GitHub user mohammadshahidkhan opened a pull request:
https://github.com/apache/carbondata/pull/1418
Support db location
**Problem:**
Currently carbon stores the database and tables at the fixed configured
location âcarbon.storeLocationâ. So even though in case of federated
cluster i.e. multiple independent Namespaces/ Namenodes only one Namespace/
Namenode can be used as storage for the database and tables.
The requirement is to support when create database can specify the
LOCATION; the location can be viewfs path, name service path.
Using database location attribute configuration different name nodes can be
used to store different databases. Having different name nodes for different
databases will scale the read/write throughput.
**Solution:**
Setting the LOCATION attribute for a new database is a way to work with
sets of files in an HDFS directory structure outside the fixed carbon store
location.
In Create database command user can specify the location, the location
where database and table under that database namespace could be stored.
1. The database at specified location could be created at defined location
using create database command with location attribute.
Syntax:
CREATE DATABASE [IF NOT EXISTS] database_name[COMMENT 'database_comment']
[LOCATION hdfs_path];
The HDFS path can be viewfs path, nameservice path.
2. The database name and database location will be retrieved from the
HiveSessionCatalog. The tables will be retrieved by scanning the table folders.
3. The read/write operation on old databases/ new databases created
without specifying the LOCATION attribute should be performed the fixed carbon
store location.
4. The table path formation will be same as the hive. The table path
should be formed from database location or fixed Carbon store location and
table name as given below.
The will be three possible scenarios:
I. Table path for the databases defined with location attribute.
tablePath = databaseLocation +â/â + tableName
II. Table path for the databases defined without location attribute.
tablePath = carbon.storeLocation + â/â +
database_Name+â.dbâ +â/â + tableName
III. New table path for the default database.
tablePath = carbon.storeLocation +â/â + tableName
5. The carbon should support hybrid Nameservice path i.e. different
operation could be performed in different name service. For example in load
command the raw CSV files could be read from the nameservice ns1 i.e.
âhdfs://ns1/user/data.csvâ and database location could point to viewfs path
âviewfs://federation_cluster/dir1/carbonstoreâ.
Example:
CREATE DATABASE carbon LOCATION
âviewfs://federation_cluster/dir1/carbonstoreâ;
CREATE TABLE carbon.carbon_table (c1 string, c2 int) stored by
âcarbondataâ;
LOAD DATA INPATH âhdfs://ns1/user/data.csvâ into table
carbon.carbon_table;
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/mohammadshahidkhan/incubator-carbondata
support_db_location
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/carbondata/pull/1418.patch
To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:
This closes #1418
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commit b92be927761391f37018f5018521813f588825b8
Author: mohammadshahidkhan <[email protected]>
Date: 2017-10-10T05:20:11Z
Support database location:
The database name and database location will be retrieved from the
HiveSessionCatalog. The tables will be retrieved by scanning the table folders.
The read/write operation on old databases/ new databases created without
specifying the LOCATION attribute should be performed the fixed carbon store
location.
commit 2a88536a19f483b8aee833039ba364ec85a78ee4
Author: mohammadshahidkhan <[email protected]>
Date: 2017-10-10T06:00:43Z
Support configurable path for the store modification info file
(modifiedTime.mdt).
commit 7ab2f29b38d35e2590a40f5e2f0939b5033715dc
Author: mohammadshahidkhan <[email protected]>
Date: 2017-10-10T10:17:00Z
Fixed drop database issue
commit 524f4532e8fcaf0c40a884c7c5b51fd0d887066e
Author: mohammadshahidkhan <[email protected]>
Date: 2017-10-11T10:00:51Z
Corrected lock file location
commit dbb3160919a28c9b0eb93ab9ed8dfecfe93129b4
Author: mohammadshahidkhan <[email protected]>
Date: 2017-10-16T08:58:07Z
Making carbon table path same as hive.
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