I have a stored procedure that use temp table and explicitly drops it when done.
What happed when same procedure is run at same time by 2 different sessions? Sessions are run as single user (webapp).
Will one session interfere with temp table, and data inside it, of other session?
I'm using Postgres 9.0.
In postgresql temporary tables are unique for each session, so no problem.
If I am not totally wrong, the result would be one temp table per query in your procedure which generates the temp table, so the two temp tables would not disturb eachother.
Related
I have two database.
Primary have a DDL triggers so i can't create memory optimized tables there. So i created secondary database and create there table with memory optimized on. Now, in procedure on primary database i need insert copy data from other table to this optimized.
For example:
INSERT INTO InMemory.dbo.DestTable_InMem SELECT * FROM #T;
And i have:
A user transaction that accesses memory optimized tables or natively compiled modules cannot access more than one user database or databases model and msdb, and it cannot write to master.
Did exists some workarounds from it?
I cannot move my procedure to second database.
There is no other way than using a native procedure to INSERT, UPDATE or DELETE in an in-memory table.
See: A Guide to Query Processing for Memory-Optimized Tables
To move from one DB to the other, the source table must exists locally
I would like to change schema of few tables in my Postgres DB. Problem is that all the time there are long running queries and as I understand schema change needs exclusive lock.
Question is how can I do it? Of course I can kill all existing queries and try to do schema rename (move table to different schema) but there is a huge chance that in the meantime new queries will appear.
Thanks for help!
run SELECT pg_backend_pid() before running the ALTER TABLE
start the ALTER TABLE statement
in a second database session, run SELECT pg_blocking_pids(12345), where 12345 is the result from the first query
cancel all the blocking transactions found with the previous query with SELECT pg_cancel_backend(23456)
In SQL stored procedures, we have an option of creating a temporary table "#temp" whose structure is as that of another table that it is referring to. Here we don't explicitly create and mention the structure of "#temp" table.
Do we have similar option is HQL Hive script to create a temp table during run time without actually creating the table structure. Thus I can dump data to temp table and use it. Below code shows an example of #temp table in SQL.
SELECT name, age, gender
INTO #MaleStudents
FROM student
WHERE gender = 'Male'
Hive has the concept of temporary tables, which are local to a user's session. These tables behave just like any other table, and can be created using CTAS commands too. Hive automatically deletes all temporary tables at the end of the Hive session in which they are created.
Read more about them here.
Hive Documentation
DWGEEK
You can create simple temporary table. On this table you can perform any operation.
Once you are done with work and log out of your session they will be deleted automatically.
Syntax for temporary table is :
CREATE TEMPORARY TABLE TABLE_NAME_HERE (key string, value string)
We are creating a Disaster Recovery System for HBase tables. Because of the restrictions we are not able to use the fancy methods to maintain the replica of the table. We are using Export/Import statements to get the data into HDFS and using that to create tables in the DR Servers.
While Importing the data into HBase table, we are using truncate command to clear the table and load the data fresh into the table. But the truncate statement is taking a long time to delete the rows. Is there are any other effective statements to clear the entire table?
(truncate takes 33 min for ~2500000 records)
disable -> drop -> create table again, maybe ? I don't know if drop takes too long.
I have been trying to figure this out the ENTIRE DAY :( ...
I have several stored procedures (in the same database as well as different databases) that do the same thing.
Creates temp table with name X.
Does processing with X.
Drops X.
The problem is that these stored procedures are creating temp tables with the same name. How do I know which temp table to drop once I'm done with the processing if they all have the name and I can't really DROP using "LIKE" because a temp table might be being used by a different stored procedure?
Here's a scenario.
SP1 starts -
Create temp table.
...and before it goes on, this happens:
SP2 is about finish
Drop temp table.
If the above happens, SP1 runs into issues. Such as "temp table does not exist"
How do I bypass this issue?
When I go to drop a temp table, I need to make sure I'm dropping the table related to the stored procedure that created it. Is this even possible?
You are trying to solve a problem you don't have. Just drop the table. If you look in SSMS you will really have unique tables. The SP knows which one to drop.
If SP1 and SP2 were using the same table you would have more problems than just drop.
IF OBJECT_ID(N'tempdb..#Temp', N'U') IS NOT NULL DROP TABLE #Temp
CREATE TABLE #Temp (sID INT PRIMARY KEY CLUSTERED);
-- look in SSMS and you will see #temp appended
-- use #temp
IF OBJECT_ID(N'tempdb..#Temp', N'U') IS NOT NULL DROP TABLE #Temp
In SP not sure you even need to drop. I think it will be dropped automatically.
But if you run the first two lines and look in SSMS you will see that you have your own #TEMP - not a shared #TEMP. Run the last line and you will see it go away.