Analysis of Oracle Database Index classification and Summarization

Before giving you a detailed introduction to Oracle table creation, let's first take a look at Oracle indexes, because good indexes can help Oracle databases better retrieve the information we want.

Oracle index logic:
Single column Single Row Index
Concatenated multi-row Index
Unique index
NonUnique non-unique index
Function-based Function Index
Domain index

Oracle index:
Partitioned partition Index
NonPartitioned non-partition Index
B-tree:
Normal B-type tree
Rever Key reverse B-tree
Bitmap Index

Oracle index structure:
B-tree:
Suitable for large numbers of additions, deletions, and changes to OLTP );
Queries that contain the OR operator cannot be used;
Suitable for columns with multiple unique values with a high base)
Typical tree structure;
Each node is a data block;
Most of them are physical, two or three layers, but logical;
The leaf block data is sorted, increasing from left to right;
The range of the index is placed in the branch block and the root block;
Bitmap:
Applicable and decision support systems;
The UPDATE cost is very high;
It is very suitable for OR operator queries;
Bitmap indexes can be created only when the base number is small;
Tree Structure:
Index Header
Start ROWID, end ROWID first list the maximum range of the index)
BITMAP
Each BIT corresponds to a ROWID. Its value is 1 or 0. If it is 1, it indicates that the ROWID corresponding to the BIT has a value;

B * tree indexes are generally applicable when accessing small data volumes. For example, if you access a table with no more than 5% data, this is only a relative ratio and is applicable to general situations. Bitmap is used in data warehouses for low-base columns, such as fields with many duplicate values such as gender. The smaller the base, the better.

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2. Summary of Oracle stored procedures
3. Code for implementing the Oracle Stored Procedure
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5. Analysis of Oracle SQL optimization rules