Media mobile per opzioni binarie 50 periodic table
A materialized view is a database object that contains the results of a query. The FROM clause of the query can name tables, views, and other materialized views. Collectively these objects are called master tables a replication term or detail tables a data warehousing term.
This reference uses "master tables" for consistency. The databases containing the master tables are called the master databases. For replication purposes, materialized views allow you to maintain copies of remote data on your local node.
The copies can be updatable with the Advanced Replication feature and are read-only without this feature. You can select data from a materialized view as you would from a table or view. In replication environments, the materialized views commonly created are primary keyrowidobjectand subquery materialized views. For data warehousing purposes, the materialized views commonly created are materialized aggregate viewssingle-table materialized aggregate viewsand materialized join views.
All three types of materialized views can be used by query rewrite, an optimization technique that transforms a user request written in terms of master tables into a semantically equivalent request that includes one or more materialized views.
Oracle Database Data Warehousing Guide for information on the types of materialized views used to support data warehousing. The privileges required to create a materialized view should be granted directly media mobile per opzioni binarie 50 periodic table than through a role. To create the materialized view with query rewrite enabledin addition to the preceding privileges:. When you create a materialized view, Oracle Database creates one internal table and at least one index, and may create one view, all in the schema of the materialized view.
Oracle Database uses these objects to maintain the materialized view data. You must media mobile per opzioni binarie 50 periodic table the privileges necessary to create these objects. Oracle Database Advanced Replication for information about the prerequisites that apply to creating replication materialized views.
Oracle Database Data Warehousing Guide for information about the prerequisites that apply to creating data warehousing materialized views. Specify the schema to contain the materialized view. If you omit schemathen Oracle Database creates the materialized view in your schema. Specify the name of the materialized view to be created. Oracle Database generates names for the table and indexes used to maintain the materialized view by adding a prefix or suffix to the materialized view name.
You can specify a column alias for each column of the materialized view. The column alias list explicitly resolves any column name conflict, eliminating the need to specify aliases in the SELECT clause of the materialized view. If you specify any column alias in this clause, then you must specify an alias for each data source referenced in the SELECT clause.
If you specify aliases, then they must media mobile per opzioni binarie 50 periodic table a one-to-one correspondence with the columns in the SELECT list of the defining query of the materialized view. This clause is particularly useful for registering large materialized views in a data warehousing environment.
The table must have the same name and be in the same schema as the resulting materialized view. If the materialized view is dropped, then the preexisting table reverts to its identity as a table.
This is the default. Each column alias in subquery must correspond to a column in the prebuilt table, and corresponding columns must have matching datatypes.
If you specify this clause, then you cannot specify a NOT NULL constraint for any column that is not referenced in subquery unless you also specify a default value for that column. If you omit this clause, then Oracle Database creates the materialized view in the default tablespace of the schema containing the materialized view.
The default is the logging characteristic of the tablespace in which the materialized view resides. In media mobile per opzioni binarie 50 periodic table a materialized view, data rows are stored in an index defined on the primary key of the materialized view. You can specify index organization for the following types of materialized views:. Read-only and updatable object materialized views. You must ensure that the master table has a primary key.
A cluster materialized view uses the space allocation of the cluster. Use these property clauses to describe a materialized view that is not based on an existing table. Partitioning of materialized views is the same as partitioning of tables.
For data that will be accessed frequently, CACHE specifies that the blocks retrieved for this table are placed at the most recently used end of the least recently used LRU list in the buffer cache when a full table scan is performed.
This attribute is useful for small lookup tables. The first deferred refresh must always be a complete refresh. Oracle Database uses the default index to speed up incremental FAST refresh of the materialized view. If the master tables of a materialized view are modified, then the data in the materialized view must be updated to make the materialized view accurately reflect the data currently in its master tables. This clause lets you schedule the times and specify the method and mode for the database to refresh the materialized view.
Specify FAST to indicate the incremental refresh method, which performs the refresh according to the media mobile per opzioni binarie 50 periodic table that have occurred to the master tables. The changes for conventional DML changes are stored in the materialized view log associated with the master table. No user intervention is needed. Materialized views are not eligible for fast refresh if the defining query contains an analytic function. Oracle Database Advanced Replication for restrictions on fast refresh in replication environments.
Oracle Database Data Warehousing Guide for restrictions on fast refresh in data warehousing environments. If you request a complete refresh, then Oracle Database performs a complete refresh even if a fast refresh is possible. Specify FORCE to indicate that when a refresh occurs, Oracle Database will perform a fast refresh if one is possible or a complete refresh if fast refresh is not possible. Specify ON COMMIT to indicate that a fast refresh is to occur whenever the database commits a transaction that operates on a master table of the materialized view.
This clause may increase the time taken to complete the commit, because the database performs the refresh operation as part of the commit process. This clause is not supported for materialized views containing object types or Oracle-supplied types. If you specify this clause, then you cannot subsequently execute a distributed transaction on any master table of this materialized view. For example, you cannot insert into the master by selecting from a remote table.
Primary key materialized views allow materialized view master tables to be reorganized without affecting the eligibility of the materialized view for fast refresh.
The master table must contain an media mobile per opzioni binarie 50 periodic table primary key constraint, and the defining query of the materialized view must specify all of the primary key columns directly.
In the defining query, the primary key columns cannot be specified as the argument to a function such as UPPER. Rowid materialized views are useful if the materialized view does not include all primary key columns of the master tables.
Rowid materialized views must be based on a single table and cannot contain any of the following:. Rowid materialized views are not eligible for fast refresh after a master table reorganization until a complete refresh has been performed.
This clause is not valid if your database is in automatic undo mode, because in that mode Oracle Database uses undo tablespaces instead of rollback segments.
Oracle strongly recommends that you use automatic undo mode. This clause is supported for backward compatibility with replication environments containing older versions of Oracle Database that still use rollback segments. One master rollback segment is stored for each media mobile per opzioni binarie 50 periodic table view and is validated during materialized view creation and refresh.
If the materialized view is complex, then the database ignores any master rollback segment you specify. The clause lets Oracle Database use unenforced constraints, such as dimension relationships or constraints in the RELY state, rather than relying only on enforced constraints during the refresh operation.
When used in conjunction with Advanced Replication, these updates will be propagated media mobile per opzioni binarie 50 periodic table the master.
You can enable query rewrite only if expressions in the statement are repeatable. Query rewrite is disabled by default, so you must specify this clause to make materialized views eligible for query rewrite. Oracle Database needs the statistics generated by this package to optimize query rewrite. Oracle Database Data Warehousing Guide for more information on query rewrite. A disabled materialized view can be refreshed. Specify the defining query of the materialized view.
When you create the materialized view, Oracle Database executes this subquery and places the results in the materialized view. This subquery is any valid SQL subquery. However, not all subqueries are fast refreshable, nor are all subqueries eligible for query rewrite. Oracle recommends that you qualify each table and view in the FROM clause of the defining query of the materialized view with the schema containing it.
Columns in the select list that are encrypted in the table are not encrypted in the materialized view. You cannot define a materialized view with a subquery in the select list of the defining query. You cannot create a materialized view log on a temporary table. If the FROM clause of the defining query references another materialized view, then you must always refresh the materialized view referenced in the defining query before refreshing the materialized view you are creating in this statement.
Materialized views with join expressions in the defining query cannot have XML datatype columns. If you want the materialized view to be eligible for fast refresh using a materialized view log, then some additional restrictions may apply.
Oracle Database Data Warehousing Guide for more information on restrictions relating to data media mobile per opzioni binarie 50 periodic table. Oracle Database Advanced Replication for more information on restrictions relating to replication. Example""Creating Subquery Materialized Views: Example"and "Creating a Nested Materialized View: Creating a Simple Materialized View: The following statement creates a very simple materialized view based on the employees media mobile per opzioni binarie 50 periodic table table in the hr schema:.
By default, Oracle Database creates a primary key materialized view media mobile per opzioni binarie 50 periodic table refresh on demand only. If a materialized view log exists on employeesthen mv1 can be altered to be capable of fast refresh.
If no such log exists, then only full refresh of mv1 is possible.
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