Percona

AUGUST 30, 2023

This can be changed later using the pg_checksums utility, but that will be a painful exercise on a big database. The most common parameter used by the PostgreSQL server (postmaster) will be PGDATA, which sets the parameter data_directory. But changing this is possible only at the server startup. 20150623 (Red Hat 4.8.5-44),

Database 105

Database Servers Open Source Tuning 105

Percona

JULY 5, 2023

Long database service downtime Some queries become slow Applications stop working due to incompatibilities Data loss This is what can happen if MySQL’s major upgrade to 8.0 You cannot load a dump of the MySQL system database from MySQL 8.0 Checking server version. EOL is set for the end of October 2023. and restore to 5.7

C++ 119

C++ Database Servers Testing 119

SQL Performance

AUGUST 12, 2020

In my examples I’ll use a sample database called TSQLV5. So it could be that the term originated in one of the database products and later adopted by some of the other database vendors. So it could be that the term originated in one of the database products and later adopted by some of the other database vendors.

C++ 140

C++ Code Design Database 140

Percona

OCTOBER 17, 2023

When multiple operations, such as reads and writes, attempt to access the database concurrently, WiredTiger uses tickets to ensure these operations do not conflict in a way that would compromise data integrity or performance. The dynamic allocation might have flaws, but it’s definitely a good addition.

Metrics 104

Metrics C++ Storage Database 104

SQL Performance

JULY 27, 2021

Continuing my series of articles on latches, this time I’m going to discuss the DBCC_OBJECT_METADATA latch and show how it can be a major bottleneck for consistency checks prior to SQL Server 2016 under certain circumstances. But remember, this bottleneck only happens for versions of SQL Server earlier than SQL Server 2016.

C++ 54

C++ Servers Database Code 54

SQL Performance

DECEMBER 9, 2020

You can create supporting tables in the user database if needed. Requirements: Implement your solution as an inline table-valued function (iTVF) named dbo.GetNumsYourName with parameters @low AS BIGINT and @high AS BIGINT. As an example, see the ones I submit at the end of this article. You can add hints as needed.

C++ 114

C++ Servers Testing Processing 114

SQL Performance

JUNE 10, 2020

The relational model and the standard querying language that is based on it are supposed to deal only with the conceptual aspects of the data and leave the physical implementation details like storage, optimization, access and processing of the data to the database platform (the implementation ).

C++ 109

C++ Database Servers Code 109

SQL Performance

MAY 11, 2022

Naturally, if a partitioning or ordering element doesn’t appear in the window function, you omit that part from the index definition. In my examples, I’ll use the sample database PerformanceV5. You can download the source code to create and populate this database here. Environment for Demos. Figure 3: Plan for Query 3.

C++ 133

C++ Database Servers Code 133

HammerDB

FEBRUARY 25, 2021

HammerDB is a load testing and benchmarking application for relational databases. All the databases that HammerDB tests implement a form of MVCC (multi-version concurrency control). On high-performance multi-core systems all the supported databases can return performance in the many millions of transactions per minute.

Programming 67

Programming Benchmarking Virtualization C++ 67

SQL Performance

JUNE 10, 2020

The relational model and the standard querying language that is based on it are supposed to deal only with the conceptual aspects of the data and leave the physical implementation details like storage, optimization, access and processing of the data to the database platform (the implementation ).

C++ 93

C++ Database Servers Code 93

SQL Performance

JULY 13, 2022

This could also happen if you need to migrate code written for another database platform with a different dialect of SQL to T-SQL. L0 AS ( SELECT 1 AS c. Sometimes, you need to solve a T-SQL querying task, and you know the natural tool to solve it is a feature that’s part of the SQL standard but isn’t available in T-SQL.

C++ 112

C++ Code Azure Database 112

SQL Performance

JANUARY 13, 2021

L0 AS ( SELECT 1 AS c. Here’s the function’s definition: CREATE OR ALTER FUNCTION dbo. L0 AS ( SELECT 1 AS c. For this reason, compile times should definitely be taken into account—especially when using the function very frequently with small ranges. This process can have both negative and positive implications.

C++ 113

C++ Code Testing Processing 113

SQL Performance

MAY 13, 2020

In my examples I'll use a sample database called TSQLV5. Here's the standard's definition for derived tables in the general sense: 4.15.3 There are three main parts to identify in a statement involving a derived table definition: The table expression (the inner query). C is what's known as a range variable.

C++ 143

C++ Code Design Servers 143

SQL Performance

MAY 12, 2021

I’ll do my testing in a database called testdb. Use the following code to create the database if it doesn’t exist, and to enable I/O and time statistics: -- DB and stats. IF DB_ID ( 'testdb' ) IS NULL CREATE DATABASE testdb ; GO. And here’s the code with the function’s definition: CREATE OR ALTER FUNCTION dbo.

C++ 111

C++ Servers Database Code 111

Percona

DECEMBER 14, 2022

In the database world there are essentially two types of database operations: Online Transaction Processing , OLTP : Online transaction processing applications have high throughput and are insert- or update-intensive in database management. And if the query processes 100 million rows, that’s definitely not trivial!

Database 93

Database Analytics Storage Processing 93

SQL Performance

APRIL 8, 2020

As Grant repeatedly points out, many who use common table expressions in T-SQL think that SQL Server persists the inner query result set, and that the reason for this belief is the use of the term table in the construct's name. When I read C. In my examples I'll use a sample database called TSQLV5. My expertise is T-SQL.

C++ 143

C++ Azure Database Servers 143

SQL Performance

APRIL 13, 2022

It’s based on a question from a public database forum. Note the definition of the primary key constraint based on the composite key (grp, ord), which results in a clustered index based on the same key. L0 AS ( SELECT 1 AS c. My test machine has four logical CPUs, running SQL Server ® 2019 Enterprise.

C++ 136

C++ Strategy Testing Servers 136

SQL Performance

MARCH 11, 2020

SQL Server handles NULLs just like non-NULL values for the purpose of enforcing a unique constraint. The standard unique constraint definition is a bit different than the T-SQL version. Suppose that you have a database in a platform that supports the standard unique constraint and you need to migrate that database to SQL Server.

C++ 135

C++ Code Servers Database 135

SQL Performance

DECEMBER 9, 2020

You can create supporting tables in the user database if needed. Requirements: Implement your solution as an inline table-valued function (iTVF) named dbo.GetNumsYourName with parameters @low AS BIGINT and @high AS BIGINT. As an example, see the ones I submit at the end of this article. You can add hints as needed.

C++ 61

C++ Servers Testing Processing 61

SQL Performance

NOVEMBER 11, 2020

In my examples I’ll continue using the sample database TSQLV5. WITH C AS ( SELECT SYSDATETIME ( ) AS dt ) SELECT @i += 1 FROM C WHERE dt = dt ; PRINT @i ; GO. -- Batch 3. Consider the following code as an example: USE TSQLV5 ; WITH C AS. ( FROM C AS C1 INNER JOIN C AS C2 ON C1.

C++ 122

C++ Code Storage Processing 122

Percona

MARCH 7, 2019

The server is a small instance: Models | 6xIntel(R) Xeon(R) CPU E5-2430 0 @ 2.20GHz 10GB RAM This symptom can be caused by various different reasons. There could be more, but this particular query was definitely hurting the performance of the server. We needed to reduce the high CPU usage on MySQL. Increase QPS by 2x.

C++ 101

C++ Traffic Servers Monitoring 101

SQL Performance

NOVEMBER 13, 2019

Never mind the likelihood for this to happen in practice in SQL Server; if I run the query again, theoretically, the row with id 2 could be assigned with row number 3 and the row with id 11 could be assigned with row number 2. Here's the definition of the POC that supports our query: CREATE INDEX idx_grp_data_i_id ON dbo.

Servers 104

Servers C++ Storage Performance 104

SQL Performance

MAY 8, 2019

GetNums ( 1 , 100 ) AS C WHERE C. If you haven’t figured it out yet, look closely at the definitions of both tables—specifically the column names—and at the column names used in the query. Since the reference to custid in the inner query is unqualified, SQL Server has to resolve which table the column is coming from.

Best Practices 68

Best Practices C++ Code Servers 68

SQL Performance

SEPTEMBER 2, 2021

A lot of things change over the course of a few major versions of our favorite database platform. SQL Server 2016 brought us STRING_SPLIT , a native function that eliminates the need for many of the custom solutions we’ve needed before. STRING_SPLIT() in SQL Server 2016 : Follow-Up #1. It’s fast, too, but it’s not perfect.

C++ 59

C++ Servers Testing Database 59

Testsigma

FEBRUARY 3, 2021

This includes- database, memory, CPU usage etc. During the manual review, we can take help of the IDE’s, or manually check the API and database calls. Dynamic analysis : The applications are executed in real-time and tested for weak spots like authentication/authorisation issues, server issues, data transfer breaches.

Mobile 82

Mobile Testing Hardware C++ 82

ScaleOut Software

JULY 14, 2021

The Microsoft Azure IoT ecosystem offers a rich set of capabilities for processing IoT telemetry, from its arrival in the cloud through its storage in databases and data lakes. It shows how real-time digital twins are distributed across multiple virtual servers organized into an in-memory computing cluster connected to Azure IoT Hub.

IoT 52

IoT Azure Analytics Serverless 52

SQL Performance

APRIL 10, 2019

I posted a suggestion to improve SQL Server by adding support for RPR in T-SQL , but I was quite limited in the space that I had to provide the feedback. price ) AS bottomprice , LAST ( C. LAST ( C. price ) , C AS C. price > PREV ( C. tradedate AS startdate , A.

C++ 73

C++ Servers Virtualization Code 73

SQL Performance

DECEMBER 11, 2019

Even among people who do have a good grasp of relational theory and SQL, you will hear very strong opinions both in favor and against using NULLs in your database. In my examples I'll use a sample database called TSQLV5. You can find the script that creates and populates this database here , and its ER diagram here.

Best Practices 117

Best Practices C++ Database Code 117

SQL Performance

JANUARY 8, 2020

I'll continue using the sample database TSQLV5 like last month in some of my examples. You can find the script that creates and populates this database here , and its ER diagram here. A much more elegant option is to use the CONCAT_WS function, which was introduced in SQL Server 2017. 3 C NULL 4 D 150.00 2 B 200.00

Design 65

Design C++ Code Database 65

SQL Performance

SEPTEMBER 25, 2020

This is because, except for the raw text stored in the object’s definition, the information is not anywhere in the catalog views. However, the problem still exists in SQL Server 2019. a AS /* comment here because -- chaos */ int = 5 , @b AS varchar ( 64 ) = 'AS = /* BEGIN @a, int = 7 */ ' 'blat' '' , @c AS int = -- 12.

Code 42

Code C++ Database Servers 42

Smashing Magazine

JANUARY 6, 2020

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? It used to provide an insight into how quickly the server outputs any data. What does it mean?

Performance 145

Performance Cache Network Metrics 145

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

Brendan Gregg

FEBRUARY 9, 2018

Plotting the percent performance loss vs syscall rate per CPU, for my microbenchmark: Applications that have high syscall rates include proxies, databases, and others that do lots of tiny I/O. It definitely works on 4.14, if you can run that, with CPUs that support pcid (check /proc/cpuinfo). Hit Ctrl-C to end.

Performance 75

Performance Benchmarking Cache Tuning 75

Brendan Gregg

FEBRUARY 8, 2018

Plotting the percent performance loss vs syscall rate per CPU, for my microbenchmark: Applications that have high syscall rates include proxies, databases, and others that do lots of tiny I/O. It definitely works on 4.14, if you can run that, with CPUs that support pcid (check /proc/cpuinfo). Hit Ctrl-C to end.

Performance 40

Performance Benchmarking Cache Tuning 40

Smashing Magazine

NOVEMBER 30, 2021

Adding A Dyslexia-Friendly Mode To A Website written by John C Barstow. And so we can definitely dig into that in a bunch of different angles, depending on where you want to take this conversation. It’s shifting all that computation onto the server to build time or pre deferred time and not on page request time. Transcript.

Technology 94

Technology Technology Servers Code 94

High Scalability

NOVEMBER 25, 2019

Application Servers. Apache FTP server. Native desktop and server hosted clients that allow both interactive as well as hybrid sync access to the entire namespace. Tens of petabytes of data stored in our servers and other object stores such as GCS, S3 and Azure Blobstore. Level of concurrent writes. Cloud Platform.

Architecture 52

Architecture Cache Azure Storage 52