Hi Jeff - yes, I'm doing a select without where - specifically: select
uuid from table limit 1000;
Not inserting nulls, and nothing is TTL'd.
At this point with zero rows, the above select fails.
Sounds like my application needs a redesign as doing 1 billion inserts,
and 100 million deletes results in an unusable table. I'm using
Cassandra to de-duplicate data and that's not a good use case for it.
-Joe
On 10/25/2021 6:51 PM, Jeff Jirsa wrote:
The tombstone threshold is "how many tombstones are encountered within
a single read command", and the default is something like 100,000 (
https://github.com/apache/cassandra/blob/trunk/conf/cassandra.yaml#L1293-L1294
)
Deletes are not forbidden, but you have to read in such a way that you
touch less than 100,000 deletes per read.
Are you doing full table scans or SELECT without WHERE?
Are you inserting nulls in some columns?
Are you TTL'ing everything ?
On Mon, Oct 25, 2021 at 3:28 PM Joe Obernberger
<joseph.obernber...@gmail.com> wrote:
Update - after 10 days, I'm able to use the table again; prior to
that all selects timed out.
Are deletes basically forbidden with Cassandra? If you have a
table where you want to do lots of inserts and deletes, is there
an option that works in Cassandra? Even thought the table now has
zero rows, after deleting them, I can no longer do a select from
the table as it times out.
Thank you!
-Joe
On 10/14/2021 3:38 PM, Joe Obernberger wrote:
I'm not sure if tombstones is the issue; is it? Grace is set to
10 days, that time has not passed yet.
-Joe
On 10/14/2021 1:37 PM, James Brown wrote:
What is gc_grace_seconds set to on the table? Once that passes,
you can do `nodetool scrub` to more emphatically remove
tombstones...
On Thu, Oct 14, 2021 at 8:49 AM Joe Obernberger
<joseph.obernber...@gmail.com> wrote:
Hi all - I have a table where I've needed to delete a number
of rows.
I've run repair, but I still can't select from the table.
select * from doc.indexorganize limit 10;
OperationTimedOut: errors={'172.16.100.37:9042
<http://172.16.100.37:9042>': 'Client request
timeout. See Session.execute[_async](timeout)'},
last_host=172.16.100.37:9042 <http://172.16.100.37:9042>
Info on the table:
nodetool tablestats doc.indexorganize
Total number of tables: 97
----------------
Keyspace : doc
Read Count: 170275408
Read Latency: 1.6486837044783356 ms
Write Count: 6821769404
Write Latency: 0.08147347268570909 ms
Pending Flushes: 0
Table: indexorganize
SSTable count: 21
Old SSTable count: 0
Space used (live): 1536557040
Space used (total): 1536557040
Space used by snapshots (total): 1728378992
Off heap memory used (total): 46251932
SSTable Compression Ratio: 0.5218383898575761
Number of partitions (estimate): 17365415
Memtable cell count: 0
Memtable data size: 0
Memtable off heap memory used: 0
Memtable switch count: 12
Local read count: 17346304
Local read latency: NaN ms
Local write count: 31340451
Local write latency: NaN ms
Pending flushes: 0
Percent repaired: 100.0
Bytes repaired: 1.084GiB
Bytes unrepaired: 0.000KiB
Bytes pending repair: 0.000KiB
Bloom filter false positives: 0
Bloom filter false ratio: 0.00000
Bloom filter space used: 38030728
Bloom filter off heap memory used: 38030560
Index summary off heap memory used: 7653060
Compression metadata off heap memory used:
568312
Compacted partition minimum bytes: 51
Compacted partition maximum bytes: 86
Compacted partition mean bytes: 67
Average live cells per slice (last five
minutes):
73.53164556962025
Maximum live cells per slice (last five
minutes): 5722
Average tombstones per slice (last five
minutes): 1.0
Maximum tombstones per slice (last five
minutes): 1
Dropped Mutations: 0
nodetool tablehistograms doc.indexorganize
doc/indexorganize histograms
Percentile Read Latency Write Latency SSTables
Partition
Size Cell Count
(micros)
(micros) (bytes)
50% 0.00 0.00 0.00
60 1
75% 0.00 0.00 0.00
86 2
95% 0.00 0.00 0.00
86 2
98% 0.00 0.00 0.00
86 2
99% 0.00 0.00 0.00
86 2
Min 0.00 0.00 0.00
51 0
Max 0.00 0.00 0.00
86 2
Any ideas on what I can do? Thank you!
-Joe
--
James Brown
Engineer
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