I am new to hive. I have successfully setup a single node hadoop cluster for development purpose and on top of it, I have installed hive and pig.
I created a dummy table in hive:
create table foo (id int, name string);
Now, I want to insert data into this table. Can I add data just like sql one record at a time? kindly help me with an analogous command to:
insert into foo (id, name) VALUES (12,"xyz);
Also, I have a csv file which contains data in the format:
1,name1
2,name2
..
..
..
1000,name1000
How can I load this data into the dummy table?
I think the best way is:
a) Copy data into HDFS (if it is not already there)
b) Create external table over your CSV like this
CREATE EXTERNAL TABLE TableName (id int, name string)
ROW FORMAT DELIMITED
FIELDS TERMINATED BY ','
LINES TERMINATED BY '\n'
STORED AS TEXTFILE
LOCATION 'place in HDFS';
c) You can start using TableName already by issuing queries to it.
d) if you want to insert data into other Hive table:
insert overwrite table finalTable select * from table name;
There's no direct way to insert 1 record at a time from the terminal, however, here's an easy straight forward workaround which I usually use when I want to test something:
Assuming that t is a table with at least 1 record. It doesn't matter what is the type or number of columns.
INSERT INTO TABLE foo
SELECT '12', 'xyz'
FROM t
LIMIT 1;
Hive apparently supports INSERT...VALUES starting in Hive 0.14.
Please see the section 'Inserting into tables from SQL' at: https://cwiki.apache.org/confluence/display/Hive/LanguageManual+DML
What ever data you have inserted into one text file or log file that can put on one path in hdfs and then write a query as follows in hive
hive>load data inpath<<specify inputpath>> into table <<tablename>>;
EXAMPLE:
hive>create table foo (id int, name string)
row format delimited
fields terminated by '\t' or '|'or ','
stored as text file;
table created..
DATA INSERTION::
hive>load data inpath '/home/hive/foodata.log' into table foo;
to insert ad-hoc value like (12,"xyz), do this:
insert into table foo select * from (select 12,"xyz")a;
this is supported from version hive 0.14
INSERT INTO TABLE pd_temp(dept,make,cost,id,asmb_city,asmb_ct,retail) VALUES('production','thailand',10,99202,'northcarolina','usa',20)
It's a limitation of hive.
1.You cannot update data after it is inserted
2.There is no "insert into table values ... " statement
3.You can only load data using bulk load
4.There is not "delete from " command
5.You can only do bulk delete
But you still want to insert record from hive console than you can do select from statck. refer this
You may try this, I have developed a tool to generate hive scripts from a csv file. Following are few examples on how files are generated.
Tool -- https://sourceforge.net/projects/csvtohive/?source=directory
Select a CSV file using Browse and set hadoop root directory ex: /user/bigdataproject/
Tool Generates Hadoop script with all csv files and following is a sample of
generated Hadoop script to insert csv into Hadoop
#!/bin/bash -v
hadoop fs -put ./AllstarFull.csv /user/bigdataproject/AllstarFull.csv
hive -f ./AllstarFull.hive
hadoop fs -put ./Appearances.csv /user/bigdataproject/Appearances.csv
hive -f ./Appearances.hive
hadoop fs -put ./AwardsManagers.csv /user/bigdataproject/AwardsManagers.csv
hive -f ./AwardsManagers.hive
Sample of generated Hive scripts
CREATE DATABASE IF NOT EXISTS lahman;
USE lahman;
CREATE TABLE AllstarFull (playerID string,yearID string,gameNum string,gameID string,teamID string,lgID string,GP string,startingPos string) row format delimited fields terminated by ',' stored as textfile;
LOAD DATA INPATH '/user/bigdataproject/AllstarFull.csv' OVERWRITE INTO TABLE AllstarFull;
SELECT * FROM AllstarFull;
Thanks
Vijay
You can use following lines of code to insert values into an already existing table. Here the table is db_name.table_name having two columns, and I am inserting 'All','done' as a row in the table.
insert into table db_name.table_name
select 'ALL','Done';
Hope this was helpful.
Hadoop file system does not support appending data to the existing files. Although, you can load your CSV file into HDFS and tell Hive to treat it as an external table.
Use this -
create table dummy_table_name as select * from source_table_name;
This will create the new table with existing data available on source_table_name.
LOAD DATA [LOCAL] INPATH '' [OVERWRITE] INTO TABLE <table_name>;
use this command it will load the data at once just specify the file path
if file is in local fs then use LOCAL if file is in hdfs then no need to use local
Related
I needed to create huge test data in hive table. I tried following commands but it only inserts one partition data at a time.
connect to beeline:
beeline --force=true -u 'jdbc:hive2://<host>:<port>/<hive database name>;ssl=true;user=<username>;password=<pw>'
create partitioned table :
CREATE TABLE p101(
Name string,
Age string)
PARTITIONED BY(fi string)
ROW FORMAT DELIMITED
FIELDS TERMINATED BY ',';
I have created ins.csv file with data and copy it to hdfs location, its data is as follows.
Name,Age
aaa,33
bbb,22
ccc,55
then I tried to load same file for multiple partition ids with following command
LOAD DATA INPATH 'hdfs_path/ins.csv' INTO TABLE p101 PARTITION(fi=1,fi=2,fi=3,fi=4,fi=5);
but it loads record only for partitionID=5.
You can only specify one partition for each insert into.
What you can do in order to have different partitions is add it into your csv file like this:
Name,Age,fi
aaa,33,1
bbb,22,2
ccc,55,3
Hive will automatically know that this is the partition.
LOAD DATA INPATH 'hdfs_path/ins.csv' INTO TABLE tmp.p101;
I am trying to copy the Hive data from one server to another server. By this, I am exporting into hive data into CSV from server1 and trying to import that CSV file into Hive in server2.
My table contains following datatypes:
bigint
string
array
Here is my commands:
export:
hive -e 'select * from sample' > /home/hadoop/sample.csv
import:
load data local inpath '/home/hadoop/sample.csv' into table sample;
After importing into Hive table, entire row data into inserted into first column only.
How can I overcome this, or else is there a better way to copy data from one server to another server?
While creating table add below line at the end of create statment
ROW FORMAT DELIMITED FIELDS TERMINATED BY ','
Like Below:
hive>CREATE TABLE sample(id int,
name String)
ROW FORMAT DELIMITED FIELDS TERMINATED BY ',';
Then Load Data:
hive>load data local inpath '/home/hadoop/sample.csv' into table sample;
For Your Example
sample.csv
123,Raju,Hello|How Are You
154,Nishant,Hi|How Are You
So In above sample data first column is bigint, second is String and third is Array separated by |
hive> CREATE TABLE sample(id BIGINT,
name STRING,
messages ARRAY<String>)
ROW FORMAT DELIMITED FIELDS TERMINATED BY ','
COLLECTION ITEMS TERMINATED BY '|';
hive> LOAD DATA LOCAL INPATH '/home/hadoop/sample.csv' INTO TABLE sample;
Most important point :
Define delimiter for collection items and don't impose the array
structure you do in normal programming.
Also, try to make the field
delimiters different from collection items delimiters to avoid
confusion and unexpected results.
You really should not be using CSV as your data transfer format
DistCp copies data between Hadoop clusters as-is
Hive supports Export, Import
Circus Train allows Hive table replication
why not use hadoop command to transfer data from one cluster to another such as
bash$ hadoop distcp hdfs://nn1:8020/foo/bar \
hdfs://nn2:8020/bar/foo
then load the data to your new table
load data inpath '/bar/foo/*' into table wyp;
your problem may caused by the delimiter
,The default delimiter '\001' if you havn't set when create a hivetable ..
if you use hive -e 'select * from sample' > /home/hadoop/sample.csv will make all cloumn to one cloumn
I'm trying to generate some parquet files with hive,to accomplish this i loaded a regular hive table from some .tbl files, throuh this command in hive:
CREATE TABLE REGION (
R_REGIONKEY BIGINT,
R_NAME STRING,
R_COMMENT STRING)
ROW FORMAT DELIMITED
FIELDS TERMINATED BY '|'
STORED AS TEXTFILE
location '/tmp/tpch-generate';
After this i just execute this 2 lines:
create table parquet_reion LIKE region STORED AS PARQUET;
insert into parquet_region select * from region;
But when i check the output generated in HDFS, i dont find any .parquet file, intead i find files names like 0000_0 to 0000_21, and the sum of their sizes are much bigger that the original tbl file.
What im i doing Wrong?
Insert statement doesn't create file with extension but these are the parquet files.
You can use DESCRIBE FORMATTED <table> to show table information.
hive> DESCRIBE FORMATTED <table_name>
Additional Note: You can also create new table from source table using below query:
CREATE TABLE new_test row STORED AS PARQUET AS select * from source_table
It will create new table as parquet format and copies the structure as well as the data.
What is the efficient way to export the data from hive/impala table with conditions into file(the data would be huge, close to 10 GB)? The format of the hive table is paraquet with snappy compressed and file is csv.
The table is partitioned daily and data needs to be extracted on daily basis, I would like to know if
1) Imapala approach
impala-shell -k -i servername:portname -B -q 'select * from table where year_month_date=$$$$$$$$' -o filename '--output_delimiter=\001'
2) Hive approach
Insert overwrite directory '/path' select * from table where year_month_date=$$$$$$$$
would be efficient
Assuming table tbl as your hive parquet table and condition as your filter condition.
CTAS command:
CREATE TABLE tbl_text ROW FORMAT DELIMITED FIELDS TERMINATED BY ',' LOCATION '/tmp/data' AS select * from tbl where condition;
You will find your CSV text file (delimited by ',') at /tmp/data in HDFS.
You can get this file to your local file system if needed using:
hadoop fs -get /tmp/data
Please try to use Dynamic Partitioning for your Hive/Impala table to efficiently export the data conditionally.
Partition your table with the columns of your interest and based on your queries for best results
Step 1: Create a Temporary Hive Table TmpTable and load your raw data into it
Step 2: Set hive parameters to support Dynamic partition
SET hive.exec.dynamic.partition.mode=non-strict;
SET hive.exec.dynamic.partition=true;
Step 3: Create your Main Hive Table with partition columns, example :
CREATE TABLE employee (
emp_id int,
emp_name string
PARTITIONED BY (location string)
STORED AS PARQUET;
Step 4: Load data from Temporary table to your employee table (Main Table)
insert overwrite table employee partition(location)
select emp_id,emp_name, location from TmpTable;
Step 5: export the data from hive with a condition
INSERT OVERWRITE DIRECTORY '/path/to/output/dir' SELECT * FROM employee WHERE location='CALIFORNIA';
Please refer this link:
Dynamic Partition Concept
Hope this is useful.
I use flume to write data to hdfs,path like /hive/logs/dt=20151002.Then,i use hive to select data,but the count of response is always 0.
Here is my create table sql,CREATE EXTERNAL TABLE IF NOT EXISTS test (id STRING) partitioned by (dt string) ROW FORMAT DELIMITED fields terminated by '\t' lines terminated by '\n' STORED AS TEXTFILE LOCATION '/hive/logs'
Here is my select sql,select count(*) from test
It seems that you are not registering partition in hive meta-store.
Although partition is present in hdfs path,Hive won't know it if its not registered in meta store. To register it you can do the following:
ALTER TABLE test ADD PARTITION (dt='20151002') location '/hive/logs/dt=20151002';