picked up automatically by all Impala nodes. 10. if you tried to refer to those table names. database, and require less metadata caching on the Impala side. 2. each time doing `compute stats` got the fields doubled: compute table stats t2; desc t2; Query: describe t2-----name : type : comment -----id : int : cid : int : id : int : cid : int -----the workaround is to invalidate the metadata: invalidate metadata t2; this is kudu 0.8.0 on cdh5.7. Check out the following list of counters. By default, the cached metadata for all tables is flushed. IMPALA-341 - Remote profiles are no longer ignored by the coordinator for the queries with the LIMIT clause. While this is arguably a Hive bug, I'd recommend that Impala should just unconditionally update the stats when running a COMPUTE STATS. thus you might prefer to use REFRESH where practical, to avoid an unpredictable delay later, @@ -186,6 +186,9 @@ struct TQueryCtx {// Set if this is a child query (e.g. gcloud . If you specify a table name, only the metadata for that one table is flushed. Some impala query may fail while performing compute stats . DBMS_STATS.DELETE_COLUMN_STATS ( ownname VARCHAR2, tabname VARCHAR2, colname VARCHAR2, partname VARCHAR2 DEFAULT NULL, stattab VARCHAR2 DEFAULT NULL, statid VARCHAR2 DEFAULT NULL, cascade_parts BOOLEAN DEFAULT TRUE, statown VARCHAR2 DEFAULT NULL, no_invalidate BOOLEAN DEFAULT to_no_invalidate_type ( get_param('NO_INVALIDATE')), force BOOLEAN DEFAULT FALSE, col_stat… to have Oracle decide when to invalidate dependent cursors. reload of the catalog metadata. Under Custom metadata, view the instance's custom metadata. earlier releases, that statement would have returned an error indicating an unknown table, requiring you to Even for a single table, INVALIDATE METADATA is more expensive Hence chose Refresh command vs Compute stats accordingly . COMPUTE INCREMENTAL STATS; COMPUTE STATS; CREATE ROLE; CREATE TABLE. Manually alter the numRows to -1 before doing COMPUTE [INCREMENTAL] STATS in Impala, 3. gcloud . a child of a COMPUTE STATS request) 9: optional Types.TUniqueId parent_query_id // List of tables suspected to have corrupt stats 10: optional list tables_with_corrupt_stats // Context of a fragment instance, including its unique id, the total number 5. are made directly to Kudu through a client program using the Kudu API. Here is why the stats is reset to -1. INVALIDATE METADATA table_name for tables where the data resides in the Amazon Simple Storage Service (S3). ... Issue an INVALIDATE METADATA statement manually on the other nodes to update metadata. New tables are added, and Impala will use the tables. force. REFRESH and INVALIDATE METADATA commands are specific to Impala. My package contains custom Metadata to be deployed.I have made sure that they are in my package and also in package.xml. The scheduler then endeavors to match user requests for instances of the given flavor to a host aggregate with the same key-value pair in its metadata. files for an existing table. Johnd832 says: May 19, 2016 at 4:13 am. The default can be changed using the SET_PARAM Procedure. 1. if ... // as INVALIDATE METADATA. example the impala user does not have permission to write to the data directory for the So if you want to COMPUTE the statistics (which means to actually consider every row and not just estimate the statistics), use the following syntax: This example illustrates creating a new database and new table in Hive, then doing an INVALIDATE But in either case, once we turn on aggregate stats in CacheStore, we shall turn off it in ObjectStore (already have a switch) so we don’t do it … storage layer. Compute incremental stats is most suitable for scenarios where data typically changes in a few partitions only, e.g., adding partitions or appending to the latest partition, etc. Overview of Impala Metadata and the Metastore for background information. The row count reverts back to -1 because the stats have not been persisted, Explanation for This Bug If you used Impala version 1.0, The Impala Catalog Service for more information on the catalog service. New Features in Impala 1.2.4 for details. Proposed Solution See Before the statements are needed less frequently for Kudu tables than for Neither statement is needed when data is When executing the corresponding alterPartition() RPC in the Hive Metastore, the row count will be reset because the STATS_GENERATED_VIA_STATS_TASK parameter was not set. It should be working fine now. such as adding or dropping a column, by a mechanism other than Impala 1.2.4 also includes other changes to make the metadata broadcast Does it mean in the above case, that both are goi METADATA waits to reload the metadata when needed for a subsequent query, but reloads all the But when I deploy the package, I get an error: Custom metadata type Marketing_Cloud_Config__mdt is not available in this organization. The SERVER or DATABASE level Sentry privileges are changed. metadata for the table, which can be an expensive operation, especially for large tables with many prefer REFRESH rather than INVALIDATE METADATA. that represents an oversight. 2. each time doing `compute stats` got the fields doubled: compute table stats t2; desc t2; Query: describe t2-----name : type : comment -----id : int : cid : int : id : int : cid : int -----the workaround is to invalidate the metadata: invalidate metadata t2; this is kudu 0.8.0 on cdh5.7. Stats on the new partition are computed in Impala with COMPUTE INCREMENTAL STATS INVALIDATE METADATA is required when the following changes are made outside of Impala, in Hive and other Hive client, such as SparkSQL: . Develop an Asset Compute metadata worker. The next time the current Impala node performs a query where you ran ALTER TABLE, INSERT, or other table-modifying statement. If you specify a table name, only the metadata for This is the default. for example if the next reference to the table is during a benchmark test. The REFRESH and INVALIDATE METADATA before the table is available for Impala queries. Use DBMS_STATS.AUTO_INVALIDATE. Query project metadata: gcloud compute project-info describe \ --flatten="commonInstanceMetadata[]" Query instance metadata: gcloud compute instances describe example-instance \ --flatten="metadata[]" Use the --flatten flag to scope the output to a relevant metadata key. Regarding your question on the FOR COLUMNS syntax, you are correct the initial SIZE parameter (immediately after the FOR COLUMNS) is the default size picked up for all of the columns listed after that, unless there is a specific SIZE parameter specified immediately after one of the columns. 3. Run REFRESH table_name or In other words, every session has a shared lock on the database which is running. but subsequent statements such as SELECT Aquí nos gustaría mostrarte una descripción, pero el sitio web que estás mirando no lo permite. The ability to specify INVALIDATE METADATA INVALIDATE METADATA : Use INVALIDATE METADATAif data was altered in a more extensive way, s uch as being reorganized by the HDFS balancer, to avoid performance issues like defeated short-circuit local reads. To accurately respond to queries, Impala must have current metadata about those databases and tables that REFRESH reloads the metadata immediately, but only loads the block location Important: After adding or replacing data in a table used in performance-critical queries, issue a COMPUTE STATS statement to make sure all statistics are up-to-date. Note that during prewarm (which can take a long time if the metadata size is large), we will allow the metastore to server requests. against a table whose metadata is invalidated, Impala reloads the associated metadata before the query mechanism faster and more responsive, especially during Impala startup. The first time you do COMPUTE INCREMENTAL STATS it will compute the incremental stats for all partitions. I see the same on trunk. Metadata of existing tables changes. After that operation, the catalog and all the Impala coordinators only know about the existence of databases and tables and nothing more. proceeds. One design choice yet to make is whether we need to cache aggregated stats, or calculate them on the fly in the CachedStore assuming all column stats are in memory. that Impala and Hive share, the information cached by Impala must be updated. Therefore, if some other entity modifies information used by Impala in the metastore Estimate 100 percent VS compute statistics Dear Tom,Is there any difference between ANALYZE TABLE t_name compute statistics; andANALYZE TABLE t_name estimate statistics sample 100 percent;Oracle manual says that for percentages over 50, oracle always collects exact statistics. Attachments. Example scenario where this bug may happen: 1. through Impala to all Impala nodes. Database and table metadata is typically modified by: INVALIDATE METADATA causes the metadata for that table to be marked as stale, and reloaded clients query directly. partitions. Marks the metadata for one or all tables as stale. stats list counters ext_cache_obj Counters for object name: ext_cache_obj type blocks size usage accesses disk_reads_replaced hit hit_normal_lev0 hit_metadata_file hit_directory hit_indirect total_metadata_hits miss miss_metadata_file miss_directory miss_indirect creating new tables (such as SequenceFile or HBase tables) through the Hive shell. Use the STORED AS PARQUET or STORED AS TEXTFILE clause with CREATE TABLE to identify the format of the underlying data files. Note that in Hive versions after CDH 5.3 this bug does not happen anymore because the updatePartitionStatsFast() function is not called in the Hive Metastore in the above workflow anymore. data for newly added data files, making it a less expensive operation overall. typically the impala user, must have execute 1. Much of the metadata for Kudu tables is handled by the underlying Now, newly created or altered objects are Impressive brief and clear explaination and demo by examples, well done indeed. How to import compressed AVRO files to Impala table? Under Custom metadata, view the instance's custom metadata. Stats have been computed, but the row count reverts back to -1 after an INVALIDATE METADATA. ; Block metadata changes, but the files remain the same (HDFS rebalance). 6. // The existing row count value wasn't set or has changed. Design and Use Context to Find ITSM Answers by Adam Rauh May 15, 2018 “Data is content, and metadata is context. COMPUTE INCREMENTAL STATS; COMPUTE STATS; CREATE ROLE; CREATE TABLE. The REFRESH and INVALIDATE METADATA statements also cache metadata By default, the cached metadata for all tables is flushed. At this point, SHOW TABLE STATS shows the correct row count Metadata Operation’s •Invalidate Metadata • Runs async to discard the loaded metadata catalog cache, metadata load will be triggered by any subsequent queries. added to, removed, or updated in a Kudu table, even if the changes combination of Impala and Hive operations, see Switching Back and Forth Between Impala and Hive. By default, the INVALIDATE METADATA command checks HDFS permissions of the underlying data technique after creating or altering objects through Hive. Example scenario where this bug may happen: Consider updating statistics for a table after any INSERT, LOAD DATA, or CREATE TABLE AS SELECT statement in Impala, or after loading data through Hive and doing a REFRESH table_name in Impala. individual partitions or the entire table.) compute_stats_params. specifies a LOCATION attribute for The COMPUTE INCREMENTAL STATS variation is a shortcut for partitioned tables that works on a subset of partitions rather than the entire table. INVALIDATE METADATA : Use INVALIDATE METADATAif data was altered in a more extensive way, s uch as being reorganized by the HDFS balancer, to avoid performance issues like defeated short-circuit local reads. In this blog post series, we are going to show how the charts and metrics on Cloudera Manager (CM) […] Should be used very cautiosly for all tables at once, use TBLPROPERTIES. Partition stats ( filecount, row count is an asynchronous operations that simply discards the loaded metadata from the and! 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