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Posted to user@cassandra.apache.org by shalom sagges <sh...@gmail.com> on 2018/04/02 20:57:01 UTC
Large Partitions
Hi All,
I ran nodetool cfstats (v2.0.14) on a keyspace and found that there are a
few large partitions. I assume that since "Compacted partition maximum
bytes": 802187438 (~800 MB) and since
"Compacted partition mean bytes": 100465 (~100 KB), it means that most
partitions are in okay size and only a few are large. Am I assuming
correctly?
If so, can anyone suggest how to find those large partitions and how to
deal with them? (cfstats output below)
Thanks!
nodetool cfstats keyspace1;
Table: table1
SSTable count: 16
Space used (live), bytes: 453844035587
Space used (total), bytes: 453844035587
Off heap memory used (total), bytes: 440787635
SSTable Compression Ratio: 0.17417149031966575
Number of keys (estimate): 33651200
Memtable cell count: 27966
Memtable data size, bytes: 41698140
Memtable switch count: 199727
Local read count: 86494530
Local read latency: 2.646 ms
Local write count: 247712138
Local write latency: 0.030 ms
Pending tasks: 0
Bloom filter false positives: 2182242
Bloom filter false ratio: 0.02251
Bloom filter space used, bytes: 53135136
Bloom filter off heap memory used, bytes: 53135008
Index summary off heap memory used, bytes: 11560419
Compression metadata off heap memory used, bytes: 376092208
Compacted partition minimum bytes: 373
*Compacted partition maximum bytes: 802187438Compacted partition mean
bytes: 100465*
Average live cells per slice (last five minutes): 37.0
Average tombstones per slice (last five minutes): 0.0
Re: Large Partitions
Posted by shalom sagges <sh...@gmail.com>.
Thanks Ali!
I use a 13 months TTL on this table. I guess I need to remodel this table.
And I'll definitely try this tool.
On Tue, Apr 3, 2018 at 1:28 AM, Ali Hubail <Al...@petrolink.com> wrote:
> system.log should show you some warnings about wide rows. Do a grep on
> system.log for 'Writing large partition' The message could be different for
> the c* version you're using though. Plus, this doesn't show you all of the
> large partitions.
>
> There is a nice tool that analyzes sstables and can show the large
> partitions:
> https://github.com/tolbertam/sstable-tools
>
>
> By "how to deal with them?" it depends. If you don't need those
> partitions then you can delete them. You can also use TTL if it fits you or
> remodel your table to only hold upto 100k rows or 100mb per partition
> (whichever comes first). If you're going to remodel the table, aim for much
> less than 100k/100mb per partition.
>
> *Ali Hubail*
>
> Confidentiality warning: This message and any attachments are intended
> only for the persons to whom this message is addressed, are confidential,
> and may be privileged. If you are not the intended recipient, you are
> hereby notified that any review, retransmission, conversion to hard copy,
> copying, modification, circulation or other use of this message and any
> attachments is strictly prohibited. If you receive this message in error,
> please notify the sender immediately by return email, and delete this
> message and any attachments from your system. Petrolink International
> Limited its subsidiaries, holding companies and affiliates disclaims all
> responsibility from and accepts no liability whatsoever for the
> consequences of any unauthorized person acting, or refraining from acting,
> on any information contained in this message. For security purposes, staff
> training, to assist in resolving complaints and to improve our customer
> service, email communications may be monitored and telephone calls may be
> recorded.
>
>
> *shalom sagges <shalomsagges@gmail.com <sh...@gmail.com>>*
>
> 04/02/2018 03:57 PM
> Please respond to
> user@cassandra.apache.org
>
> To
> user@cassandra.apache.org,
>
> cc
> Subject
> Large Partitions
>
>
>
>
> Hi All,
>
> I ran nodetool cfstats (v2.0.14) on a keyspace and found that there are a
> few large partitions. I assume that since "Compacted partition maximum
> bytes": 802187438 (~800 MB) and since
> "Compacted partition mean bytes": 100465 (~100 KB), it means that most
> partitions are in okay size and only a few are large. Am I assuming
> correctly?
>
> If so, can anyone suggest how to find those large partitions and how to
> deal with them? (cfstats output below)
>
> Thanks!
>
>
> nodetool cfstats keyspace1;
>
> Table: table1
> SSTable count: 16
> Space used (live), bytes: 453844035587
> Space used (total), bytes: 453844035587
> Off heap memory used (total), bytes: 440787635
> SSTable Compression Ratio: 0.17417149031966575
> Number of keys (estimate): 33651200
> Memtable cell count: 27966
> Memtable data size, bytes: 41698140
> Memtable switch count: 199727
> Local read count: 86494530
> Local read latency: 2.646 ms
> Local write count: 247712138
> Local write latency: 0.030 ms
> Pending tasks: 0
> Bloom filter false positives: 2182242
> Bloom filter false ratio: 0.02251
> Bloom filter space used, bytes: 53135136
> Bloom filter off heap memory used, bytes: 53135008
> Index summary off heap memory used, bytes: 11560419
> Compression metadata off heap memory used, bytes: 376092208
> Compacted partition minimum bytes: 373
>
> * Compacted partition maximum bytes: 802187438 Compacted partition mean
> bytes: 100465*
> Average live cells per slice (last five minutes): 37.0
> Average tombstones per slice (last five minutes): 0.0
>
>
Re: Large Partitions
Posted by Ali Hubail <Al...@petrolink.com>.
system.log should show you some warnings about wide rows. Do a grep on
system.log for 'Writing large partition' The message could be different
for the c* version you're using though. Plus, this doesn't show you all of
the large partitions.
There is a nice tool that analyzes sstables and can show the large
partitions:
https://github.com/tolbertam/sstable-tools
By "how to deal with them?" it depends. If you don't need those partitions
then you can delete them. You can also use TTL if it fits you or remodel
your table to only hold upto 100k rows or 100mb per partition (whichever
comes first). If you're going to remodel the table, aim for much less than
100k/100mb per partition.
Ali Hubail
Confidentiality warning: This message and any attachments are intended
only for the persons to whom this message is addressed, are confidential,
and may be privileged. If you are not the intended recipient, you are
hereby notified that any review, retransmission, conversion to hard copy,
copying, modification, circulation or other use of this message and any
attachments is strictly prohibited. If you receive this message in error,
please notify the sender immediately by return email, and delete this
message and any attachments from your system. Petrolink International
Limited its subsidiaries, holding companies and affiliates disclaims all
responsibility from and accepts no liability whatsoever for the
consequences of any unauthorized person acting, or refraining from acting,
on any information contained in this message. For security purposes, staff
training, to assist in resolving complaints and to improve our customer
service, email communications may be monitored and telephone calls may be
recorded.
shalom sagges <sh...@gmail.com>
04/02/2018 03:57 PM
Please respond to
user@cassandra.apache.org
To
user@cassandra.apache.org,
cc
Subject
Large Partitions
Hi All,
I ran nodetool cfstats (v2.0.14) on a keyspace and found that there are a
few large partitions. I assume that since "Compacted partition maximum
bytes": 802187438 (~800 MB) and since
"Compacted partition mean bytes": 100465 (~100 KB), it means that most
partitions are in okay size and only a few are large. Am I assuming
correctly?
If so, can anyone suggest how to find those large partitions and how to
deal with them? (cfstats output below)
Thanks!
nodetool cfstats keyspace1;
Table: table1
SSTable count: 16
Space used (live), bytes: 453844035587
Space used (total), bytes: 453844035587
Off heap memory used (total), bytes: 440787635
SSTable Compression Ratio: 0.17417149031966575
Number of keys (estimate): 33651200
Memtable cell count: 27966
Memtable data size, bytes: 41698140
Memtable switch count: 199727
Local read count: 86494530
Local read latency: 2.646 ms
Local write count: 247712138
Local write latency: 0.030 ms
Pending tasks: 0
Bloom filter false positives: 2182242
Bloom filter false ratio: 0.02251
Bloom filter space used, bytes: 53135136
Bloom filter off heap memory used, bytes: 53135008
Index summary off heap memory used, bytes: 11560419
Compression metadata off heap memory used, bytes: 376092208
Compacted partition minimum bytes: 373
Compacted partition maximum bytes: 802187438
Compacted partition mean bytes: 100465
Average live cells per slice (last five minutes): 37.0
Average tombstones per slice (last five minutes): 0.0