January 2025 - discuss - lists.mariadb.org

MariaDb Master/Replica. How to recover replication when reverting Master to an earlier backup?
by Simon Avery 12 Jan '25

12 Jan '25

Hello We have two Mariadb 10.11.10 servers acting as Master and Replica. Both have unique local databases, plus seven that are replicated from Master to Replica with Replicate_Wild_Do_Table: DB1Name.%, DB2Name.% etc The size of the replicated databases is just over 1Tb, with the single largest being almost 500Gb. Both machines are in vmware and on the same network. Yesterday, we hit an issue with the Master which required that vm to be restored to a backup four hours previously. This got … [View More]

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Re: Inquiry Regarding Slow Index Creation with MariaDB 11.7 RC (SIFT1M)
by Sergei Golubchik 12 Jan '25

12 Jan '25

Hi, kase, First: please send questions like this to discuss(a)lists.mariadb.org. it's a public mailing list dedicated to MariaDB and how to use it better. I am subscribed, so I'll see you mail there, and you may be sure I will, because it won't be accidentally catched by my spam filter, or sorted out in some obscure folder. Furthermore other subscribers will see your question and could reply if I will be not available (e.g. I could be travelling). Thank you. On Jan 12, kase jojo wrote: > … [View More]

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MariaDB Day @ Brussels 01.02.2025
by Anna Widenius 05 Jan '25

05 Jan '25

Hi All! We are at it again, MariaDB Day is coming to Brussels 1.02.2025 - https://www.meetup.com/mariadb-server/events/305194675/ MariaDB Day events bring together the MariaDB Foundation and community to celebrate and share the latest developments in MariaDB Server. Theme: Vectors, RAG, and everything new in MariaDB Server. With the imminent GA release of MariaDB Vector in MariaDB 11.7, we’re excited to showcase new functionality, real-world use cases, and the promise of Gen AI capabilities … [View More]

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Re: Question: Performance impact of adding Nullable FK to a new column in large tables
by Guillermo Céspedes Tabárez 03 Jan '25

03 Jan '25

Hi Jeff, Thank you for your response! To clarify, my question is more hypothetical and focused on understanding how the database engine handles this specific scenario. If the column being added is new and starts with all values as NULL, does it make sense to temporarily disable FOREIGN_KEY_CHECKS during the ALTER TABLE operation? My main concern is whether the database performs any additional checks or processes, even though the column is empty (NULL), or if the operation is already optimized … [View More]and skipping the checks automatically. I'm not debating the use of foreign keys or their impact on runtime performance. I'm specifically curious if disabling FOREIGN_KEY_CHECKS in this situation saves any resources during the ALTER TABLE, or if it's unnecessary because the database doesn't do anything in this case that would benefit from skipping checks. Best regards, Guillermo El vie, 20 dic 2024 a la(s) 5:14 p.m., Jeff Dyke (jeff.dyke(a)gmail.com) escribió: > > While i'm not really sure what performance issues you are referring to. FK are going to have a small performance hit on row changes, but for data integrity, its what you need. When you start to design FKs with Null values, you are talking some of the work off of the database work that can be done for you, and moving it to your developers. Also parent_id should be indexed to assist in select performance. > > Most times that I have seen this done in the past, its normally removed and the index is kept. if parent_ids are going to be duplicated and only null for a period of time, that is a good one to many relationships, that will enforce integrity once populated. > > If you think this will improve overall performance, that is not the goal of Foreign Keys. > > > On Fri, Dec 20, 2024 at 11:03 AM Guillermo Céspedes Tabárez via discuss <discuss(a)lists.mariadb.org> wrote: >> >> Hi, >> >> I’d like to understand the performance impact of adding a FOREIGN KEY >> constraint to a new column in a large table. If the column is nullable >> and defaults to NULL, does the engine perform any checks or >> validations on existing rows? Or is the operation optimized since the >> column starts with all values as NULL? >> >> Here’s a simplified example: >> >> ALTER TABLE child_table >> ADD COLUMN parent_id INT NULL, >> ADD CONSTRAINT fk_child_parent FOREIGN KEY (parent_id) REFERENCES >> parent_table (id) >> ON UPDATE CASCADE ON DELETE SET NULL; >> >> Both child_table and parent_table are large, and the new column >> (parent_id) is empty initially. >> >> Does adding the foreign key have any measurable performance impact in >> this case? Additionally, would it make sense to temporarily disable >> FOREIGN_KEY_CHECKS for this ALTER TABLE operation and then re-enable >> it? Could this save any resources or improve performance? >> >> Thanks for any insights! >> >> Best regards, >> Guillermo. >> _______________________________________________ >> discuss mailing list -- discuss(a)lists.mariadb.org >> To unsubscribe send an email to discuss-leave(a)lists.mariadb.org [View Less]

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