Hi Wei, Let us know if fine tuning the number of map tasks solved your problem or we should dig further into it. Thanks, Liz
On Fri, Jul 1, 2016 at 7:57 AM, Wei Yan <[email protected]> wrote: > Thanks, Erzsebet and Markus. Tuning the number of map tasks can be a > reasonal solution here, and I'll try that. > As Sqoop 1 is a MapReduce job, I think it's hard to have both (1) many > small queries and (2) limited concurrent executing queries. > > -Wei > > On Thu, Jun 30, 2016 at 3:50 PM, Erzsebet Szilagyi < > [email protected]> wrote: > >> Hi Wei, >> Markus (in CC) offered the following explanation: >> >> " >> The Sqoop1 default is 4 map tasks. When working with customers I usually >> start with 1 and double the number of map tasks (e.g. 1, 2, 4, 8) until >> finding a performance sweet spot while keeping in mind the potential rdbms >> impact. >> >> Estimating the real rdbms impact is often challenging for some of the >> following reasons: >> 1. DBAs are often not present >> 2. Jobs are often reviewed in isolation (excluding other simultaneous >> Sqoop or non-sqoop workloads) >> 3. Tests are often performed against smaller data volumes and/or virtual >> resources than what will be in production (includes rdbms, network and had >> pop cluster) >> 4. There is not a uniform way to monitor/analyze impact across rdbms >> vendors. >> 4.1. I have not really tried to review Sqoop console debug from a dB >> impact context, perhaps it could be used. >> 5. Once deployed production job volumes often change >> >> Thanks, Markus >> " >> >> On Wed, Jun 29, 2016 at 7:35 PM, Wei Yan <[email protected]> wrote: >> >>> Hi, >>> >>> Would like to check whether Sqoop supports this type of ingestion: >>> consider we have records with range [1,12], and we have 3 mappers. So in >>> default, the 3 mappers will be assigned [1,4], [5, 8], [9, 12]. >>> >>> Not sure whether we can split the range to smaller one, like, [1], [2], >>> [3], ..., [12]. But still using 3 mappers instead of 12 mappers. We want >>> this feature because: (1) if configured smaller mapper number, each mapper >>> will be assigned a larger range and take much longer time to finish, and >>> the infra may kill long running query; (2) But if we configured a larger >>> mapper number, each mapper has a smaller range, but meanwhile we generates >>> lots of network traffic to the database, which will also be bad. One good >>> way we want is: still 12 ranges, but 3 mappers, and at most 3 concurrent >>> connections at most. >>> >>> Appreciate any help here. >>> >>> -Wei >>> >> >> >> >> -- >> Erzsebet Szilagyi >> Software Engineer >> [image: www.cloudera.com] <http://www.cloudera.com> >> > > -- Erzsebet Szilagyi Software Engineer [image: www.cloudera.com] <http://www.cloudera.com>
