Microsoft Sql Server Transaction Log Truncate Meaning

AvatarHandler.ashx?radfile=%5CUsers%5C4%5Cshrink%20log%5F01%2Epng' alt='Microsoft Sql Server Transaction Log Truncate Meaning' title='Microsoft Sql Server Transaction Log Truncate Meaning' />Dynamic Data Masking is a new security feature introduced in SQL Server 2016 that limits the access of unauthorized users to sensitive data at the database layer. As. When a new TSQL feature is introduced in SQL Server, it usually takes some time before users realize certain aspects of working with the feature. In time, people. This topic covers the main Oracle SQL Developer concepts, and explains how to use the major SQL Developer features. Edgewood Solutions is a technology company focused on Microsoft SQL Server and founder of MSSQLTips. View all my tips. Microsoft Sql Server Transaction Log Truncate Meaning' title='Microsoft Sql Server Transaction Log Truncate Meaning' />SQL Server Mirroring A Practical Approach. In this post Ill take a practical approach at talking about what SQL Server Mirroring is, the advantages and considerations that follows. Availability, not scalability. SQL Server Mirroring aims to increase database availability, not scalability. Boiled down, a mirrored database consists of a principal database on SQL Server instance X and an exact mirror of that database on instance Y. Everytime a transaction has occured on X, it is executed on Y as well. While this is happening, the Y instance database is in recovery mode, meaning you cannot query it directly, and thus you cannot use this as a secondary readonly database to achieve scalability. While you can run mirroring on different SQL Server instances on the same machine, this defeats the purpose as most errors will be hardwaresystem based, and usually these will affect all instances on the same phyiscal server. Trying out mirroring across instances is a good way to test it out however. In my demos I will be using virtual PCs, each loaded with SQL Server 2. Enterprise sp. 1. Operating modes. SQL Server supports three different operating modes. High performance asynchronousAs the name implies, maintaining high performance is the key issue in this mode. Whenever a transaction is completed on the principal, the log is sent to the mirror, but the principal does not wait for this to complete. Thus if the mirror were to die out, throw an error during execution, the databases would become out of synch. The mirror could also trail behind due to a difference in computing power or other external factors. Microsoft SQL Server Version. Download links and complete information for all Microsoft SQL Server versions and builds. Headers Frequently used terms and acronyms. Does anyone have a good way of implementing something like a sequence in SQL server Sometimes you just dont want to use a GUID, besides the fact that they are ugly. Using the Teradata JDBC Driver. This chapter describes using the Teradata JDBC Driver software in Java programs, and guides you through the process of getting. As SQL Server database development is a good candidate for code documentation, this development workflow applies and this article will focus on following steps. If the principal fails, you will have to do a manual failover to the mirror. High safety synchronous also known as high protectionAs with the high performance mode, each time a transaction occurs on the principal, it is sent to the mirror. The principal will not commit the transaction until the mirror has committed the transaction also. Thus you will never risk your databases being out of synch. The downside is that your mirrored setup will be no faster than the slowest machine that is part of the mirror, plus the implicit overhead in server chatting. As with the high performance mode, you will have to make a manual failover in case of principal failure. High safety with automatic failover synchronousThis mode involves a third instance besides the principal and mirror, known as the witness. The witness instance constantly monitors the principal for availability, and if a problem is detected, it will automatically perform a failover. At this point, the database as a whole will still be available, but you should manually get the failed mirror up and running again and reinitiate mirroring. Prerequisites. There are a couple of things that should be in place before attempting to setup database mirroring. Service pack 1. Make sure all instances have been upgraded to service pack 1. If you do not have service pack 1, you will receive the following warning when trying to start the mirror Unified SQL Server service account. If youre using Active Directory, make sure the SQL Server service accounts are running as the same user. Local System will not work as it does not have any network credentials. If youre not using Active Directory, just make sure the services are running on an account with the same name password on each machine. Make sure you change the service account through the SQL Server Configuration application and not the services console. Alternatively you can specify user accounts that should be used for mirror replication, but having the servers run on the same domain account is the easiest way. Full recovery model. Make sure the database you want to mirror is setup to use the full recovery backup model, otherwise therell be no log to ship to the mirror instance and mirroring will not be possible. Licensing. Mirroring is supported in the SQL Server Standard and Enterprise editions. Neither Express nor Workgroup edition will work. Enterprise supports the high performance operating mode, Standard only supports the two high safety modes. You can use the free Express version for the mirror server. Note that you do NOT need an extra SQL Server license for the mirroring server, provided that it does nothing else but maintain the mirrored database take note of the 3. Test setup. My demos will be using three servers, all running Windows Server 2. Standard fully updated through Virtual PC. All three have SQL Server 2. Enterprise installed. I will be using the Microsoft sample database Adventureworks. You can download the Adventure. Works database at Code. Plex. The three servers are RIO, MANDALAY and MGM yes, I like Vegas. MGM will only be used for setting up a witness, RIO and MANDALAY will both host the actual databases, MANDALAY being the initial principal and RIO being the initial mirror. All servers are completely fresh installations using SQL Server authentication. I will be connecting to the instances from SQL Server Management Studio running on my desktop computer. Initial setup of the databases. The first step is to restore the Adventure. Works. bak backup file to both servers. On the principal MANDALAY we should make a normal restore RESTORE WITH RECOVERY so the database is online. On the mirror RIO, we should restore into the recovering state so no changes can be made RESTORE WITH NORECOVERY. You can watch how its done here, or skip on to the next section. Mirroring configuration. Now that weve got both databases setup, were ready to setup the actual mirror. A couple of notes on what Im doing during the setup. In the first demo, Ill setup a synchronous high safety mirror with a witness. As all the virtual PCs are running on the same machine, Ill have to use different ports for the endpoints. Whether you want to use encryption for the endpoint communication is scenario specific. Encryption will have an overhead albeit a minor one so its up to you to determine if its neccessary. As our SQL Services are running on the same account across the machines, we do not have to specify any custom service account names during the setup. For some reason, SQL Server needs a fully qualified domain name for the instance addresses. If youre setting this up on a computer that is part of the domain, you should simply use the domain name, Computer. In this example my desktop is not part of the Active Directory domain and thus itll use addresses like TCP COMPUTER PORT which is not accepted. Ill fix it by simply writing the machine IP addresses manually instead. The IP for MANDALAY is 1. RIO its 1. 92. 1. Note that you should ALWAYS use FQDNs, using IPs are not recommended as it may result in configuration as well as runtime issues. See Adam Machanics blogpost on the same issue as I ran into a couple of times. Testing the mirror. Besides my DBA excesses, Im a developer. And whats more natural than to whip together a small application that tests the mirrors availabilityIt continuously attempts to connect to the databases using three different connection strings string principal. Lagu Guitar Hero Extreme Vol 2 Bird. Connection Data SourceMandalay Connect Timeout1 Initial CatalogAdventure. Works User Idsa Passwordsadpassword Poolingfalse. Connection Data SourceRio Connect Timeout1 Initial CatalogAdventure. Firmware Modem Dlink Dsl 500B. Works User Idsa Passwordsadpassword Poolingfalse. Connection Data SourceMandalay Failover PartnerRio Connect Timeout1 Initial CatalogAdventure.