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Questions tagged [mapper]

The mapper is the first step in MapReduce framework, a component of a larger scalable, parallel-izable algorithm.

Maps input key/value pairs to a set of intermediate key/value pairs.

Maps are the individual tasks which transform input records into a intermediate records. The transformed intermediate records need not be of the same type as the input records. A given input pair may map to zero or many output pairs.

The most common map reduce framework is Apache Hadoop.

See also MapReduce Wiki.

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Mapstruct "Can't find related attribute"

I have this Mapper class, I'm trying to combine all tree objects into a single Dto for a the view to use the Dto object : @Mapping(source = "childSeat.id", target = "childSeatId") @Mapping(source = "childSeatCol.id", target =…
Charlo Poitras
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Cannot get keycloak protocol mapper to invoke when retrieving a token

Keycloak 7.3.0GA Server Using Library keycloak-services 3.4.3 Our team is having trouble getting our Keycloak protocol mapper to invoke during a token call: The mapper is registered at startup and is available in the list of mappers for our…
Marco
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Spring Boot Cannot Deserialize Object That contanis OffsetDateTime

I'm trying to call a rest endpoint which returns a pojo object which looks like this: public class Process { @JsonProperty("id") private String id = null; @JsonProperty("processDefinitionId") private String processDefinitionId = null; …
Truica Sorin
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How to get Authorization (permissions) in keycloak JWT?

Objective: I am trying to add authorization details to the JWT using a custom mapper for Keycloak, so that when a user logs in using the login page, his token will also contain all the permissions that are applicable. As an example, here's the…
C Smith
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partitions in hive interview questions

1) If the partitioned column doesn't have data, so when you query on that, what error will you get? 2)If some rows doesn't have the partitioned column , the how those rows will be handled? will there be any data loss? 3)Why bucketing needs to be…
Anonymous
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keycloak client protocol mapper (script mapper) to add request header into token

When I'm requesting a token from keycloak I want a specific header value (or extra form data) that was supplied in the request to be put in the JWT payload of the generated token. I've tried using a Script Mapper to get access to header values but I…
Shane Rowatt
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Need classic mapper example for SqlAlchemy single table inheritance

I found an example of how to do single table inheritance using Class mappings. http://docs.sqlalchemy.org/en/latest/orm/inheritance.html#single-table-inheritance But for the life of me, I cannot find an example of how to do this with classic mapper…
Alex Paransky
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Hadoop stacked when mapreduce and spark compete

I manage a cluster with several machines that is shared with other colleagues. Some using spark and some using Map Reduce. Spark users usually open a context and have it open for days or weeks, while in MR the jobs start and finish. The problem is a…
user1753235
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How to connect a ResultHandler in MyBatis Mapper XML

I found several examples how to connect a custom ResultHandler to a MyBatis Query: e.g. https://code.google.com/p/mybatis/wiki/ResultHandlerExample Unfortunately the ResultHandler given in the example never gets invoked. (As the last comment already…
Mahatma_Fatal_Error
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Connect QComboBox::currentIndexChanged(int) to QSignalMapper::map()

I'm trying to figure out how to achieve this in Qt5: connect(qcombobox, SIGNAL(currentIndexChanged(int), qsignalmappe, SLOT(map())); I tried this: connect(comboBox, static_cast
Szőke Szabolcs
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Can reducers and mappers be on the same data node?

I have started reading about Big Data and Hadoop, so this question may sound very stupid to you. This is what I know. Each mapper processes a small amount of data and produces an intermediate output. After this, we have the step of shuffle and…
user2441151
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How to configure Hadoop MapReduce mapper output compression if I use org.apache.hadoop.mapreduce (new) API?

Is it possible to turn on mapper output compression on new mapreduce API and if so could you please point how? I see lot of examples doing so based on hadoop.mapred.JobConf API but no one for mapreduce API. If it is not configurable through new API…
Roman Nikitchenko
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Does it make sense to use PHP setters for type safety only?

I have a bunch of Domain Objects and I am using overloading to get and set properties. My form filters are comprehensive. If properties of the wrong type or value sneak through, I am confident that I can pick them up in the mapper. Worst case…
DatsunBing
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Hadoop Streaming and multiple reducer steps without a mapper between each step

I am troubleshooting how to sort my data multiple times without have to go back through the mapper each time. Id like to setup: mapper 1 --> reducer 1 ---> reducer 2 ---> reducer 3 I want to make reducer 1 output (key, data) and then have it go…
user1179295
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Glue vs Automapper vs Emit vs ValueInjecter entity mappers

I'm working on a DDD project where a lot of field mapping is going on. I'm looking for a fast and solid mapping library as opposed to writing all the mappings by hand and there seems to be a lot of options out there. At the moment I'm leaning more…
GFoley83
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