accumulo-dev mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Adam J. Shook" <adamjsh...@gmail.com>
Subject Re: Apache Accumulo integrated with Presto
Date Mon, 13 Jun 2016 16:42:04 GMT
Maybe.  I'd be interested in what they'd done to get the big gains.  My
approach was, for a full table scan (vs. using the index), the connector
creates one Presto split for each tablet.  The Accumulo metadata table is
scanned to get the tablet location, and the host hint for the Presto split
is set to where the tablet is located.  Using this approach, the query
times were nearly identical whether the workers were co-located with tablet
servers or not.

On Mon, Jun 13, 2016 at 11:55 AM, Josh Elser <josh.elser@gmail.com> wrote:

>
>
> Adam J. Shook wrote:
>
>> A few clarifications:
>>
>> - Presto supports hash-based distributed joins as well as broadcast joins
>>
>> - Presto metadata is stored in ZooKeeper, but metadata storage is
>> pluggable
>> and could be stored in Accumulo instead
>>
>> - The connector does use tablet locality when scanning Accumulo, but our
>> testing has shown you get better performance by giving Accumulo and Presto
>> their own dedicated machines, making locality a moot point.  This will
>> certainly change based on types of queries, data sizes, network quality,
>> etc.
>>
>
> I'm a little confused by this. Co-locating presto workers and tservers
> doesn't necessarily mean that you're going to get local reads/writes at the
> Accumulo layer. I remember this is something that the Argyle Data folks had
> found was a big gain for them when they were doing Presto+Accumulo. Maybe
> your findings were more based on your specific circumstances?
>
>
> - You can insert the results of a query into a Presto table using INSERT
>> INTO foo SELECT ..., as well as create a table from the results of a query
>> (CTAS).  Though, for large inserts, it is typically best to bypass the
>> Presto layer and insert directly into the Accumulo tables using the
>> PrestoBatchWriter API
>>
>> Cheers,
>> --Adam
>>
>> On Mon, Jun 13, 2016 at 7:20 AM, Christopher<ctubbsii@apache.org>  wrote:
>>
>> Thanks for that summary, Dylan! Very helpful.
>>>
>>> On Mon, Jun 13, 2016, 01:36 Dylan Hutchison<dhutchis@cs.washington.edu>
>>> wrote:
>>>
>>> Thanks for sharing Sean.  Here are some notes I wrote after reading the
>>>> article on Presto-Accumulo design.  I have a research interest in the
>>>> relationship between relational (SQL) and non-relational (Accumulo)
>>>> systems, so I couldn't resist reading the post in detail.
>>>>
>>>>     - Places the primary key in the Accumulo row.
>>>>     - Performs row-at-a-time processing (each tuple is one row in
>>>>     Accumulo) using WholeRowIterator behavior.
>>>>     - Relational table metadata is stored in the Presto infrastructure
>>>> (as
>>>>     opposed to an Accumulo table).
>>>>     - Supports the creation of index tables for any attributes. These
>>>>     index tables speed up queries that filter on indexed attributes.  It
>>>>
>>> is
>>>
>>>>     standard secondary indexing, which provides speedups when the
>>>>
>>> selectivity
>>>
>>>>     of the query is roughly<10% of the original table.
>>>>     - Only database->client querying is supported.  You cannot run
>>>> "select
>>>>     ... into result_table".
>>>>     - As far as I can see, Presto only has one join strategy: *broadcast
>>>>     join*.  The right table of every join is scanned into one of the
>>>>     Presto worker's memory.  Subsequently the size of the right table is
>>>>     limited by worker memory.
>>>>     - There is one Presto worker for each Accumulo tablet, which enables
>>>>     good scaling.
>>>>     - The Presto bridge classes track internal Accumulo information such
>>>>     as the assignment of tablets to tablet servers by reading Accumulo's
>>>>     Metadata table. Presto uses tablet locations to provide better
>>>>
>>> locality.
>>>
>>>>     - The Presto bridge comes with several Accumulo server-side
>>>> iterators
>>>>     for filtering and aggregating.
>>>>     - The code is quite nice and clean.
>>>>
>>>> This image below gives Presto's architecture.  Accumulo takes the role
>>>> of
>>>> the DB icon in the bottom-right corner.
>>>>
>>>> [image: Inline image 2]
>>>>
>>>> Bloomberg ran 13 out of the 22 TPC-H queries.  There is no fundamental
>>>> reason why they cannot run all the queries; they just have not
>>>>
>>> implemented
>>>
>>>> everything required ('exists' clauses, non-equi join, etc.).
>>>>
>>>> The interface looks like this, though they use a compiled java jar to
>>>> insert entries from a csv file (it wraps around a BatchWriter).
>>>>
>>>> [image: Inline image 3]
>>>>
>>>> Here are performance results.  They don't say what hardware or data
>>>> sizes
>>>> they use.  Whatever it is, they must have the ability to fit the smaller
>>>> table of any join into memory as a result of Presto's broadcast join
>>>> strategy.  The strong scaling looks very nice.
>>>>
>>>> [image: Inline image 4]
>>>>
>>>> They have one other plot that shows how secondary indexing speeds up
>>>> some
>>>> queries with low selectivity.
>>>>
>>>> Cheers, Dylan
>>>>
>>>>
>>>>
>>>> On Sun, Jun 12, 2016 at 7:06 PM, Sean Busbey<busbey@cloudera.com>
>>>>
>>> wrote:
>>>
>>>> Bloomberg have a post about a connector they made to query Accumulo from
>>>>> Presto:
>>>>>
>>>>>
>>>>>
>>>>>
>>> http://www.bloomberg.com/company/announcements/open-source-at-bloomberg-reducing-application-development-time-via-presto-accumulo/
>>>
>>>> --
>>>>> Sean Busbey
>>>>>
>>>>>
>>>>
>>

Mime
  • Unnamed multipart/alternative (inline, None, 0 bytes)
View raw message