I built a galera cluster out of three Pi. The users are automatically copied to all servers. The databasename, tablename, columnname too. But they are always empty. So a select on a table only returns entries on the created server. I am absolutely new to the cluster area. Thank you if someone can help LG
I assume that you are using mariadb.
Make sure there is Primary Component in the cluster, you may check in using Status variable wsrep_cluster_status
Also, please always check the server log, if something goes wrong. Log is your friend.
Related
We have an application that is connecting to a Galera Cluster we are using a connection string with multiple hosts. I.E. with MariaDB Connector J. If the first host in the connection string becomes a donor and we issue an insert statement the insert will hang until the donor stops being a donor and resumes as a regular node. We are using MariaDB Connector J is there any way to automatically switch to another host when the initial Host becomes a Donor? We tried using the keyword sequential, but it did not work in this case. Is there a setting in Galera that will allow a donor to immediatly execute an insert statement and return? How is this normally handled? Resynch can take up to 20 minutes and our program cannot pause that long.
I think I might have figured it out. I changed the setting wsrep_sst_donor_rejects_queries to on. With the keyword sequential, this allowed the driver to skip the donor and move to the next up host. If anyone has any alternative solution please post it. I thought I should post my solution so it would help others facing a similar challenge.
In app config file. I used initial catalog ='jana' as database name.
Then i run it use it for some times.
Then later i changed initial catalog ='siva' as database name . That i changed database name alone and saved it. Whenever i run this 'siva' as initial catalog , select queries is using 'siva' database at the same time inserting /updating queries using my previous database 'jana'. Its really weird.
thanks for considering my query. I rectified mistake by myself.
Actually while inserting/updating queries , i have used databasename.dbo.tablename for all queries. That is the cause whenever i used different database , the one which i used on creating was always affected.
Hope u understand my scenario.
Thanks for all.
I'm working with a moderately sized database of about 60,000 records. I am working on building a mobile application which will be able to check out a single table into a compact .sdf on for viewing and altering on the device, then allow the user to sync their changes back up with the main server and receive any new information.
I have set it up with the Sync Framework using a WCF Service Library. When setting up the connection for some reason the database won't let me check "Use SQL Server Change Tracking" and throws up the error:
"'Unable to initialize the client database, because the schema for table 'Inventory' could >not be retrieved by the GetSchema() method of DbServerSyncProvider. Make sure that you can >establish a connection to the client database and that either the >SelectIncrementalInsertsCommand property or the SelectIncrementalUpdatesCommand property of >the SyncAdapter is specified correctly."
So I leave it unchecked and set it to use some already created columns "AddDateTime" and "LastEditTime" it seems to work okay, and after a massive amount of tweaking I have it partially working. The changes on the device sync up perfectly with the database, updates, deletes, all get applied. However, changes on the server side...never get updated. I've made sure everything is set up right with the bidirectional setup so that shouldn't be the problem. And, I let it sit overnight so the database received ~500 new records, this morning it actually synced the latest 24 entries to the database...out of 500 new. So that should be further proof that it's able to receive information from the server, but for all useful purposes, it's not.
I've tried pretty much everything and I'm honestly getting close to losing it. If anyone has any ideas they can throw out I can chase after I would be most grateful.
I'm not sure if I just need to go back and figure out why I can't do it with the "SQL Server Change Tracking". Or if there is a simple explanation for why it's not actually syncing 99% of the changes on the server back to the client.
Also, the server database table schema can't be altered as a lot of other services use it. But the compact database can be whatever the heck in needs to be to just store the table and sync properly in both directions.
Thank you!!
Quick Overview:
Using WCF and syncing without SQL Server Change Tracking (Fully enabled on server and database)
Syncing changes from client to server works perfectly
Syncing from server back to the client not so much: out of 500 new entries overnight, on a sync it downloaded 24.
EDIT: JuneT got me thinking about the time and their anchors. When I synced this morning it pulled 54 of about 300 new added records. I went in to the line (there are about 60 or so columns, so I removed them for readability, this is kind of a joke)
this.SelectIncrementalUpdatesCommand.CommandText = #"SELECT [Value], [Value], [Value] FROM >TABLE WHERE ([LastEditDate] > #sync_last_received_anchor AND [LastEditDate] <= >#sync_new_received_anchor AND [AddDateTime] <= #sync_last_received_anchor)";
And replaced #sync_last_received_anchor with two DIFFERENT times. Upon syncing it now returns the rows trapped between those two and took out the middle one giving me:
this.SelectIncrementalUpdatesCommand.CommandText = #"SELECT[Value], [Value], [Value] FROM >TABLE WHERE ([LastEditDate] > '2012-06-13 01:03:07.470' AND [AddDateTime] <= '2012-06-14 >08:54:27.727')"; (NOTE: The second date is just the current time now)
Though it returned a few hundred more rows than initially planned (set the date gap for 600, it returned just over 800). It does in fact sync the client up with the the new server changes.
Can anyone explain why I can't use #sync_last_received_anchor and what I should be looking for. I suppose I could always add box that allows the user to select the date to begin updating from? Or maybe add some sort of xml file to store the sync date that would be updated anytime a sync was -successfully- completed?
Thanks!
EDIT:
Ran the SQL profiler on it...the date (#sync_last_received_anchor) is getting set to 8 hours ahead of whatever time it really is. I have no idea how or why it's doing this, but that would definitely make sense.
Turns out the anchors are collected like this:
this.SelectNewAnchorCommand.CommandText = "Select #sync_new_received_anchor = GETUTCDATE()";
That UTC date is what was causing the 8 hours gap. To fix it either change it to GETDATE(), or convert your columns to UTC time in the WHERE clause of the commands.
After spending many hours with many cups of coffee, I've figured out how to solve this error of mine. While I was running the code on desktop testing area, everything seemed to be working perfectly; however the same code and webservice on target device gave this error repeatedly. Then, suddenly, the "dbo_" prefixes on compact database table names started looking interesting, like they were trying to tell me something really important. So, I've listened...
Configuration.SyncTables.Add("Products);
on ClientSyncAgent.cs should be changed to
Configuration.SyncTables.Add("dbo_Products");
[Exeunt]
We have a merge replication setup on SQL Server that goes like this: 1 SQL server at the office, another SQL server traveling around the world. The publisher is the SQL server at the office.
In about 1% of the cases, two of our tables with a column of XML Data type (not bound to a schema) are replicated with rows containing empty XML columns. ( This only happened when data is sent from the "traveling server" back home, but then again, data seems to be changed more often there ). We only have this in prod. environment ( WAN replication ).
Things i have verified:
The row is replicated, as the last modification date on the row is refreshed but the xml column is empty. Of course it is not empty on the other SQL Server.
No conflicts are displayed in the replication conflicts UI.
It is not caused by the size of the data inside the XML Column as some are very small.
Usually, the problem occurs in batch. ( The xml column of 8-9 consecutive rows will be empty )
The problem occurs if a row was inserted OR updated. No pattern there.
The problem seems to occur, but this is pure speculation on my part when the connection is weaker. ( We've seen this problem happen more often when the server was far away as compared to when it was close by. )
Sorry if i have confused some things, I am not really a DBA, more of a DEV with knowledge of SQL but since the application using the database keeps getting blamed for the problems ( the XML column must not be empty!! ) I have taken it at heart to try and find the problem instead of just manually patching the data each time ( Whats the use of replication if you have to do that? )
If anyone could help out with this problem, or at least suggest some ways of being able to debug / investigate this it would be greatly appreciated.
I did search alot on google and I did find this: Hot Fix . But we do have the latest service pack and the problem seems a bit different.
fyi: We have a replication setup locally here but the problem never occurs. We will be trying a WAN simulator on it as well to see if that can help.
Thanks
Edit: hot fix is now available for my issue: http://support.microsoft.com/kb/2591902
After logging this issue with Microsoft, we were able to reproduce the problem without a slow link ( Big thanks to the competent escalation engineer at Microsoft ). The repro is a bit different from our scenario, but highlights the timing issue we were getting perfectly.
Create 2 tables – One parent one child (have a PK-FK relationship)
Insert 2 rows in the parent table
Set up replication – configure merge agent to run ON DEMAND
Sync
Once all is replicated:
On the PUBLISHER: delete one row from the parent table
On the SUBSCRIBER: Insert 2 rows of data that references the parentid you deleted above
Insert 5 rows of data that references the parentid that will stay in the table
Sync, Merge agent will fail, Sync again, Merge agent will succeed
Missing XML data on the publisher on the 5 rows.
Seems it is a bug that is in SQL Server 2005/2008 and 2008R2.
It will be addressed in a hot fix in 2008 and up. ( As SQL Server 2005 is no longer being altered )
Cheers.
You may want to start out by slapping a bandaid on this perplexing situation to buy some time to fully investigate and fix (or more likely get MS to fix it). SQL Data Compare is an excellent tool that might help.
Figured i'd put an update here as this issue got me a few gray hairs and I am somewhat closer to a solution now.
I finally had some time to work on this and managed to reproduce this issue in our test environment, using a WAN simulator and slowing down the link and injecting some random packet loss. ( to best simulate the production environment where the server is overseas on a really bad line ).
After doing some SQL tracing, and some verbose logging here are my conclusions:
When replicating a row with an XML column, the process is done in 2 steps. First an insert is done of the full row but with an empty string for the XML column. Right after, an update is done this time with the XML column having data. Since the link is slow, in some situations a foreign key violation occured.
In this scenario, Table2 depends on Table1. After finishing replicating table1, and starting to replicate table2 (Enumration of insert/updates which takes time on a slow link), some entries were added to table1 and table2. Therefore some inserts on Table2 failed because Table1 entries were not in the database and were only going to be replicated next batch. The next time the replication occured, no more foreign key violations occured, however when it tried to insert the row that had previously failed in Table2 ( XML column row ), the update part of it was missing ( I could see that in the SQL profiler ) and that is why the row ended up after all was done with an empty XML.
Setting "Enforce for replication" to false on the foreign keys seems to address the problem, however I do still think that this whole process should work with the option set to true.
I logged a support call with Microsoft for this. I have sent the traces and logs to Microsoft and will see what they have to say.
I've read this article: http://msdn.microsoft.com/en-us/library/ms152529(v=SQL.90).aspx. But for me, setting this option to false is kind of a work around, no?
What do you guys think?
ps: Hope this is clear, tried to explain it the best I could. English is not my first language.
I'm trying to pull user data from 2 tables, one locally and one on a linked server, but I get the wrong results when querying the remote server.
I've cut my query down to
select * from SQL2.USER.dbo.people where persId = 475785
for testing and found that when I run it I get no results even though I know the person exists.
(persId is an integer, db is SQL Server 2000 and dbo.people is a table by the way)
If I copy/ paste the query and run it on the same server as the database then it works.
It only seems to affect certain user ids as running for example
select * from SQL2.USER.dbo.people where persId = 475784
works fine for the user before the one I want.
Strangely I've found that
select * from SQL2.USER.dbo.people where persId like '475785'
also works but
select * from SQL2.USER.dbo.people where persId > 475784
brings back records with persIds starting at 22519 not 475785 as I'd expect.
Hope that made sense to somebody
Any ideas ?
UPDATE:
Due to internal concerns about doing any changes to the live people table, I've temporarily moved my database so they're both on the same server and so the linked server issue doesn't apply. Once the whole lot is migrated to a separate cluster I'll be able to investigate properly. I'll update the update once this happens and I can work my way through all the suggestions. Thanks for your help.
The fact that LIKE operates is not a major clue: LIKE forces integers to string (so you can say WHERE field LIKE '2%' and you will get all records that start with a 2, even when field is of integer type). Your incorrect comparisons would lead me to think your indexes are corrupt, but you say they work when not used via the link... however, the selected index might be different depending on the use? (I seem to recall an instance when I had duplicate indexes and only one was stale, although that was too long ago to recall the exact cause).
Nevertheless, I would try rebuilding your index using the DBCC DBREINDEX (tablenname) command. If it turns out that doing so fixes your query, you may want to rebuild them all: here is a script for rebuilding them all easily.
Is dbo.people a table or a view? I've seen something similar where the underlying table schema had been changed and dropping and recreating the view fixed the problem, although the fact that the query works if run directly on the linked server does indicate something index based..
Is the linked server using the same collation? Depending on the index used, I could see something like this perhaps happening if the servers were not collation compatible, but the linked server was set up with collation compatible (which tells Sql Server it can run the query on the remote server).
I would check the following:
Check your definition on the linked server, and confirm that SQL2 is the
server you expect it to be
Check and compare the execution plans both from the remote and local servers
Try linking by IP address rather than name, to ensure you have the proper machine
Put the code into a stored procedure on the remote machine, and try calling that instead
Sounds like a bug to me - I;ve read of some issues along these lines, btu can't remember specifically what. What version of SQL Server are you running?
select * from SQL2.USER.dbo.people where persId = 475785
for a PersID which fails how does:
SELECT *
FROM OpenQuery(SQL2, 'SELECT * FROM USER.dbo.people WHERE persId = 475785')
behave?