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Fundamentals of table expressions, Part 7 – CTEs, optimization considerations

SQL Performance

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.

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Use Physical Backups With MySQL InnoDB Redo Log Archiving

Percona

This issue most often occurs when there is significant MySQL server activity during the backup operation, and the redo log file storage media operates faster than the backup storage media. Enabling redo log archiving on the server requires setting a value for the innodb_redo_log_archive_dirs system variable. Press ^C to stop.

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The DBCC_OBJECT_METADATA Latch

SQL Performance

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.

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MongoDB Rollback: How to Minimize Data Loss

Scalegrid

Recovering from a MongoDB rollback involves locating rollback files, using mongorestore to load data into a separate server, cleansing unneeded data, and importing the data back into the primary cluster, coupled with ongoing monitoring and maintenance of replica sets to maintain system health.

Database 130
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Fundamentals of table expressions, Part 7 – CTEs, optimization considerations

SQL Performance

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.

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"0 to 60" : Switching to indirect checkpoints

SQL Performance

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.

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How To Use systemd in Linux to Configure and Manage Multiple MySQL Instances

Percona

Why do you need multiple instances on the same server? You can have a host with two or three instances configured as a delayed replica of the source server with SQL Delay of, let’s say, 24hr, 12hr, and 6/3hrs. You can run multiple instances on a server to test your backups with the correct version and configs.