slow sql

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  1. Richard To
    Thread

    How to tune SQL in a Database Object with Plan Guide for SQL Server?

    Leveraging Plan Guides in MS SQL Server can prove beneficial for optimizing the performance of a particular query within database objects like...
    Thread by: Richard To, Aug 25, 2023, 0 replies, in forum: SQL Server
  2. Richard To
    Thread

    How to tune Ad-hoc SQL with Plan Guide for SQL Server?

    Using Plan Guides to tune third-party applications SQL in MS SQL Server can be a useful technique when you need to optimize the performance of a...
    Thread by: Richard To, Aug 8, 2023, 0 replies, in forum: SQL Server
  3. Richard To
    Thread

    How to analyze the performance impact of a database environment change using what-if analysis?

    To properly evaluate the impact of a set of SQL statements during a database environment change, it's crucial to have a thorough understanding of...
    Thread by: Richard To, Jul 19, 2023, 0 replies, in forum: Oracle
  4. Richard To
    Thread

    An Example to Show How to Tune SQL with Query Store for SQL Server

    The Query Store feature in SQL Server serves as a valuable tool for troubleshooting performance issues by allowing users to quickly identify...
    Thread by: Richard To, Jul 12, 2023, 0 replies, in forum: SQL Server
  5. Richard To
    Thread

    How to tune SQL with Query Store for SQL Server?

    The Query Store feature in SQL Server serves as a valuable tool for troubleshooting performance issues by allowing users to quickly identify...
    Thread by: Richard To, Jul 6, 2023, 0 replies, in forum: SQL Server
  6. Richard To
    Thread

    How To Use 80/20 Rule To Tune A Database Application II?

    The previous article “How To Use 80/20 Rule To Tune A Database Application I “ demonstrated how the 80/20 Rule can be applied to evaluate the...
    Thread by: Richard To, Jul 3, 2023, 0 replies, in forum: Oracle
  7. Richard To
    Thread

    How to Tune SQL Statement with CASE Expression by Hints Injection for Oracle?

    Here the following is a simple SQL statement with a CASE expression syntax. SELECT * FROM employee WHERE CASE WHEN emp_salary<...
    Thread by: Richard To, Oct 10, 2022, 0 replies, in forum: Oracle
  8. Richard To
    Thread

    How to use ROWID to improve an UPDATE statement for Oracle?

    Here the following is an Update SQL with a subquery that updates the EMPLOYEE table if the emp_dept satisfies the records returned from a...
    Thread by: Richard To, Jul 4, 2022, 0 replies, in forum: Oracle
  9. Richard To
    Thread

    How to build indexes for slow first execution SQL - SQL Server?

    You may suffer from SQL statements with a slow first execution time due to the long data cache process. The following SQL is simple that retrieves...
    Thread by: Richard To, Apr 14, 2022, 0 replies, in forum: SQL Server
  10. Richard To
    Thread

    How to index SQL with aggregate function SQL for Oracle?

    Here the following is an example SQL shows you that select the maximum emp_address which is not indexed in the EMPLOYEE table with 3 million...
    Thread by: Richard To, Feb 21, 2022, 0 replies, in forum: Oracle
  11. Richard To
    Thread

    How to build indexes for multiple Max() functions for SQL Server?

    For some SQL statements with multiple Max() functions in the select list and nothing in the Where clause, we have different methods to create new...
    Thread by: Richard To, Jan 24, 2022, 0 replies, in forum: SQL Server
  12. Richard To
    Thread

    How is the order of the columns in a composite index affecting a subquery performance for Oracle?

    We know the order of the columns in a composite index will determine the usage of the index or not against a table. A query will use a composite...
    Thread by: Richard To, Jan 10, 2022, 0 replies, in forum: Oracle
  13. Richard To
    Thread

    Do not undermine your SQL Server’s potential ability

    For some SQL statements that are failed to be tuned by syntax rewrite, hints injection, and all necessary indexes are built, people may think that...
    Thread by: Richard To, Dec 8, 2021, 0 replies, in forum: SQL Server
  14. Richard To
    Thread

    How to use ORDERED Hint to Tune a SQL with subquery for Oracle?

    Here the following is the description of the ORDERED hint. The ORDERED hint causes Oracle to join tables in the order in which they appear in the...
    Thread by: Richard To, Nov 12, 2021, 0 replies, in forum: Oracle
  15. Richard To
    Thread

    How to Tune SQL Statements with NO_RANGE_OPTIMIZATION Injection?

    There are some SQL statements with performance problem can be tuned by Hints injection only. Here is an example to show you how to use...
    Thread by: Richard To, Oct 8, 2021, 0 replies, in forum: MySQL
  16. Richard To
    Thread

    How to tune a SQL that cannot be tuned?

    Some mission-critical SQL statements are already reached their maximum speed within the current indexes configuration. It means that those SQL...
    Thread by: Richard To, Sep 13, 2021, 0 replies, in forum: Oracle
  17. Richard To
    Thread

    How to Tune SQL Statement with CASE Expression for SQL Server II?

    We have discussed how to tune a CASE expression SQL with hardcoded literals in my last blog: How to Tune SQL Statement with CASE Expression for...
    Thread by: Richard To, Aug 19, 2021, 0 replies, in forum: SQL Server
  18. Richard To
    Thread

    How to Tune SQL Statement with CASE Expression for SQL Server I?

    Here the following is a simple SQL statement with a CASE expression syntax. SELECT * FROM EMPLOYEE WHERE CASE when emp_id < 1001000 then 'Old...
    Thread by: Richard To, Jul 19, 2021, 0 replies, in forum: SQL Server
  19. Richard To
    Thread

    How to Tune SQL Statements with Rewrite and Hints Injection for MySQL?

    There are some SQL statements with performance problem have to be tuned by SQL syntax rewrite and Hints injection, it is a little bit difficult...
    Thread by: Richard To, Jun 29, 2021, 0 replies, in forum: MySQL
  20. Richard To
    Thread

    How to Tune SQL Statements to Run SLOWER… but Make Users Feel BETTER (Oracle)?

    Your end-users may keep on complaining about some functions of their database application are running slow, but you may found that those SQL...
    Thread by: Richard To, Jun 16, 2021, 0 replies, in forum: Oracle
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