Search code examples
hadoophcatalog

Where does Hadoop Hcatalog store databases and tables?

I am new to Hadoop. I have been doing the following tutorial based on a prebuilt Hadoop virtual machine running on Linux.

hadoop tutorial

I did create a Hcatalog table on the default database based on a file. I would like to know if those databases and tables can be seen on the Hadoop filesystem or if they are on some kind of special store.

Solution

  • HCatalog is built on top of the Hive metastore so where it stores it's metadata will depend on how you have hive set up. If you are using an external database for your metastore it will be there if you are using the default configuration it is stored in a local derby database. You woun't be able to see the "databases and tables" on the hadoop filesystem. Hive provides a mechanism to project structure onto this data (which is on hdfs) and query the data using a SQL-like language called HiveQL.

    https://cwiki.apache.org/confluence/display/Hive/HCatalog+UsingHCat