So today we learnt how to show partitions in Hive Table. Donate # HDFS # Hive. In Hive, we can rename a column, change its type and position. Most ALTER TABLE operations do not actually rewrite, move, and so on the actual data files. SHOW PARTITIONS table_name [PARTITION(partition_spec)] [WHERE where_condition] [ORDER BY column_list] [LIMIT rows]; Conclusion. For all other operations, an 'X' lock is taken on the partition. You can add new column to the table. HIVE queries can take advantage of the partitioned data for better performance. Partition is helpful when the table has one or more Partition keys. Add Hadoop archive option to Hive table. ALTER TABLE lookup_table REPLACE COLUMNS (id string,name string); Note : The ALTER command will only modify Hive metadata and not the data. Change Column. In Impala, this is primarily a logical operation that updates the table metadata in the metastore database that Impala shares with Hive. ALTER TABLE lookup_table ADD COLUMNS (comments string); Replace all columns other than the partition columns. One option is to delete existing external table and create new table that includes new column. ALTER TABLE some_table DROP IF EXISTS PARTITION(year = 2012); This command will remove the data and metadata for this partition. Type: Bug Status: Closed. If we have a large table then queries may take long time to execute on the whole table. ALTER TABLE table_identifier ADD [IF NOT EXISTS] (partition_spec [partition_spec ... ALTER TABLE SET command is used for setting the SERDE or SERDE properties in Hive tables. Adding columns. The primary difference in usability is that `alter table recover partitions` works from dbcli or directly ODAS through the REST API. Without partitioning, any query on the table in Hive will read the entire data in the table. So, we definitely want to keep year, month, day as the partitions in our external hive table. The table identifier parameter in all statements has the following form: table_identifier [database_name.] When I tried using the following hive command it gives me error. Make hive be able to read JSON. Add or drop table partition. New partitions must be of the same type (LIST, RANGE or HASH) as existing partitions. alter the table named table_name; add a partition, ... After execution of the SQL, the HDFS folder is loaded as a partition of Hive external table, without data moving. Since every line in our data is a JSON object, we need to tell hive how to comprehend it as a set of fields. Export. Let's see the updated schema of the table. delta.``: The location of an existing Delta table. Below command to add the partition to the table already created earlier. The following query is used to add a partition to the employee table. OR alter table salesdata_ext add partition (date_of_sale=’10-27-2017’); Rename Hive table column. Since this is Hive metadata operation, your data files wont be touched. Partition locations to be used with Athena must use the s3 protocol (for example, s3://bucket/folder/). Hive> ALTER TABLE std_details ADD PARTITION (std_class=’1’); Once the above statement successfully executed, the partition added to std_db.std_details table. `Alter table recover partitions` is effectively an alias for `msck repair table`. Downside is that you will have to execute alter table command to redefine partitions on new table. We should use an ALTER TABLE query in such cases. Most ALTER TABLE operations do not actually rewrite, move, and so on the actual data files. table_name: A table name, optionally qualified with a database name. msck repair table salesdata_ext; show partitions salesdata_ext; O/p: date_of_sale=10-27-2017. The data is well divided into daily chunks. Syntax. The ALTER TABLE statement changes the structure or properties of an existing Impala table.. XML Word Printable JSON. Drop or Delete Hive Partition. XML Word Printable JSON. Is there a way to alter the table Here, we are changing the name of the column by using the following signature: - However, beginning with Spark 2.1, Alter Table Partitions is also supported for tables defined using the datasource API. HIVE-9430; NullPointerException on ALTER TABLE ADD PARTITION if no value given. Description. Uses of Hive ALTER TABLE Command. Log In. A 'S' lock on table and relevant partition is acquired when a read is being performed. For partitions that are not compatible with Hive, use ALTER TABLE ADD PARTITION to load the partitions so that you can query their data. The ALTER TABLE statement changes the structure or properties of an existing Impala table.. Details. ADD PARTITION. There is no upper limit to the number of defined partitions in a partitioned table. HIVE Partition – Managed Table Partitioning. You can add, modify existing columns in Hive tables. Solved: I am using hdp 2.4.2 (hive - 1.2.1.2.4). In Impala, this is primarily a logical operation that updates the table metadata in the metastore database that Impala shares with Hive. MSCK REPAIR is a resource-intensive query and using it to add single partition is not recommended especially when you huge number of partitions. ALTER TABLE ADD statement adds partition to the partitioned table. For the partition to reflect in the table metadata, we will either have to repair the table or add partition by using the alter command that we are discussing later. 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. If this post helps you, please consider to buy a cup of coffee for me. You can also manually update or drop a Hive partition directly on HDFS using Hadoop commands, if you do so you need to run the MSCK command to synch up HDFS files with Hive … You can use ALTER TABLE with DROP PARTITION option to drop a partition for a table. Export. Do you want dynamic or static partitions? Also the use of where limit order by clause in Partitions which is introduced from Hive 4.0.0. Unfortunately, you cannot add/create partition in existing table which was not partitioned while creation of the table. ... None. Add PARTITION after creating TABLE in hive. However, if the change is only applicable to the newer partitions, a 'S' lock is acquired on the table, whereas if the change is applicable to all partitions, a 'X' lock is acquired on the table. First create a table in such a way so that you don't have partition column in the table. Similarly, multiple partitions for each class can be set by using ADD PARTITION. Partition column is a virtual column that does not exist on the file as a column. Hive Partitions is a way to organizes tables into partitions by dividing tables into different parts based on partition keys. Hive - Alter Table - This chapter explains how to alter the attributes of a table such as changing its table name, changing column names, adding columns, and deleting or replacing c This is supported only for tables created using the Hive format. The above function is used to run queries on Athena using athenaClient i.e. Let us discuss the HIVE partition concept for the managed table first. Please refer to both the create and alter commands below: Priority: Major . The command I tried is given below. Partition keys are basic elements for determining how the data is stored in the table. Hive Alter Table - SQL ALTER TABLE statement is used to rename a table.The SQL ALTER TABLE statement is used to add, modify, or drop/delete columns in a table.It is used to alter a table in Hive. ALTER TABLE table_name ADD PARTITION (partCol = 'value1') location 'loc1'; ALTER TABLE table_name ADD PARTITION (partCol = 'value2') location 'loc2';... ALTER TABLE table_name ADD PARTITION (partCol = 'valueN') location 'locN'; Dynamic Partitions 动态分区. ALTER TABLE ADD COLUMNS statement adds mentioned ... ALTER TABLE SET command is used for setting the SERDE or SERDE properties in Hive tables. Hive; HIVE-1868; ALTER TABLE ADD PARTITION can't handle partition key names that conflict with HQL keywords.
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