Wouldn't the "number of keys" part of *nodetool cfstats* run on every node, summed and divided by replication factor give you a decent approximation? Or are you really after a completely precise number?
On Mon, 11 Apr 2016 at 16:18 Jack Krupansky <jack.krupan...@gmail.com> wrote: > Agreed, that anything requiring a full table scan, short of batch > analytics,is an antipattern, although the goal is not to do a full scan per > se, but just get the row count. It still surprises people that Cassandra > cannot quickly get COUNT(*). The easy answer: Use DSE Search and do a Solr > query for q=*:* and that will very quickly return the total row count. I > presume that Stratio will handle this fine as well. > > > -- Jack Krupansky > > On Mon, Apr 11, 2016 at 11:10 AM, <sean_r_dur...@homedepot.com> wrote: > >> Cassandra is not good for table scan type queries (which count(*) >> typically is). While there are some attempts to do that (as noted below), >> this is a path I avoid. >> >> >> >> >> >> Sean Durity >> >> >> >> *From:* Max C [mailto:mc_cassan...@core43.com] >> *Sent:* Saturday, April 09, 2016 6:19 PM >> *To:* user@cassandra.apache.org >> *Subject:* Re: 1, 2, 3... >> >> >> >> Looks like this guy (Brian Hess) wrote a script to split the token range >> and run count(*) on each subrange: >> >> >> >> https://github.com/brianmhess/cassandra-count >> >> >> >> - Max >> >> >> >> On Apr 8, 2016, at 10:56 pm, Jeff Jirsa <jeff.ji...@crowdstrike.com> >> wrote: >> >> >> >> SELECT COUNT(*) probably works (with internal paging) on many datasets >> with enough time and assuming you don’t have any partitions that will kill >> you. >> >> >> >> No, it doesn’t count extra replicas / duplicates. >> >> >> >> The old way to do this (before paging / fetch size) was to use manual >> paging based on tokens/clustering keys: >> >> >> >> https://docs.datastax.com/en/cql/3.1/cql/cql_using/paging_c.html – >> SELECT’s WHERE clause can use token(), which is what you’d want to use to >> page through the whole token space. >> >> >> >> You could, in theory, issue thousands of queries in parallel, all for >> different token ranges, and then sum the results. That’s what something >> like spark would be doing. If you want to determine rows per node, limit >> the token range to that owned by the node (easier with 1 token than vnodes, >> with vnodes repeat num_tokens times). >> >> >> >> ------------------------------ >> >> 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. The Home Depot >> disclaims all responsibility and liability for the accuracy and content of >> this attachment and for any damages or losses arising from any >> inaccuracies, errors, viruses, e.g., worms, trojan horses, etc., or other >> items of a destructive nature, which may be contained in this attachment >> and shall not be liable for direct, indirect, consequential or special >> damages in connection with this e-mail message or its attachment. >> > >
