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From Jeff Jirsa <jeff.ji...@crowdstrike.com>
Subject Re: Row cache not working
Date Mon, 03 Oct 2016 22:58:29 GMT
That’s true for versions 2.1 and newer. However, it’s possible that 3.0 engine rewrite
introduced a bug or two that haven’t yet been found. 

 

 

From: Hannu Kröger <hkroger@gmail.com>
Reply-To: "user@cassandra.apache.org" <user@cassandra.apache.org>
Date: Monday, October 3, 2016 at 3:52 PM
To: "user@cassandra.apache.org" <user@cassandra.apache.org>
Subject: Re: Row cache not working

 

If I remember correctly row cache caches only N rows from the beginning of the partition.
N being some configurable number. 

 

See this link which is suggesting that:

http://www.datastax.com/dev/blog/row-caching-in-cassandra-2-1

 

Br,

Hannu

 

On 4 Oct 2016, at 1.32, Edward Capriolo <edlinuxguru@gmail.com> wrote:

Since the feature is off by default. The coverage might could be only as deep as the specific
tests that test it.

 

On Mon, Oct 3, 2016 at 4:54 PM, Jeff Jirsa <jeff.jirsa@crowdstrike.com> wrote:

Seems like it’s probably worth opening a jira issue to track it (either to confirm it’s
a bug, or to be able to better explain if/that it’s working as intended – the row cache
is probably missing because trace indicates the read isn’t cacheable, but I suspect it should
be cacheable). 

                                                                                         
                                                                                         
                                                        

Do note, though, that setting rows_per_partition to ALL can be very very very dangerous if
you have very wide rows in any of your tables with row cache enabled.

 

 

 

From: Abhinav Solan <abhinav.solan@gmail.com>
Reply-To: "user@cassandra.apache.org" <user@cassandra.apache.org>
Date: Monday, October 3, 2016 at 1:38 PM
To: "user@cassandra.apache.org" <user@cassandra.apache.org>
Subject: Re: Row cache not working

 

It's cassandra 3.0.7,  

I had to set caching = {'keys': 'ALL', 'rows_per_partition': 'ALL'}, then only it works don't
know why.

If I set 'rows_per_partition':'1' then it does not work.

 

Also wanted to ask one thing, if I set row_cache_save_period: 60 then this cache would be
refreshed automatically or it would be lazy, whenever the fetch call is made then only it
caches it.

 

On Mon, Oct 3, 2016 at 1:31 PM Jeff Jirsa <jeff.jirsa@crowdstrike.com> wrote:

Which version of Cassandra are you running (I can tell it’s newer than 2.1, but exact version
would be useful)? 

 

From: Abhinav Solan <abhinav.solan@gmail.com>
Reply-To: "user@cassandra.apache.org" <user@cassandra.apache.org>
Date: Monday, October 3, 2016 at 11:35 AM
To: "user@cassandra.apache.org" <user@cassandra.apache.org>
Subject: Re: Row cache not working

 

Hi, can anyone please help me with this 

 

Thanks,

Abhinav

 

On Fri, Sep 30, 2016 at 6:20 PM Abhinav Solan <abhinav.solan@gmail.com> wrote:

Hi Everyone, 

 

My table looks like this -

CREATE TABLE test.reads (

    svc_pt_id bigint,

    meas_type_id bigint,

    flags bigint,

    read_time timestamp,

    value double,

    PRIMARY KEY ((svc_pt_id, meas_type_id))

) WITH bloom_filter_fp_chance = 0.1

    AND caching = {'keys': 'ALL', 'rows_per_partition': '10'}

    AND comment = ''

    AND compaction = {'class': 'org.apache.cassandra.db.compaction.LeveledCompactionStrategy'}

    AND compression = {'chunk_length_in_kb': '64', 'class': 'org.apache.cassandra.io.compress.LZ4Compressor'}

    AND crc_check_chance = 1.0

    AND dclocal_read_repair_chance = 0.1

    AND default_time_to_live = 0

    AND gc_grace_seconds = 864000

    AND max_index_interval = 2048

    AND memtable_flush_period_in_ms = 0

    AND min_index_interval = 128

    AND read_repair_chance = 0.0

    AND speculative_retry = '99PERCENTILE';

 

Have set up the C* nodes with

row_cache_size_in_mb: 1024

row_cache_save_period: 14400

 

and I am making this query 

select svc_pt_id, meas_type_id, read_time, value FROM cts_svc_pt_latest_int_read where svc_pt_id
= -9941235 and meas_type_id = 146;

 

with tracing on every time it says Row cache miss

 

activity                                                                                 
                                                                        | timestamp      
           | source          | source_elapsed

-------------------------------------------------------------------------------------------------------------------------------------------------------------------+----------------------------+-----------------+----------------

                                                                                         
                                                      Execute CQL3 query | 2016-09-30 18:15:00.446000
|  192.168.199.75 |              0

 Parsing select svc_pt_id, meas_type_id, read_time, value FROM cts_svc_pt_latest_int_read
where svc_pt_id = -9941235 and meas_type_id = 146; [SharedPool-Worker-1] | 2016-09-30 18:15:00.446000
|  192.168.199.75 |            111

                                                                                         
                               Preparing statement [SharedPool-Worker-1] | 2016-09-30 18:15:00.446000
|  192.168.199.75 |            209

                                                                                         
                reading data from /192.168.170.186 [SharedPool-Worker-1] | 2016-09-30 18:15:00.446001
|  192.168.199.75 |            370

                                                                             Sending READ
message to /192.168.170.186 [MessagingService-Outgoing-/192.168.170.186] | 2016-09-30 18:15:00.446001
|  192.168.199.75 |            450

                                                              REQUEST_RESPONSE message received
from /192.168.170.186 [MessagingService-Incoming-/192.168.170.186] | 2016-09-30 18:15:00.448000
|  192.168.199.75 |           2469

                                                                                         
         Processing response from /192.168.170.186 [SharedPool-Worker-8] | 2016-09-30 18:15:00.448000
|  192.168.199.75 |           2609

                                                                            READ message received
from /192.168.199.75 [MessagingService-Incoming-/192.168.199.75] | 2016-09-30 18:15:00.449000
| 192.168.170.186 |             75

                                                                                         
                                    Row cache miss [SharedPool-Worker-2] | 2016-09-30 18:15:00.449000
| 192.168.170.186 |            218

                                              Fetching data but not populating cache as query
does not query from the start of the partition [SharedPool-Worker-2] | 2016-09-30 18:15:00.449000
| 192.168.170.186 |            246

                                                                              Executing single-partition
query on cts_svc_pt_latest_int_read [SharedPool-Worker-2] | 2016-09-30 18:15:00.449000 | 192.168.170.186
|            259

                                                                                         
                      Acquiring sstable references [SharedPool-Worker-2] | 2016-09-30 18:15:00.449001
| 192.168.170.186 |            281

                                                                                         
                         Merging memtable contents [SharedPool-Worker-2] | 2016-09-30 18:15:00.449001
| 192.168.170.186 |            295

                                                                                         
                       Merging data from sstable 8 [SharedPool-Worker-2] | 2016-09-30 18:15:00.449001
| 192.168.170.186 |            326

                                                                                         
                       Key cache hit for sstable 8 [SharedPool-Worker-2] | 2016-09-30 18:15:00.449001
| 192.168.170.186 |            351

                                                                                         
                       Merging data from sstable 7 [SharedPool-Worker-2] | 2016-09-30 18:15:00.449001
| 192.168.170.186 |            439

                                                                                         
                       Key cache hit for sstable 7 [SharedPool-Worker-2] | 2016-09-30 18:15:00.449001
| 192.168.170.186 |            468

                                                                                         
                 Read 1 live and 0 tombstone cells [SharedPool-Worker-2] | 2016-09-30 18:15:00.449001
| 192.168.170.186 |            615

                                                                                         
             Enqueuing response to /192.168.199.75 [SharedPool-Worker-2] | 2016-09-30 18:15:00.449002
| 192.168.170.186 |            766

                                                                   Sending REQUEST_RESPONSE
message to /192.168.199.75 [MessagingService-Outgoing-/192.168.199.75] | 2016-09-30 18:15:00.449002
| 192.168.170.186 |            897

                                                                                         
                                                        Request complete | 2016-09-30 18:15:00.448888
|  192.168.199.75 |           2888

 

Can please anyone tell me what I am doing wrong?

 

Thanks,

Abhinav

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____________________________________________________________________
CONFIDENTIALITY NOTE: This e-mail and any attachments are confidential and may be legally
privileged. If you are not the intended recipient, do not disclose, copy, distribute, or use
this email or any attachments. If you have received this in error please let the sender know
and then delete the email and all attachments.

 

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