Puneet, In addition to creating an initial number of regions, it appears, salt buckets is also used for determining the # of threads (?) while doing skip scan. Explain plan shows something like "client 60-way skip scan...". So, having a higher number of salt buckets should, theoretically, help query performance. Could you explain what kind of issues could pop-up having 150 to 200+ salt bytes?
On Thu, Feb 26, 2015 at 2:57 AM, Puneet Kumar Ojha < puneet.ku...@pubmatic.com> wrote: > Yes you can have more salt buckets than no of regions servers. Salt > buckets specififed will create thoe many number of regions. > > > > Depending upon what regions size is optimal –(dependent on table data) you > need to opt the salt bucket numbers. > > > > > > *From:* Vamsi Krishna [mailto:vamsi.attl...@gmail.com] > *Sent:* Thursday, February 26, 2015 11:25 AM > *To:* user@phoenix.apache.org > *Subject:* Re: Salt buckets optimization > > > > Can we have more no of salt buckets than the no of region servers? > > According to Phoenix documentation, I've read "*For optimal performance, > number of salt buckets should match number of region servers*". > > http://phoenix.apache.org/performance.html > > > > In our case, we are evaluating on a small cluster with two region servers > and we are observing better performance with 10 salt buckets compared to 2 > salt buckets and 20 salt buckets. > > > > Could someone please explain what's happening behind the scenes? > > > > Thanks, > > Vamsi Attluri. > > > > On Wed, Feb 25, 2015 at 6:56 PM, Puneet Kumar Ojha < > puneet.ku...@pubmatic.com> wrote: > > For big tables keep the salt bucket high, generally around 60-90. > > Smaller or join tables should have salt buckets as minimal may be 1-4. > > > > > > Thanks > > > > > > ------ Original message------ > > *From: *Krishna > > *Date: *Thu, Feb 26, 2015 07:42 > > *To: *d...@phoenix.apache.org;user@phoenix.apache.org; > > *Subject:*Salt buckets optimization > > > > Are there any recommendations for estimating and optimizing salt buckets > during table creation time? What, if any, are the cons of having high > number (200+) of salt buckets? Is it possible to update salt buckets after > table is created? > > > > Thanks > > > > >
