materialized-views

问题 I have a table that holds information about different events, for example CREATE TABLE events ( id int not null primary key, event_date date, ... ) I realized that 90% of all queries access only today events; the older rows are stored for history and eventually moved to an archive table. However, events table is still large, and I wonder if I can improve the performance by creating a materialized view that has something like WHERE event_date = trunc(sysdate) and maybe index on event_date ? Is

问题 I have a table that holds information about different events, for example CREATE TABLE events ( id int not null primary key, event_date date, ... ) I realized that 90% of all queries access only today events; the older rows are stored for history and eventually moved to an archive table. However, events table is still large, and I wonder if I can improve the performance by creating a materialized view that has something like WHERE event_date = trunc(sysdate) and maybe index on event_date ? Is

问题 Good day to all. I'm trying to write functional tests for some Spring endpoints (Spring is not a key here) which use my REST application as a black box and try to connect to it via http. Algorithm is as follows: The application starts with empty test database Test starts, in @Before method it fills the database with needed data Test performs a http request to application and receives the answer Test compares given response with the expected one. Almost all of the tests work good but in one

问题 This question already has answers here : Closed 7 years ago . Possible Duplicate: Optimization of count query for PostgreSQL Using PostgreSQL 9.2, we are trying to figure out if there is a way to keep track of the number of results for a query, and return that number in an efficient manner. This query should be executed several (possibly tens to hundreds or even thousands) of times per second. The query we have right now looks like this, but we wonder if this is inefficient: -- Get # of rows

问题 I kind of understand materialized views and have worked with them before. Recently a question came up as to why a particular report didn't show latest data, I looked into the issue. Apparently, they had a temp table loaded with crontab earlier and switched to Materialized view later. When I looked into the database with the below query (name of the table changed): SELECT * FROM all_objects WHERE object_name = 'TEMP_DATA'; This actually showed 2 objects in the same schema: one table and

问题 What is the difference between Views and Materialized Views in Oracle? 回答1: Materialized views are disk based and are updated periodically based upon the query definition. Views are virtual only and run the query definition each time they are accessed. 回答2: Views They evaluate the data in the tables underlying the view definition at the time the view is queried . It is a logical view of your tables, with no data stored anywhere else. The upside of a view is that it will always return the

问题 create or replace TRIGGER REFRESH_REST_VIEW AFTER INSERT OR UPDATE ON tbl_contract BEGIN execute DBMS_MVIEW.REFRESH('REST_VIEW'); END REFRESH_REST_VIEW; commit; This is my sql trigger i am using to refresh Materialized View. But it says.. Warning: execution completed with warning TRIGGER REFRESH_REST_VIEW Compiled. P.S. : The trigger will be executed when the data of table (used by Materialized View) takes any DML operation. I have googled enough, many post says it is possible but I am not

问题 My friend has created a materialized view but the View does not receive new data from Mater Table. The view is receiving data only in creation, after it the news data are not included. Anyone can help me to resolve this issue? Fallow below my materialized view. CREATE or REPLACE MATERIALIZED VIEW DATABASE.MyMatView LOGGING TABLESPACE SDBANCO PCTFREE 10 INITRANS 2 STORAGE ( INITIAL 65536 NEXT 1048576 MINEXTENTS 1 MAXEXTENTS UNLIMITED BUFFER_POOL DEFAULT ) NOCOMPRESS NOCACHE NOPARALLEL REFRESH

问题 I have a MATERIALIZED VIEW that is created via a migration. class MyView < ActiveRecord::Migration def up ActiveRecord::Base.connection.execute <<-SQL CREATE MATERIALIZED VIEW my_view AS ( SELECT DISTINCT something, something_else, other.thing as real_thing, thing.some_id FROM some_table JOIN another_table on another_table.id = something JOIN one_more_table on some_table.id = other_id ORDER BY order_column) WITH DATA; SQL add_index :table, [:key_part_one, :key_part_two] end ... end Note: I've

问题 I've done countless searches on materialized views and SQLite. Of what I can find there seems to be mentions in 2004 and 2006 that SQLite DOES NOT have materialized views. Followed immediately by SQLite's changelog from March 2008 where it specifically mentions optimizing materialized views. Now, I figure logically either the 2004 and 2006 are outdated, or the 2008 changelog is wrong. Any idea which it is? If materialized views ARE now in SQLite, how are they created? 回答1: I'd say what other