Importance of partitioning in Data-intensive Analytics Solution Design
Vivek Kumar, CQF
Product Manager, Risk Data & Analytics at Standard Chartered Bank
Data Query performance in big data environment as well as in data warehousing environment is critical for the efficient analytics solution. Data Query performance depends on optimal partitioning of storage & processing pipelines.
Partitioning a dataset refers to the splitting of a dataset based on one or multiple dimensions. When a dataset is partitioned, each chunk or partition of the dataset contains a subset of the data, and the partitions are built independently of each other. When new data is added at regular intervals, such as daily, processing can be performed only for the partition that contains the new data.
Suitable usage of partitioning mechanism to organize data into manageable chunks improves performance. ?Designing partitions that align with the way data would be queried is important.
Partition is required for both file-based datasets and SQL-based datasets. For file-based datasets, the partitioning is based on the filesystem hierarchy of the dataset. For SQL-based datasets, partition is created for each unique value of the column. Usually, it does not involve splitting the dataset into multiple tables.
Files-based partitioning: ?This method is used for all datasets based on a filesystem hierarchy. This includes Filesystem, HDFS, Amazon S3, Azure Blob Storage, Google Cloud Storage and Network datasets. In this method, partitioning is defined by the layout of the files on disk. Important point is that the data in the files is not used to decide which records belong to which partition. Partitioning a files-based dataset cannot be defined by the content of a column within this dataset. Files-based partitioning is defined by a matching pattern that maps each file to a given partition identifier.
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Column-based partitioning: This method is used for datasets based on structured storage engines like all different SQL databases, NoSQL databases like MongoDB, Cassandra and Elasticsearch etc. In this method, the partitioning is derived from one column or multiple columns which is part of the dataset. An important point is that in this method, the schema of the dataset does contain the partitioning data. Datasets based on SQL tables support partitioning based on the values of specified columns: the partitioning columns must be part of the schema of the table.
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Partitioning plays a crucial role in the design and optimization of data-intensive analytics solutions, following are key reasons behind the importance of partitioning:
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Performance Improvement:
Parallel Processing: Partitioning allows for parallel processing of data. When data is divided into partitions, each partition can be processed independently by different nodes or workers in a distributed computing environment. This parallelism significantly improves query performance.
Reduced Data Scans: By organizing data into partitions, the system can skip unnecessary data scans when executing queries. This is especially beneficial when dealing with large datasets, as it minimizes the amount of data that needs to be read for a specific query.
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Query Optimization:
Predicate Pushdown: Partitioning supports predicate pushdown, where the query engine can eliminate unnecessary data early in the query execution process. This reduces the amount of data that needs to be processed, leading to faster query response times.
Filter Pruning: With proper partitioning, the system can skip reading entire partitions that are not relevant to the query. This filter pruning optimizes query performance by avoiding unnecessary data retrieval.
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Data Organization:
Logical Grouping: Partitioning allows to logically group and organize data based on certain criteria, such as date ranges or categorical values. This makes it easier to manage and maintain large datasets.
Time-Series Data: For datasets with a time component, such as event logs or financial data, time-based partitioning can significantly enhance the efficiency of querying specific time ranges.
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Optimized Storage:
Compression and Encoding: Partitioning can be combined with compression and encoding techniques to optimize storage efficiency. By partitioning and compressing data together can result reduction in storage costs and enhancement in data retrieval speed.
Storage Tiering: Different partitions can be stored on different storage tiers based on access patterns and query frequency. Frequently accessed partitions can be stored on high-performance storage, while less frequently accessed partitions can be stored on lower-cost storage.
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Scalability:
Scalable Processing: Partitioning allows for scalable processing in distributed computing environments. As data grows, application can easily scale system by adding more nodes, and the partitioning strategy enables efficient data distribution across the expanded infrastructure.
Load Balancing: Well-designed partitioning helps in load balancing across nodes, ensuring that each node gets a relatively equal amount of work, which is crucial for maintaining system performance and avoiding bottlenecks.
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Maintenance and Data Lifecycle Management:
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Ease of Maintenance: Partitioning simplifies data maintenance tasks, such as archiving or purging old data. Instead of operating on the entire dataset, processing is focused on specific partitions, making operations more efficient.
Data Lifecycle Management: Partitioning facilitates the implementation of data lifecycle management strategies, enabling to manage and retain relevant data while archiving or discarding less critical or outdated data.
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Partitioning is a fundamental aspect of designing data-intensive analytics solutions. It directly contributes to improved performance, query optimization, efficient data organization, storage optimization, scalability, and ease of maintenance. Well-planned partitioning strategies can make a significant difference in the overall effectiveness and responsiveness of analytics systems dealing with large volumes of data. However partitioning strategy evolves over time.
Following are some of the common approaches to iteratively improve the partitioning strategy, ensuring that it aligns with data and query patterns for optimal performance for bigdata solutions
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Understand Data and Query Patterns:
Data Analysis: Start by analyzing the nature of data, understand the distribution of data across different columns, identify key fields, and assess data growth patterns.
Query Analysis: Examine the types of queries that are commonly executed. Identify frequently used filters and columns in the WHERE clause, as these are candidates for partitioning.
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Prototype Initial Partitioning:
Choose Key Columns: Based on the analysis, select key columns that are frequently used in queries. These columns can be used for partitioning.
Date Partitioning: If time-based queries are common, consider partitioning by date. This is especially useful for time-series data.
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Monitor Performance:
Collect Metrics: Implement the initial partitioning strategy and monitor query performance. Collect metrics such as query execution time, resource utilization, and data scan sizes.
Identify Bottlenecks: Identify any bottlenecks or areas where performance can be improved. This might involve examining the execution plans of queries and understanding how they interact with the partitioning strategy.
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Evolve Partitioning:
Iterative Refinement: Based on the performance metrics and identified bottlenecks, iteratively refine the partitioning strategy. This could involve changing the partitioning columns, adjusting partition sizes, or exploring different partitioning methods.
Consider Dynamic Partitioning: Depending on use case, consider implementing dynamic partitioning, where new partitions are created automatically based on incoming data.
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Automation and Maintenance:
Automate Partitioning Updates: Develop scripts or processes to automate the evolution of partitioning strategies based on changing data patterns. This ensures that tables stay optimized over time.
Regular Maintenance: Schedule regular reviews of data and query patterns. As data evolves, so the partitioning strategy should evolve.
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Backup and Rollback:
Backup Data: Before making significant changes to partitioning, ensure you have a backup strategy in place to prevent data loss.
Rollback Plan: Define a rollback plan in case the new partitioning strategy introduces unexpected issues. This might involve reverting to a previous partitioning scheme.
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