Github user chenliang613 commented on a diff in the pull request:
https://github.com/apache/carbondata/pull/2215#discussion_r186900225
--- Diff: docs/datamap/lucene-datamap-guide.md ---
@@ -0,0 +1,213 @@
+# CarbonData Lucene DataMap
+
+* [Quick Example](#quick-example)
+* [DataMap Management](#datamap-management)
+* [Lucene Datamap](#lucene-datamap-introduction)
+* [Loading Data](#loading-data)
+* [Querying Data](#querying-data)
+* [Data Management](#data-management-with-pre-aggregate-tables)
+
+## Quick example
+1. Download and unzip spark-2.2.0-bin-hadoop2.7.tgz, and export
$SPARK_HOME.
+
+2. Package carbon jar, and copy
assembly/target/scala-2.11/carbondata_2.11-x.x.x-SNAPSHOT-shade-hadoop2.7.2.jar
to $SPARK_HOME/jars.
+ ```shell
+ mvn clean package -DskipTests -Pspark-2.2
+ ```
+
+3. Start spark-shell in new terminal, type :paste, then copy and run the
following code.
+ ```scala
+ import java.io.File
+ import org.apache.spark.sql.{CarbonEnv, SparkSession}
+ import org.apache.spark.sql.CarbonSession._
+ import org.apache.spark.sql.streaming.{ProcessingTime, StreamingQuery}
+ import org.apache.carbondata.core.util.path.CarbonStorePath
+
+ val warehouse = new File("./warehouse").getCanonicalPath
+ val metastore = new File("./metastore").getCanonicalPath
+
+ val spark = SparkSession
+ .builder()
+ .master("local")
+ .appName("luceneDatamapExample")
+ .config("spark.sql.warehouse.dir", warehouse)
+ .getOrCreateCarbonSession(warehouse, metastore)
+
+ spark.sparkContext.setLogLevel("ERROR")
+
+ // drop table if exists previously
+ spark.sql(s"DROP TABLE IF EXISTS datamap_test")
+
+ // Create main table
+ spark.sql(
+ s"""
+ |CREATE TABLE datamap_test (
+ |name string,
+ |age int,
+ |city string,
+ |country string)
+ |STORED BY 'carbondata'
+ """.stripMargin)
+
+ // Create lucene datamap on the main table
+ spark.sql(
+ s"""
+ |CREATE DATAMAP dm
+ |ON TABLE datamap_test
+ |USING "lucene"
+ |DMPROPERTIES ('TEXT_COLUMNS' = 'name,country')
+ """.stripMargin)
+
+ import spark.implicits._
+ import org.apache.spark.sql.SaveMode
+ import scala.util.Random
+
+ // Load data to the main table, if
+ // lucene index writing fails, the datamap
+ // will be disabled in query
+ val r = new Random()
+ spark.sparkContext.parallelize(1 to 10)
+ .map(x => ("c1" + x % 8, x % 8, "city" + x % 50, "country" + x % 60))
+ .toDF("name", "age", "city", "country")
+ .write
+ .format("carbondata")
+ .option("tableName", "datamap_test")
+ .option("compress", "true")
+ .mode(SaveMode.Append)
+ .save()
+
+ spark.sql(
+ s"""
+ |SELECT *
+ |from datamap_test where
+ |TEXT_MATCH('name:c10')
+ """.stripMargin).show
+
+ spark.sql(
+ s"""
+ |SELECT *
+ |from datamap_test where
+ |TEXT_MATCH_WITH_LIMIT('name:c10', 10)
+ """.stripMargin).show
+
+ spark.stop
+ ```
+
+#### DataMap Management
+Lucene DataMap can be created using following DDL
+ ```
+ CREATE DATAMAP [IF NOT EXISTS] datamap_name
+ ON TABLE main_table
+ USING "lucene"
+ DMPROPERTIES ('index_columns'='city, name', ...)
+ ```
+
+DataMap can be dropped using following DDL:
+ ```
+ DROP DATAMAP [IF EXISTS] datamap_name
+ ON TABLE main_table
+ ```
+To show all DataMaps created, use:
+ ```
+ SHOW DATAMAP
+ ON TABLE main_table
+ ```
+It will show all DataMaps created on main table.
+
+
+## Lucene DataMap Introduction
+ Lucene is a high performance, full featured text search engine. Lucene
is integrated to carbon as
+ index datamap and managed along with main tables by CarbonData.User can
create lucene datamaps
+ to improve query performance on string columns.
+
+ For instance, main table called **datamap_test** which is defined as:
+
+ ```
+ CREATE TABLE datamap_test (
+ name string,
+ age int,
+ city string,
+ country string)
+ STORED BY 'carbondata'
+ ```
+
+ User can create Lucene datamap using the Create DataMap DDL:
+
+ ```
+ CREATE DATAMAP dm
+ ON TABLE datamap_test
+ USING "lucene"
+ DMPROPERTIES ('TEXT_COLUMNS' = 'name, country')
+ ```
+
+## Loading data
+When loading data to main table, lucene index files will be generated for
all the
+index_columns(String Columns) given in DMProperties which contains
information about the data
+location of index_columns. These index files will be written inside a
folder named with datamap name
+inside each segment folders.
+
+A system level configuration carbon.lucene.compression.mode can be added
for best compression of
+lucene index files. The default value is speed, where the index writing
speed will be more. If the
+value is compression, the index file size will be compressed.
+
+## Querying data
+As a technique for query acceleration, Lucene indexes cannot be queried
directly.
+Queries are to be made on main table. when a query with
TEXT_MATCH('name:c10') or
+TEXT_MATCH_WITH_LIMIT('name:n10',10)[the second parameter represents the
number of result to be
+returned, if user does not specify this value, all results will be
returned without any limit] is
+fired, two jobs are fired.The first job writes the temporary files in
folder created at table level
+which contains lucene's seach results and these files will be read in
second job to give faster
+results. These temporary files will be cleared once the query finishes.
+
+User can verify whether a query can leverage Lucene datamap or not by
executing `EXPLAIN`
+command, which will show the transformed logical plan, and thus user can
check whether TEXT_MATCH()
+filter is applied on query or not.
+
+Below like queries can be converted to text_match queries as following:
+```
+select * from datamap_test where name='n10'
+
+select * from datamap_test where name like 'n1%'
+
+select * from datamap_test where name like '%10'
--- End diff --
I tested, the result is different for the below two query, please double
check:
select * from datamap_test where name like '%10'
select * from datamap_test where TEXT_MATCH('name:*10')
---
