> Write performance decreases. > Check the logs for WARN messages from the GCInspector. With 2Gb and only 2 Cores you may be seeing ParNew compaction which pauses the server.
> Sometimes I have to wait 3-4 seconds to get a count even though there're only > couple of thousand small entries in a table. Count of columns in a row ? Could also be a GC issue. Cheers ----------------- Aaron Morton Freelance Cassandra Consultant New Zealand @aaronmorton http://www.thelastpickle.com On 19/04/2013, at 9:48 AM, Oleksandr Petrov <oleksandr.pet...@gmail.com> wrote: > Write performance decreases. > > Reads are basically blocked, too. Sometimes I have to wait 3-4 seconds to get > a count even though there're only couple of thousand small entries in a table. > > > On Thu, Apr 18, 2013 at 8:37 PM, aaron morton <aa...@thelastpickle.com> wrote: >> After about 1-2K inserts I get significant performance decrease. > > A decrease in performance doing what ? > > Cheers > > ----------------- > Aaron Morton > Freelance Cassandra Consultant > New Zealand > > @aaronmorton > http://www.thelastpickle.com > > On 19/04/2013, at 4:43 AM, Oleksandr Petrov <oleksandr.pet...@gmail.com> > wrote: > >> Hi, >> >> I'm trying to persist some event data, I've tried to identify the >> bottleneck, and it seems to work like that: >> >> If I create a table with primary key based on (application, environment, >> type and emitted_at): >> >> CREATE TABLE events (application varchar, environment varchar, type varchar, >> additional_info map<varchar, varchar>, hostname varchar, emitted_at >> timestamp, >> PRIMARY KEY (application, environment, type, emitted_at)); >> >> And insert events via CQL, prepared statements: >> >> INSERT INTO events (environment, application, hostname, emitted_at, type, >> additional_info) VALUES (?, ?, ?, ?, ?, ?); >> >> Values are: "local" "analytics" "noname" #inst >> "2013-04-18T16:37:02.723-00:00" "event_type" {"some" "value"} >> >> After about 1-2K inserts I get significant performance decrease. >> >> I've tried using only emitted_at (timestamp) as a primary key, OR writing >> additional_info data as a serialized JSON (varchar) instead of Map. Both >> scenarios seem to solve the performance degradation. >> >> I'm using Cassandra 1.2.3 from DataStax repository, running it on 2-core >> machine with 2GB Ram. >> >> What could I do wrong here? What may cause performance issues?.. >> Thank you >> >> >> -- >> alex p > > > > > -- > alex p
