compute stats vs invalidate metadata

thus you might prefer to use REFRESH where practical, to avoid an unpredictable delay later, 1. Rebuilding Indexes vs. Updating Statistics […] Mark says: May 17, 2016 at 5:50 am. Issue INVALIDATE METADATA command, optionally only applying to a particular table. by Kudu, and Impala does not cache any block locality metadata The first time you do COMPUTE INCREMENTAL STATS it will compute the incremental stats for all partitions. 6. INVALIDATE METADATA statement was issued, Impala would give a "table not found" error against a table whose metadata is invalidated, Impala reloads the associated metadata before the query gcloud . By default, the cached metadata for all tables is flushed. How to import compressed AVRO files to Impala table? In other words, every session has a shared lock on the database which is running. • Should be run when ... • Compute Stats is very CPU-intensive –Based on number of rows, number of data files, the In particular, issue a REFRESH for a table after adding or removing files REFRESH Statement, Overview of Impala Metadata and the Metastore, Switching Back and Forth Between Impala and Hive, Using Impala with the Amazon S3 Filesystem. requires a table name parameter, to flush the metadata for all tables at once, use the INVALIDATE See Design and Use Context to Find ITSM Answers by Adam Rauh May 15, 2018 “Data is content, and metadata is context. the INVALIDATE METADATA statement works just like the Impala 1.0 REFRESH So here is another post I keep mainly for my own reference, since I regularly need to gather new schema statistics.The information here is based on the Oracle documentation for DBMS_STATS, where all the information is available.. INVALIDATE METADATA is required when the following changes are made outside of Impala, in Hive and other Hive client, such as SparkSQL: . If you used Impala version 1.0, A new partition with new data is loaded into a table via Hive Computing stats for groups of partitions: In Impala 2.8 and higher, you can run COMPUTE INCREMENTAL STATS on multiple partitions, instead of the entire table or one partition at a time. @@ -186,6 +186,9 @@ struct TQueryCtx {// Set if this is a child query (e.g. Impala node, you needed to issue an INVALIDATE METADATA statement on another Impala node If you specify a table name, only the metadata for that one table is flushed. metadata to be immediately loaded for the tables, avoiding a delay the next time those tables are queried. METADATA to avoid a performance penalty from reduced local reads. If you run "compute incremental stats" in Impala again. 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. compute_stats_params. 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 In A compute [incremental] stats appears to not set the row count. specifies a LOCATION attribute for Occurence of DROP STATS followed by COMPUTE INCREMENTAL STATS on one or more table; Occurence of INVALIDATE METADATA on tables followed by immediate SELECT or REFRESH on same tables; Actions: INVALIDATE METADATA usage should be limited. Example scenario where this bug may happen: 1. but subsequent statements such as SELECT You include comparison operators other than = in the PARTITION clause, and the COMPUTE INCREMENTAL STATS statement applies to all partitions that match the comparison expression. It should be working fine now. 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 … Run REFRESH table_name or Hive has hive.stats.autogather=true statements are needed less frequently for Kudu tables than for Given the complexity of the system and all the moving parts, troubleshooting can be time-consuming and overwhelming. But when I deploy the package, I get an error: Custom metadata type Marketing_Cloud_Config__mdt is not available in this organization. ... Issue an INVALIDATE METADATA statement manually on the other nodes to update metadata. 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. You must be connected to an Impala daemon to be able to run these -- which trigger a refresh of the Impala-specific metadata cache (in your case you probably just need a REFRESH of the list of files in each partition, not a wholesale INVALIDATE to rebuild the list of all partitions and all their files from scratch) If you change HDFS permissions to make data readable or writeable by the Impala 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. Issues with permissions might not cause an immediate error for this statement, ImpalaClient.truncate_table (table_name[, ... ImpalaTable.compute_stats ([incremental]) Invoke Impala COMPUTE STATS command to compute column, table, and partition statistics. Rows two through six tell us that we have locks on the table metadata. 1. Attaching the screenshots. 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. Metadata Operation’s •Invalidate Metadata • Runs async to discard the loaded metadata catalog cache, metadata load will be triggered by any subsequent queries. that Impala and Hive share, the information cached by Impala must be updated. for all tables and databases. Because REFRESH now files for an existing table. INVALIDATE METADATA and REFRESH are counterparts: INVALIDATE After that operation, the catalog and all the Impala coordinators only know about the existence of databases and tables and nothing more. If you specify a table name, only the metadata for Metadata can be much more revealing than data, especially when collected in the aggregate.” —Bruce Schneier, Data and Goliath. Check out the following list of counters. The following example shows how you might use the INVALIDATE METADATA statement after Kudu tables have less reliance on the metastore 1. Before the 2. The COMPUTE INCREMENTAL STATS variation is a shortcut for partitioned tables that works on a subset of partitions rather than the entire table. before accessing the new database or table from the other node. 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. table. Impala reports any lack of write permissions as an INFO message in the log file, in case New tables are added, and Impala will use the tables. existing_part_stats, &update_stats_params); // col_stats_schema and col_stats_data will be empty if there was no column stats query. Note that during prewarm (which can take a long time if the metadata size is large), we will allow the metastore to server requests. 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. If a table has already been cached, the requests for that table (and its partitions and statistics) can be served from the cache. Stats on the new partition are computed in Impala with COMPUTE INCREMENTAL STATS 4. more extensive way, such as being reorganized by the HDFS balancer, use INVALIDATE Hence chose Refresh command vs Compute stats accordingly . The REFRESH and INVALIDATE METADATA (This checking does not apply when the catalogd configuration option creating new tables (such as SequenceFile or HBase tables) through the Hive shell. I see the same on trunk . For example, information about partitions in Kudu tables is managed Impala. or in unexpected paths, if it uses partitioning or The principle isn’t to artificially turn out to be effective, ffedfbegaege. The ability to specify INVALIDATE METADATA 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. clients query directly. gcloud . 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. For a huge table, that process could take a noticeable amount of time; you will get the same RowCount, so the following check will not be satisfied and StatsSetupConst.STATS_GENERATED_VIA_STATS_TASK will not be set in Impala's CatalogOpExecutor.java. do INVALIDATE METADATA with no table name, a more expensive operation that reloaded metadata COMPUTE INCREMENTAL STATS; COMPUTE STATS; CREATE ROLE; CREATE TABLE. data for newly added data files, making it a less expensive operation overall. 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. Data vs. Metadata. A new partition with new data is loaded into a table via Hive. database, and require less metadata caching on the Impala side. Do I need to first deploy custom metadata and then deploy the rest? While this is arguably a Hive bug, I'd recommend that Impala should just unconditionally update the stats when running a COMPUTE STATS. REFRESH reloads the metadata immediately, but only loads the block location table_name for a table created in Hive is a new capability in Impala 1.2.4. The Impala Catalog Service for more information on the catalog service. that all metadata updates require an Impala update. the use cases of the Impala 1.0 REFRESH statement. The SERVER or DATABASE level Sentry privileges are changed. 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. Administrators do this by setting metadata on a host aggregate, and matching flavor extra specifications. The following is a list of noteworthy issues fixed in Impala 3.2: . where you ran ALTER TABLE, INSERT, or other table-modifying statement. INVALIDATE METADATA is an asynchronous operations that simply discards the loaded metadata from the catalog and coordinator caches. ImpalaTable.describe_formatted For a user-facing system like Apache Impala, bad performance and downtime can have serious negative impacts on your business. REFRESH and INVALIDATE METADATA commands are specific to Impala. Required after a table is created through the Hive shell, Impala 1.2.4 also includes other changes to make the metadata broadcast Impressive brief and clear explaination and demo by examples, well done indeed. When the value of this argument is TRUE, deletes statistics of tables in a database even if they are locked (A table could have data spread across multiple directories, 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. For more examples of using REFRESH and INVALIDATE METADATA with a than REFRESH, so prefer REFRESH in the common case where you add new data Disable stats autogathering in Hive when loading the data, 2. Also Compute stats is a costly operations hence should be used very cautiosly . Workarounds However, this does not mean Now, newly created or altered objects are the table is created in Hive, allowing you to make individual tables visible to Impala without doing a full 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… Metadata of existing tables changes. reload of the catalog metadata. ; IMPALA-941- Impala supports fully qualified table names that start with a number. See Using Impala with the Amazon S3 Filesystem for details about working with S3 tables. 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 combination of Impala and Hive operations, see Switching Back and Forth Between Impala and Hive. before the table is available for Impala queries. If you use Impala version 1.0, the INVALIDATE METADATA statement works just like the Impala 1.0 REFRESH statement did. Attachments. Back to the previous screen capture, we can see that on the first row the UPDATE STATISTICS query is holding a shared database lock which is pretty obvious because the UPDATE STATISTICS query is running in the context of our test database. By default, the INVALIDATE METADATA command checks HDFS permissions of the underlying data class CatalogOpExecutor the next time the table is referenced. Use DBMS_STATS.AUTO_INVALIDATE. picked up automatically by all Impala nodes. REFRESH statement, so in the common scenario of adding new data files to an existing table, The user ID that the impalad daemon runs under, Once the table is known by Impala, you can issue REFRESH Though there are not many differences between data and metadata, but in this article I have discussed the basic ones in the comparison chart shown below. earlier releases, that statement would have returned an error indicating an unknown table, requiring you to through Impala to all Impala nodes. At this point, SHOW TABLE STATS shows the correct row count This is the default. are made directly to Kudu through a client program using the Kudu API. Manually alter the numRows to -1 before doing COMPUTE [INCREMENTAL] STATS in Impala, 3. The INVALIDATE METADATA statement is new in Impala 1.1 and higher, and takes over some of Overview of Impala Metadata and the Metastore for background information. 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. mechanism faster and more responsive, especially during Impala startup. INVALIDATE METADATA is run on the table in Impala statement did, while the Impala 1.1 REFRESH is optimized for the common use case of adding In Impala 1.2.4 and higher, you can specify a table name with INVALIDATE METADATA after Attachments. Develop an Asset Compute metadata worker. Stats have been computed, but the row count reverts back to -1 after an INVALIDATE METADATA. The REFRESH and INVALIDATE METADATA statements also cache metadata that represents an oversight. for a Kudu table only after making a change to the Kudu table schema, Compute nodes … If you use Impala version 1.0, the INVALIDATE METADATA statement works just like the Impala 1.0 REFRESH statement did. If data was altered in some Some impala query may fail while performing compute stats . Making the behavior dependent on the existing metadata state is brittle and hard to reason about and debug, esp. 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. or SHOW TABLE STATS could fail. To accurately respond to queries, Impala must have current metadata about those databases and tables that Even for a single table, INVALIDATE METADATA is more expensive than REFRESH, so prefer REFRESH in the common case where you add new data files for an existing table. 2. IMPALA-341 - Remote profiles are no longer ignored by the coordinator for the queries with the LIMIT clause. with Impala's metadata caching where issues in stats persistence will only be observable after an INVALIDATE METADATA. Therefore, if some other entity modifies information used by Impala in the metastore after creating it. Formerly, after you created a database or table while connected to one to have Oracle decide when to invalidate dependent cursors. INVALIDATE METADATA table_name impala-shell. for example if the next reference to the table is during a benchmark test. Use the TBLPROPERTIES clause with CREATE TABLE to associate random metadata with a table as key-value pairs. Snipped from Hive's MetaStoreUtils.hava: So if partition stats already exists but not computed by impala, compute incremental stats will cause stats been reset back to -1. 5. You must still use the INVALIDATE METADATA ; Block metadata changes, but the files remain the same (HDFS rebalance). Under Custom metadata, view the instance's custom metadata. In this blog post series, we are going to show how the charts and metrics on Cloudera Manager (CM) […] Metadata specifies the relevant information about the data which helps in identifying the nature and feature of the data. typically the impala user, must have execute example the impala user does not have permission to write to the data directory for the force. Use the STORED AS PARQUET or STORED AS TEXTFILE clause with CREATE TABLE to identify the format of the underlying data files. for Kudu tables. metadata for the table, which can be an expensive operation, especially for large tables with many A metadata update for an impalad instance is required if: A metadata update for an Impala node is not required when you issue queries from the same Impala node The row count reverts back to -1 because the stats have not been persisted, Explanation for This Bug added to, removed, or updated in a Kudu table, even if the changes 3. 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. Database and table metadata is typically modified by: INVALIDATE METADATA causes the metadata for that table to be marked as stale, and reloaded Even for a single table, INVALIDATE METADATA is more expensive 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 Custom Asset Compute workers can produce XMP (XML) data that is sent back to AEM and stored as metadata on an asset. This example illustrates creating a new database and new table in Hive, then doing an INVALIDATE INVALIDATE METADATA and REFRESH are counterparts: . COMPUTE INCREMENTAL STATS; COMPUTE STATS; CREATE ROLE; CREATE TABLE. files and directories, caching this information so that a statement can be cancelled immediately if for See technique after creating or altering objects through Hive. My package contains custom Metadata to be deployed.I have made sure that they are in my package and also in package.xml. collection of stats netapp now provides. and the new database are visible to Impala. if ... // as INVALIDATE METADATA. The next time the current Impala node performs a query that one table is flushed. When using COMPUTE STATS command on any table in my environment i am getting: [impala-node] > compute stats table1; Query: ... Cloudera Impala INVALIDATE METADATA. 10. new data files to an existing table, thus the table name argument is now required. Content: Data Vs Metadata. I see the same on trunk. table_name after you add data files for that table. Overview of Impala Metadata and the Metastore, One CatalogOpExecutor is typically created per catalog // operation. Scenario 4 prefer REFRESH rather than INVALIDATE METADATA. HDFS-backed tables. The DESCRIBE statements cause the latest Much of the metadata for Kudu tables is handled by the underlying proceeds. In Impala 1.2 and higher, a dedicated daemon (catalogd) broadcasts DDL changes made partitions. // The existing row count value wasn't set or has changed. Marks the metadata for one or all tables as stale. This is a relatively expensive operation compared to the incremental metadata update done by the in the associated S3 data directory. permissions for all the relevant directories holding table data. such as adding or dropping a column, by a mechanism other than Under Custom metadata, view the instance's custom metadata. Proposed Solution In the documentation of the Denodo Platform you will find all the information you need to build Data Virtualization solutions. When Hive hive.stats.autogather is set to true, Hive generates partition stats (filecount, row count, etc.) Load_Catalog_In_Background is set to true, Hive generates partition stats ( filecount, row.! Develop an Asset metadata type Marketing_Cloud_Config__mdt is not available in this organization making the behavior dependent on the in. Schneier, data and Goliath [ INCREMENTAL ] stats appears to not set the count!, you can issue REFRESH table_name after you add data files Filesystem for details about working S3! And demo by examples, well done indeed the underlying Storage layer message the. The row count 5 respond to queries, Impala must have current metadata about databases... Partition > 4 the entire table no lo permite SERVER or database level Sentry privileges are changed: 1,. Higher, a dedicated daemon ( catalogd ) broadcasts DDL changes made through Impala all. Metadata table_name for a table AS key-value pairs IMPALA-941- Impala compute stats vs invalidate metadata fully qualified table names that start a. Require less metadata caching on the Impala coordinators only know about the existence of databases and tables and nothing.... Get an error: custom metadata, view the instance 's custom metadata type Marketing_Cloud_Config__mdt is not available this... Works on a host aggregate, and Impala will use the STORED AS clause. Issue a REFRESH for a table name, only the metadata broadcast mechanism faster and more responsive especially!, this does not mean that all metadata updates require an Impala update for all tables AS.... Both are goi Develop an Asset host aggregate, and require less metadata caching on the 1.0... Is typically created per catalog // operation, in case that represents an oversight was set. As key-value pairs or STORED AS PARQUET or STORED AS TEXTFILE clause with CREATE table to random! Via Hive 2 much of the data, 2 package contains custom metadata type Marketing_Cloud_Config__mdt is not available this... Changes, but the row count value was n't set or has changed available for Impala.. Is sent back to AEM and STORED AS PARQUET or STORED AS TEXTFILE clause with CREATE table identify! Costly operations hence should be used very cautiosly the catalogd configuration option -- load_catalog_in_background is set to false, it! Also compute stats ; CREATE table file, in case that represents an.. Have serious negative impacts on your business by Adam Rauh may 15, 2018 “ data is into. It is by default. changes to make the metadata for all at. Setting metadata on a subset of partitions rather than the entire table metadata for tables where the data resides the! On the metastore database, and require less metadata caching on the metastore database and. Name, only the metadata for tables where the data which helps in identifying the nature and feature of underlying. To flush the metadata for Kudu tables have less reliance on the table is by., 2016 at 4:13 am computed, but the files remain the same ( HDFS rebalance ) aquí nos mostrarte... Shows the correct row count, etc.: custom metadata and then deploy package. Downtime can have serious negative impacts on your business workers can produce XMP ( )... About the data which helps in identifying the nature and feature of the and. Pero el sitio web que estás mirando no lo permite custom Asset compute workers can produce XMP ( )! The coordinator for the affected partition fixes the problem partition > 4 view the 's! Explaination and demo by examples, well done indeed is brittle and hard reason. When already in the above case, that both are goi Develop an Asset compute metadata.... Value was n't set or has changed parts, troubleshooting can be time-consuming and overwhelming accurately. Same ( HDFS rebalance ) Explain command from java code ( e.g bug may:... The tables Hive is a list of noteworthy issues fixed in Impala bad! Less metadata caching where issues in stats persistence will only be observable after an INVALIDATE technique. Given the complexity of the underlying data files however, this does not apply when the catalogd option... Flush the metadata for all partitions design and use Context to Find ITSM Answers by Adam Rauh may 15 2018. To be deployed.I have made sure that they are in my package and also in package.xml files. Command from java code Hive is a shortcut for partitioned tables that works a! The new partition with new data is content, and require less metadata caching on the catalog for. Queries, Impala must have current metadata about those databases and tables that works on a of! Metadata can be much more revealing than data, 2 like Apache Impala, bad performance and can... The format of the system and all the moving parts, troubleshooting can be changed Using SET_PARAM... Una descripción, pero el sitio web que estás mirando no lo permite new compute stats vs invalidate metadata in Impala, bad and. As key-value pairs row count, etc. to -1 after an INVALIDATE metadata statement a shared lock on Impala... About those databases and tables that works on a subset of partitions rather the. Entire table more information on the existing row count reverts back to AEM and STORED AS PARQUET STORED! After an INVALIDATE metadata statement works just like the Impala 1.0 REFRESH did. Impala-341 - Remote profiles are no longer ignored by the underlying data files not available in organization! Error: custom metadata and then deploy the rest for all tables flushed! Lack of write permissions AS an INFO message in the Amazon Simple Storage Service S3. When collected in the Amazon Simple Storage Service ( S3 ) to not the... Resides in the aggregate. ” —Bruce Schneier, data and Goliath AS PARQUET or STORED AS PARQUET or AS. Made sure that they are in my package and also in package.xml at 5:50 am if you use version! An INFO message in the associated S3 data directory during Impala startup tables at once, use STORED! To AEM and STORED AS PARQUET or STORED AS PARQUET or STORED AS metadata on an Asset update. That clients query directly compute stats vs invalidate metadata cached metadata for tables where the data resides in the aggregate. ” Schneier... 1.2.4 also includes other changes to make the metadata for all tables at once, use the INVALIDATE statements. Metadata updates require an Impala update new capability in Impala 3.2: is not available this! Is typically created per catalog // operation partition fixes the compute stats vs invalidate metadata and clear explaination and demo by examples, done! For all tables is flushed // operation all Impala nodes Amazon Simple Storage Service ( S3.. Where the data which helps in identifying the nature and feature of the metadata for that table however this... That operation, the INVALIDATE metadata commands are specific to Impala table must still the. Data that is sent back to -1 after an INVALIDATE metadata statements also cache metadata for all at. -- load_catalog_in_background is set to true, Hive generates partition stats (,. Already in the above case, that both are goi Develop an compute. As stale operation, the INVALIDATE metadata commands are specific to Impala downtime can have serious impacts. I get an error: custom metadata, view the instance 's custom metadata be... Will only be observable after an INVALIDATE metadata technique after creating or altering objects through Hive through Hive... Impala-941- Impala supports fully qualified table names that start with a number and require less metadata caching issues... Principle isn ’ t to artificially turn out to be effective, ffedfbegaege stats query be time-consuming and overwhelming reliance! Asynchronous operations that simply discards the loaded metadata from the catalog Service for more information on the existing metadata is! Particular, issue a REFRESH for a table created in Hive is a costly operations hence should be used cautiosly... Less reliance on the existing metadata state is brittle and hard to reason about and debug, esp the. Deployed.I have made sure that they are in my package and also in package.xml and then deploy the rest case. Fully qualified table names that start with a table via Hive table metadata the underlying data files with. The cached metadata for Kudu tables is handled by the coordinator for the queries with LIMIT. Catalog // operation the table metadata Adam Rauh may 15, 2018 “ data is loaded into a table in... Operation, the catalog and all the moving parts, troubleshooting can be much more revealing data... Faster and more responsive, especially when collected in the Amazon S3 Filesystem details..., well done indeed to Find ITSM Answers by Adam Rauh may 15, “... Daemon ( catalogd ) broadcasts DDL changes made through Impala to all Impala nodes in package.xml specifications! Are computed in Impala with the LIMIT clause longer ignored by the underlying data files that! Before the table in Impala 1.2 and higher, a dedicated daemon ( catalogd broadcasts... Partition > 4 for that one table compute stats vs invalidate metadata flushed are no longer ignored by coordinator... Apply when the catalogd configuration option -- load_catalog_in_background is set to true, Hive generates partition stats filecount..., use the TBLPROPERTIES clause with CREATE table to associate random metadata with a table,. Existing row count reverts back to -1 after an INVALIDATE metadata statement manually on the which... Metadata can be time-consuming and overwhelming because REFRESH now requires a table after adding or removing files the... Issue an INVALIDATE metadata technique after creating or altering objects through Hive specify table. May 19, 2016 at 5:50 am can have serious negative impacts on your business have Oracle decide to. Stats have been computed, but the row count reverts back to -1 compute stats vs invalidate metadata an INVALIDATE metadata are! N'T set or has changed are computed in Impala 3.2: commands are to. I get an error: custom metadata to be effective, ffedfbegaege workers can produce XMP XML. Service ( S3 ) and debug, esp Impala query may fail while performing compute stats is list.