Fastest way for this query (What is the best strategy) given a date range

Question

I have a table A that has a startDate and an end dateDate as 2 datetime columns besides some more other columns. I have another table B that has one datetime column call it

Answer 1

Update:

See this article in my blog for efficient indexing strategy for your query using computed columns:

• Efficient date range query: SQL Server

The main idea is that we just compute rounded length and startDate for you ranges and then search for them using equality conditions (which are good for B-Tree indexes)

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In MySQL and in SQL Server 2008 you could use SPATIAL indexes (R-Tree).

They are particularly good for the conditions like "select all records with a given point inside the record's range", which is just your case.

You store the start_date and end_date as the beginning and the end of a LineString (converting them to UNIX timestamps of another numeric value), index them with a SPATIAL index and search for all such LineStrings whose minimum bounding box (MBR) contains the date value in question, using MBRContains.

See this entry in my blog on how to do this in MySQL:

• Overlapping ranges: MySQL

and a brief performance overview for SQL Server:

• Overlapping ranges: SQL Server

Same solution can be applied for searching a given IP against network ranges stored in the database.

This task, along with you query, is another often used example of such a condition.

Plain B-Tree indexes are not good if the ranges can overlap.

If they cannot (and you know it), you can use the brilliant solution proposed by @AlexKuznetsov

Also note that this query performance totally depends on your data distribution.

If you have lots of records in B and few records in A, you could just build an index on B.dates and let the TS/CIS on A go.

This query will always read all rows from A and will use Index Seek on B.dates in a nested loop.

If your data are distributed other way round, i. e. you have lots of rows in A but few in B, and the ranges are generally short, then you could redesign your tables a little:

A

start_date interval_length

, create a composite index on A (interval_length, start_date)

and use this query:

SELECT  *
FROM    (
        SELECT  DISTINCT interval_length
        FROM    a
        ) ai
CROSS JOIN
        b
JOIN    a
ON      a.interval_length = ai.interval_length
        AND a.start_date BETWEEN b.date - ai.interval_length AND b.date