Redshift refresh materialized view11/28/2023 Then a single row is inserted into the underlying table, and the materialized view is refreshed. The SQL command sequence induced by creating the materialized view is captured and examined. Auto refresh is off, and a window function is used in the materialized view definition to ensure a full refresh is in use. Creation and RefreshĪ normal, empty table is created, and then a materialized view is created using that table. Since this is not a performance test in the usual sense, but more of a discovery, where extremes matter, all five times form the results. This is repeated five times, to give a range of auto-refresh times. The test is then repeated, but now immediately before each check of the materialized view, a single row is inserted into the underlying table, on every check. The table then has ten exactly full blocks inserted, and then the materialized view is monitored, once per second, to time how long auto-refresh takes. Auto-RefreshĪn empty single column table is created, and then a materialized view, with auto refresh on, is created, which uses that table. This document then examines the internal implementation of materialized views and assesses and critiques their behaviour. The concept of pre-computing results is useful and widespread, but I aver there are in Redshift’s implementation numerous design and implementation flaws which ensure that materialized views are the exact same amount of development work and complexity, but with much less performance, than manually creating and maintaining your own pre-computed results, and as such, there are no circumstances where it is correct to use them. Materialized views are a method for pre-computing the results of a query, so that when the results come to be used, the time and work to compute them has already been expended.Ī Redshift materialized view is defined in the same way as a normal view, as an SQL statement, but unlike a normal view - where the name of the view is replaced by its SQL in the text of an SQL query issued against the view - a materialized view actually produces the rows of the SQL defining the materialized view and stores them on disk, in a table, and a query issued against the materialized view actually uses that table. Redshift added support for materialized views near the end of 2019. Materialized Views Are Only Auto-Vacuumed.REFRESH MATERIALIZED VIEW (Incremental Refresh).CREATE MATERIALIZED VIEW (Incremental Refresh).Materialized View Text From pg_views (Incremental Refresh).Table, View and Proc Counts (B/A CMV, Incremental Refresh).Materialized View Full Column List (Two Source Tables, Incremental Refresh).Materialized View Full Column List (One Source Table, Incremental Refresh).REFRESH MATERIALIZED VIEW (Full Refresh).CREATE MATERIALIZED VIEW (Full Refresh).Materialized View Text From pg_views (Full Refresh).Table, View and Proc Counts (B/A CMV, Full Refresh).Materialized View Full Column List (Two Source Tables, Full Refresh).
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