#Data corruption DBCC CHECKDB

[thedbahub]

Ensuring Database Integrity with DBCC CHECKDB in SQL Server

Introduction Maintaining the integrity of your SQL Server databases is crucial for ensuring data reliability and preventing corruption. One of the most powerful tools available for this purpose is DBCC CHECKDB. In this article, we’ll explore what DBCC CHECKDB does, how to use it effectively, and provide practical T-SQL code examples to help you incorporate it into your database maintenance…

[prashantjayaram]

SQL Server Data Management Life Cycle

SQL Server Data Management Life Cycle

This is the second article in the “Backup and Restore (or Recovery) in SQL Server” stairway series (see the full TOC below). This article deals with the different phases of data management life cycle and it encompasses the following topics: Introduction to data corruption Defining data corruption and its causes Discussion on the impact of data corruption Explaining data prevention mechanisms Data…

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Sql Server Error - a Quick Overview

Why Almost Everything You've Learned About Sql Server Error Is Wrong

In case the query touches less data it'll be less inclined to encounter the issue. Problem is going to be resolved after following the above mentioned measures. The issue needs to be resolved. The issue with the error log file is that there's so much data collected it is occasionally tough to figure out where the real errors lie. 

Everything beyond is thought of as an error To have the ability to use an apostrophe in a string, it must be escaped, so that it's not regarded as a string delimiter. Occasionally you will notice an error stating that the database can't be recovered and it's marked suspect. For example, the next error points out that we would have to restore our database or endeavor to rebuild the log. Now it doesn't even wish to me register and throwing the exact same 18452 error. In the event the above mentioned manual solutions to repair the error do not do the job, then it may be that the database may have corrupt. If you come across a severity 22 error, you'll need to run DBCC CHECKDB to figure out the magnitude of the damage. 

Now you're seeing errors on-screen, but in a manufacturing environment, you don't acquire such flexibility. The error can be encountered at the right time of upgrading SQL server to some other version. Accordingly, so as to receive your critical data back, you will need to understand how to fix SQL server error 823. The error that's captured in the SQL Server error log can be a result of different factors. The error 823 can cause severe data loss circumstances. SetWindowText returns success and there's no runtime error, but the text doesn't appear. All the data are kept in a database in the shape of MDF and NDF files. In addition, it is going to continue to keep the data safe means with no loss. The real data is stored in the remaining part of the pages. 

The Chronicles of Sql Server Error

You should inspect the error log daily to make sure that all prospective issues are investigated as speedily as possible. Also by default, the latest error log is named ERRORLOG and it does not have any extension. The very first step to receive it resolve is to look at the SQL Server error log. 

The Argument About Sql Server Error

Make it part of your routine database maintenance. SQL Server service was paused. It is trying to intialize SSL support but it cannot find the requisite information. 

Sql Server Error - What Is It?

Your default database may be missing. When a query is run, SQL attempts to allocate the optimum quantity of memory in order for it to run efficiently. Thus, for optimum compatibility, it's suggested that you use anytime you run queries returning more than 1 result even if the specific driver you're using allows you to do otherwise. System databases are made automatically if we install MS SQL Server. When seeking to log in, the database might not be prepared to accept the connection. The entire database will be impacted. 

The server wasn't found or wasn't accessible. It enables easy storage and retrieval of data from application running on the same computer or other computers residing in the same network. SQLEXPRESS'' folders, you have to install SQL Server. SQL Server deliberately hides the character of the authentication error and provides State 1. It cannot roll committed transactions forward because it has no room on the disk. Begin your SQL Server instance and you may then connect to SQL Server utilizing the SA login.

In MS SQL Server, two forms of databases are readily available. Testdb database is going to be created as shown in the subsequent snapshot. Therefore, backing up database regularly is a great practice that aids in restoring data is true of disaster. The AdventureWorks 2014 sample database is utilized via the report. 

New Questions About Sql Server Error

If you are working to connect using Windows Authentication, verify that you're properly logged into the proper domain. Your login may not be authorized to connect. The login was created. It failed for user is one of the most common error which everyone might have seen at least once. As a consequence the user doesn't have permission to use SQL database. Therefore, users are continuously querying about the reason for the same i.e. exact cause of the SQL Server operating system error 3. So, they will understand the causes and prevent Server from the future disaster. 

You're unlikely ever to should alter the processor affinity defaults if you don't encounter performance issues but it's still worthwhile understanding what they are and the way in which they work. A Unix socket file is used if you don't specify a host name or whenever you Sql Server Error specify the particular host name localhost. Since you can see above that LOG folder consists of many files. The absolute most current error log file is known as ERRORLOG.

[tonkiking]

Snap assist windows table mode

#Snap assist windows table mode how to

You can determine if the database is corrupted or not by running the following DBCC CHECKDB command. Step 4: A suspect database might not be corrupted. NOTE: If you cannot set the database in emergency mode, skip to the next solution. Step 3: In the Query editor window, enter the following code to turn off the suspect flag on the database and set it to EMERGENCY: EXEC sp_resetstatus ‘db_name’ ĪLTER DATABASE db_name SET EMERGENCY Figure 4: Set Database in Emergency Mode Step 1: Open SSMS and connect to the database. If the backup is not available, proceed with the following steps.įollow the steps in sequence given below to recover MS SQL database from suspect mode: NOTE: You can try restoring the database in suspect mode from a good known backup. How to get SQL database out of suspect mode? Database files are being held by the operating system, third-party backup software, etc.SQL cannot complete a rollback or roll forward operation.SQL Server tries to open a database, and the file belonging to that database is already open by anti-virus software installed on your system.SQL server crashes or restarts in the middle of a transaction, resulting in a corrupt or inaccessible transactions log file.System fails to open the device where the data or log file of SQL server resides.When SQL server suspects the primary filegroup of the database to be damaged or if the database file is missing, the database status is set to ‘Suspect’.Īlso, there are a wide range of errors that could result in SQL database in suspect mode. When does SQL database goes to suspect mode? Figure 1: Database in Suspect ModeĬheck out the Infographic below for quick solutions to recover database from suspect mode in SQL Server 2008, and higher versions. In such a situation, you will neither be able to connect to the database nor recover it during server startup. When SQL database goes into suspect mode, it becomes inaccessible.

#Snap assist windows table mode how to

How to get SQL database out of suspect mode?.When does SQL database goes to suspect mode?.

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SQL- Tips to resolve “Table error: Object O_ID… page P_ID was not encountered.” Error

sql-server-recovery-blog1:

The records in Microsoft SQL Server database can be placed and located in the form of a B-tree. These records are divided into various pages (child pages), each having a unique index page, which is one level up in hierarchy from the child page. Corruption in the hierarchical tree structure (metadata structure corruption) primarily results in loosing the reference of the child page from the Index page. In such situations, the data stored in the database becomes inaccessible. For accessing the data stored in the database, an ideal way is to restore it from an updated database backup. But if in case of absence of an valid database backup, you will need to use advanced MS SQL Database Recovery application to repair your database. Consider a practical scenario, where you receive the below error message when you attempt to access the records stored in table: “Table error: Object ID O_ID, index ID I_ID. Parent node for page P_ID was not encountered.” The above error message makes the data stored in table inaccessible. Moreover, the error message repeatedly repeats every time you attempt to access the records stored in the table. Cause: The root cause for the occurrence of the above error message is SQL database corruption due to metadata structure damage. Note: SQL database can be corrupted either due to logical or physical factors. Resolution: To resolve the above error message and to access the table records, you will need to follow the below measures:

To solve all the corruption issues caused due to physical damage, swap the corrupt system component with a new component.

To solve  all the corruption issues caused due to logical damage, run DBCC CHECKDB command with correct repair clause.

The first measure is competent enough to resolve all the physical damage issues. The second measure, however, fails to resolve all logical corruption problems. For such situations, the database table can be repaired by using advanced MS SQL Database Repair software. These SQL Server Recovery utilities employ effective scanning methods to completely repair the corrupt table after all logical database corruption scenarios. Resource: http://ezinearticles.com/?Tips-to-Resolve-table-Error—Object-O_id-Page-P_id-Was-Not-Encountered-Error&id=3451876

Source: sql-server-recovery-blog

[marcosplavsczyk]

Database status overview

Every database in a SQL Server environment has two basic states: full availability (online state) or full unavailability (offline state).

SQL Server incorporates and utilizes seven possible database states, which are present in the grid below, ordered by availability (from fully available to fully unavailable), and with a short explanation for each state:

Database state Description Availability Online Database is functioning normally, and it is available for use. Available Restoring Database is in process of restoration, which means that user initiated the database restoring. Unavailable (without errors, user-induced) Recovering Database is in process of recovering. If succeed, it will change state to online. If process fails, it will change state to suspect. Unavailable (without errors) Recovery pending Recovery process failed in between, but database is not damaged. Further user action is required in order to solve the issue (see in the next paragraph). Unavailable (error occurred) Suspect In this state, there is possibility that database is or was damaged during the recover process. Further user action is required in order to solve the issue. Unavailable (error occurred) Emergency This database state change is user-induced, in order to safely perform maintenance, restore or recovering process on particular database. One note: sysadmin rights are required to manage this database state. Unavailable (without errors, user-induced) Offline Database is not functioning, and is unavailable for use. This state is also user-induced, and it requires further action, in order to change a database state. Unavailable (without errors, user-induced)

Quick reference when transition between database states is interrupted

There are several occasions when a smooth transition between database states could fail. Transitions from restoring, recovering or recovery pending database states to online state can be interrupted by events that stop previously active processes of database back up, restoring or recovery. These events could be disk failures, network connection issues, corrupted database files and other.

In order to solve these database states, perform actions shown below with caution, and with note that causes why interruptions happen can be various (already mentioned issues during the process of database restoration/recover etc.):

If the database is in a permanent restoring state: run this script, to force the recovering process and set database state to online:

RESTORE DATABASE < database_name > WITH RECOVERY

If the database is in a permanent recovering state:

stop SQL Server service;

move the log file for that database (usually in c:\Program Files\Microsoft SQL Server\MSSQL12.MSSQLSERVER\MSSQL\DATA\<database_name>_log.ldf) to another place;

take problematic database offline;

move back the log file to its original folder and take database online.

If the database is in a permanent recovery pending state: take database offline, then online:

ALTER DATABASE < database_name > SET OFFLINE GO ALTER DATABASE < database_name > SET ONLINE GO

If needed, run this script if the database is in a suspect state:

EXEC sp_resetstatus < database_name > GO ALTER DATABASE < database_name > SET EMERGENCY GO DBCC CHECKDB (< database_name >) GO ALTER DATABASE < database_name > SET SINGLE_USER WITH ROLLBACK IMMEDIATE GO DBCC CHECKDB ( < database_name >, REPAIR_ALLOW_DATA_LOSS ) GO ALTER DATABASE < database_name > SET MULTI_USER GO

Determine a database(s) status changes

Database status changes can be determined programmatically with PowerShell, by parsing events related to offline and online database(s) states from Application log within Event Viewer:

#The first part of the script is fetching events related to OFFLINE status; Get-WinEvent -FilterHashtable @{logname=’application’;id=5084;} | ?{$_.message -match "Setting database option OFFLINE"} -ErrorAction SilentlyContinue | Out-File d:\DatabaseStatusChange.txt -Append -Force ## #The second part of the script is fetching events related to ONLINE status; Get-WinEvent -FilterHashtable @{logname=’application’;id=5084;} | ?{$_.message -match "Setting database option ONLINE"} -ErrorAction SilentlyContinue | Out-File d:\DatabaseStatusChange.txt -Append -Force #After data fetching, all events will be parsed into one text file, and every next attempt of executing this script will be appended in the same text file;

The result should appear like this:

Within this filtered log file, moments when particular database went offline or online can be easily compared by timestamp (in TimeCreated column).

To constantly monitor database status change, include the script from above within SQL Server Agent job (refer to this article in order to create mentioned job), if needed.

Monitoring database status change with ApexSQL Monitor

As SQL Server performance monitoring tool, ApexSQL Monitor is continuously auditing status of all databases and their changes present on a monitored SQL server instance, with corresponding metric and alerts.

Information about database status change from Dashboard

On the left pane, when All instances is selected, the information on all databases status will appear in the Dashboard’s grid:

In this case, shown above, all databases are in function.

If some of the databases on the selected instance changed the status in some moment, the Databases counter on the top will show the corresponding number of alert(s), and alert icon will appear in the grid, like shown below:

Select the particular instance in the left pane, scroll down within Overview tab, and check all databases, for their status, database size, log size and related alerts:

In the picture above, there is an alert (or alerts) related to the Test database, which means that Test database’s status has changed.

Also, information about status and related alerts about databases are present in Database performance tab, along with information like recovery model, compatibility level etc.:

Status changed special performance counter

Placed under Database metrics, “Status changed” is the special performance counter, which actually tracks these events:

Status changed counter can be set to particular databases by clicking icon close to the metric name, and Database metric dialog will appear:

Resolving alerts related to Status changed counter

To examine and resolve alerts related to the database status change, go to the Alerts view:

In the General view, present on the picture above, it can be easily seen on which instance particular database (Test) changed its status. Also, the previously mentioned seven database statuses are present on the graph to show the transition between the states.

The selected alert represents the moment when Test database went offline, and the next shows when the same database changed status to online, with exact dates and times.

Automating alerts for database status changes

During monitoring of database status changes, to be effectively notified when a database changes status, set the email profile and/or use the custom command alert action, to make sure that particular database is always functioning.

Change the status of the particular database from offline to online (PowerShell)

In order to set this alert action, download Change_Database_Status.ps1 PowerShell script from this location, and place it on a desired location.

This script collects information on particular database’s status, and if the status is offline, the script will set it online. If it is already online (aka normal), the script will terminate.

[System.Reflection.Assembly]::LoadWithPartialName('Microsoft.SqlServer.SMO') | out-null $s = New-Object ('Microsoft.SqlServer.Management.Smo.Server') <server_name> $db = $s.Databases.item('<database_name>') $db.status if ($db.status -eq 'OFFLINE, AUTOCLOSED'){$db.SetOnline()} else {Break}

Next, customize the downloaded script, particularly <server_name> and <database_name> strings with valid and desired ones, bolded above.

After downloading and customizing the script file, set the custom command alert action within the Status Changed counter, and include this script:

powershell.exe "d:\change_database_status.ps1"

Every time the monitored database status is changed, the alert action will call the Change_Database_Status file and execute the script. Also, within alert action profile, multiple custom command alert actions can be included, just set different servers and databases in mentioned PowerShell script.

Downloads

Please download the script(s) associated with this article on our GitHub repository.

Please contact us for any problems or questions with the scripts.

The post How to monitor database status changes in SQL Server appeared first on Solution center.

[yourcodesupport-blog]

SQL - Tips to resolve “Table error: Object O_ID…page P_ID was not encountered.” Error

sql-server-recovery-blog1:

The records in Microsoft SQL Server database can be placed and located in the form of a B-tree. These records are divided into various pages (child pages), each having a unique index page, which is one level up in hierarchy from the child page. Corruption in the hierarchical tree structure (metadata structure corruption) primarily results in loosing the reference of the child page from the Index page. In such situations, the data stored in the database becomes inaccessible. For accessing the data stored in the database, an ideal way is to restore it from an updated database backup. But if in case of absence of an valid database backup, you will need to use advanced MS SQL Database Recovery application to repair your database. Consider a practical scenario, where you receive the below error message when you attempt to access the records stored in table: “Table error: Object ID O_ID, index ID I_ID. Parent node for page P_ID was not encountered.” The above error message makes the data stored in table inaccessible. Moreover, the error message repeatedly repeats every time you attempt to access the records stored in the table. Cause: The root cause for the occurrence of the above error message is SQL database corruption due to metadata structure damage. Note: SQL database can be corrupted either due to logical or physical factors. Resolution: To resolve the above error message and to access the table records, you will need to follow the below measures:

To solve all the corruption issues caused due to physical damage, swap the corrupt system component with a new component.

To solve  all the corruption issues caused due to logical damage, run DBCC CHECKDB command with correct repair clause.

The first measure is competent enough to resolve all the physical damage issues. The second measure, however, fails to resolve all logical corruption problems. For such situations, the database table can be repaired by using advanced MS SQL Database Repair software. These SQL Server Recovery utilities employ effective scanning methods to completely repair the corrupt table after all logical database corruption scenarios. Resource: http://ezinearticles.com/?Tips-to-Resolve-table-Error—Object-O_id-Page-P_id-Was-Not-Encountered-Error&id=3451876

Source: sql-server-recovery-blog1