CODEWITHSUNDEEP
sql-server-2008cachingdatabase-performance
user278618
user278618

Reputation: 20292

Create a view or new table for caching records

I'm experiencing huge performance problem in one legacy application.

There is a search form where user can search records with given value. A result row contains 10 columns. Then a SP returns any row which contains in any column that value.

This SP uses 8 Tables and some of them have about million records. Every minute I get a new record. This SP conducts paging as well. Execution of this SP takes sometimes around 40 seconds.

What I did was, I created a new table and put there all records by using a query from this SP, but without conditions. When there is a new update or update in one of source table I use a trigger and update this new "cache" table. Now waiting for results from this new table takes only 1-3 seconds.

Has someone experience with something like this?

One of my colleagues said I better use view, but then every time I will be making JOINS.

What do you think? Is there another way?

Upvotes: 3

Views: 892

Answers (3)

Samvel Avanesov
Samvel Avanesov

Reputation: 422

Your solution is a robust way of doing what is called in Microsoft SQL Server "an indexed view" or "materialized view" in Oracle.

Basically you are correct - it's faster to navigate single indexed table then a dozen ones which are updated constantly.

You should really try creating an indexed view (some start here https://technet.microsoft.com/en-us/library/dd171921(v=sql.100).aspx) and it will probably solve all your performance issues.

Upvotes: 2

Brian Pressler
Brian Pressler

Reputation: 6713

Often times temporary tables can help you resolve performance issues. One approach might be to collect only the records that you need to consider into temporary tables and then create your final select statement from the temporary tables joined to any other tables that you're not filtering.

As an example, let's say one of the fields you are searching for is field1 in table1. Start by inserting into table #table1 only records that have the value of field1 you are looking for:

select PrimaryKeyTable1, Field1, Field2, Field3, etc...
into #table1
from table1
where Field1 = 'Whatever you are looking for'

This should be pretty fast even for a big tables, especially if you have an index on Field1. You do this for every table with search fields to collect all the records that have relevant records you are searching.

Then you also need to be sure to insert any records into your temporary tables that might have foreign key references to any of your other temporary tables. So let's say you also built a table #table2 with the above method that has a foreign key to table1 called PrimaryKeyTable1. You would insert those records like:

Insert into #table1
    (PrimaryKeyTable1, Field1, Field2, Field3, etc...)
select table1.PrimaryKeyTable1, table1.Field1, table1.Field2, table1.Field3, etc...
from table1
join #table2
on table1.PrimaryKeyTable1 = table2.PrimaryKeyTable1
where table1.PrimaryKeyTable1 not in
    (Select PrimaryKeyTable1 from #table1)

Now you will also have any records in #table1 that match to a record in #table2 that contain records that match the search criteria. You do this for all your temporary tables that have relevant foreign keys. The order that you do the inserts matters; be sure that you don't reference any temporary tables until after the last insert statement while collecting the foreign key referenced records.

Then you can simply do your final select statement, replacing the actual tables with the temporary tables you have built and eliminating all the filters that search your field data. Depending on the structure of your query there might be other optimizations, but that is the general idea.

If you've already explored all of your indexing options and this still doesn't help, MS SQL Server has "Change Tracking" features that maybe be of use to you in building your cache table. You enable the database for change tracking and configure which tables you wish to track. SQL Server then creates change records on every update, insert, delete on a table and then lets you query for changes to records that have been made since the last time you checked. This is very useful for syncing changes and is more efficient than using triggers. It's also easier to manage than making your own tracking tables. This has been a feature since SQL Server 2005.

How to: Use SQL Server Change Tracking

Change tracking only captures the primary keys of the tables and let's you query which fields might have been modified. Then you can query the tables join on those keys to get the current data. If you want it to capture the data also you can use Change Capture, but it requires more overhead and at least SQL Server 2008 enterprise edition.

Change Data Capture

Upvotes: 3

harsh pareek
harsh pareek

Reputation: 61

You can use schema binding View and create cluster index on view.it will store your view data physically.but after creating schema binding view you can not alter your table.

Upvotes: 1

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