The provided image shows the result of an EXPLAIN SELECT * FROM ... query, which analyzes the execution plan for a SQL query joining tables order_detail, order, customer, and product from a business_schema. The key columns to evaluate are rows and filtered, which indicate the number of rows processed and the percentage of rows filtered by the query optimizer, respectively. The results are:
order_detail: 155 rows, 100.00% filtered
order: 122 rows, 100.00% filtered
customer: 121 rows, 100.00% filtered
product: 1 row, 100.00% filtered
The rows column reflects the estimated number of rows the MySQL optimizer expects to process for each table, while filtered indicates the efficiency of the index usage (100% filtered means no rows are excluded by the optimizer, suggesting poor index utilization or missing indices). According to Appian's Database Performance Guidelines and MySQL optimization best practices, high row counts with 100% filtered values indicate that the joins are not leveraging indices effectively, leading to full table scans, which degrade performance-especially with large datasets.
Option C (The join between the tables order_detail, order, and customer needs to be fine-tuned due to indices):
This is correct. The tables order_detail (155 rows), order (122 rows), and customer (121 rows) all show significant row counts with 100% filtering. This suggests that the joins between these tables (likely via foreign keys like order_number and customer_number) are not optimized. Fine-tuning requires adding or adjusting indices on the join columns (e.g., order_detail.order_number and order.order_number) to reduce the row scan size and improve query performance.
Option D (The join between the tables order_detail and product needs to be fine-tuned due to indices):
This is also correct. The product table has only 1 row, but the 100% filtered value on order_detail (155 rows) indicates that the join (likely on product_code) is not using an index efficiently. Adding an index on order_detail.product_code would help the optimizer filter rows more effectively, reducing the performance impact as data volume grows.
Option A (The request is good enough to support a high volume of data, but could demonstrate some limitations if the developer queries information related to the product): This is partially misleading. The current plan shows inefficiencies across all joins, not just product-related queries. With 100% filtering on all tables, the query is unlikely to scale well with high data volumes without index optimization.
Option B (The worst join is the one between the table order_detail and order): There's no clear evidence to single out this join as the worst. All joins show 100% filtering, and the row counts (155 and 122) are comparable to others, so this cannot be conclusively determined from the data.
Option E (The worst join is the one between the table order_detail and customer): Similarly, there's no basis to designate this as the worst join. The row counts (155 and 121) and filtering (100%) are consistent with other joins, indicating a general indexing issue rather than a specific problematic join.
The conclusions focus on the need for index optimization across multiple joins, aligning with Appian's emphasis on database tuning for integrated applications.
Reference:
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