We need to push data from one database A to database B while maintaining consistency in current transactions happening in database B.
Problem:Data cannot be pushed directly to tables in database B because the customers might see inconsistent data,since it is join of 3-4 tables.
Approach:We have tried to create loading tables and loaded tables.We have created one synonym to point to loaded tables.Data will be pushed to loading tables first and once all data is pushed,we will copy that data to loaded tables and at that time synonym will be pointed to loading tables.Once all the data is copied to loaded tables,synonym will again point to loaded tables.
The problem with this approach is while switching synonym we need to drop synonym ad create same pointing to other(loading or loaded) table and at that time any incoming transaction might fail,if it could not find synonym.
Is there any other way to to cater this problem?
Related
As stated I need help deleting all data from every table in a test database. There are 3477 tables and some of the tables were created by a past employee so I was unable to create a schema of the DB and recreate it empty.
Is there a fast way to delete all of the data and keep all of the tables and their structure? Also, I noticed when deleting data from the DB with Delete table_name, that the data file wasn't decreasing in size. Any reason why? Then I tried to just delete the data file to see what would happen and it erased everything, so i had to restore the test database. Now I'm back at block one....
Any help or guidance would be appreciated.... I've read a lot and everything just says use Delete or Truncate, but rather not do that for 3477 tables.
The TRUNCATE TABLE command deletes the data inside a table, but not the table itself.
You have a lot of tables (more than 3000...), so take a look to following link to truncate all tables:
Truncate all tables in a SQL Server database
When you create a view, the column structure of the view is created and stored, and thus you can see it in object explorer:
When you alter the source data tables, sometimes things go wacky, because the view may have been built with "Select *" yet the schema created for you has the old information without the additional columns.
Does SQL Server have an easy way to rebuild the view schemas?
Do not use SELECT * in views. I say this as someone who has spent much too much time (in the past) debugging views that had this "feature".
When you do create a view in a production system, create it with SCHEMABINDING:
SCHEMABINDING
Binds the view to the schema of the underlying table or tables. When SCHEMABINDING is specified, the base table or tables cannot be modified in a way that would affect the view definition. The view definition itself must first be modified or dropped to remove dependencies on the table that is to be modified.
Although this adds an extra step when trying to modify tables, the increased resilience of the system is worth it.
I have a Microsoft SQL Server instance Instance1 with a database called Maintenance, with a table called TempWorkOrder. I have another SQL Server instance Instance2 that has a database called MaintenanceR1 with a table called WorkOrder.
Instance2 is a linked database on Instance1. I want to copy any changed or new records from Instance2.MaintenanceR1.WorkOrder to Instance1.Maintenance.TempWorkOrder every hour.
I thought about creating a job that deletes all of the records in Instance1.Maintenance.TempWorkOrder and repopulates it with Instance2.MaintenanceR1.WorkOrder every hour. I am afraid this approach will let the log file get out of control as far as size goes.
Would I be better off dropping the table and re-creating it to keep the log file size reasonable? The table contains about 30,000 rows of data.
30,000 rows really shouldnt cause anything to get out of control. If you are really worried about log size, you can truncate instead of delete and bulk load with minimal logging your insert into the table.
https://www.mssqltips.com/sqlservertip/1185/minimally-logging-bulk-load-inserts-into-sql-server/
https://learn.microsoft.com/en-us/sql/t-sql/statements/truncate-table-transact-sql
I want to create a temp table so as to be able to join it to a few tables because joining those tables with the content of the proposed temporary table takes a lot of time (fetching the content of the temporary table is time consuming.Repeating it over and over takes more and more time). I am dropping the temporary table when my needs are accomplished.
I want to know if these temporary tables would be visible over other client session(my requirement is to make them visible only for current client session). I am using postgresql. It would be great if you could suggest better alternatives to the solution I am thinking of.
PostgreSQL then is the database for you. Temporary tables done better than the standard. From the docs,
Although the syntax of CREATE TEMPORARY TABLE resembles that of the SQL standard, the effect is not the same. In the standard, temporary tables are defined just once and automatically exist (starting with empty contents) in every session that needs them. PostgreSQL instead requires each session to issue its own CREATE TEMPORARY TABLE command for each temporary table to be used. This allows different sessions to use the same temporary table name for different purposes, whereas the standard's approach constrains all instances of a given temporary table name to have the same table structure.
Pleas read the documentation.
Temporary tables are only visible in the current session and are automatically dropped when the database session ends.
If you specify ON COMMIT, the temporary table will automatically be dropped at the end of the current transaction.
If you need good table statistics on a temporary table, you have to call ANALYZE explicitly, as these statistics are not collected automatically.
By default , temporary tables are visible for current session only and temporary tables are dropped automatically after commit or closing that transaction, so you don't need to drop explicitly.
The auto vacuum daemon cannot access and therefore cannot vacuum or analyze temporary tables. For this reason, appropriate vacuum and analyze operations should be performed via session SQL commands. For example, if a temporary table is going to be used in complex queries, it is wise to run ANALYZE on the temporary table after it is populated.
Optionally, GLOBAL or LOCAL can be written before TEMPORARY or TEMP. This presently makes no difference in PostgreSQL and is deprecated
I'm trying to figure out if there's a method for copying the contents of a main schema into a table of another schema, and then, somehow updating that copy or "refreshing" the copy as the main schema gets updated.
For example:
schema "BBLEARN", has table users
SELECT * INTO SIS_temp_data.dbo.bb_users FROM BBLEARN.dbo.users
This selects and inserts 23k rows into the table bb_course_users in my placeholder schema SIS_temp_data.
Thing is, the users table in the BBLEARN schema gets updated on a constant basis, whether or not new users get added, or there are updates to accounts or disables or enables, etc. The main reason for copying the table into a temp table is for data integration purposes and is unrelated to the question at hand.
So, is there a method in SQL Server that will allow me to "update" my new table in the spare schema based on when the data in the main schema gets updated? Or do I just need to run a scheduled task that does a SELECT * INTO every few hours?
Thank you.
You could create a trigger which updates the spare table whenever an updated or insert is performed on the main schema
see http://msdn.microsoft.com/en-us/library/ms190227.aspx