Author Archive

Upgrading to MySQL 8? Think of the default authentication plugin

As explained in a post at the default authentication plugin has been changed from mysql_native_password to caching_sha2_password. And that would certainly break all PHP-based applications because at the time of writing PHP doesn’t support caching_sha2_password. Please, keep an eye on the related request #76243. Once it’s implemented it would be possible to switch to […]

Posted on May 15, 2018 at 10:15 am by sergeyt · Permalink · Leave a comment

“WT_CONNECTION.open_session: only configured to support 20020”

Frankly speaking, the explanation provided in SERVER-30421 and SERVER-17364 is a bit vague and “hand wavy” to me but at least there are steps that could help mitigate it: Decrease idle cursor timeout (default value is 10 minutes): In mongodb.conf: setParameter: cursorTimeoutMillis: 30000 Using mongo cli: use admin db.runCommand({setParameter:1, cursorTimeoutMillis: 30000}) Increase session_max: storage: wiredTiger: […]

Posted on February 22, 2018 at 9:26 am by sergeyt · Permalink · Leave a comment
In: MongoDB

Changing Oplog size or when root role is not enough

Managing MongoDB sometimes involves increasing Oplog size sine the default setting (5% of free disk space if running wiredTiger on a 64-bit platform) is not enough. And if you’re running MongoDB older than 3.6 that requires some manual intervention described in the documentation. It’s pretty straightforward even if it requires a node downtime as part […]

Posted on February 2, 2018 at 9:34 am by sergeyt · Permalink · Leave a comment
In: MongoDB

Yandex internal CTF 2017

This year CTF at Yandex brought not only the excitement and sleepless nights but a bunch of awesome swag.

Posted on December 6, 2017 at 7:40 pm by sergeyt · Permalink · Leave a comment
In: Life, Linux, Security

No video during the flight

Don’t know what version of Linux they were running but looks like one of the following code paths triggered the issue: static int pca953x_read_regs(struct pca953x_chip *chip, int reg, u8 *val) { int ret; ret = chip->read_regs(chip, reg, val); if (ret < 0) { dev_err(&chip->client->dev, “failed reading register\n”); return ret; } return 0; } static int […]

Posted on November 13, 2017 at 10:09 am by sergeyt · Permalink · Leave a comment
In: Life, Linux

Things to keep in mind about HTTP/2

This talk is just unbelievably helpful.

Posted on September 21, 2017 at 9:52 am by sergeyt · Permalink · Leave a comment
In: Uncategorized

MongoDB 3.4 or stay on 3.2?

If you’re herding multiple shards this one should be convincing enough to jump on 3.4 bandwagon: mongos> sh.getBalancerHost() getBalancerHost is deprecated starting version 3.4. The balancer is running on the config server primary host.

Posted on September 11, 2017 at 12:39 pm by sergeyt · Permalink · Leave a comment
In: MongoDB

Moving to OmniOS Community Edition

Had a small snag when I tried to upgrade my old (r151018) OmniOS installation to OmniOS CE as described in the ANNOUNCEMENT OmniOS Community Edition – OmniOSce r151022h During “pkg update” stage I got something similar to the following: pkg update: The certificate which issued this certificate:/C=US/ST=Maryland/O=OmniTI/OU=OmniOS/CN=OmniOS r151018 Release Signing Certificate/emailAddress=omnios-supp… could not be found. […]

Posted on August 14, 2017 at 11:22 am by sergeyt · Permalink · Leave a comment
In: Solaris

How to reuse dropped sharded collection’s name

It happens that sometimes you want to drop your sharded collection and be able to reuse its name again. However, it might not be as straightforward as one expects it to be: mongos>sh.shardColelction(“your_database.your_collection”, { “sharded_key”: 1}) “code” : 13449, “ok” : 0, “errmsg” : “exception: collection your_database.your_collection already sharded” The error message might be different […]

Posted on July 19, 2017 at 12:35 pm by sergeyt · Permalink · Leave a comment
In: MongoDB

TIL MongoDB Index Build could exceed 100%

A quote from SERVER-7631: Since data can be inserted while its running, this can go over 100 by design.

Posted on July 4, 2017 at 2:23 pm by sergeyt · Permalink · Leave a comment
In: MongoDB