Brendan Gregg

SEPTEMBER 5, 2017

Hit Ctrl-C to end. ^C C operation = 'read' usecs : count distribution 0 -> 1 : 0 | | 2 -> 3 : 0 | | 4 -> 7 : 4479 | *| 8 -> 15 : 1028 | | 16 -> 31 : 14 | | 32 -> 63 : 1 | | [.]. Oracle VM Server is based on Xen. Many new tools can now be written, and the main toolkit we're working on is [bcc]. Tracing ZFS operation latency.

Virtualization 76

Virtualization AWS Engineering Hardware 76

SQL Performance

OCTOBER 14, 2020

I explained that when SQL Server optimizes a query involving derived tables, it applies transformation rules to the initial tree of logical operators produced by the parser, possibly shifting things around across what were originally table expression boundaries. Here’s the attempted solution using a CTE: WITH C AS. ( FROM Sales.

C++ 52

C++ Servers Code Efficiency 52

SQL Performance

FEBRUARY 12, 2020

Curiously, SQL Server's query processor already supports an internal comparison operator IS, which uses the same semantics as the desired IS operator I described here. Here's the complete solution code: WITH C AS. ( 10249 2017-07-10 10252 2017-07-11 10250 2017-07-12. Figure 1: Plan for Query 1.

C++ 120

C++ Code Servers Database 120

Percona

JUNE 4, 2023

This blog post was originally published in November 2017 and was updated in June 2023. In this blog, we’ll provide a comparison between MariaDB vs. MySQL (including Percona Server for MySQL ). MariaDB Server, on the other hand, is a fork of MySQL 5.5.

Open Source 52

Open Source Servers Storage Scalability 52

SQL Server According to Bob

FEBRUARY 10, 2019

. · Failures occur from remote clients or sqlcmd executed directory on the server (/opt/mssql-tools/bin). SQL Server 2017 CU10 does not show behavior. · SQL Server 2017 CU12 exhibits the behavior. Server is a Superdome with lots of CPUs and RAM. Here is an example of a valid SQL Server login.

Servers 40

Servers Network Database Systems 40

SQL Performance

SEPTEMBER 5, 2019

I briefly mentioned that batch mode data is normalized in my last article Batch Mode Bitmaps in SQL Server. You will need SQL Server 2016 (or later) and Developer Edition (or equivalent) to reproduce the results shown here. c = COUNT_BIG ( * ) FROM #T AS T WHERE 1 = ( SELECT 1 ) -- Avoid trivial plan.

Performance 81

Performance C++ Storage Servers 81

SQL Performance

DECEMBER 11, 2019

WHERE NOT ( shippeddate = '20190102' ) ; This query returns the following output: orderid shippeddate -- -- 10249 2017-07-10 10252 2017-07-11 10250 2017-07-12. WHERE shippeddate IS NOT NULL ; This query generates the following output: orderid shippeddate -- -- 10249 2017-07-10 10252 2017-07-11 10250 2017-07-12.

Best Practices 117

Best Practices C++ Database Code 117

Brendan Gregg

SEPTEMBER 25, 2021

This server is spending about a third of its CPU cycles just checking the time! As (C) looked like a kernel rebuild, I started with (D) and (E). ## 5. I also rewrote this in C and called gettimeofday(2) directly: $ cat gettimeofdaybench.c. 30.14% in the middle of the flame graph. Try changing the kernel clocksource.

Speed 126

Speed Java AWS Virtualization 126

SQL Performance

MAY 1, 2020

In a recent tip , I described a scenario where a SQL Server 2016 instance seemed to be struggling with checkpoint times. A SQL Server DBA myth a day: (15/30) checkpoint only writes pages from committed transactions. How It Works: When is the FlushCache message added to SQL Server Error Log? group_id = c. ( WHERE. (

C++ 58

C++ Database Servers Storage 58

Percona

JANUARY 17, 2019

I will compare AWS Aurora with MySQL (Percona Server) 5.6 84.1 | | version_comment | Percona Server (GPL), Release 84.1, 84.1 | | version_comment | Percona Server (GPL), Release 84.1, AWS Aurora (based on MySQL 5.6) MySQL on ec2. MySQL on ec2.

Cache 46

Cache C++ AWS Airlines 46

SQL Server According to Bob

JANUARY 28, 2018

Note: SQL Server can be a client using a linked server, allowing SQL Server to become an APP and/or an RM ). The application then uses the SQL Server client (SQL Server ODBC for this example) to establish a TDS based connection to the target SQL Server (local or remote.). Local Host Name. The olehlp!

Servers 40

Servers Azure Engineering Java 40

SQL Server According to Bob

JANUARY 29, 2017

Launch: lldb -c core.sqlservr.8917 FEB 1, 2017 UPDATE – CHANGE ACCEPTED. Bob Dorr – Principal Software Engineer SQL Server. Using the -O command line parameter, when you start LLDB, indicates to LLDB to execute the command before the files are loaded. This lets you log information while loading the core dump.

Servers 40

Servers Programming Media Open Source 40

SQL Performance

MAY 13, 2020

Customers AS C WHERE country = N'USA' ; Also here, the common assumption is that AS C is just a way to rename, or alias, the table Customers for the purposes of this query, starting with the logical query processing step where the name is assigned and onwards. C is what's known as a range variable. Orders AS O ON C.

C++ 143

C++ Code Design Servers 143

SQL Performance

JUNE 14, 2019

However, a typical bug when converting the existing solution to one that applies the join is to leave the computation of the order count as COUNT(*), as shown in the following query (call it Query 1): SELECT C. Customers AS C LEFT OUTER JOIN Sales. Orders AS O ON C. GROUP BY C. ORDER BY C. Orders AS O ON C.

Best Practices 93

Best Practices C++ Database Processing 93

SQL Server According to Bob

FEBRUARY 13, 2020

​​ When the utility attempted to issue the thaw command the command would be queued, and the database could not return to an operational state until SQL Server was restarted. ​​ While the name can be any string it is commonly a Guid accommodating the ​​ uniqueness requirements.

Servers 40

Servers Availability Transportation Database 40

SQL Performance

SEPTEMBER 2, 2021

SQL Server 2016 brought us STRING_SPLIT , a native function that eliminates the need for many of the custom solutions we’ve needed before. I’ve written several articles about this function (and STRING_AGG, which arrived in SQL Server 2017) since this post was written: Performance Surprises and Assumptions : STRING_SPLIT().

C++ 59

C++ Servers Testing Database 59

The Morning Paper

JANUARY 19, 2020

STELLA: report from the SNAFU-catchers workshop on coping with complexity , Woods 2017, Coping with Complexity workshop. Today’s choice is a report from a 2017 workshop convened with that title, and recommended to me by John Allspaw – thank you John! Take a trivial example with three components A, B, and C.

C++ 50

C++ Systems Software Software 50

Brendan Gregg

SEPTEMBER 25, 2021

This server is spending about a third of its CPU cycles just checking the time! As (C) looked like a kernel rebuild, I started with (D) and (E). ## 6. I also rewrote this in C and called gettimeofday(2) directly: $ cat gettimeofdaybench.c 30.14% in the middle of the flame graph. Try changing the kernel clocksource. us on Ubuntu.

Speed 40

Speed Java AWS Virtualization 40

Percona

JANUARY 14, 2019

To simulate text messages I have used ~3 billion of reddit comments (10 years from 2007 to 2017), downloaded from pushshift.io. This is all true for ClickHouse, however, we may be able to live with it for our task. Vadim published a blog post about analyzing reddit comments with ClickHouse. compose','xamarin','markdown','scrum','comic'] ?

Database 40

Database Analytics Blockchain Healthcare 40

Brendan Gregg

AUGUST 8, 2017

TABLE OF EXP(-T/C) FOR T = 5 SEC. EXPFF: EXP 0.920043902 ;C = 1 MIN EXP 0.983471344 ;C = 5 MIN EXP 0.994459811 ;C = 15 MIN. Thankfully, I found some older linux-devel mailing list archives, rescued from server backups, often stored as tarballs of digests. My search was starting to feel cursed. to the load average.

Latency 111

Latency Metrics C++ Systems 111

Smashing Magazine

JANUARY 7, 2019

Is it worth exploring tree-shaking, scope hoisting, code-splitting, and all the fancy loading patterns with intersection observer, server push, clients hints, HTTP/2, service workers and — oh my — edge workers? Long FMP usually indicates JavaScript blocking the main thread, but could be related to back-end/server issues as well.

Performance 103

Performance Cache Metrics Network 103

SQL Performance

JANUARY 8, 2020

A much more elegant option is to use the CONCAT_WS function, which was introduced in SQL Server 2017. ( 1 , 'A' , 100.00 ) , ( 2 , 'B' , 200.00 ) , ( 3 , 'C' , NULL ) ; Notice that contacts 1 and 2 have applicable hourly rates, and contact 3 doesn't, so its hourly rate is set to NULL. 3 C NULL 4 D 150.00

Design 65

Design C++ Code Database 65

Smashing Magazine

JANUARY 21, 2019

An API is the communication channel for an application to load data from the server. This relationship can be expressed through an associative array (an array of key => property) on the server-side, in which each module states its name as the key attribute and its inner modules under the property modules. Large preview ).

Social Media 64

Social Media Database Media Website 64

O'Reilly

MARCH 23, 2023

It’s clear that ChatGPT is not your run-of-the-mill automated chat server. The LLaMA source code has been ported to C++ , and a small version of the model itself (7B) has been leaked to the public, yielding a model that can run on laptops. It can pretend to be an operating system. Or a text adventure game. It’s much more.

Google 104

Google Open Source Programming Code 104