CREATE EXTERNAL TABLE IF NOT EXISTS LOGS (LGACT STRING,NTNAME STRING)
ROW FORMAT DELIMITED FIELDS TERMINATED BY '\t'
LOCATION '/user/hive/warehouse/LOGS/test';
under 'test' folder I am writing files daily. for eg:
/user/hive/warehouse/LOGS/test/20170420
/user/hive/warehouse/LOGS/test/20170421
/user/hive/warehouse/LOGS/test/20170422
I cannot see any data inside LOGS table that i have created.
But, I create the table using
LOCATION '/user/hive/warehouse/LOGS/test/20170422';
I can see that days records.
I want to see all the data under /test directory in my HIVE table, also the /test directory is populated daily with new files.
Option 1
In order to support sub-directories
set mapred.input.dir.recursive=true;
and if you Hive version is lower than 2.0.0 then also
set hive.mapred.supports.subdirectories=false;
Option 2
Create a partitioned table
CREATE EXTERNAL TABLE IF NOT EXISTS LOGS (LGACT STRING,NTNAME STRING)
partitioned by (dt date)
ROW FORMAT DELIMITED FIELDS TERMINATED BY '\t'
LOCATION '/user/hive/warehouse/LOGS/test';
alter table LOGS add if not exists partition (dt=date '2017-04-20') LOCATION '/user/hive/warehouse/LOGS/test/20170420';
alter table LOGS add if not exists partition (dt=date '2017-04-21') LOCATION '/user/hive/warehouse/LOGS/test/20170421';
alter table LOGS add if not exists partition (dt=date '2017-04-22') LOCATION '/user/hive/warehouse/LOGS/test/20170422';
It would be easier to manage if you keep your directories using the standard convention, e.g. dt=2017-04-20 instead of 20170420
By default hive reads only the files (not directories) inside the specified location in external table. If you want to enable adding the directories, then set the below parameter:
set mapred.input.dir.recursive=true;
Related
When load data from HDFS to Hive, using
LOAD DATA INPATH 'hdfs_file' INTO TABLE tablename;
command, it looks like it is moving the hdfs_file to hive/warehouse dir.
Is it possible (How?) to copy it instead of moving it, in order, for the file, to be used by another process.
from your question I assume that you already have your data in hdfs.
So you don't need to LOAD DATA, which moves the files to the default hive location /user/hive/warehouse. You can simply define the table using the externalkeyword, which leaves the files in place, but creates the table definition in the hive metastore. See here:
Create Table DDL
eg.:
create external table table_name (
id int,
myfields string
)
location '/my/location/in/hdfs';
Please note that the format you use might differ from the default (as mentioned by JigneshRawal in the comments). You can use your own delimiter, for example when using Sqoop:
row format delimited fields terminated by ','
I found that, when you use EXTERNAL TABLE and LOCATION together, Hive creates table and initially no data will present (assuming your data location is different from the Hive 'LOCATION').
When you use 'LOAD DATA INPATH' command, the data get MOVED (instead of copy) from data location to location that you specified while creating Hive table.
If location is not given when you create Hive table, it uses internal Hive warehouse location and data will get moved from your source data location to internal Hive data warehouse location (i.e. /user/hive/warehouse/).
An alternative to 'LOAD DATA' is available in which the data will not be moved from your existing source location to hive data warehouse location.
You can use ALTER TABLE command with 'LOCATION' option. Here is below required command
ALTER TABLE table_name ADD PARTITION (date_col='2017-02-07') LOCATION 'hdfs/path/to/location/'
The only condition here is, the location should be a directory instead of file.
Hope this will solve the problem.
I want to make table in hive containing of only 1 column and 2 values: 'Y' and 'N'
I already try this:
create external table if not exists tx_test_table (FLAG string)
row format delimited fields terminated by ','
stored as textfile location "/user/hdd/data/";
My question is : why it locate at default table?
how to make it through the path I desire?
When I make query from the table I jut make, it failed to show the field (using select * from )
Bad status for request TFetchResultsReq(fetchType=0,
operationHandle=TOperationHandle(hasResultSet=True, modifiedRowCount=None,
operationType=0,
operationId=THandleIdentifier(secret='pE\xff\xfdu\xf6B\xd4\xb3\xb7\x1c\xdd\x16\x95\xb85',
guid="\n\x05\x16\xe7'\xe4G \xb6R\xe06\x0b\xb9\x04\x87")),
orientation=4, maxRows=100):
TFetchResultsResp(status=TStatus(errorCode=0,
errorMessage='java.io.IOException: java.io.IOException: Not a file:
hdfs://nameservice1/user/hdd/data/AC22', sqlState=None,
infoMessages=['*org.apache.hive.service.cli.HiveSQLException:java.io.IOException:
java.io.IOException: Not a file: hdfs://nameservice1/user/hdd/data/AC22:14:13',
'org.apache.hive.service.cli.operation.SQLOperation:getNextRowSet:SQLOperation.java:496',
'org.apache.hive.service.cli.operation.OperationManager:getOperationNextRowSet:OperationManager.java:297',
'org.apache.hive.service.cli.session.HiveSessionImpl:fetchResults:HiveSessionImpl.java:869', 'org.apache.hive.service.cli.CLIService:fetchResults:CLIService.java:507',
'org.apache.hive.service.cli.thrift.ThriftCLIService:FetchResults:ThriftCLIService.java:708',
'org.apache.hive.service.rpc.thrift.TCLIService$Processor$FetchResults:getResult:TCLIService.java:1717',
'org.apache.hive.service.rpc.thrift.TCLIService$Processor$FetchResults:getResult:TCLIService.java:1702',
'org.apache.thrift.ProcessFunction:process:ProcessFunction.java:39',
'org.apache.thrift.TBaseProcessor:process:TBaseProcessor.java:39', 'org.apache.hadoop.hive.thrift.HadoopThriftAuthBridge$Server$TUGIAssumingProcessor:process:HadoopThriftAuthBridge.java:605',
'org.apache.thrift.server.TThreadPoolServer$WorkerProcess:run:TThreadPoolServer.java:286',
'java.util.concurrent.ThreadPoolExecutor:runWorker:ThreadPoolExecutor.java:1149',
'java.util.concurrent.ThreadPoolExecutor$Worker:run:ThreadPoolExecutor.java:624', 'java.lang.Thread:run:Thread.java:748',
'*java.io.IOException:java.io.IOException: Not a file: hdfs://nameservice1/user/hdd/data/AC22:18:4',
'org.apache.hadoop.hive.ql.exec.FetchOperator:getNextRow:FetchOperator.java:521'
, 'org.apache.hadoop.hive.ql.exec.FetchOperator:pushRow:FetchOperator.java:428',
'org.apache.hadoop.hive.ql.exec.FetchTask:fetch:FetchTask.java:146',
'org.apache.hadoop.hive.ql.Driver:getResults:Driver.java:2227',
'org.apache.hive.service.cli.operation.SQLOperation:getNextRowSet:SQLOperation.java:491',
'*java.io.IOException:Not a file: hdfs://nameservice1/user/hdd/data/AC22:21:3',
'org.apache.hadoop.mapred.FileInputFormat:getSplits:FileInputFormat.java:329',
'org.apache.hadoop.hive.ql.exec.FetchOperator:getNextSplits:FetchOperator.java:372',
'org.apache.hadoop.hive.ql.exec.FetchOperator:getRecordReader:FetchOperator.java:304',
'org.apache.hadoop.hive.ql.exec.FetchOperator:getNextRow:FetchOperator.java:459'], statusCode=3),
results=None, hasMoreRows=None)
Each table in HDFS has it's own location. And location you specified for your table seems used as common location where other table folders are located.
According to the exception: java.io.IOException:Not a file: hdfs://nameservice1/user/hdd/data/AC22:21:3', at least one folder (not a file) was found in the /user/hdd/data/ location. I guess it belongs to some other table.
You should specify table location where will be stored only files which belong to this table, not the common data warehouse location, in which other table locations are.
Usually table location is named as table name: /user/hdd/data/tx_test_table
Fixed create table sentence:
create external table if not exists tx_test_table (FLAG string)
row format delimited fields terminated by ','
stored as textfile location "/user/hdd/data/tx_test_table";
Now table will have it's own location which will contain it's files, not mixed with other table folders or files.
You can put files into /user/hdd/data/tx_test_table location or load data into the table using INSERT, files will be created in the location.
I have created an external table in Hive using following:
create external table hpd_txt(
WbanNum INT,
YearMonthDay INT ,
Time INT,
HourlyPrecip INT)
ROW FORMAT DELIMITED
FIELDS TERMINATED BY ','
LINES TERMINATED BY '\n'
stored as textfile
location 'hdfs://localhost:9000/user/hive/external';
Now this table is created in location */hive/external.
Step-1: I loaded data in this table using:
load data inpath '/input/hpd.txt' into table hpd_txt;
the data is successfully loaded in the specified path ( */external/hpd_txt)
Step-2: I delete the table from */hive/external path using following:
hadoop fs -rmr /user/hive/external/hpd_txt
Questions:
why is the table deleted from original path? (*/input/hpd.txt is deleted from hdfs but table is created in */external path)
After I delete the table from HDFS as in step 2, and again I use show tables; It still gives the table hpd_txt in the external path.
so where is this coming from.
Thanks in advance.
Hive doesn't know that you deleted the files. Hive still expects to find the files in the location you specified. You can do whatever you want in HDFS and this doesn't get communicated to hive. You have to tell hive if things change.
hadoop fs -rmr /user/hive/external/hpd_txt
For instance the above command doesn't delete the table it just removes the file. The table still exists in hive metastore. If you want to delete the table then use:
drop if exists tablename;
Since you created the table as an external table this will drop the table from hive. The files will remain if you haven't removed them. If you want to delete an external table and the files the table is reading from you can do one of the following:
Drop the table and then remove the files
Change the table to managed and drop the table
Finally the location of the metastore for hive is by default located here /usr/hive/warehouse.
The EXTERNAL keyword lets you create a table and provide a LOCATION so that Hive does not use a default location for this table. This comes is handy if you already have data generated. Else, you will have data loaded (conventionally or by creating a file in the directory being pointed by the hive table)
When dropping an EXTERNAL table, data in the table is NOT deleted from the file system.
An EXTERNAL table points to any HDFS location for its storage, rather than being stored in a folder specified by the configuration property hive.metastore.warehouse.dir.
Source: Hive docs
So, in your step 2, removing the file /user/hive/external/hpd_txt removes the data source(data pointing to the table) but the table still exists and would continue to point to hdfs://localhost:9000/user/hive/external as it was created
#Anoop : Not sure if this answers your question. let me know if you have any questions further.
Do not use load path command. The Load operation is used to MOVE ( not COPY) the data into corresponding Hive table. Use put Or copyFromLocal to copy file from non HDFS format to HDFS format. Just provide HDFS file location in create table after execution of put command.
Deleting a table does not remove HDFS file from disk. That is the advantage of external table. Hive tables just stores metadata to access data files. Hive tables store actual data of data file in HIVE tables. If you drop the table, the data file is untouched in HDFS file location. But in case of internal tables, both metadata and data will be removed if you drop table.
After going through you helping comments and other posts, I have found answer to my question.
If I use LOAD INPATH command then it "moves" the source file to the location where external table is being created. Which although, wont be affected in case of dropping the table, but changing the location is not good. So use local inpath in case of loading data in Internal tables .
To load data in external tables from a file located in the HDFS, use the location in the CREATE table query which will point to the source file, for example:
create external table hpd(WbanNum string,
YearMonthDay string ,
Time string,
hourprecip string)
ROW FORMAT DELIMITED
FIELDS TERMINATED BY ','
LINES TERMINATED BY '\n'
stored as textfile
location 'hdfs://localhost:9000/input/hpd/';
So this sample location will point to the data already present in HDFS in this path. so no need to use LOAD INPATH command here.
Its a good practice to store a source files in their private dedicated directories. So that there is no ambiguity while external tables are created as data is in a properly managed directory system.
Thanks a lot for helping me understand this concept guys! Cheers!
I'm using hive (with external tables) to process data stored on amazon S3.
My data is partitioned as follows:
DIR s3://test.com/2014-03-01/
DIR s3://test.com/2014-03-02/
DIR s3://test.com/2014-03-03/
DIR s3://test.com/2014-03-04/
DIR s3://test.com/2014-03-05/
s3://test.com/2014-03-05/ip-foo-request-2014-03-05_04-20_00-49.log
s3://test.com/2014-03-05/ip-foo-request-2014-03-05_06-26_19-56.log
s3://test.com/2014-03-05/ip-foo-request-2014-03-05_15-20_12-53.log
s3://test.com/2014-03-05/ip-foo-request-2014-03-05_22-54_27-19.log
How to create a partition table using hive?
CREATE EXTERNAL TABLE test (
foo string,
time string,
bar string
) PARTITIONED BY (? string)
ROW FORMAT DELIMITED
FIELDS TERMINATED BY '\t'
LOCATION 's3://test.com/';
Could somebody answer this question ? Thanks!
First start with the right table definition. In your case I'll just use what you wrote:
CREATE EXTERNAL TABLE test (
foo string,
time string,
bar string
) PARTITIONED BY (dt string)
ROW FORMAT DELIMITED
FIELDS TERMINATED BY '\t'
LOCATION 's3://test.com/';
Hive by default expects partitions to be in subdirectories named via the convention s3://test.com/partitionkey=partitionvalue. For example
s3://test.com/dt=2014-03-05
If you follow this convention you can use MSCK to add all partitions.
If you can't or don't want to use this naming convention, you will need to add all partitions as in:
ALTER TABLE test
ADD PARTITION (dt='2014-03-05')
location 's3://test.com/2014-03-05'
If you have existing directory structure that doesn't comply <partition name>=<partition value>, you have to add partitions manually. MSCK REPAIR TABLE won't work unless you structure your directory like so.
After you specify location on table creation like:
CREATE EXTERNAL TABLE test (
foo string,
time string,
bar string
)
PARTITIONED BY (dt string)
ROW FORMAT DELIMITED
FIELDS TERMINATED BY '\t'
LOCATION 's3://test.com/';
You can add partition without specifying full path:
ALTER TABLE test ADD PARTITION (dt='2014-03-05') LOCATION '2014-03-05';
Although I've never checked it, I suggest you to move your partitions into a folder inside the bucket, not directly in the bucket itself. E.g. from s3://test.com/ to s3://test.com/data/.
If you are going to partition using date field you need s3 folder structure as mentioned below:
s3://test.com/date=2014-03-05/ip-foo-request-2014-03-05_04-20_00-49.log
In such case you can create external table with partition column as date
and run MSCK REPAIR TABLE EXTERNAL_TABLE_NAME to update hive meta store.
Please look at the response posted above by Carter Shanklin. You need to make sure your files are stored in the directory structure as partitionkey=partitionvalue i.e. Hive by default expects partitions to be in subdirectories named via the convention.
In your example it should be stored as
s3://test.com/date=20140305/ip-foo-request-2014-03-05_04-20_00-49.log.
Steps to be followed:
i) Make sure data exists in the above structure
ii) Create the external table
iii) Now run the msck repair table.
I think the the data is present in the s3 location and might not updated in the metadata, (emrfs). In order this to work first do emrfs import and emrfs sync.
And then apply the msck repair.
It will add all the partitions that are present in s3
I've created a working hive script to backup data from dynamodb to a file in S3 bucket in AWS. A code snippet is shown below
INSERT OVERWRITE DIRECTORY '${hiveconf:S3Location}'
SELECT *
FROM DynamoDBDataBackup;
When I run the hive script it probably deletes the old file and creates a new file but if there are errors in the backup process I guess it rolls back to the old data because the file is still there when an error has occurred.
Each day we want to make a backup but I need to know if an error has occurred so I want to delete the previous days backup first then create a backup. If it fails then there is no file in the folder which we can automatically detect.
The filename gets automatically named 000000
In my hive script I've tried unsuccesfully:
delete FILE '${hiveconf:S3Location}/000000'
and
delete FILE '${hiveconf:S3Location}/000000.0'
Perhaps the filename is wrong. I haven't set any permissions on the file.
I've just tried this but fails at STORED
SET dynamodb.endpoint= ${DYNAMODBENDPOINT};
SET DynamoDBTableName = "${DYNAMODBTABLE}";
SET S3Location = ${LOCATION};
DROP TABLE IF EXISTS DynamoDBDataBackupPreferenceStore;
CREATE TABLE IF NOT EXISTS DynamoDBDataBackupPreferenceStore(UserGuid STRING,PreferenceKey STRING,DateCreated STRING,DateEmailGenerated STRING,DateLastUpdated STRING,ReceiveEmail STRING,HomePage STRING,EmailFormat STRING,SavedSearchCriteria STRING,SavedSearchLabel STRING),
STORED BY 'org.apache.hadoop.hive.dynamodb.DynamoDBStorageHandler'
LOCATION '${hiveconf:S3Location}',
TBLPROPERTIES ("dynamodb.table.name" = ${hiveconf:DynamoDBTableName}, "dynamodb.column.mapping" = "UserGuid:UserGuid,PreferenceKey:PreferenceKey,DateCreated:DateCreated,DateEmailGenerated:DateEmailGenerated,DateLastUpdated:DateLastUpdated,ReceiveEmail:ReceiveEmail,HomePage:HomePage,EmailFormat:EmailFormat,SavedSearchCriteria:SavedSearchCriteria,SavedSearchLabel:SavedSearchLabel");
You manage files directly using Hive Table commands
Firstly if you want to use external data controlled outside Hive use the External Command when creating the table
set S3Path='s3://Bucket/directory/';
CREATE EXTERNAL TABLE IF NOT EXISTS S3table
( data STRING
)
ROW FORMAT DELIMITED
FIELDS TERMINATED BY ','
LOCATION ${hiveconf:S3Path};
You can now insert data into this table
INSERT OVERWRITE TABLE S3table
SELECT data
FROM DynamoDBtable;
This will create text files in S3 inside the directory location
Note depending on the data size and number of reducers there may be multiple text files.
Files names are also random GUID element i.e. 03d3842f-7290-4a75-9c22-5cdb8cdd201b_000000
DROP TABLE S3table;
Dropping the table just breaks the link to the files
Now if you want to manage the directory you can create a table that will take control of the S3 directory (Note there is no external command)
CREATE TABLE IF NOT EXISTS S3table
( data STRING
)
ROW FORMAT DELIMITED
FIELDS TERMINATED BY ','
LOCATION ${hiveconf:S3Path};
If you now issue a drop table command all files in the folder are delete immediately
DROP TABLE S3table;
I suggest you create a non external table then drop it and carry on with the rest of your script. If you encounter errors you will have a blank directory after the job finishes
Hope this covers what you need