Cluster table in Your HD
Tags: apache, postgres, database, mysql
Published: 2023-04-18 00:45:23

Cluster Table or Index organized table-IOT or clustered index. what is mean? why it is important and how effectively use it?, simply, it is dangerous not to be aware of what MySQL do in the default mode for you.

## What is clustering.
Database clustering is a technique used to group similar data points together into clusters or groups. This approach is commonly used in data mining and machine learning to identify patterns and relationships within large datasets. The goal of clustering is to partition the data in a way that maximizes the similarity within each cluster while minimizing the similarity between clusters

In the context of database optimization, clustering can be used to minimize the number of disk reads required to access target data, which can improve query performance and speed up data retrieval. By grouping related data together in clusters, the database can access multiple data points with a single disk read, reducing the overall number of disk reads required.
pencil of cluster refers to the process of optimizing the clustering approach to maximize the amount of information stored in each page while minimizing disk reads. This involves carefully selecting the size and composition of each cluster and choosing the right UUID to identify and group related data points together.
Choosing the right UUID for clustering can be a challenging task. It requires predicting the most frequent queries and identifying the centroid of each cluster to create a single UUID for that cluster. The centroid is the point at the center of each cluster, which can be used to represent the entire cluster. By selecting the right UUID, related data points can be grouped together efficiently and effectively.
## Cluster based on what is needed
To implement clustered indexing, you would need to select the appropriate index key, which in this case would be the grades. You would then need to group the data into clusters based on the grades index key. This would involve identifying the ranges of grades and clustering the data within those ranges. it is quite similar to fragmentation in your disk when cluster.

It's important to note that clustering based on the most frequently requested queries may not always be the best approach. In some cases, it may be more beneficial to cluster data based on other factors, such as the frequency of updates or the relationships between data points. The key is to identify the most important factors for optimizing database performance and clustering the data accordingly. in MYSQL the seek is to cluster the database based on the cluster index which could be useful at some cases. 
## Can I cluster based on different index
well, you don't want to duplicate your database don't you?. the other thing is to use the The reclusters property in PostgreSQL allows for the reordering of data based on a specific index. This can be useful in cases where there are multiple queries with different frequency patterns, and it's difficult to optimize the database for all of them simultaneously. By using the reclusters property, you can optimize the database for a specific query based on its frequency, while still maintaining some level of efficiency for other queries.


## Clusters in PostgreSQL
When using PostgreSQL to cluster a table, the table will be locked exclusively during the clustering process. This means that no reads or writes can be performed on the table while it is being clustered. This can be quite expensive and can potentially impact the performance of the database, particularly if the table is large.

In addition, clustering a table based on a given value does not guarantee that all new inserts will be clustered in the same way. While clustering can be fast and efficient, it is not always guaranteed to produce optimal results.

Despite these limitations, clustering can still be a useful technique for optimizing database performance in certain situations. It's important to carefully consider the trade-offs and benefits of clustering before implementing it and to monitor the performance of the database to ensure that it is meeting the required performance standards.

### clustering at this level of Disk can really make or break your quires 

Thanks for reading ✅✅