SQL Server trace flags are configuration handles that can be used to enable or disable a specific SQL Server characteristic or to change a specific SQL Server behavior. It is an advanced SQL Server mechanism that allows drilling down into a hidden and advanced SQL Server features to ensure more effective troubleshooting and debugging, advanced monitoring of SQL Server behavior and diagnosing of performance issues, or turning on and off various SQL Server features
The WRITELOG wait type is one of those wait types that can often be seen quite frequently on SQL Server, and that can cause a lot of headaches for DBAs. The WRITELOG wait time represents the time that accumulates while waiting for the content of the transaction log cache to be flushed to the physical disk that stores the transaction log file. To understand better the WTITELOG wait type, there are some basics of SQL Server mechanism for storing the data in the transaction log file is to be explained first
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When maintaining SQL Server, it is essential to get an accurate perception of how busy it is. Two metrics that are often considered as indicators of how busy SQL Server is are Batch Requests/sec and Transaction/sec. When those metrics trend higher, they often affect all other metrics and make them go higher as well. While they could look similar, they are using a different type of starting point for measurement; the batches and transactions. So, to correctly understand those important metrics, lets first try to understand what the batches and transactions in SQL Server are and what are the differences between the two
Read more »SQL Server indexes are essentially copies of the data that already exist in the table, ordered and filtered in different ways to improve the performance of executed queries. Seeks, scans and lookups operators are used to access SQL Server indexes.
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As discussed in the article All about latches in SQL Server, spinlocks are also a special form of locks that SQL Server uses to protect data. Spinlocks are lightweight objects used by the SQL Server Operating System (SQLOS) to protect data structure access. To understand, properly, the difference between latches and spinlocks and why the spinlock is an important SQL Server’ object type, it is vital to understand the cycle of query execution in SQL Server
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SQL Server locks, discussed in the article All about locking in SQL Server, which is applied on data for the duration of the logical operation to preserve logical transaction consistency. SQL Server latches, however, are a special type of low-level system locks which are held as long as the physical operation lasts on the memory page in order to protect memory consistency
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Locking is essential to successful SQL Server transactions processing and it is designed to allow SQL Server to work seamlessly in a multi-user environment. Locking is the way that SQL Server manages transaction concurrency. Essentially, locks are in-memory structures which have owners, types, and the hash of the resource that it should protect. A lock as an in-memory structure is 96 bytes in size.
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Digital certificates are form of electronic authorizations used to verify the identities of persons, companies, computers, and other network entities.
Read more »The ASYNC_NETWORK_IO wait type is one of those wait types that can be seen very often by DBAs, and it can be worrisome when excessive values occur, as it is one of the most difficult wait types to fix.
Read more »One of the most common wait type seen on SQL Server and definitely one that causes a lot of troubles to less experienced database administrators is the PAGEIOLATCH_SH wait type. This is one of those wait types that clearly indicates one thing, but which background and potential causes are much subtler and may lead to erroneous conclusions and worse, incorrect solutions
Read more »The SQL Server CXPACKET wait type is one of the most misinterpreted wait stats. The CXPACKET term came from Class Exchange Packet, and in its essence, this can be described as data rows exchanged among two parallel threads that are the part of a single process. One thread is the “producer thread” and another thread is the “consumer thread”. This wait type is directly related to parallelism and it occurs in SQL Server whenever SQL Server executes a query using the parallel plan.
Read more »The SQL Server SOS_SCHEDULER_YIELD is a fairly common wait type and it could indicate one of two things:
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