Gordon Thanks for your thoughts again.
Sorry for being up demons from 15 years ago. 😂 Best Mike ________________________________ From: Gordan Bobic <[email protected]> Sent: Saturday, November 1, 2025 12:38:52 PM To: Michael Caplan <[email protected]> Cc: Gordan Bobic via discuss <[email protected]> Subject: Re: [MariaDB discuss] Re: EXTERNAL: Re: Well Performing Queries Goes Sideways Unexpectantly You don't often get email from [email protected]. Learn why this is important<https://aka.ms/LearnAboutSenderIdentification> I'm still confused how the optimizer in any scenario would choose an index with no relevant columns to complete a join. Is there ever a scenario where such a choice makes sense? I used to ask such questions until about 15 years ago. I never got an entirely satisfactory answer. To add to the mix, how table stats would change in such a way to lead the optimizer in such a direction, where for years it behaved reasonably. Statistics that drive the optimised heuristics change over time. And every time they get updated there is a very small but not 0 chance that the random dive into the index tree will get sufficiently unlucky to get an estimate that is far enough removed from reality to misinform the optimiser into a suboptimal execution plan. Confidentiality Notice: The information contained in this electronic message and any attachments to this message are intended only for the individual(s) addressed in the message and may contain proprietary and confidential information. If you are not the intended recipient, you should not disseminate, distribute, or copy this e-mail. Please notify the sender and destroy this message. WARNING: Computer viruses can be transmitted via email. The recipient should scan this email before opening it. The company accepts no liability for any damage caused by any virus transmitted by this email. Confidentiality Notice: The information contained in this electronic message and any attachments to this message are intended only for the individual(s) addressed in the message and may contain proprietary and confidential information. If you are not the intended recipient, you should not disseminate, distribute, or copy this e-mail. Please notify the sender and destroy this message. WARNING: Computer viruses can be transmitted via email. The recipient should scan this email before opening it. The company accepts no liability for any damage caused by any virus transmitted by this email.
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