There is no normative metric for index selectivity in Oracle

How is your script written? Inserting a hood finch also invalidates the index? The first time I heard of it...

It should be that your script is too boring and there is a problem.

For example, when deleting a partition, there is no update global indexes, let me see the script first, in addition, is the index on your partition buried table a partition index, a local index or a global index?

Project Measurement Goals.

Metric Objective 1: Workload Data Metric Objective 2: Deviation Rate Data Metric Objective 3: Review Statistics.

Metric Objective 4: Defect Rate Data.

Objective 5: Quality Assurance Data 2Measure Collection Data Metric Objective 1 Required Data: Workload Statistics Table in the Project.

Measure the data required for objective two: The rate of plan deviation in the project.

Data required for Metric Objective 3: Project Review Statistical Table.

Measure the data required for Goal 4: Defect rate in the project.

Data required for metric objective five: Quality assurance data in the project.

select company,period,item,a*100 sum(a) over() from tab a;

This is the proportion of each company, if you want to target the proportion of each company, you can cover this as follows;

select company,period,item,a*100/sum(a) over(partition by company) from tab a;

1. Grammar. create bitmap index index name on tablename(field);

2. Take an example and you will understand:

If there is a test(id,name,address) data. 1, Zhang San, Dalian).

2, Li Si, Tianjin).

3, Wang Wu, Beijing).

4, Zhao Liu, Dalian).

For data like this, if the office asks you to use [where address=] when asking for information'Dalian'Because there is a lot of such data in the database, the shouting of the finger will not cause the effect of query speedup.

You know, the records of indexes and tables in oracle are determined according to their binary height, binary height, you are right, but here, the internal transformation of the oracle does not happen according to priority, like where, slqwyw

Just query as before, and the system will know which one to execute first!

You can use the hint syntax to specify the index to use for the query.

Are you still bothered by the change of the execution plan of the SQL statement under the CBO selector? Still struggling with whether to add *+rule* in front of the SQL statement? Through the introduction of this article, you will understand why there are differences in the execution plan of the same SQL statement under CBO, and how we can achieve the purpose of stable SQL statement execution plan in the CBO environment through Stored Outlines.

The b-tree index is one-to-one, with one index entry pointing to a row; In the bitmap index, so there are very few entries, each entry points to multiple rows, which is suitable for some special environments; It is not possible to simply compare their performance, because the environment of the application is different.