Contents
What is a partition index?
A partitioned index is made up of a set of index partitions , each of which contains the index entries for a single data partition. Each index partition contains references only to data in its corresponding data partition. Both system- and user-generated indexes can be partitioned.
Does truncate partition invalidate index?
Use the ALTER TABLE TRUNCATE PARTITION statement to remove all rows from a table partition. Truncating a partition is similar to dropping a partition, except that the partition is emptied of its data, but not physically dropped. You cannot truncate an index partition. …
What is index key compression?
Index. Key Compression (also known as prefix compression) eliminates duplicate copies of pre-defined number of index prefix columns at. the index leaf block level and is an effective way to permanently reduce the index. size, both on disk and in cache.
How do I truncate a partition?
Use the ALTER TABLE… TRUNCATE PARTITION command to remove the data from the specified partition, leaving the partition structure intact. When you truncate a partition, any subpartitions of that partition are also truncated.
What are the benefits of index compression?
Index Key Compression allows us to compress portions of the key values in an index segment (or Index Organized Table), by reducing the storage inefficiencies of storing repeating values.
What is Oracle Advanced compression?
Oracle Advanced Compression provides a comprehensive set of compression features designed to reduce costs and improve performance by enabling compression for structured data, unstructured data, indexes, database backups, network traffic and for Data Guard redo.
How to use compression on partitioned tables with Bitmap indexes?
There are several necessary steps before using compression on partitioned tables with bitmap indexes. To use table compression on partitioned tables with bitmap indexes, you must do the following before you introduce the compression attribute for the first time: Mark bitmap indexes unusable. Set the compression attribute. Rebuild the indexes.
How to configure compression on a table or index?
On the Select Compression Type page, select the compression type to apply to each partition in the table or index you want to compress. When finished, select Next. The following options are available on the Select Compression Type page: Select to configure the same compression setting for all partitions.
How are partitioning indexes similar to partitioning tables?
Partitioning indexes has recommendations and considerations in common with partitioning tables. The rules for partitioning indexes are similar to those for tables: The index is a cluster index. The index is defined on a clustered table. You can mix partitioned and nonpartitioned indexes with partitioned and nonpartitioned tables:
What happens when a table is partitioned and compressed?
Having a partitioned table with compressed partitions can lead to slightly larger bitmap index structures for the uncompressed partitions. The bitmap index structures for the compressed partitions, however, are usually smaller than the appropriate bitmap index structure before table compression.