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Contents → Related Documents Conventions Changes in This Release for Oracle Database VLDB and Partitioning Guide … Partitioning VLDB and Partitioning Partitioning As the Foundation for Information Lifecycle Management
VLDB and Partitioning → A very large database has no minimum absolute size. Although a VLDB is a database like smaller … databases, there are specific challenges in managing a VLDB. These challenges are related to the sheer … challenges surrounding backup and recovery for a VLDB. Storage is a key component of a very large … database. Storage Management
4.9 Oracle Database VLDB and Partitioning Guide → Note the following changes in Oracle Database VLDB and Partitioning Guide: It was incorrectly
PQ_CONCURRENT_UNION Hint → UNION and UNION ALL operations. See Also: \"NO_PQ_CONCURRENT_UNION Hint\" Oracle Database VLDB and Partitioning Guide for information about using this hint
NO_PQ_CONCURRENT_UNION Hint → processing of UNION and UNION ALL operations. See Also: \"PQ_CONCURRENT_UNION Hint\" Oracle Database VLDB
Changes in This Release for Oracle Database VLDB and Partitioning Guide → This chapter describes changes to Oracle Database VLDB and Partitioning Guide. Changes for Very
ENABLE_PARALLEL_DML Hint → ALTER SESSION ENABLE PARALLEL DML statement. See Also: Oracle Database VLDB and Partitioning Guide
21.2.9 Consider Parallelizing Index Creation → creation. See Also: Oracle Database VLDB and Partitioning Guide for information about using parallel execution
Partitioned Indexes → \" Oracle Database VLDB and Partitioning Guide and Oracle Database SQL Tuning Guide for more information
Use the PARALLEL_SERVER_LIMIT directive attribute to specify the maximum percentage of the parallel… → degree of parallelism for a consumer group. See Also: Oracle Database VLDB and Partitioning Guide for
Changes for Very Large Databases and Partitioning in Oracle Database 12c Release 1 (188.8.131.52) → The following are changes in Very Large Databases and Partitioning for Oracle Database 12 c Release 1 (184.108.40.206). New Features
Changes for Very Large Databases and Partitioning in Oracle Database 12c Release 1 (220.127.116.11) → Automatic Big Table Caching Automatic big table caching enhances in-memory query capabilities of Oracle Database in both single instance and Oracle Real Application Clusters (Oracle RAC) environments using a temperature based algorithm with the big table cache. In Oracle RAC environments, this feature is supported only with parallel queries. In single instance environments, this feature is supported
20.2.2 Specify the Type of Table to Create → administration. Partitioned tables are discussed in Oracle Database VLDB and Partitioning Guide.
In range partitioning, the database maps rows to partitions based on ranges of values of the partitioning… → , whereas a query that uses a local nonprefixed index might not. See Also: Oracle Database VLDB and
20.6.1 Reasons for Using the ALTER TABLE Statement → subpartitions at a time, such as split partition and merge partitions operations. See Oracle Database VLDB
BEGIN_SQL_BLOCK Procedure → Parallel Statement Queuing with Resource Manager\" in Oracle Database VLDB and Partitioning Guide.
79 DBMS_ILM → ) strategies using Automatic Data Optimization (ADO) policies. See Also: Oracle Database VLDB and
C.3.128 resmgr:pq queued → degree of parallelism Parameter Description location Location of the wait See Also: Oracle Database VLDB
36 DBMS_COMPRESSION → Oracle Database SQL Language Reference Oracle Database Data Warehousing Guide Oracle Database VLDB and
END_SQL_BLOCK Procedure → Statement Queuing with Resource Manager\" in Oracle Database VLDB and Partitioning Guide.
20.3.3 Parallelizing Table Creation → number of parallel execution servers when creating the table. See Also: Oracle Database VLDB and
Oracle Database includes the following components: the Oracle Database instance, which is a collection… → UPDATE INDEXES ONLINE; See Also: Oracle Database VLDB and Partitioning Guide Oracle Database SQL Language Reference
Secondary Indexes on Index-Organized Tables → index-organized table Oracle Database VLDB and Partitioning Guide to learn about creating secondary indexes on indexed-organized table partitions
20.7.9 Online Redefinition of One or More Partitions → subpartition that is being moved. See \" Moving a Table to a New Segment or Tablespace \". See Also: Oracle Database VLDB and Partitioning Guide
5.6.1 About Parallel Execution Servers → Database SQL Tuning Guide for information about using parallel hints Oracle Database VLDB and
About the Database Buffer Cache → statements Oracle Database VLDB and Partitioning Guide for information about parallel execution
Manually Specifying the Degree of Parallelism → A specific DOP can be requested from Oracle Database for both tables and indexes. For example, you can set a fixed DOP at a table level with the following: ALTER TABLE sales PARALLEL 8; ALTER TABLE customers PARALLEL 4; In this example, queries accessing just the sales table use a requested DOP of 8 and queries accessing the customers table request a DOP of 4. A query accessing both the sales and
Implementing an ILM System Manually Using Partitioning → Example 5-11 illustrates how to manually create storage tiers and partition a table across those storage tiers and then setup a virtual private database (VPD) policy on that database to restrict access to the online archive tier data. See Also: Oracle Database SQL Language Reference for information about the CREATE TABLE SQL statement Oracle Database PL/SQL Packages and Types Reference for information
Modifying a Subpartition Template → You can modify a subpartition template of a composite partitioned table by replacing it with a new subpartition template. Any subsequent operations that use the subpartition template (such as ADD PARTITION or MERGE PARTITIONS ) now use the new subpartition template. Existing subpartitions remain unchanged. If you modify a subpartition template of an interval-* composite partitioned table, then interval
Renaming a Table Subpartition → Likewise, you can assign new names to subpartitions of a table. In this case you would use the ALTER TABLE RENAME SUBPARTITION syntax.
Single-Level Partitioning → A table is defined by specifying one of the following data distribution methodologies, using one or more columns as the partitioning key: Range Partitioning Hash Partitioning List Partitioning For example, consider a table with a column of type NUMBER as the partitioning key and two partitions less_than_five_hundred and less_than_one_thousand. The less_than_one_thousand partition contains rows where
PARALLEL_MIN_TIME_THRESHOLD → This parameter specifies the minimum execution time a statement should have before the statement is considered for automatic degree of parallelism. Automatic degree of parallelism is only enabled if PARALLEL_DEGREE_POLICY is set to AUTO or LIMITED. See Also: Oracle Database Reference for information about the PARALLEL_MIN_TIME_THRESHOLD initialization parameter
Creating a Composite Range-List Partitioned Table → Example 4-10 illustrates how range-list partitioning might be used. The example tracks sales data of products by quarters and within each quarter, groups it by specified states. A row is mapped to a partition by checking whether the value of the partitioning column for a row falls within a specific partition range. The row is then mapped to a subpartition within that partition by identifying the subpartition
Adding a Subpartition to a *-Hash Partitioned Table → You use the MODIFY PARTITION ADD SUBPARTITION clause of the ALTER TABLE statement to add a hash subpartition to a [range | list | interval]-hash partitioned table. The newly added subpartition is populated with rows rehashed from other subpartitions of the same partition as determined by the hash function. For an interval-hash partitioned table, you can only add subpartitions to range or interval
Truncating Multiple Partitions → You can truncate multiple partitions from a range or list partitioned table with the TRUNCATE PARTITION clause of the ALTER TABLE statement. The corresponding partitions of local indexes are truncated in the operation. Global indexes must be rebuilt unless UPDATE INDEXES is specified.For example, the following SQL statement truncates multiple partitions in the range-partitioned sales table. ALTER
Local Partitioned Indexes → In a local index, all keys in a particular index partition refer only to rows stored in a single underlying table partition. A local index is created by specifying the LOCAL attribute. Oracle constructs the local index so that it is equipartitioned with the underlying table. Oracle partitions the index on the same columns as the underlying table, creates the same number of partitions or subpartitions,
Flashback Database and Guaranteed Restore Points → Flashback Database is a fast, continuous point-in-time recovery method to repair widespread logical errors. Flashback Database relies on additional logging, called flashback logs, which are created in the fast recovery area and retained for a user-defined time interval according to the recovery needs. These logs track the original block images when they are updated. When a Flashback Database operation
Splitting a *-Hash Partition → This is the opposite of merging *-hash partitions. When you split *-hash partitions, the new subpartitions are rehashed into either the number of subpartitions specified in a SUBPARTITIONS or SUBPARTITION clause. Or, if no such clause is included, the new partitions inherit the number of subpartitions (and tablespaces) from the partition being split. The inheritance of properties is different when
HASH_AREA_SIZE → has been deprecated and you should use PGA_AGGREGATE_TARGET instead.
SORT_AREA_SIZE → has been deprecated and you should use PGA_AGGREGATE_TARGET instead.
About Adding a Partition or Subpartition to a Reference-Partitioned Table → A partition or subpartition can be added to a parent table in a reference partition definition just as partitions and subpartitions can be added to a range, hash, list, or composite partitioned table. The add operation automatically cascades to any descendant reference partitioned tables. The DEPENDENT TABLES clause can set specific properties for dependent tables when you add partitions or subpartitions
Partition Pruning → Partition pruning is an essential performance feature for data warehouses. In partition pruning, the optimizer analyzes FROM and WHERE clauses in SQL statements to eliminate unneeded partitions when building the partition access list. This functionality enables Oracle Database to perform operations only on those partitions that are relevant to the SQL statement. This section contains the following
More Data Means a Longer Backup Window → The most obvious characteristic of the data warehouse is the size of the database. This can be upward of 100's of terabytes. Hardware is the limiting factor to a fast backup and recovery. However, today's tape storage continues to evolve to accommodate the amount of data that must be offloaded to tape (for example, advent of Virtual Tape Libraries which use disks internally with the standard tape
Default Parallelism → If the PARALLEL clause is specified but no degree of parallelism is listed, the object gets the default DOP. Default parallelism uses a formula to determine the DOP based on the system configuration, as in the following: For a single instance, DOP = PARALLEL_THREADS_PER_CPU x CPU_COUNT For an Oracle RAC configuration, DOP = PARALLEL_THREADS_PER_CPU x CPU_COUNT x INSTANCE_COUNT By default, INSTANCE_COUNT
How Parallel Execution Works → This section discusses the parallel execution process for SQL statements. This section contains the following topics: Parallel Execution of SQL Statements How Parallel Execution Servers Communicate Degree of Parallelism About Parallel Statement Queuing Parallel Execution Server Pool Granules of Parallelism Balancing the Workload to Optimize Performance Parallel Execution Using Oracle RAC
Merging Subpartitions in a *-List Partitioned Table → You can merge the contents of any two arbitrary list subpartitions belonging to the same partition. The resulting subpartition value-list descriptor includes all of the literal values in the value lists for the partitions being merged. The following statement merges two subpartitions of a table partitioned using range-list method into a new subpartition located in tablespace ts4: ALTER TABLE quarterly_regional_sales
SHARED_POOL_SIZE → Parallel execution requires memory resources in addition to those required by serial SQL execution. Additional memory is used for communication and passing data between query server processes and the query coordinator. Oracle Database allocates memory for query server processes from the shared pool. Tune the shared pool as follows: Allow for other clients of the shared pool, such as shared cursors
Interval Partitioning → Interval partitioning is an extension of range partitioning which instructs the database to automatically create partitions of a specified interval when data inserted into the table exceeds all of the existing range partitions. You must specify at least one range partition. The range partitioning key value determines the high value of the range partitions, which is called the transition point, and
Automatic Big Table Caching → Automatic big table caching integrates queries with the buffer cache to enhance the in-memory query capabilities of Oracle Database, in both single instance and Oracle RAC environments. In Oracle Real Application Clusters (Oracle RAC) environments, this feature is supported only with parallel queries. In single instance environments, this feature is supported with both parallel and serial queries.
Critical Parallel Statement Prioritization → The parallel_stmt_critical parameter specifies consumer groups as critical in respect to parallel statements in the plan directive. When a consumer group is marked as critical, parallel statements issued from these consumer groups bypass the parallel statement queue and execute immediately. Because critical parallel statements bypass the parallel statement queue, the system may encounter more active
Step 3: Create Data Access and Migration Policies → The next step is to ensure that only authorized users have access to the data and to specify how to move the data during its lifetime. As the data ages, there are multiple techniques that can migrate the data between the storage tiers.
Splitting Index Partitions → You cannot explicitly split a partition in a local index. A local index partition is split only when you split a partition in the underlying table. However, you can split a global index partition as is done in the following example: ALTER INDEX quon1 SPLIT PARTITION canada AT ( 100 ) INTO PARTITION canada1..., PARTITION canada2...); ALTER INDEX quon1 REBUILD PARTITION canada1; ALTER INDEX quon1 REBUILD
Introduction to Partitioning → Partitioning addresses key issues in supporting very large tables and indexes by decomposing them into smaller and more manageable pieces called partitions, which are entirely transparent to an application. SQL queries and Data Manipulation Language (DML) statements do not need to be modified to access partitioned tables. However, after partitions are defined, data definition language (DDL) statements
Global Partitioned Indexes → Oracle offers global range partitioned indexes and global hash partitioned indexes, discussed in the following topics: Global Range Partitioned Indexes Global Hash Partitioned Indexes Maintenance of Global Partitioned Indexes
Space Considerations for Parallel DML → Parallel UPDATE uses the existing free space in the object, while direct-path INSERT gets new extents for the data. Space usage characteristics may be different in parallel than serial execution because multiple concurrent child transactions modify the object.
Performance → in OLTP environments heavily relies on efficient index access, thus the choice of the most appropriate index strategy becomes crucial. The following section discusses best practices for deciding whether to partition indexes in an OLTP environment.
Global Hash Partitioned Indexes → Global hash partitioned indexes improve performance by spreading out contention when the index is monotonically growing. In other words, most of the index insertions occur only on the right edge of an index, which is uniformly spread across N hash partitions for a global hash partitioned index.
Using Table Compression with Partitioned Tables → For heap-organized partitioned tables, you can compress some or all partitions using table compression. The compression attribute can be declared for a tablespace, a table, or a partition of a table. Whenever the compress attribute is not specified, it is inherited like any other storage attribute. Example 4-21 creates a range-partitioned table with one compressed partition costs_old. The compression
A B, A A → Global Prefixed (range partitioning only) No 2
Modifying Real Attributes of a Subpartition → With the MODIFY SUBPARTITION clause of ALTER TABLE you can perform the same actions as listed previously for partitions, but at the specific composite partitioned table subpartition level. For example: ALTER TABLE employees_rebuild_index MODIFY SUBPARTITION p3_s1 REBUILD UNUSABLE LOCAL INDEXES;