-- impala a, Hive ，Hive
create table a(id int ,name string);
-- Hive b， impala ，impala
create table b(id int ,name string);
--
invalidate metadata;
-- 1. Hive impala a ，
-- 2.vi /etc/passwd hdfs hdfs:x:996:993:Hadoop HDFS:/var/lib/hadoop-hdfs:/sbin/nologin hdfs:x:996:993:Hadoop HDFS:/var/lib/hadoop-hdfs:/bin/bash
-- 3. su hdfs hdfs dfs -chmod -R 777 /
-- 4. Hive set mapreduce.framework.name=local;
-- 5. Hive ， impala ， a ， refresh a;
--
impala-shell -i localhost
--
impala-shell --quiet
--
--
impala-shell -q 'select * from a'
--
impala-shell -q 'select * from a' -o a.txt
-- -b -o --output_delimiter=','
impala-shell -q 'select * from a' -B --output_delimiter=',' -o a.txt
-- shell impala shell
shell hdfs dfs -ls /;
explain select * from a;
+------------------------------------------------------------------------------------+
| Explain String |
+------------------------------------------------------------------------------------+
| Max Per-Host Resource Reservation: Memory=8.00KB Threads=3 |
| Per-Host Resource Estimates: Memory=64MB |
| WARNING: The following tables are missing relevant table and/or column statistics. |
| default.a |
| |
| PLAN-ROOT SINK |
| | |
| 01:EXCHANGE [UNPARTITIONED] |
| | |
| 00:SCAN HDFS [default.a] |
| partitions=1/1 files=6 size=34B |
| row-size=15B cardinality=unavailable |
+------------------------------------------------------------------------------------+
[cdh01:21000] default> explain select count(1) from a;
+------------------------------------------------------------------------------------+
| Explain String |
+------------------------------------------------------------------------------------+
| Max Per-Host Resource Reservation: Memory=8.00KB Threads=3 |
| Per-Host Resource Estimates: Memory=84MB |
| WARNING: The following tables are missing relevant table and/or column statistics. |
| default.a |
| |
| PLAN-ROOT SINK |
| | |
| 03:AGGREGATE [FINALIZE] |
| | output: count:merge(*) |
| | row-size=8B cardinality=1 |
| | |
| 02:EXCHANGE [UNPARTITIONED] |
| | |
| 01:AGGREGATE |
| | output: count(*) |
| | row-size=8B cardinality=1 |
| | |
| 00:SCAN HDFS [default.a] |
| partitions=1/1 files=6 size=34B |
| row-size=0B cardinality=unavailable |
+------------------------------------------------------------------------------------+
--
select current_database();
--
show tables in default;
--
show tables in default like 't*';
--
desc tb_name
--
desc formatted tb_name;
