8/23/2023 0 Comments Mysql union in viewIndexes can be used during generation of the temporary tables).Ĭonclusion: The UNION in your query hinders the view from using the indexes. Unable to take advantage of indexes on its underlying tables (although However, a view that is processed with the temptable algorithm is Indexes can be used for views processed using the merge algorithm. use the temptable alghorithm to process the data. Thus as a view is a 'shortcut' for your more complex query, when calling the select it will again execute the union, use a temporary table. When using UNION in a SELECT mysql creates a temporary table to save the data. Why does your Query not make use of the indexes? I hope things go as smooth as I'm planning. UPDATE, which will be on a 20 to 1 ratio. The view "refresh" will occur every time someone runs an INSERT or "materializedView" with correct SKU, Store and Period indexes. Stock for product "A", instead, I'll have all SELECTs towards the Regular view for my SELECTs, I'll be asking the server to make tons ofĬalculations every time someone needs to know how many items are on We will have a lot more SELECTs than inserts/updates. I'm planning to use this in an application I'm doing right now, where That way all indexes from materializedView are preserved on every INSERT INTO materializedView SELECT * FROM regularView Something like this: LOCK TABLES materializedView WRITE Needs, having the exact same structure as the view, and then running My solution is to create a correctly indexed table according to my The only problem is that we are inheriting the lack of indexes MySQL There is a workaround mentioned in the comments of another part of the documentation: In which you create a regular table and set your specialized index and load the data from the view into the table.Ĭreating a materialized view emulation as described above looks good, You can not create an index on a view:, so you have to hope the index is used. \N,UNION RESULT,ALL,\N,\N,\N,\N,\N,Using temporaryĪs you can see, no index is adjusted on view selection. Id,select_type,table,type,possible_keys,key,key_len,ref,rows,Extraġ,SIMPLE,table_a,ref,table_a_idx01,table_a_idx01,153,const,5,Using index conditionġ,SIMPLE,table_b,ref,table_b_idx01,table_b_idx01,306,const,const,1,Using index conditionġ,PRIMARY,ref,306,const,const,1,Using where How do I make the indexes work on this query? When I query on myview as below, no index is used. Table_a has an index on col1, table_b has an index on source, col1. If the view is defined by a complex, multi-table query then simple queries on the views may take considerable time.I created a view named 'myview' as below. Views create the appearance of a table, but MySQL must still translate queries against the view into queries against the underlying source tables. What are the disadvantages of views Performance If data is accessed and entered through a view, the MySQL database can automatically check the data to ensure that it meets the specified integrity constraints. ConsistencyĪ view can present a consistent, unchanged image of the structure of the database, even if the underlying source tables are split, restructured, or renamed. You can give users permission to access the database only through a small set of views that contain the specific data the user is authorized to see, thus restricting the user’s access to stored data. This helps enhance database security and integrity. You can use views to hide table columns from users by granting them access to the view and not to the table itself. Allow for changes made to the base table via a view that preserves the schema of the original table to accommodate other applications.When using Google Data Studio for reporting and your source connector is a MySQL table, you can use the view to consolidate your join or union as in Google Data Studio when you set a data source you can only select one table, with a view you can join or union or selecting a set of rows with WHERE clauses.You could create a summary that may or may not involve calculations.You can use a view for a search function and hide irrelevant information.To the database user, the view appears just like a real table, with a set of named columns and rows of data. MySQL views are a way of storing queries on the database level and producing virtual tables in the database whose contents are defined by a query. In Google Data Studio I could do a custom query, I decided to go down the path of using a view in MySql. My business case was to be able to query data from several tables. That was my plan as well, I found that after connecting to the server the MySql was running on, I could in Google Data studio only select a table. In Google Data Studio you can set up a connector to connect to a MySql database on a server. I recently was working with Google Data Studio to create a report from data that was stored in a MySQL table.
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