted partition maximum bytes: 1629722 Compacted partition mean bytes: 1773 Average live cells per slice (last five minutes): 0.0 Average tombstones per slice (last five minutes): 0.0 @Tyler Hobbs we are using cassandra 2.0.15 so https://issues.apache.org/jira/browse/CASSANDRA-8525 shouldnt occur. Other problems looks like will be fixed in 3.0 .. we will mostly try and slot in an upgrade to 3.x version towards second quarter of this year. @Daemon Latencies seem to have higher ratios, attached is the graph. I am mostly trying to look at Bloom filters, because the way we do reads, we read data with non existent partition keys and it seems to be taking long to respond, like for 720 queries it takes 2 seconds, with all 721 queries not returning anything. the 720 queries are done in sequence of 180 queries each with 180 of them running in parallel. thanks anishek On Fri, Feb 19, 2016 at 3:09 AM, Jaydeep Chovatia <chovatia.jayd...@gmail.com<mailto:chovatia.jayd...@gmail.com>> wrote: How many partition keys exists for the table which shows this problem (or provide nodetool cfstats for that table)? On Thu, Feb 18, 2016 at 11:38 AM, daemeon reiydelle <daeme...@gmail.com<mailto:daeme...@gmail.com>> wrote: The bloom filter buckets the values in a small number of buckets. I have been surprised by how many cases I see with large cardinality where a few values populate a given bloom leaf, resulting in high false positives, and a surprising impact on latencies! Are you seeing 2:1 ranges between mean and worse case latencies (allowing for gc times)? Daemeon Reiydelle On Feb 18, 2016 8:57 AM, "Tyler Hobbs" <ty...@datastax.com<mailto:ty...@datastax.com>> wrote: You can try slightly lowering the bloom_filter_fp_chance on your table. Otherwise, it's possible that you're repeatedly querying one or two partitions that always trigger a bloom filter false positive. You could try manually tracing a few queries on this table (for non-existent partitions) to see if the bloom filter rejects them. Depending on your Cassandra version, your false positive ratio could be inaccurate: https://issues.apache.org/jira/browse/CASSANDRA-8525 There are also a couple of recent improvements to bloom filters: * https://issues.apache.org/jira/browse/CASSANDRA-8413 * https://issues.apache.org/jira/browse/CASSANDRA-9167 On Thu, Feb 18, 2016 at 1:35 AM, Anishek Agarwal <anis...@gmail.com<mailto:anis...@gmail.com>> wrote: Hello, We have a table with composite partition key with humungous cardinality, its a combination of (long,long). On the table we have bloom_filter_fp_chance=0.010000. On doing "nodetool cfstats" on the 5 nodes we have in the cluster we are seeing "Bloom filter false ratio:" in the range of 0.7 -0.9. I thought over time the bloom filter would adjust to the key space cardinality, we have been running the cluster for a long time now but have added significant traffic from Jan this year, which would not lead to writes in the db but would lead to high reads to see if are any values. Are there any settings that can be changed to allow better ratio. Thanks Anishek -- Tyler Hobbs DataStax<http://datastax.com/> ________________________________ The information in this Internet Email is confidential and may be legally privileged. It is intended solely for the addressee. Access to this Email by anyone else is unauthorized. If you are not the intended recipient, any disclosure, copying, distribution or any action taken or omitted to be taken in reliance on it, is prohibited and may be unlawful. When addressed to our clients any opinions or advice contained in this Email are subject to the terms and conditions expressed in any applicable governing The Home Depot terms of business or client engagement letter. 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