SQL Query Optimization for Faster Data Retrieval

This SQL query retrieves information from multiple tables, including t_dts_collect, t_patch_info, t_dts_details, and t_issue_track_summary_info. To optimize this query, we can implement the following strategies:

1. Indexing: Add indexes to frequently used columns such as collect.patch_id, collect.dts_biz_no, and details.parent_no. Indexing helps the database quickly locate the required data, speeding up the query.

2. Window Functions: Replace the subquery with window functions to improve performance. For instance, the issue subquery can be optimized as:

SELECT cmm_id,
       string_agg(l3_flag, ';') OVER (PARTITION BY cmm_id) AS l3_flag,
       string_agg(care_id, ';') OVER (PARTITION BY cmm_id) AS care_id,
       string_agg(care_name, ';') OVER (PARTITION BY cmm_id) AS care_name,
       string_agg(ump_id, ';') OVER (PARTITION BY cmm_id) AS issue_id
FROM t_issue_track_summary_info
WHERE deleted IS NULL

3. Join Order: Reorder joins to minimize the size of intermediate result sets. Consider placing the subquery as the last join to reduce data volume in earlier stages.

4. Avoid Functions: Avoid using functions in query conditions. For example, replace collect.version_id = '23735486' with a direct string comparison for better efficiency.

Optimized Query:

SELECT collect.id,
       CASE WHEN issue.l3_flag IS NULL THEN '' ELSE issue.l3_flag END AS L3flag,
       issue.care_id,
       CASE WHEN issue.care_name IS NULL THEN '' ELSE issue.care_name END AS CareName,
       issue.issue_id,
       collect.patch_plan,
       collect.patch_id,
       collect.cur_step,
       collect.turns,
       collect.cur_test,
       ...
FROM t_dts_collect collect
LEFT JOIN t_patch_info patch ON collect.patch_id = patch.id
LEFT JOIN t_dts_details details ON collect.dts_biz_no = details.dts_biz_no
LEFT JOIN t_dts_details details_parent ON details.parent_no = details_parent.dts_biz_no
LEFT JOIN (
    SELECT cmm_id,
           string_agg(l3_flag, ';') OVER (PARTITION BY cmm_id) AS l3_flag,
           string_agg(care_id, ';') OVER (PARTITION BY cmm_id) AS care_id,
           string_agg(care_name, ';') OVER (PARTITION BY cmm_id) AS care_name,
           string_agg(ump_id, ';') OVER (PARTITION BY cmm_id) AS issue_id
    FROM t_issue_track_summary_info
    WHERE deleted IS NULL
) issue ON collect.dts_biz_no = issue.cmm_id
WHERE collect.is_deleted = 0
  AND collect.version_id = '23735486'
  AND collect.patch_plan IN ('CP2118')
ORDER BY details.create_time DESC
LIMIT 200

By implementing these optimization techniques, you can significantly improve the performance of your SQL queries and ensure faster data retrieval.