Hi Josh,
thank you for your answer.
Yes, I am using HDP 2.3.4. You're right, with the newer versions it may improve the performance significantly. However, we are going to have a release shortly, so now it's not possible for an upgrade. But yes, it should happen in the upcoming application release.
The table has 21 columns:
- the first 3 (id,type and timestamp) make up the PK
- the following 18 columns are unsigned int.
No, there is no secondary indexes defined for the table.
An example query:
SELECT timestamp,VALUE04,VALUE15
FROM T.TABELLE
WHERE id='ID1' and type='A' and timestamp>=TO_TIMESTAMP('...') timestamp<=TO_TIMESTAMP('...')
ORDER BY id ASC, type ASC, timestamp ASC;
Explain plan:
| CLIENT 7-CHUNK PARALLEL 7-WAY RANGE SCAN OVER T.TABELLE [0,'ID1','A','2015-12-02 00:00:00.000'] - [0,'ID1','A','2017-01-01 00:00:00.000']
| SERVER FILTER BY (A.VALUE04 IS NOT NULL OR A.VALUE15 IS NOT NULL)
| CLIENT MERGE SORT
It looks like you suspect that phoenix is firstly reading the data and then post-filtering / sorting the data.
But why it take sometimes so much time in the first next() call?
When I try to send the request sequentially, the 1.next() always takes about less than 200 ms for processing. But when a large number of requests are coming in parallel, the processing time is increasing significantly to even more than 20, 30 secs.
Is it something relating to HBase, as the table is minor compacted from time to time and it has impact to the read performance?
I am not sure how the next() call is implemented in the phoenix 4.4.0? Which component can be the bottleneck in such concurrent processing scenario?
Thanks in advance
Lee
<quote author="Josh Elser-2">
I'm guessing that you're using a version of HDP? If you're using those
versions from Apache, please update as they're dreadfully out of date.
What is the DDL of the table you're reading from? Do you have any
secondary indexes on this table (if so, on what columns)? What kind of
query are you running? What is the output of `EXPLAIN <sql>` for these
queries?
For example, this could be easily explained if Phoenix is reading the
data table and post-filtering records. It could take significant amounts
of time to read data that does not satisfy your query until you get to
some data which does...
Lee wrote:
> Hi all,
>
> currently I am struggling with a performance issue in my Rest API. The API
> receives loads of requests coming from frontend in parallel, makes SQL
> queries using Phoenix JDBC driver to fetch data from HBase. For each
> request, the api makes only 1 query to phoenix/hbase.
>
> I find out, that the very first ResultSet.next() always take long time to
> get data from hbase. As far as I know, it gets data in batch, stores them in
> main memory, enables the following next() to get data directly from main
> memory and thus save up the network overload. The following next() takes
> usually less than 10 ms to finish.
>
> Sometimes this first next() takes more than 10 seconds and gets increasing
> from time to time to 30 or even 40 secs. For each query we expect maximal
> 25000 rows.
> What can be here the bottleneck for this behaviour?
>
> Some information regarding my setup:
> Hadoop: 2.7.1
> HBase: 1.1.2
> Phoenix: 4.4.0 Hbase 1.1
> Table has 605M rows - salted in 7 buckets - 26 regions across 10 region
> servers
> phoenix.query.threadPoolSize = 128 (default)
> phoenix.query.queueSize = 5000 (default)
>
> Thanks!
> Lee
>
>
>
> --
> View this message in context: http://apache-phoenix-user-
> Sent from the Apache Phoenix User List mailing list archive at Nabble.com.
</quote>
