Get row count from all tables in hive, The HQL command is explain select * from table_name; but when not optimized not shows rows in the TableScan. Alternatively, you could use Hive Radiator Valves on your main radiators for room-by-room temperature control of your home. We can see the Hive tables structures using the Describe commands. Since this is an external table (EXTERNAL_TABLE), Hive will not keep any stats on the table since it is assumed that another application is changing the underlying data at will.Why keep stats if we can't trust that the data will be the same in another 5 minutes? Create Table Statement. Users should be aware of the skew key. Use ANALYZE to collect statistics for existing 1. Since Hive doesn't push down the filter predicate, you're pulling all of the data back to the client and then applying the filter. This can vastly improve query times on the table because it collects the row count, file count, and file size (bytes) that make up the data in the table and gives that to the query planner before execution. Is this ready for review, or is it a initial design ? So in HDP, we have /apps/hive/warehouse as the location to store all the files. Is the hash table (small table's), created for the entire table or only for the selected and join key columns? To increase your query performance indexing will definitely help. struct StringColumnStatsData { 1: required i64 maxColLen, 2: required double avgColLen, 3: required i64 numNulls, 4: required i64 numDVs, struct BinaryColumnStatsData { 1: required i64 maxColLen, 2: required double avgColLen, 3: required i64 numNulls }, struct Decimal {1: required binary unscaled,3: required i16 scale}, struct DecimalColumnStatsData {1: optional Decimal lowValue,2: optional Decimal highValue,3: required i64 numNulls,4: required i64 numDVs,5: optional string bitVectors}, struct Date {1: required i64 daysSinceEpoch}, struct DateColumnStatsData {1: optional Date lowValue,2: optional Date highValue,3: required i64 numNulls,4: required i64 numDVs,5: optional string bitVectors}, union ColumnStatisticsData {1: BooleanColumnStatsData booleanStats,2: LongColumnStatsData longStats,3: DoubleColumnStatsData doubleStats,4: StringColumnStatsData stringStats,5: BinaryColumnStatsData binaryStats,6: DecimalColumnStatsData decimalStats,7: DateColumnStatsData dateStats}, struct ColumnStatisticsObj { 1: required string colName, 2: required string colType, 3: required ColumnStatisticsData statsData }, struct ColumnStatisticsDesc { 1: required bool isTblLevel, 2: required string dbName, 3: required string tableName, 4: optional string partName, 5: optional i64 lastAnalyzed }, struct ColumnStatistics { 1: required ColumnStatisticsDesc statsDesc, 2: required list statsObj; }. Helpers are active players who wish to help others, and are passionate about engaging with the community. Hive table row count. HiveQL currently supports the analyze commandto compute statistics on tables and partitions. To view column stats : Note that delete_column_statistics is needed to remove the entries from the metastore when a table is dropped. ... time of clicking around with no idea of what am i doing i was sure that there is an easier way to filter data from the hive data base. The Command is similar to CREATE TABLE command, except it dumps DDL instead of creating tables. I've the patch on both JIRA and reviewboard. See SHOW Statement for details. ALTER TABLE COLUMN_STATISTICS ADD CONSTRAINT COLUMN_STATISTICS_FK1 FOREIGN KEY (PART_ID) REFERENCES PARTITIONS (PART_ID) INITIALLY DEFERRED; We propose to add the following Thrift structs to transport column statistics: struct BooleanColumnStatsData { 1: required i64 numTrues, 2: required i64 numFalses, 3: required i64 numNulls }. Hive Hint: Hive Multizone has been designed to let you control up to six heating zones in your home. HiveQL’s analyze command will be extended to trigger statistics computation on one or more column in a Hive table/partition. hive1 by default. The CBO engine in Hive uses statistics in the Hive Metastore to produce optimal query plans. DESCRIBE EXTENDED TABLE1; For example; DESCRIBE EXTENDED test1; You should see the basic table statistics in parameter tag. The Hive Multizone kit contains the thermostat and receiver (your Hive Hub will come with your Hive Active Heating). Please note that this goes beyond HIVE-3421 - this patch adds the stats specified on both this wiki and the JIRA page. @Guilherme Braccialli If you've already analyzed the columns you can issue a describe table command to get column stats: "As of Hive 0.10.0, the optional parameter FOR COLUMNS computes column statistics for all columns in the specified table (and for all partitions if the table is partitioned). Analyzing a table (also known as computing statistics) is a built-in Hive operation that you can execute to collect metadata on your table. Example: hive> explain select a. Create Table is a statement used to create a table in Hive. struct DoubleColumnStatsData { 1: required double lowValue, 2: required double highValue, 3: required i64 numNulls, 4: required i64 numDVs. If you use the Hive-based methods of gathering statistics, see the Hive wiki for information about the … HiveQL’s analyze command will be extended to trigger statistics computation on one or more column in a Hive table/partition. HiveQL currently supports the analyze command to compute statistics on tables and partitions. Users can quickly get the answers for some of their queries by only querying stored statistics rather than firing lon… Also, can you go over https://issues.apache.org/jira/browse/HIVE-3421 and see how the two are related ? table, table name to write to. Use case: One table has huge skew values on the joining column. These statistics are stored in the data dictionary and can be used by the optimizer to choose the most efficient execution plan for SQL statements accessing analyzed objects. For general information about Hive statistics, see Statistics in Hive. That doesn’t mean much more than when you drop the table, both the schema/definition AND the data are dropped. If the table is partitioned here is a quick command for you: hive> ANALYZE TABLE ops_bc_log PARTITION(day) COMPUTE STATISTICS noscan; output is. Use can get data distribution details as well, DB_NAME VARCHAR(128) NOT NULL, COLUMN_NAME VARCHAR(128) NOT NULL, COLUMN_TYPE VARCHAR(128) NOT NULL, TABLE_NAME VARCHAR(128) NOT NULL, PART_NAME VARCHAR(128) NOT NULL. The hash table (created in map side join) spills to disk, if it does not Shreepadma, is there a jira for this ? View Hive Table Statistics. By enabling compression at various phases (i.e. 2. 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