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Splitting Index in Oracle RDBMS related to Detection of missing Indexes

In an Oracle RDBMS, index splitting is a technique used to improve the performance of an index by redistributing its entries and dividing it into multiple smaller, more manageable parts. This process can be particularly helpful when dealing with large, heavily accessed indexes. Detecting missing indexes and materialized views is crucial to maintain optimal database performance. The following instructions describe how to identify these missing elements and perform index splitting in an Oracle RDBMS:

1. Detecting missing indexes:

  1. Analyze SQL execution plans: Review the execution plans of poorly performing SQL statements using the EXPLAIN PLAN feature. Identify full table scans or inefficient nested loop operations that could benefit from an index.
  2. Use Automatic Database Diagnostic Monitor (ADDM): ADDM provides comprehensive performance analysis and recommendations for your Oracle database, including identifying missing indexes that may improve query performance.
  3. Utilize Oracle's SQL Tuning Advisor: This tool generates recommendations for creating, modifying, or dropping indexes based on the SQL workload. It helps identify missing indexes that could enhance query performance.

2. Detecting missing materialized views:

  1. Examine repetitive query patterns: Analyze frequently executed queries and identify patterns where pre-computed results could be stored in materialized views to improve performance.
  2. Utilize the DBMS_ADVISOR package: This package provides the Materialized View Advisor, which analyzes the workload and recommends suitable materialized views for your database.

3. Splitting an index:

  1. Identify the index: Determine the index you want to split based on the analysis of missing indexes, materialized views, and performance metrics.
  2. Partition the index: Split the identified index into smaller, more manageable partitions using either range, hash, or list partitioning methods.
    1. Range partitioning: Divide the index based on a specified range of key values. This is suitable for data with natural, contiguous ranges.
    2. Hash partitioning: Distribute the index data evenly across multiple partitions using a hash function. This method is ideal for uniformly distributing data to avoid hotspots.
    3. List partitioning: Partition the index based on a predefined list of key values. This approach is useful for data with distinct, known values.
  3. Create the partitioned index: Use the CREATE INDEX statement with the appropriate partitioning clause (RANGE, HASH, or LIST) to create the new partitioned index.
  4. Test and validate: Verify the performance improvements of the partitioned index by examining query execution plans and comparing response times before and after the index split.

By detecting missing indexes and materialized views and performing index splitting in an Oracle RDBMS, you can optimize query performance, reduce response times, and maintain a scalable and efficient database system. Regular monitoring and proactive tuning are essential to ensure continued optimal performance.

Splitting an Oracle Index

Oracle provides table and index maintenance tools (Oracle 10g online reorganization). In order to keep Oracle running fast, Oracle chose not to incur the overhead of
  1. coalescing table rows and
  2. restructuring indexes
during peak update times.
This is why we have the DBA maintenance utilities. The challenge is knowing when to use the Oracle 10g DBA tools.
Oracle 10g and beyond has offered huge improvements in Oracle indexing, especially related to the detection of missing indexes and materialized views and the automation of index histogram detection for the SQL optimizer.
We also see these improvements to table maintenance in Oracle 10g:
Oracle Database 10g includes the following online data reorganization enhancements:
  1. Online table redefinition enhancements
  2. Easy cloning of indexes, grants, constraints, etc
  3. Convert from LONG to LOB online
  4. Allow unique index instead of primary key
  5. Change tables without recompiling stored procedures
  6. Online segment shrink
Despite all of the great automated tools, the Oracle DBA must still perform routine table and index maintenance to keep highly active databases performing at peak levels.