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 <edlinuxg...@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.ji...@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.so...@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.ji...@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.so...@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.so...@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 >> >> ____________________________________________________________________ >> CONFIDENTIALITY NOTE: This e-mail and any attachments are confidential and >> may be legally privileged. 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