ALTER Statement on HIVE Table. 1. Tables, Partitions, and Buckets are the parts of Hive data modeling. Determine How to delete some rows from hive Table: The best approach is to partition your data such that the rows you want to drop are in a partition themselves. Inserts can be done to a table or a partition. You can use ALTER TABLE with DROP PARTITION option to drop a partition for a table. However, the latest version of Apache Hive supports ACID transaction, but using ACID transaction on table with huge amount of data may kill the performance of Hive server. TRUNCATE TABLE. Update hive table using spark The insert command is used to load the data Hive table. 3. Athena leverages Apache Hive for partitioning data. What is Partitions? A common strategy in Hive is to partition data by date. Lets check it with an example. The above test confirms that files remain in the target partition directory when table was newly created with no partition definitions. To fix this issue, you can run the following hive query before the “INSERT OVERWRITE” to recover the missing partition definitions: MSCK REPAIR TABLE partition_test; This will insert data to year and month partitions for the order table. ALTER TABLE ADD PARTITION in Hive. ALTER TABLE customer EXCHANGE PARTITION (spender) WITH TABLE expenses. Addresses how data can be stored into hive if the data /records resides in a single file or in different folders. rename hive table ALTER TABLE tbl_nm RENAME TO new_tbl_nm; In the above statement the table name was changed from tbl_nm to new_tbl_nm. Hive Partitions is a way to organizes tables into partitions by dividing tables into different parts based on partition keys. Hive will not create the partitions for you this way. DELETE : used to delete particular row with where condition and you can all delete all the rows from the given table. After the merge process, the managed table is identical to the staged table at T = 2, and all records are in their respective partitions. This post explains about Hive partitioning. Hive - external (dynamically) partitioned table, Hi, i created an external table in HIVE with 150 columns. This chapter describes how to drop a table in Hive. In order to truncate multiple partitions at once, specify the partitions in partition_spec.If no partition_spec is specified, removes all partitions in the table. A common practice is to partition the data based on time, often leading to a multi-level partitioning scheme. Apache Hive is not designed for online transaction processing and does not offer real-time queries and row level updates and deletes. 2 Answers 2. Synopsis. Copy the data from one table to another table in Hive. a. INSERT INTO. for deleting and updating the record from table you can use the below statements. TRUNCATE: used to truncate all the rows, which can not even be restored at all, this actions deletes data in Hive meta store. It is widely used to log or fire hooks in case the table or partition is modified. Drop a Hive partition. Drop or Delete Hive Partition. Think of Trash folder as recycle bin in desktop. The deleted file can be recovered from TRASH folder , but once deleted from here then the file is permanently deleted. alter table salesdata_ext drop partition (date_of_sale=10-27-2017) ; (external table) Partition will be dropped but the subdirectory will not be deleted since this is an external table. By partitioning your data, you can restrict the amount of data scanned by each query, thus improving performance and reducing cost. You “statically” add a partition in the table and move the file into the partition of the table. Input Files :-Suppose we have 2 departments – HR and BIGDATA. Use Case 2: Update Hive Partitions. DROP: it drops the table along with the data associated with Hive … This will delete the partition from the table. Using partitions, we can query the portion of the data. Load Data into Table Partitions from File/Directory. static and dynamic partitioning . The purpose of using this command is to read the metadata and write it back. It initially goes into Trash folder. Hive dynamic partition external table. We can load data into a Hive table partition directly from a file OR from a directory(all the files in the directory will be loaded in the Hive table partition). Note that there is no impact on the data that resides in the table. The table must not be a view or an external or temporary table. If you also want to drop data along with partition fro external tables then you have to do it manually. I want to keep the partition intact and remove data from specific partitions. You can partition your data by any key. Each partition of a table is associated with a particular value(s) of partition column(s). The underlying table’s changes would not be reflected in the view; however, the underlying table must be present; otherwise, the view will fail. If the external table is dropped, the table metadata is deleted but the data is kept. When you delete a file/folder it is not removed permanently . Along with the primitive data types, the Hive also supports data types like maps, arrays, and struct. Let’s see a few variations of drop partition. Syntax: Static Partition : In static partitioning we need to pass the values of the partitioned column manually when we load the data into the table. Step 5 : Create a Partition table with Partition key. Partitioning allows Hive to run queries on a specific set of data in the table based on the value of partition column used in the query. The INSERT command in Hive loads the data into a Hive table. Here we will discuss how we can change table level properties. In addition, we can use the Alter table add partition command to add the new partitions for a table. For example, to drop the first partition, issue the following statements: DELETE FROM sales partition (dec98); ALTER TABLE sales DROP PARTITION dec98; This method is most appropriate for small tables, or for large tables when the partition being dropped contains a small percentage of the total data in the table. hive> INSERT OVERWRITE TABLE test_partitioned PARTITION (p) SELECT salary, 'p1' AS p FROM sample_07; hive> INSERT OVERWRITE TABLE test_partitioned PARTITION (p) SELECT salary, 'p1' AS p FROM sample_07; Of course, you will have to enable dynamic partitioning for the above query to run. 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. say, I have created partitions on a table, It has 5 partitions (1,2,3,4,5) and I want to remove data only from 2nd and 3rd partition. Alter table statement is used to change the table structure or properties of an existing table in Hive. Hive - Partitioning - Hive organizes tables into partitions.