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Aman Sinha resolved IMPALA-10723. --------------------------------- Fix Version/s: Impala 4.1.0 Resolution: Fixed > Allow basic querying and computing stats on a materialized view > --------------------------------------------------------------- > > Key: IMPALA-10723 > URL: https://issues.apache.org/jira/browse/IMPALA-10723 > Project: IMPALA > Issue Type: Improvement > Components: Frontend > Reporter: Aman Sinha > Assignee: Aman Sinha > Priority: Major > Fix For: Impala 4.1.0 > > > Currently, in Impala, a Materialized View (MV) created via Hive is visible > through the metadata catalog and can be queried but the query is expanded to > its corresponding view definition. This is incorrect because a materialized > view is a regular (physical) table, not a view. Even though Impala does not > support either creating MV or automatic rewriting to use MV, querying an MV > directly should be allowed. > Here's the current behavior: > {noformat} > [localhost:21050] functional> explain select * from materialized_view; > Query: explain select * from materialized_view > +------------------------------------------------------------------------------------+ > | Explain String > | > +------------------------------------------------------------------------------------+ > | Max Per-Host Resource Reservation: Memory=4.00MB Threads=2 > | > | Per-Host Resource Estimates: Memory=10MB > | > | WARNING: The following tables are missing relevant table and/or column > statistics. | > | functional.insert_only_transactional_table > | > | > | > | PLAN-ROOT SINK > | > | | > | > | 01:EXCHANGE [UNPARTITIONED] > | > | | > | > | 00:SCAN HDFS [functional.insert_only_transactional_table] > | > | HDFS partitions=1/1 files=0 size=0B > | > | row-size=4B cardinality=0 > | > +------------------------------------------------------------------------------------+ > {noformat} > Note that the plan shows the scan of the underlying table instead of the > materialized_view table. We should only be scanning the MV (including > applying partition pruning, predicate pushdown etc.) and not treating this as > a view. > This JIRA is to enhance the frontend to recognize a materialized view as a > table rather than a view. This will further allow commands such as COMPUTE > STATS, DROP STATS, SHOW [TABLE | COLUMN] STATS to be run on the MV. One > motivation for doing this is to allow an external frontend that supports > automatic query rewrites using MVs to leverage the statistics on MVs. > Since Impala is not creating the MV, we will need to block DML operations on > the MV. Further, special handling needs to be done for Ranger authorization > policies such that any column masking/row filtering policies defined on the > source tables of the MV are taken into consideration. -- This message was sent by Atlassian Jira (v8.20.1#820001)