I need to diagnose some issues in production but I cannot query the event_log, query times out.
I was trying to executing the following query on Master database in my Azure database,
select * from sys.event_log where start_time>='2016-02-20:12:00:00' and end_time<='2016-02-20 12:00:00'
Query starts executing, and runs over more than 8 mins and Cancels query execution. I am pretty sure that the eventlog must be a very large one in this database server. How to overcome this situation and query the sys.event_log table?
Even the top 10 query times out. Need some help!
Query I ran was, this might also get a time out, just keep trying (worked for me in the 3rd time)
SELECT *
,CAST(event_data AS XML).value('(/event/#timestamp)[1]', 'datetime2') AS TIMESTAMP
,CAST(event_data AS XML).value('(/event/data[#name="error"]/value)[1]', 'INT') AS error
,CAST(event_data AS XML).value('(/event/data[#name="state"]/value)[1]', 'INT') AS STATE
,CAST(event_data AS XML).value('(/event/data[#name="is_success"]/value)[1]', 'bit') AS is_success
,CAST(event_data AS XML).value('(/event/data[#name="database_name"]/value)[1]', 'sysname') AS database_name
FROM sys.fn_xe_telemetry_blob_target_read_file('el', NULL, NULL, NULL)
WHERE object_name = 'database_xml_deadlock_report'
This gives very useful details in the xml data field.
Use an XML viewer to view details. I used XMLGrid.
It will show what are the two processes (deadlock victim and winner) and the good news is that it gives you the SQL statements those processes were trying to execute.
In my case two processes were trying to update one data table, but two different rows. Winner process was using a SQL "Merge" which creates a table lock for the row update. Solution was I changed that Merge query to use SQL UPDATE.
Related
We have external table created, we need to run select on the table and select all the records, the select runs very very slow. Its not completing even after 30 mins, the table contains around 2millon recs
We also need to query this table from another DB and even this runs very very slow, doesn't return even after 30 mins.
Select is of the form:
select col1, col2,...col3 from ext_table;
Need help in:
1. Any suggestions on reducing the time taken for execution?
Note: we need to select entire content of the table so where condition might not be used.
Thanks in advance.
If you are not using the WHERE clause to push parameters to the remote database, then there is no way to optimize the performance of the query. You are returning the whole table.
My suggestion is to use SQL Data Sync to have a local copy of the table on this SQL Database that synchronizes with the remote Azure SQL Database at X interval of time.
I'm working on a data virtualization solution. The user is able to write his own SQL queries as filters for a query i make. I would like not having to run this filter query every time i select something from the database(It will likely be a complex series of joins).
My idea was to use a # temp table at script level and keep the connection alive. This #temp table would then be selected from but updated only when the user changes the filter. The idea being i can actually use it from stored procedures and the table is scoped to that connection.
I got the idea from someone who suggested to use dynamic sql and ## global temp tables named with the connection process ID so to make each connection have a unique global temp table. This was to overcome sharing temp tables across stored procedures. But it seems a bit clumsy.
I did a quick test with the below code and seemed to work fine
-- Run script at connection open from some app
SELECT * INTO #test
FROM dataTable
-- Now we can use stored procedures with #test table
EXECUTE selectFromTempTable
EXECUTE updateTempTable #sqlFilterString
EXECUTE selectFromTempTable
Only real problem i can see is the connection have to be kept alive for the duration which can be a few hours maybe. A single user can have multiple connections running at the same time. The number of users on a single database server would be like max 20.
If its a huge issue i could make it so the application can close and open them as needed so each user only have 1 connection open at a time. And maybe even then close it if not in use, and reopen when needed again with the delay of having to wait for the query to run.
Would this be bad practice? or kill any performance benefit from not running the filter query? This is on SQL Server 2008 and up.
I think I would create a permanent table, using the spid (process ID) as a key value. Each connection has its own process ID, so anyone can use it to identify their entries in the table:
create table filter(
spid int,
filternum int,
filterstring varchar(255),
<other cols> );
create unique index filterindx on filter(spid, filternum);
Then when a user creates filter entries:
delete from filter where spid = ##spid
insert into filter(spid, filternum, filterstring) select ##spid, 1, 'some sql thing'
insert into filter(spid, filternum, filterstring) select ##spid, 2, 'some other sql thing'
Then you can access each user's filter values by selecting where spid = ##spid etc
I want to insert some data on the local server into a remote server, and used the following sql:
select * into linkservername.mydbname.dbo.test from localdbname.dbo.test
But it throws the following error
The object name 'linkservername.mydbname.dbo.test' contains more than the maximum number of prefixes. The maximum is 2.
How can I do that?
I don't think the new table created with the INTO clause supports 4 part names.
You would need to create the table first, then use INSERT..SELECT to populate it.
(See note in Arguments section on MSDN: reference)
The SELECT...INTO [new_table_name] statement supports a maximum of 2 prefixes: [database].[schema].[table]
NOTE: it is more performant to pull the data across the link using SELECT INTO vs. pushing it across using INSERT INTO:
SELECT INTO is minimally logged.
SELECT INTO does not implicitly start a distributed transaction, typically.
I say typically, in point #2, because in most scenarios a distributed transaction is not created implicitly when using SELECT INTO. If a profiler trace tells you SQL Server is still implicitly creating a distributed transaction, you can SELECT INTO a temp table first, to prevent the implicit distributed transaction, then move the data into your target table from the temp table.
Push vs. Pull Example
In this example we are copying data from [server_a] to [server_b] across a link. This example assumes query execution is possible from both servers:
Push
Instead of connecting to [server_a] and pushing the data to [server_b]:
INSERT INTO [server_b].[database].[schema].[table]
SELECT * FROM [database].[schema].[table]
Pull
Connect to [server_b] and pull the data from [server_a]:
SELECT * INTO [database].[schema].[table]
FROM [server_a].[database].[schema].[table]
I've been struggling with this for the last hour.
I now realise that using the syntax
SELECT orderid, orderdate, empid, custid
INTO [linkedserver].[database].[dbo].[table]
FROM Sales.Orders;
does not work with linked servers. You have to go onto your linked server and manually create the table first, then use the following syntax:
INSERT INTO [linkedserver].[database].[dbo].[table]
SELECT orderid, orderdate, empid, custid
FROM Sales.Orders
WHERE shipcountry = 'UK';
I've experienced the same issue and I've performed the following workaround:
If you are able to log on to remote server where you want to insert data with MSSQL or sqlcmd and rebuild your query vice-versa:
so from:
SELECT * INTO linkservername.mydbname.dbo.test
FROM localdbname.dbo.test
to the following:
SELECT * INTO localdbname.dbo.test
FROM linkservername.mydbname.dbo.test
In my situation it works well.
#2Toad: For sure INSERT INTO is better / more efficient. However for small queries and quick operation SELECT * INTO is more flexible because it creates the table on-the-fly and insert your data immediately, whereas INSERT INTO requires creating a table (auto-ident options and so on) before you carry out your insert operation.
I may be late to the party, but this was the first post I saw when I searched for the 4 part table name insert issue to a linked server. After reading this and a few more posts, I was able to accomplish this by using EXEC with the "AT" argument (for SQL2008+) so that the query is run from the linked server. For example, I had to insert 4M records to a pseudo-temp table on another server, and doing an INSERT-SELECT FROM statement took 10+ minutes. But changing it to the following SELECT-INTO statement, which allows the 4 part table name in the FROM clause, does it in mere seconds (less than 10 seconds in my case).
EXEC ('USE MyDatabase;
BEGIN TRY DROP TABLE TempID3 END TRY BEGIN CATCH END CATCH;
SELECT Field1, Field2, Field3
INTO TempID3
FROM SourceServer.SourceDatabase.dbo.SourceTable;') AT [DestinationServer]
GO
The query is run on DestinationServer, changes to right database, ensures the table does not already exist, and selects from the SourceServer. Minimally logged, and no fuss. This information may already out there somewhere, but I hope it helps anyone searching for similar issues.
June 29, 2010 - I had an un-committed action from a previous delete statement. I committed the action and I got another error about conflicting primary id's. I can fix that. So morale of the story, commit your actions.
Original Question -
I'm trying to run this query:
with spd_data as (
select *
from openquery(IRPROD,'select * from budget_user.spd_data where fiscal_year = 2010')
)
insert into [IRPROD]..[BUDGET_USER].[SPD_DATA_BUD]
(REC_ID, FISCAL_YEAR, ENTITY_CODE, DIVISION_CODE, DEPTID, POSITION_NBR, EMPLID,
spd_data.NAME, JOB_CODE, PAY_GROUP_CODE, FUND_CODE, FUND_SOURCE, CLASS_CODE,
PROGRAM_CODE, FUNCTION_CODE, PROJECT_ID, ACCOUNT_CODE, SPD_ENC_AMT, SPD_EXP_AMT,
SPD_FB_ENC_AMT, SPD_FB_EXP_AMT, SPD_TUIT_ENC_AMT, SPD_TUIT_EXP_AMT,
spd_data.RUNDATE, HOME_DEPTID, BUD_ORIG_AMT, BUD_APPR_AMT)
SELECT REC_ID, FISCAL_YEAR, ENTITY_CODE, DIVISION_CODE, DEPTID, POSITION_NBR, EMPLID,
spd_data.NAME, JOB_CODE, PAY_GROUP_CODE, FUND_CODE, FUND_SOURCE, CLASS_CODE,
PROGRAM_CODE, FUNCTION_CODE, PROJECT_ID, ACCOUNT_CODE, SPD_ENC_AMT, SPD_EXP_AMT,
SPD_FB_ENC_AMT, SPD_FB_EXP_AMT, SPD_TUIT_ENC_AMT, SPD_TUIT_EXP_AMT,
spd_data.RUNDATE, HOME_DEPTID, lngOrig_amt, lngAppr_amt
from spd_data
left join Budgets.dbo.tblAllPosDep on project_id = projid
and job_code = jcc and position_nbr = psno
and emplid = empid
where OrgProjTest = 'EQUAL';
Basically I'm selecting a table from IRPROD (an oracle db), joining it with a local table, and inserting the results back on IRPROD.
The problem I'm having is that while the query runs, it never stops. I've let it run for an hour and it keeps going until I cancel it. I can see on a bandwidth monitor on the SQL Server data going in and out. Also, if I just run the select part of the query it returns the results in 4 seconds.
Any ideas why it's not finishing? I've got other queryies setup in a similar manner and do not have any problems (granted those insert from local tables and not a remote table).
You didn't included any volume metrics. But I would recommend to use a temporary table to gather the results.
Then you should try to insert the first couple of rows. If this succeeds you'll have a strong indicator that everything is fine.
Try to break down each insert task by project_id or emplid to avoid large transactions logs.
You should also think about crafting a bulk batch process.
If you run just the select without the insert, how many records are returned? Does the data look right or are there multiple records due to the join?
Are there triggers on the table you are inserting into? If you are returning many records and triggers are on the table that are designed to run row-byrow this could be slowing things down. You are also sending to another server, so the network pipeline could be what is slowing you down. Maybe it would be better to send the budget data to the Oracle server and do the insert from there rather than from the SQL Server.
I have a LINQ to SQL query that generates the following SQL :
exec sp_executesql N'SELECT COUNT(*) AS [value]
FROM [dbo].[SessionVisit] AS [t0]
WHERE ([t0].[VisitedStore] = #p0) AND (NOT ([t0].[Bot] = 1)) AND
([t0].[SessionDate] > #p1)',N'#p0 int,#p1 datetime',
#p0=1,#p1='2010-02-15 01:24:00'
(This is the actual SQL taken from SQL Profiler on SQL Server 2008.)
The query plan generated when I run this SQL from within Query Analyser is perfect.
It uses an index containing VisitedStore, Bot, SessionDate.
The query returns instantly.
However when I run this from C# (with LINQ) a different query plan is used that is so inefficient it doesn't even return in 60 seconds. This query plan is trying to do a key lookup on the clustered primary key which contains a couple million rows. It has no chance of returning.
What I just can't understand though is that the EXACT same SQL is being run - either from within LINQ or from within Query Analyser yet the query plan is different.
I've ran the two queries many many times and they're now running in isolation from any other queries. The date is DateTime.Now.AddDays(-7), but I've even hardcoded that date to eliminate caching problems.
Is there anything i can change in LINQ to SQL to affect the query plan or try to debug this further? I'm very very confused!
This is a relatively common problem that surprised me too when I first saw it. The first thing to do is ensure your statistics are up to date. You can check the age of statistics with:
SELECT
object_name = Object_Name(ind.object_id),
IndexName = ind.name,
StatisticsDate = STATS_DATE(ind.object_id, ind.index_id)
FROM SYS.INDEXES ind
order by STATS_DATE(ind.object_id, ind.index_id) desc
Statistics should be updated in a weekly maintenance plan. For a quick fix, issue the following command to update all statistics in your database:
exec sp_updatestats
Apart from the statistics, another thing you can check is the SET options. They can be different between Query Analyzer and your Linq2Sql application.
Another possibility is that SQL Server is using an old cached plan for your Linq2Sql query. Plans can be cached on a per-user basis, so if you run Query Analyser as a different user, that can explain different plans. Normally you could add Option (RECOMPILE) to the application query, but I guess that's hard with Linq2Sql. You can clear the entire cache with DBCC FREEPROCCACHE and see if that speeds up the Linq2Sql query.
switched to a stored procedure and the same SQL works fine. would really like to know what's going on but can't spend any more time on this now. fortunately in this instance the query was not too dynamic.
hopefully this at least helps anyone in the same boat as me