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How to improve this query
Message
From
13/05/2021 14:15:27
Mike Yearwood
Toronto, Ontario, Canada
 
General information
Forum:
Visual FoxPro
Category:
Databases,Tables, Views, Indexing and SQL syntax
Miscellaneous
Thread ID:
01680377
Message ID:
01680405
Views:
27
>>>Hi,
>>>
>>>When one of the features of the application is called (VFP form is opened), my application loads ALL records from the SQL Server DB. This is a spare parts table. Let's put aside that - maybe - I need to change the logic and get only those records the user needs.
>>>Right now, one of the customers has about 25000 record in this table. They timed that it takes from 30 to 40 seconds to load them into the application window. Is it reasonable (I know it is subjective), but in general?
>>>
>>>I use the code
>>>
>>>select * from MyTable
>>>
>>>when pulling all records.
>>>
>>>How can I improve the above SQL Select?
>>>
>>>TIA
>>>
>>>UPDATE. The customer just sent me an email and wrote that sometimes pulling the records takes as little as 3 seconds. Just like right now.
>>>
>>>UPDATE 2. Actually I found that the query is not "select * ..." but listing all fields/columns of the table. So, the query is:
>>>
>>>select field1, field2... and so on from MyTable
>>>
>>>
>>>I probably need to change this to "select * "
>>
>>If both queries are for the same table, having one with select * and another with select (list all field names), will result in 2 entries in the query plan cache and one may not optimize like the other.
>
>The SQL Select that I am talking about - above - is used (one time) in the CursorAdapter property .SelectCmd
>That is, when the CA gets the data, it uses this property. I am sure Walter Meester knows more about query efficiencies and he mentioned that changing from listing all columns (in the SQL Select) to selecting all (select * ) won't make much of a difference. But maybe I will still try. At least, on the surface, I see no harm

Which is rude. Walter knows more about query efficiency than who?

2 queries get different query plans. Each plan may have different optimization.
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