Tag Archives: query

新的 DNS Resolver:9.9.9.9

看到新的 DNS Resolver 服務,也拿到了還不錯的 IP address,9.9.9.9:「New “Quad9” DNS service blocks malicious domains for everyone」,服務網站是「Quad 9 | Internet Security and Privacy in a Few Easy Steps」,主打宣稱過濾已知的危險站台... 由政府單位、IBM 以及 Packet Clearing House 成立的: The Global Cyber Alliance (GCA)—an organization founded by law … Continue reading

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Amazon Aurora (MySQL) 推出的 Asynchronous Key Prefetch

Amazon Aurora (MySQL) 推出新的效能改善,可以改善 JOIN 時的效能:「Amazon Aurora (MySQL) Speeds Join Queries by More than 10x with Asynchronous Key Prefetch」。 看起來像是某個情況的 optimization,將可能的 random access 換成 sequential access 而得到大量的效能: This feature applies to queries that require use of the Batched Key Access … Continue reading

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Route 53 的 Query 記錄

Amazon Route 53 可以收 query log 了,會丟到 CloudWatch Logs:「Amazon Route 53 Announces Support For DNS Query Logging」。 If you are using Amazon Route 53 as your public, authoritative DNS, you will now have the capability to easily log DNS queries … Continue reading

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MySQL 總算要拔掉 mysql_query_cache 了

半官方的 MySQL blog 上宣佈了拔掉 mysql_query_cache 的計畫:「MySQL 8.0: Retiring Support for the Query Cache」。 作者開頭引用了 ProxySQL 的人對 MySQL Query Cache 的說明: Although MySQL Query Cache was meant to improve performance, it has serious scalability issues and it can easily become a … Continue reading

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透過 DNS TXT 傳遞指令的惡意程式

看到「New Fileless Malware Uses DNS Queries To Receive PowerShell Commands」這篇,所以是有人開始這樣惡搞了... Distributed through an email phishing campaign, the DNSMessenger attack is completely Fileless, as it does not involve writing files to the targeted system; instead, it uses DNS TXT messaging capabilities … Continue reading

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Swap 對 InnoDB 的影響

Percona 的老大拿 5.7 版做實驗,確認 swap 對 InnoDB 的影響:「The Impact of Swapping on MySQL Performance」。 測試的機器是 32GB RAM,作業系統 (以及 swap) 裝在已經有點年紀的 Intel 520 SSD 上,而 MySQL 則是裝在 Intel 750 NVMe 上。透過對 innodb_buffer_pool 的調整來看情況。 可以看到設為 24GB (記憶體 75% 的量) 時很穩定的在 44K QPS … Continue reading

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Amazon Aurora 支援 Auditing

AWS 的人把 auditing plugin 移植到 Amazon Aurora 的 MySQL 環境上了:「Auditing an Amazon Aurora Cluster」。 官方宣稱的效能很好,打開後不會掉太多: 主要原因是把寫 auditing log 這塊改寫掉: 這樣看起來頗不錯,平常其實可以開起來讓他記錄?

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Amazon Athena:直接在 S3 上進行分析

Amazon Athena 提供另外一種選擇,讓分析的便利性增加了許多:「Amazon Athena – Interactive SQL Queries for Data in Amazon S3」。 以往都需要開 server 起來分析,這個新的服務直接使用就好: Athena is based on the Presto distributed SQL engine and can query data in many different formats including JSON, CSV, log files, text with … Continue reading

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關閉 MySQL 的 Query Cache

MySQL 的 Query Cache 是目前已知效能不好的主要因素之一 (global mutex lock 的緣故),在正式環境裡的 best practice 一般都是關閉,之前測過也是一開下去效能就會狂掉... 而 Percona 的人在討論要怎麼樣才能完全關閉 MySQL 的 Query Cache:「Is Your Query Cache Really Disabled?」,而他們發現只有在 query_cache_type 與 query_cache_size 都設為 0,而且重開 MySQL 才能完全避免 global mutex lock: [W]e can see it is not … Continue reading

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Route53 也支援 IPv6 了...

Amazon Route 53 也宣佈支援 IPv6 了:「Amazon Route 53 Now Supports DNS Queries over IPv6 Networks」。 依照說明應該是無痛切換過去: The change is seamless and requires no action from you; your end users and clients can begin making DNS queries over IPv6 immediately. 不過測了 … Continue reading

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