Comments for Percona Database Performance Blog

Comment on Redis, Valkey, and Percona’s Ongoing Support of Open Source by Mark Tomandl

Mark Tomandl — Mon, 06 May 2024 19:02:20 +0000

I am very glad to hear that you guys are getting involved with OSS Redis/Valkey! We’re in the middle of rethinking our memcached infrastructure and Redis was obviously on the list of possible replacements. I’ll be looking at Valkey now.

Comment on PostgreSQL Sharding: An Overview and MongoDB Comparison by Aurélien LEQUOY

Aurélien LEQUOY — Mon, 29 Apr 2024 13:23:33 +0000

It’s look like spider of MAriaDB =)

Comment on When Manipulating MySQL User Tables Goes Wrong: Troubleshooting ERROR 1396 by newmysqluser

newmysqluser — Thu, 25 Apr 2024 15:21:40 +0000

i got same error in mysql 8.0 after I run ALTER root@localhost, i saw error: Error 'Operation ALTER USER failed for 'root'@'localhost'' on query. Default database: 'mysql'. Query: 'ALTER USER 'root'@'localhost' IDENTIFIED WITH 'mysql_native_password' AS is anyway can fix this issue?

Comment on WAL Compression in PostgreSQL and Recent Improvements in Version 15 by Jobin Augustine

Jobin Augustine — Thu, 25 Apr 2024 05:10:00 +0000

In reply to cjah. Thank you for your input

Comment on Bringing Percona Experts to a City Near You by David Quilty

David Quilty — Wed, 24 Apr 2024 19:47:37 +0000

In reply to Mark Tomandl. Hi Mark, thanks for the shoutout! However, for these events, there are no workshops.

Comment on Bringing Percona Experts to a City Near You by David Quilty

David Quilty — Wed, 24 Apr 2024 19:46:28 +0000

In reply to john. The general agenda for each location is on their individual location page (you can click through), and more customized agendas will be available as we get a little closer to each event. These events are more designed for attendees to be fairly local vs. having to travel.

Comment on Bringing Percona Experts to a City Near You by Mark Tomandl

Mark Tomandl — Wed, 24 Apr 2024 17:56:36 +0000

The best part of the conferences in the past were the workshops, are there any workshops in these mini-conferences?

Comment on Bringing Percona Experts to a City Near You by john

john — Wed, 24 Apr 2024 13:27:07 +0000

how about a detailed agenda to help determine if it’s worth traveling to see this. Key word is “detailed”

Comment on WAL Compression in PostgreSQL and Recent Improvements in Version 15 by cjah

cjah — Tue, 23 Apr 2024 11:09:16 +0000

Command:
/usr/pgsql-15/bin/pg_config | grep “zstd|lz4”

Command grep in article is wrong one, it should be:
/usr/pgsql-15/bin/pg_config | egrep “zstd|lz4”
or
/usr/pgsql-15/bin/pg_config | grep -E “zstd|lz4”

Comment on Why SELECT COUNT(*) FROM TABLE Is Sometimes Very Slow in MySQL or MariaDB by Jean-François Gagné

Jean-François Gagné — Thu, 18 Apr 2024 21:30:46 +0000

Nice finding Przemysław. About MVCC, I think the variations are caused by a combination of the plan chosen by the optimizer (you imply this by mentioning Bug #80580 and WL #10398)) and the way InnoDB implements MVCC on secondary indexes (you do not mention this at all). I am giving more info about InnoDB MVCC and secondary indexes below. My recollection is vague on the subject, not much time to find references, but from what I understood (probably from reading content fromn Mark Callaghan or Marko Mäkelä), secondary indexes do not contain "row level MVCC information", only "page level MVCC information". So when this page-level information tells InnoDB that something is "outdated" in the secondary index, a clustered-index lookup is needed to get the "good" version of the row. It looks like the slow-log entry showing a slower query matches this as the number of "Pages_accessed" matches the number of Rows_examined (11.510.893 and 10.000.000). So with DELETE, if the optimizer uses the clustered-index, things will be fast (might scan more data), but if using a secondary index, the best case is better (scanning less data) and the worse case is much worse (needing a PK lookup for each row). I actually found a reference to this in Marko's talk at the MariaDB 2023 (Un)Conference: How InnoDB Undo Logs and the Purge of History Work (goto 5:38 in YouTube video).

Comment on How Patroni Addresses the Problem of the Logical Replication Slot Failover in a PostgreSQL Cluster by Shaan

Shaan — Mon, 15 Apr 2024 15:32:07 +0000

In reply to Jobin Augustine. below comment can be ignored and removed.

Comment on Using MySQL 8 Dual Passwords by john

john — Mon, 15 Apr 2024 13:07:13 +0000

Does proxysql support this?

Comment on How to Replicate and Rename a Database in MariaDB by Georgi Sotirov

Georgi Sotirov — Mon, 15 Apr 2024 09:15:23 +0000

The problem with replicate_do_db is understandable, because rewrite-db filter is applied before any other replication filters.

Comment on How Patroni Addresses the Problem of the Logical Replication Slot Failover in a PostgreSQL Cluster by Shaan

Shaan — Fri, 12 Apr 2024 16:43:36 +0000

Comment on MongoDB Log and the Message “RSM Not Processing Response” by Igor Solodovnikov

Igor Solodovnikov — Wed, 03 Apr 2024 19:23:21 +0000

Great explanation!
BTW sometimes it is very handy to know that 7-digit message identifier refers to the ticket in MongoDB’s jira which introduced this message into the codebase. For example in this case 4495400 refers to SERVER-44954. Moreover, from the comments on that ticket you can quickly lookup the link to the commit on github: https://github.com/mongodb/mongo/commit/e5b78551eb666c3ae61691acfe8e9ea1c6b33651

Comment on Best Practices for Database Security by Fazal Majid

Fazal Majid — Mon, 25 Mar 2024 18:48:58 +0000

One of the best ways to enhance security in PostgreSQL is to remove table SELECT access from the clients and force them instead to access using SECURITY DEFINER stored procedures. For instance if your webapp uses a client login table, have a procedure to authenticate. That way, even if your webapp is compromised, it would be unable to enumerate the users or extract the password hashes for cracking.

Comment on Help Us Improve MySQL Usability and Double Win! by Bartek Gatz

Bartek Gatz — Wed, 20 Mar 2024 17:30:24 +0000

Hi.

Thank you to everyone who participated in the survey. I will be sharing the results and contacting some of the participants shortly.

Warm regards,
Bartek.

Comment on Analyzing Slow Queries After MongoDB 4.4 by Peter Colclough

Peter Colclough — Thu, 14 Mar 2024 15:52:35 +0000

Alternatively you can install. Elasticsearch and pipe all that formatted how you want ontobelsdtic with logstash , snd graph it with insane. Been doing that for k dr 20 years since v1 of mongodb. Solved sll the issues you had…plus can store all the wueries..think the most I had was around 2nm )yes billion) on elastic..so you get the full story. Not missing any queries means you don’t lose hhe first one get caused an issue, because it’s malformed.

gor h the ose with DTafog..you can use that as well…or instead of,

Comment on MySQL General Tablespaces: A Powerful Storage Option for Your Data by Mike

Mike — Wed, 06 Mar 2024 03:57:18 +0000

I have moved a deployment to general tablespaces per schema, where there is a db-per-client pattern, resulting in lots of disk space savings and much faster xtrabackup.

Watch out for upstream bug 111709

Comment on PostgreSQL Column Alignment and Padding – How To Improve Performance With Smarter Table Design by Rishabh

Rishabh — Fri, 01 Mar 2024 07:04:01 +0000

"We are not considering variable-length data types here because they are not as straightforward" - Please write an article on this. Also does the same concept apply to MySQL (InnoDB)?