sqoop在导入数据时，可以使用--query搭配sql来指定查询条件，并且还需在sql中添加\$CONDITIONS，来实现并行运行mr的功能。
运行测试
测试均基于sqoop1，mysql数据准备如下。
（1）只要有--query+sql，就需要加\$CONDITIONS，哪怕只有一个maptask。
# 只有一个maptask
[hadoop@node01 /kkb/bin]$ sqoop import --connect jdbc:mysql://node01:3306/sqooptest --username root --password 123456 --target-dir /sqoop/conditiontest --delete-target-dir --query 'select * from Person where score>50' --m 1 Warning: /kkb/install/sqoop-1.4.6-cdh5.14.2/../hcatalog does not exist! HCatalog jobs will fail. Please set $HCAT_HOME to the root of your HCatalog installation. Warning: /kkb/install/sqoop-1.4.6-cdh5.14.2/../accumulo does not exist! Accumulo imports will fail. Please set $ACCUMULO_HOME to the root of your Accumulo installation. Warning: /kkb/install/sqoop-1.4.6-cdh5.14.2/../zookeeper does not exist! Accumulo imports will fail. Please set $ZOOKEEPER_HOME to the root of your Zookeeper installation. 20/02/07 10:43:20 INFO sqoop.Sqoop: Running Sqoop version: 1.4.6-cdh5.14.2 20/02/07 10:43:20 WARN tool.BaseSqoopTool: Setting your password on the command-line is insecure. Consider using -P instead. 20/02/07 10:43:20 INFO manager.MySQLManager: Preparing to use a MySQL streaming resultset. 20/02/07 10:43:20 INFO tool.CodeGenTool: Beginning code generation
# 提示需要添加$CONDITIONS参数 20/02/07 10:43:20 ERROR tool.ImportTool: Import failed: java.io.IOException: Query [select * from Person where score>50] must contain '$CONDITIONS' in WHERE clause. at org.apache.sqoop.manager.ConnManager.getColumnTypes(ConnManager.java:332) at org.apache.sqoop.orm.ClassWriter.getColumnTypes(ClassWriter.java:1858) at org.apache.sqoop.orm.ClassWriter.generate(ClassWriter.java:1657) at org.apache.sqoop.tool.CodeGenTool.generateORM(CodeGenTool.java:106) at org.apache.sqoop.tool.ImportTool.importTable(ImportTool.java:494) at org.apache.sqoop.tool.ImportTool.run(ImportTool.java:621) at org.apache.sqoop.Sqoop.run(Sqoop.java:147) at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:70) at org.apache.sqoop.Sqoop.runSqoop(Sqoop.java:183) at org.apache.sqoop.Sqoop.runTool(Sqoop.java:234) at org.apache.sqoop.Sqoop.runTool(Sqoop.java:243) at org.apache.sqoop.Sqoop.main(Sqoop.java:252) You have new mail in /var/spool/mail/root
（2）如果只有一个maptask，可以不加--split-by来区分数据，因为处理的是整份数据，无需切分。
[hadoop@node01 /kkb/bin]$ sqoop import --connect jdbc:mysql://node01:3306/sqooptest --username root --password 123456 --target-dir /sqoop/conditiontest --delete-target-dir --query 'select * from Person where score>50 and $CONDITIONS' --m 1 Warning: /kkb/install/sqoop-1.4.6-cdh5.14.2/../hcatalog does not exist! HCatalog jobs will fail. Please set $HCAT_HOME to the root of your HCatalog installation. Warning: /kkb/install/sqoop-1.4.6-cdh5.14.2/../accumulo does not exist! Accumulo imports will fail. Please set $ACCUMULO_HOME to the root of your Accumulo installation. Warning: /kkb/install/sqoop-1.4.6-cdh5.14.2/../zookeeper does not exist! Accumulo imports will fail. Please set $ZOOKEEPER_HOME to the root of your Zookeeper installation. 20/02/07 10:44:08 INFO sqoop.Sqoop: Running Sqoop version: 1.4.6-cdh5.14.2 20/02/07 10:44:08 WARN tool.BaseSqoopTool: Setting your password on the command-line is insecure. Consider using -P instead. 20/02/07 10:44:08 INFO manager.MySQLManager: Preparing to use a MySQL streaming resultset. 20/02/07 10:44:08 INFO tool.CodeGenTool: Beginning code generation Fri Feb 07 10:44:08 CST 2020 WARN: Establishing SSL connection without server's identity verification is not recommended. According to MySQL 5.5.45+, 5.6.26+ and 5.7.6+ requirements SSL connection must be established by default if explicit option isn't set. For compliance with existing applications not using SSL the verifyServerCertificate property is set to 'false'. You need either to explicitly disable SSL by setting useSSL=false, or set useSSL=true and provide truststore for server certificate verification. 20/02/07 10:44:09 INFO manager.SqlManager: Executing SQL statement: select * from Person where score>50 and (1 = 0) 20/02/07 10:44:09 INFO manager.SqlManager: Executing SQL statement: select * from Person where score>50 and (1 = 0) 20/02/07 10:44:09 INFO manager.SqlManager: Executing SQL statement: select * from Person where score>50 and (1 = 0) 20/02/07 10:44:09 INFO orm.CompilationManager: HADOOP_MAPRED_HOME is /kkb/install/hadoop-2.6.0-cdh5.14.2 Note: /tmp/sqoop-hadoop/compile/ed46f1d7a2aeb419d32799b64aabdc82/QueryResult.java uses or overrides a deprecated API. Note: Recompile with -Xlint:deprecation for details. 20/02/07 10:44:13 INFO orm.CompilationManager: Writing jar file: /tmp/sqoop-hadoop/compile/ed46f1d7a2aeb419d32799b64aabdc82/QueryResult.jar SLF4J: Class path contains multiple SLF4J bindings. SLF4J: Found binding in [jar:file:/kkb/install/hadoop-2.6.0-cdh5.14.2/share/hadoop/common/lib/slf4j-log4j12-1.7.5.jar!/org/slf4j/impl/StaticLoggerBinder.class] SLF4J: Found binding in [jar:file:/kkb/install/hbase-1.2.0-cdh5.14.2/lib/slf4j-log4j12-1.7.5.jar!/org/slf4j/impl/StaticLoggerBinder.class] SLF4J: See http://www.slf4j.org/codes.html#multiple_bindings for an explanation. SLF4J: Actual binding is of type [org.slf4j.impl.Log4jLoggerFactory] 20/02/07 10:44:13 WARN util.NativeCodeLoader: Unable to load native-hadoop library for your platform... using builtin-java classes where applicable 20/02/07 10:44:14 INFO tool.ImportTool: Destination directory /sqoop/conditiontest is not present, hence not deleting. 20/02/07 10:44:14 INFO mapreduce.ImportJobBase: Beginning query import. 20/02/07 10:44:14 INFO Configuration.deprecation: mapred.jar is deprecated. Instead, use mapreduce.job.jar 20/02/07 10:44:15 INFO Configuration.deprecation: mapred.map.tasks is deprecated. Instead, use mapreduce.job.maps 20/02/07 10:44:15 INFO client.RMProxy: Connecting to ResourceManager at node01/192.168.200.100:8032 Fri Feb 07 10:44:21 CST 2020 WARN: Establishing SSL connection without server's identity verification is not recommended. According to MySQL 5.5.45+, 5.6.26+ and 5.7.6+ requirements SSL connection must be established by default if explicit option isn't set. For compliance with existing applications not using SSL the verifyServerCertificate property is set to 'false'. You need either to explicitly disable SSL by setting useSSL=false, or set useSSL=true and provide truststore for server certificate verification. 20/02/07 10:44:21 INFO db.DBInputFormat: Using read commited transaction isolation 20/02/07 10:44:21 INFO mapreduce.JobSubmitter: number of splits:1 20/02/07 10:44:21 INFO mapreduce.JobSubmitter: Submitting tokens for job: job_1581042804134_0001 20/02/07 10:44:22 INFO impl.YarnClientImpl: Submitted application application_1581042804134_0001 20/02/07 10:44:22 INFO mapreduce.Job: The url to track the job: http://node01:8088/proxy/application_1581042804134_0001/ 20/02/07 10:44:22 INFO mapreduce.Job: Running job: job_1581042804134_0001 20/02/07 10:44:33 INFO mapreduce.Job: Job job_1581042804134_0001 running in uber mode : true 20/02/07 10:44:33 INFO mapreduce.Job: map 0% reduce 0% 20/02/07 10:44:36 INFO mapreduce.Job: map 100% reduce 0% 20/02/07 10:44:36 INFO mapreduce.Job: Job job_1581042804134_0001 completed successfully 20/02/07 10:44:36 INFO mapreduce.Job: Counters: 32 File System Counters FILE: Number of bytes read=0 FILE: Number of bytes written=0 FILE: Number of read operations=0 FILE: Number of large read operations=0 FILE: Number of write operations=0 HDFS: Number of bytes read=100 HDFS: Number of bytes written=181519 HDFS: Number of read operations=128 HDFS: Number of large read operations=0 HDFS: Number of write operations=6 Job Counters Launched map tasks=1 Other local map tasks=1 Total time spent by all maps in occupied slots (ms)=0 Total time spent by all reduces in occupied slots (ms)=0 TOTAL_LAUNCHED_UBERTASKS=1 NUM_UBER_SUBMAPS=1 Total time spent by all map tasks (ms)=1825 Total vcore-milliseconds taken by all map tasks=0 Total megabyte-milliseconds taken by all map tasks=0 Map-Reduce Framework Map input records=1 Map output records=1 Input split bytes=87 Spilled Records=0 Failed Shuffles=0 Merged Map outputs=0 GC time elapsed (ms)=44 CPU time spent (ms)=950 Physical memory (bytes) snapshot=160641024 Virtual memory (bytes) snapshot=3020165120 Total committed heap usage (bytes)=24555520 File Input Format Counters Bytes Read=0 File Output Format Counters Bytes Written=21 20/02/07 10:44:36 INFO mapreduce.ImportJobBase: Transferred 177.2646 KB in 21.4714 seconds (8.2558 KB/sec) 20/02/07 10:44:36 INFO mapreduce.ImportJobBase: Retrieved 1 records.