http://kafka.apache.org/10/documentation.html#consumerapi

<dependency>
    <groupId>org.apache.kafka</groupId>
    <artifactId>kafka-clients</artifactId>
    <version>1.0.1-kafka-3.1.0</version>
</dependency>

http://kafka.apache.org/10/documentation.html#newconsumerconfigs

http://kafka.apache.org/10/documentation.html#oldconsumerconfigs

https://tonglin0325.github.io/xml/kafka/1.0.1-kafka-3.1.0/new-consumer-api.xml

https://dzone.com/articles/elasticsearch5-how-to-build-a-plugin-and-add-a-lis
https://github.com/chrisshayan/es-changes-feed-plugin
https://blog.csdn.net/qq_16164711/article/details/87872383
https://blog.gaiaproject.club/es-develop-plugin/
https://blog.51cto.com/13755625/2117995

https://github.com/elastic/elasticsearch/tree/master/server/src/main/java/org/elasticsearch/plugins

1、Antlr定义SQL的语法规则，完成SQL词法，语法解析，将SQL转化为抽象语法树AST Tree
2、遍历AST Tree，抽象出查询的基本组成单元QueryBlock
3、遍历QueryBlock，翻译为执行操作树OperatorTree
4、逻辑层优化器进行OperatorTree变换，合并不必要的ReduceSinkOperator，减少shuffle数据量
5、遍历OperatorTree，翻译为MapReduce任务
6、物理层优化器进行MapReduce任务的变换，生成最终的执行计划

select * from xx.xx limit 1

<property>
    <name>hive.fetch.task.conversion</name>
    <value>more</value>
    <description>
      Expects one of [none, minimal, more].
      Some select queries can be converted to single FETCH task minimizing latency.
      Currently the query should be single sourced not having any subquery and should not have any aggregations or distincts (which incurs RS), lateral views and joins.
      0. none : disable hive.fetch.task.conversion
      1. minimal : SELECT STAR, FILTER on partition columns, LIMIT only
      2. more  : SELECT, FILTER, LIMIT only (support TABLESAMPLE and virtual columns)
    </description>
</property>

<property>
  <name>hive.fetch.task.conversion.threshold</name>
  <value>1073741824</value>
  <description>
    Input threshold for applying hive.fetch.task.conversion. If target table is native, input length
    is calculated by summation of file lengths. If it's not native, storage handler for the table
    can optionally implement org.apache.hadoop.hive.ql.metadata.InputEstimator interface.
  </description>
</property>

~/software/apache/elasticsearch-6.2.4/config/analysis-ik$ ls | grep mydic.dic
mydic.dic

我给祖国献石油

https://ci.apache.org/projects/flink/flink-docs-release-1.12/zh/dev/user_defined_functions.html

class MyMapFunction implements MapFunction<String, Integer> {
  public Integer map(String value) { return Integer.parseInt(value); }
};
data.map(new MyMapFunction());

class MyMapFunction extends RichMapFunction<String, Integer> {
  public Integer map(String value) { return Integer.parseInt(value); }
};

https://ci.apache.org/projects/flink/flink-docs-release-1.12/zh/dev/user_defined_functions.html#%E7%B4%AF%E5%8A%A0%E5%99%A8%E5%92%8C%E8%AE%A1%E6%95%B0%E5%99%A8

https://ci.apache.org/projects/flink/flink-docs-release-1.12/zh/dev/datastream_execution_mode.html

bin/flink run -Dexecution.runtime-mode=BATCH examples/streaming/WordCount.jar

StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();
env.setRuntimeMode(RuntimeExecutionMode.BATCH);

https://ci.apache.org/projects/flink/flink-docs-release-1.12/zh/dev/batch/

ExecutionEnvironment env = ExecutionEnvironment.getExecutionEnvironment();

readTextFile(path) / TextInputFormat - Reads files line wise and returns them as Strings.

readTextFileWithValue(path) / TextValueInputFormat - Reads files line wise and returns them as StringValues. StringValues are mutable strings.

readCsvFile(path) / CsvInputFormat - Parses files of comma (or another char) delimited fields. Returns a DataSet of tuples or POJOs. Supports the basic java types and their Value counterparts as field types.

readFileOfPrimitives(path, Class) / PrimitiveInputFormat - Parses files of new-line (or another char sequence) delimited primitive data types such as String or Integer.

readFileOfPrimitives(path, delimiter, Class) / PrimitiveInputFormat - Parses files of new-line (or another char sequence) delimited primitive data types such as String or Integer using the given delimiter.

fromCollection(Collection) - Creates a data set from a Java.util.Collection. All elements in the collection must be of the same type.

fromCollection(Iterator, Class) - Creates a data set from an iterator. The class specifies the data type of the elements returned by the iterator.

fromElements(T ...) - Creates a data set from the given sequence of objects. All objects must be of the same type.

fromParallelCollection(SplittableIterator, Class) - Creates a data set from an iterator, in parallel. The class specifies the data type of the elements returned by the iterator.

generateSequence(from, to) - Generates the sequence of numbers in the given interval, in parallel.

readFile(inputFormat, path) / FileInputFormat - Accepts a file input format.

createInput(inputFormat) / InputFormat - Accepts a generic input format.