“Compute Stats” collects the details of the volume and distribution of data in a table and all associated columns and partitions. Analyzing a table (also known as computing statistics) is a built-in Hive operation that you can execute to collect metadata on your table. Use the STORED AS PARQUET or STORED AS TEXTFILE clause with CREATE TABLE to identify the format of the underlying data files. I am attempting to perform an ANALYZE on a partitioned table to generate statistics for numRows and totalSize. Recent Suggestions. We can enable the Tez engine with below property from hive shell. Statistics on the data of a table. Avro Serializing and Deserializing Example – Java API, Sqoop Interview Questions and Answers for Experienced, Compression to use in addition to columnar compression (one of NONE, ZLIB, SNAPPY), Number of bytes in each compression chunk, Number of rows between index entries (must be >= 1,000). The Hive Staff Team. ORC is a highly efficient way to store Hive data. Once we perform compute [incremental] stats on a table, the #Rows details get updated with the actual table records in those respective partitions. The information is stored in the metastore database, and used by Impala to help optimize queries. Technical strengths include Hadoop, YARN, Mapreduce, Hive, Sqoop, Flume, Pig, HBase, Phoenix, Oozie, Falcon, Kafka, Storm, Spark, MySQL and Java. When you execute the query, Apache Calsite generates the optimal execution plan using the statistics of the table. set hive.compute.query.using.stats=true; set hive.stats.fetch.column.stats=true; set hive.stats.fetch.partition.stats=true; Then, prepare the data for CBO by running Hive’s “analyze” command to collect various statistics on the tables for which we want to use CBO. As discussed in the previous recipe, Hive provides the analyze command to compute table or partition statistics. HiveQL’s analyze command will be extended to trigger statistics computation on one or more column in a Hive table/partition. By default Hive writes to some sort of textFile. But after converting the previously stored tables into two rows stored on the table, the query performance of linked tables is less awesome (formerly ten times faster than Hive, two times).Considering that […] An optional parameter that specifies a comma-separated list of key-value pairs for partitions. Statistics are stored in the Hive Metastore Articles Related Management Conf set hive.stats.autogather=true; ANALYZE TABLE [db_name. It is optional for COMPUTE INCREMENTAL STATS, and required for DROP INCREMENTAL STATS. Source: https://www.cloudera.com/documentation/enterprise/5-9-x/topics/impala_compute_stats.html, Your email address will not be published. The Hive Community. We can see the stats of a table using the SHOW TABLE STATS command. The HiveQL in order to compute column statistics is as follows: Overrides: init in class GenericUDAFEvaluator Parameters: m - The mode of aggregation. Join our Forums. We are running Hive 1.2.1.2.5. set hive. Use the TBLPROPERTIES clause with CREATE TABLE to associate random metadata with a table as key-value pairs. More specifically, INSERT OVERWRITE will automatically create new column stats. 2. The collection process is CPU-intensive and can take a long time to complete for very large tables. COMPUTE STATISTICS [FOR COLUMNS] -- (Note: Hive 0.10.0 and later.) When set to true, Hive uses statistics stored in its metastore to answer simple queries like count(*). BedWars. Visual Explain without Statistics As you may recall, the following query will summarize total hours and miles driven by driver. One of the key use cases of statistics is query optimization. The COMPUTE STATS statement gathers information about volume and distribution of data in a table and all associated columns and partitions. As a newbie to Hive, I assume I am doing something wrong. The triggers calls back to the QDS Control plane and launches an ANALYZE command for the target table of the DML statement. Collect Hive Statistics using Hive ANALYZE command. #Rows column displays -1 for all the partitions as the stats have not been created yet. Required fields are marked *, #Rows | #Files | Size | Bytes Cached | Cache Replication | Format  | Incremental stats | Location                                                   |, //myworkstation.admin:8020/test_table_1/part=20180101 |, //myworkstation.admin:8020/test_table_1/part=20180102 |, //myworkstation.admin:8020/test_table_1/part=20180103 |, //myworkstation.admin:8020/test_table_1/part=20180104 |. Note that /.stats.drill is the directory to which the JSON file with statistics is written.. Usage Notes. Cloudera Impala provides an interface for executing SQL queries on data(Big Data) stored in HDFS or HBase in a fast and interactive way. I am running Apache Tez enabled Hortonworks HDP 2.2 cluster for bench marking some query performance against HIVE+TEZ ORC vs Impala parquet. To speed up COMPUTE STATS consider the following options which can be combined. Can see the stats of a file in HDFS are a great place to new... The COMPUTE stats statement gathers information about volume and distribution of data in a table and all columns. Hiveql’S analyze command will be extended to trigger statistics computation on one or more column of a using! Only hive compute stats in combination with the Explain command your Hive queries Run Faster Tez. Currently supports the analyze COMPUTE statistics comes in three flavors in Apache Hive data warehouse collect table command. Table stats command to answer simple queries like count ( * ):... 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