High fetch times


(Arik Gaisler) #1

Im using ElasticHQ to monitor our cluster and I am noticing that our Search
Fetch times are about 5X more then query times, which seems unreasonable
(20ms vs ~4ms)

Im also noticing a 1.44 mb swap space on one of the nodes (the other node
is at 0)

We're using a 2 node cluster, 2 shards 1 replica on EC2 m1.small instances

Our index contains about 27K docs, total size of ~ 60mb (pretty small -
hence the small instance)

Any suggestions to why?

Arik

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(Itamar Syn-Hershko) #2

What is the query type you are using?
http://www.elasticsearch.org/guide/en/elasticsearch/reference/current/search-request-search-type.html

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Itamar Syn-Hershko
http://code972.com | @synhershko https://twitter.com/synhershko
Freelance Developer & Consultant
Author of RavenDB in Action http://manning.com/synhershko/

On Wed, Jan 15, 2014 at 4:45 PM, Arik Gaisler arikgaisler@gmail.com wrote:

Im using ElasticHQ to monitor our cluster and I am noticing that our
Search Fetch times are about 5X more then query times, which seems
unreasonable (20ms vs ~4ms)

Im also noticing a 1.44 mb swap space on one of the nodes (the other node
is at 0)

We're using a 2 node cluster, 2 shards 1 replica on EC2 m1.small instances

Our index contains about 27K docs, total size of ~ 60mb (pretty small -
hence the small instance)

Any suggestions to why?

Arik

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(Arik Gaisler) #3

We are doing a query then fetch serach type

On Wednesday, January 15, 2014 4:48:58 PM UTC+2, Itamar Syn-Hershko wrote:

What is the query type you are using?
http://www.elasticsearch.org/guide/en/elasticsearch/reference/current/search-request-search-type.html

--

Itamar Syn-Hershko
http://code972.com | @synhershko https://twitter.com/synhershko
Freelance Developer & Consultant
Author of RavenDB in Action http://manning.com/synhershko/

On Wed, Jan 15, 2014 at 4:45 PM, Arik Gaisler <arikg...@gmail.com<javascript:>

wrote:

Im using ElasticHQ to monitor our cluster and I am noticing that our
Search Fetch times are about 5X more then query times, which seems
unreasonable (20ms vs ~4ms)

Im also noticing a 1.44 mb swap space on one of the nodes (the other node
is at 0)

We're using a 2 node cluster, 2 shards 1 replica on EC2 m1.small instances

Our index contains about 27K docs, total size of ~ 60mb (pretty small -
hence the small instance)

Any suggestions to why?

Arik

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(Itamar Syn-Hershko) #4

I believe this makes sense then - search is entirely in-memory operation
(after a certain warm up), and fetch involves disk IO. Try keep your docs
as small as possible and don't disable _source, but other than that you're
bounded by the speed of your disks.

--

Itamar Syn-Hershko
http://code972.com | @synhershko https://twitter.com/synhershko
Freelance Developer & Consultant
Author of RavenDB in Action http://manning.com/synhershko/

On Wed, Jan 15, 2014 at 5:31 PM, Arik Gaisler arikgaisler@gmail.com wrote:

We are doing a query then fetch serach type

On Wednesday, January 15, 2014 4:48:58 PM UTC+2, Itamar Syn-Hershko wrote:

What is the query type you are using? http://www.
elasticsearch.org/guide/en/elasticsearch/reference/
current/search-request-search-type.html

--

Itamar Syn-Hershko
http://code972.com | @synhershko https://twitter.com/synhershko
Freelance Developer & Consultant
Author of RavenDB in Action http://manning.com/synhershko/

On Wed, Jan 15, 2014 at 4:45 PM, Arik Gaisler arikg...@gmail.com wrote:

Im using ElasticHQ to monitor our cluster and I am noticing that our
Search Fetch times are about 5X more then query times, which seems
unreasonable (20ms vs ~4ms)

Im also noticing a 1.44 mb swap space on one of the nodes (the other
node is at 0)

We're using a 2 node cluster, 2 shards 1 replica on EC2 m1.small
instances

Our index contains about 27K docs, total size of ~ 60mb (pretty small -
hence the small instance)

Any suggestions to why?

Arik

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(Arik Gaisler) #5

Thanks Itamar

Im also seeing that the refresh is pretty high137.4ms

Another factor is that the fetch times are constantly growing - while the
query times are cinctantly the same

Arik

On Wednesday, January 15, 2014 5:33:51 PM UTC+2, Itamar Syn-Hershko wrote:

I believe this makes sense then - search is entirely in-memory operation
(after a certain warm up), and fetch involves disk IO. Try keep your docs
as small as possible and don't disable _source, but other than that you're
bounded by the speed of your disks.

--

Itamar Syn-Hershko
http://code972.com | @synhershko https://twitter.com/synhershko
Freelance Developer & Consultant
Author of RavenDB in Action http://manning.com/synhershko/

On Wed, Jan 15, 2014 at 5:31 PM, Arik Gaisler <arikg...@gmail.com<javascript:>

wrote:

We are doing a query then fetch serach type

On Wednesday, January 15, 2014 4:48:58 PM UTC+2, Itamar Syn-Hershko wrote:

What is the query type you are using? http://www.
elasticsearch.org/guide/en/elasticsearch/reference/
current/search-request-search-type.html

--

Itamar Syn-Hershko
http://code972.com | @synhershko https://twitter.com/synhershko
Freelance Developer & Consultant
Author of RavenDB in Action http://manning.com/synhershko/

On Wed, Jan 15, 2014 at 4:45 PM, Arik Gaisler arikg...@gmail.comwrote:

Im using ElasticHQ to monitor our cluster and I am noticing that our
Search Fetch times are about 5X more then query times, which seems
unreasonable (20ms vs ~4ms)

Im also noticing a 1.44 mb swap space on one of the nodes (the other
node is at 0)

We're using a 2 node cluster, 2 shards 1 replica on EC2 m1.small
instances

Our index contains about 27K docs, total size of ~ 60mb (pretty small -
hence the small instance)

Any suggestions to why?

Arik

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(Itamar Syn-Hershko) #6

If such latency worries you, use in-memory structures to pull the original
documents based on the IDs of the results. Your dataset is small enough to
do that, really. But I suspect this is premature optimization that you are
trying to do.

--

Itamar Syn-Hershko
http://code972.com | @synhershko https://twitter.com/synhershko
Freelance Developer & Consultant
Author of RavenDB in Action http://manning.com/synhershko/

On Wed, Jan 15, 2014 at 5:56 PM, Arik Gaisler arikgaisler@gmail.com wrote:

Thanks Itamar

Im also seeing that the refresh is pretty high137.4ms

Another factor is that the fetch times are constantly growing - while the
query times are cinctantly the same

Arik

On Wednesday, January 15, 2014 5:33:51 PM UTC+2, Itamar Syn-Hershko wrote:

I believe this makes sense then - search is entirely in-memory operation
(after a certain warm up), and fetch involves disk IO. Try keep your docs
as small as possible and don't disable _source, but other than that you're
bounded by the speed of your disks.

--

Itamar Syn-Hershko
http://code972.com | @synhershko https://twitter.com/synhershko
Freelance Developer & Consultant
Author of RavenDB in Action http://manning.com/synhershko/

On Wed, Jan 15, 2014 at 5:31 PM, Arik Gaisler arikg...@gmail.com wrote:

We are doing a query then fetch serach type

On Wednesday, January 15, 2014 4:48:58 PM UTC+2, Itamar Syn-Hershko
wrote:

What is the query type you are using? http://www.elasticsearc
h.org/guide/en/elasticsearch/reference/current/search-request-search-
type.html

--

Itamar Syn-Hershko
http://code972.com | @synhershko https://twitter.com/synhershko
Freelance Developer & Consultant
Author of RavenDB in Action http://manning.com/synhershko/

On Wed, Jan 15, 2014 at 4:45 PM, Arik Gaisler arikg...@gmail.comwrote:

Im using ElasticHQ to monitor our cluster and I am noticing that our
Search Fetch times are about 5X more then query times, which seems
unreasonable (20ms vs ~4ms)

Im also noticing a 1.44 mb swap space on one of the nodes (the other
node is at 0)

We're using a 2 node cluster, 2 shards 1 replica on EC2 m1.small
instances

Our index contains about 27K docs, total size of ~ 60mb (pretty small

  • hence the small instance)

Any suggestions to why?

Arik

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(system) #7