I need to store some data in a SQL DB for DataWarehousing purposes.
We will be using a replicated SQL Server Database.
Is it possible to insert into only the replicated DB (and not the main DB) so that we do not effect the main DB and still allow reporting and extraction of data out of the replicated DB?
Yes, but I would advise against it. Specifically, I tend to treat replication subscribers as expendable. Which is to say that I make the choice to not back them up. What you're suggesting means that there is data in the system that exists only at the subscriber which implies that the subscriber should be backed up. You're now re-backing up days that has been backed up at the publisher.
Also, I'd completely advise against putting that data in the same table as is being subscribed. On an article re-initialization, there's too much risk of it being deleted.
Related
Can anyone explain the differences from a replication db vs a mirroring db server?
I have huge reports to run. I want to use a secondary database server to run my report so I can off load resources from the primary server.
Should I setup a replication server or a mirrored server and why?
For your requirements the replication is the way to go. (asumming you're talking about transactional replication) As stated before mirroring will "mirror" the whole database but you won't be able to query unless you create snapshots from it.
The good point of the replication is that you can select which objects will you use and you can also filter it, and since the DB will be open you can delete info if it's not required( just be careful as this can lead to problems maintaining the replication itself), or create specific indexes for the report which are not needed in "production". I used to maintain this kind of solutions for a long time with no issues.
(Assuming you are referring to Transactional Replication)
The biggest differences are: 1) Replication operates on an object-by-object basis whereas mirroring operates on an entire database. 2) You can't query a mirrored database directly - you have to create snapshots based on the mirrored copy.
In my opinion, mirroring is easier to maintain, but the constant creation of snapshots may prove to be a hassle.
As mentioned here
Database mirroring and database replication are two high data
availability techniques for database servers. In replication, data and
database objects are copied and distributed from one database to
another. It reduces the load from the original database server, and
all the servers on which the database was copied are as active as the
master server. On the other hand, database mirroring creates copies of
a database in two different server instances (principal and mirror).
These mirror copies work as standby copies and are not always active
like in the case of data replication.
This question can also be helpful or have a look at MS Documentation
I need a clarification about tempdb in SQL Server and need some clarifications on following things
What is the purpose of its?
Can we create a own tempdb and how to make refer the own tempdb to own database?
FROM MSDN
The tempdb system database is a global resource that is available to all users connected to the instance of SQL Server and is used to hold the following:
Temporary user objects that are explicitly created, such as: global
or local temporary tables, temporary stored procedures, table
variables, or cursors.
Internal objects that are created by the SQL Server Database Engine,
for example, work tables to store intermediate results for spools or
sorting.
Row versions that are generated by data modification transactions in
a database that uses read-committed using row versioning isolation
or snapshot isolation transactions.
Row versions that are generated by data modification transactions
for features, such as: online index operations, Multiple Active
Result Sets (MARS), and AFTER triggers.
Operations within tempdb are minimally logged.
This enables transactions to be rolled back. tempdb is re-created every time SQL Server is started so that the system always starts with a clean copy of the database.
Temporary tables and stored procedures are dropped automatically on disconnect, and no connections are active when the system is shut down. Therefore, there is never anything in tempdb to be saved from one session of SQL Server to another. Backup and restore operations are not allowed on tempdb.
TempdB is a system database and we cant create system databases .Tempdb is a global resource for all databases ,which means temp tables,table variables,version store for user databases...all will use tempdb..This is a pretty basic explanation for tempdb.Refer to below links on how it is used for other purposes like database emails,..
https://msdn.microsoft.com/en-us/library/ms190768.aspx
1: It is what it says. A temporary storage. FOr example when you ask for DISTINCT results, SQL Server must remember what rows it already sent you. Same with a temporary table.
2: Makes no sense. Tempdb is not a database but a server thing - ONE TempDB regardless how many database. You can change where it is and how it is (file number, size) but it is never related to one database (except obviously if you only have one database on a SQL Server instance). Having your own Tempdb is NOT how SQL Server works. And while we are at it - no need to ever make a backup (of tempdb). When SQL Server starts, Tempdb is reinitialized as empty.
And, btw., this would be obvious if you would bother with such things as being borderline competent. Which includes for me reading the documentation of every major technology I work with once. You should consider this to be something to adopt because it is the only way to know what you are doing.
I have a local SQL Server database that I copy large amounts of data from and into a remote SQL Server database. Local version is 2008 and remote version is 2012.
The remote DB has transactional replication set-up to one local DB and another remote DB. This all works perfectly.
I have created an SSIS package that empties the destination tables (the remote DB) and then uses a Data Flow object to add the data from the source. For flexibility, I have each table in it's own Sequence Container (this allows me to run one or many tables at a time). The data flow settings are set to Keep Identity.
Currently, prior to running the SSIS package, I drop the replication settings and then run the package. Once the package completes, I then re-create the replication settings and reinitialise the subscribers.
I do it this way (deleting the replication and then re-creating) for fear of overloading the server with replication commands. Although most tables are between 10s and 1000s of rows, a couple of them are in excess of 35 million.
Is there a recommended way of emptying and re-loading the data of a large replicated database?
I don't want to replicate my local DB to the remote DB as that would not always be appropriate and doing a back and restore of the local DB would also not work due to the nature of the more complex permissions, etc. on the remote DB.
It's not the end of the world to drop and re-create the replication settings each time as I have it all scripted. I'm just sure that there must be a recommended way of managing this...
Not doing it. Empty / Reload is bad. Try to update the table via merge - this way you can avoid the drop and recreate, which also will result in 2 replicated operations. Load the new data into temp tables on the other server (not replicated), then merge them into the replicated tables. If a lot of data is unchanged, this will seriously reduce the replication load.
I'd like to have some degree of fault tolerance / redundancy with my SQL Server Express database. I know that if I upgrade to a pricier version of SQL Server, I can get "Replication" built in. But I'm wondering if anyone has experience in managing replication on the client side. As in, from my application:
Every time I need to create, update or delete records from the database -- issue the statement to all n servers directly from the client side
Every time I need to read, I can do so from one representative server (other schemes seem possible here, too).
It seems like this logic could potentially be added directly to my Linq-To-SQL Data Context.
Any thoughts?
Every time I need to create, update or
delete records from the database --
issue the statement to all n servers
directly from the client side
Recipe for disaster.
Are you going to have a distributed transaction or just let some of the servers fail? If you have a distributed transaction, what do you do if a server goes offline for a while.
This type of thing can only work if you do it at a server-side data-portal layer where application servers take in your requests and are aware of your database farm. At that point, you're better off just using a higher grade of SQL Server.
I have managed replication from an in-house client. My database model worked on an insert-only mode for all transactions, and insert-update for lookup data. Deletes were not allowed.
I had a central table that everything was related to. I added a field to this table for a date-time stamp which defaulted to NULL. I took data from this table and all related tables into a staging area, did BCP out, cleaned up staging tables on the receiver side, did a BCP IN to staging tables, performed data validation and then inserted the data.
For some basic Fault Tolerance, you can scheduling a regular backup.
Say you have 2 database servers, one database is the 'master' database where all write operations are performed, it is treated as the 'real/original' database. The other server's database is to be a mirror copy of the master database (slave?), which will be used for read only operations for a certain part of the application.
How do you go about setting up a slave database that mirrors the data on the master database? From what I understand, the slave/readonly database is to use the master db's transaction log file to mirror the data correct?
What options do I have in terms of how often the slave db mirrors the data? (real time/every x minutes?).
What you want is called Transactional Replication in SQL Server 2005. It will replicate changes in near real time as the publisher (i.e. "master") database is updated.
Here is a pretty good walk through of how to set it up.
SQL Server 2008 has three different modes of replication.
Transactional for one way read only replication
Merge for two way replication
Snapshot
From what I understand, the slave/readonly database is to use the master db's transaction log file to mirror the data correct?
What options do I have in terms of how often the slave db mirrors the data? (real time/every x minutes?).
This sounds like you're talking about log shipping instead of replication. For what you're planning on doing though I'd agree with Jeremy McCollum and say do transactional replication. If you're going to do log shipping when the database is restored every x minutes the database won't be available.
Here's a good walkthrough of the difference between the two. Sad to say you have to sign up for an account to read it though. =/ http://www.sqlservercentral.com/articles/Replication/logshippingvsreplication/1399/
The answer to this will vary depending on the database server you are using to do this.
Edit: Sorry, maybe i need to learn to look at the tags and not just the question - i can see you tagged this as sqlserver.
Transactional replication is real time.
If you do not have any updates to be done on your database , what you need is just retrieving of data say once a day : then use snapshot replication instead of transactional replication. In snapshot replication, changes will replicate when and as defined by the user say once in 24 hrs.