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Displaying posts with tag: optimization (reset)
Optimized Pagination using MySQL

Dealing with large data sets makes it necessary to pick out only the newest or the hottest elements and not displaying everything. In order to have older items still available, Pagination navigation's have become established. However, implementing a Pagination with MySQL is one of those problems that can be optimized poorly with MySQL and certainly other RDBM systems. However, knowing the underlying database can also help in optimizing pagination queries, because there is no real copy and paste solution.

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Optimized Pagination using MySQL

Dealing with large data sets makes it necessary to pick out only the newest or the hottest elements and not displaying everything. In order to have older items still available, Pagination navigation's have become established. However, implementing a Pagination with MySQL is one of those problems that can be optimized poorly with MySQL and certainly other RDBM systems. However, knowing the underlying database can also help in optimizing pagination queries, because there is no real copy and paste solution.

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OR conditions considered bad... Or? And a workaround.

Some things are known to be just bad. GOTOs used to be one such thing (something I still use them, but only where appropriate, which isn't that many places). Maybe it is just so, that some things are useful, but not for everything, so maybe the issue is that they are used inappropriately. Or?

The OR condition is one such things in MySQL circles! Oh, you have an OR condition! That is going to be so slow! sort of. And the reason an OR is "slow" is that as MySQL will use only one index for each statement, only one "side" or the or condition can use an index. Or sometimes even worse, MySQL will consider using an index that is common to the two "sides" or is outside the OR conditition, despite that fact that there are perfectly fine, highly selective indexes on both sides of the OR condition.

If you ask me, this is not a fault with the OR condition but rather a problem with the MySQL optimizer. Why in heavens name can't a …

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On Covering Indexes and Their Impact on Performance

The purpose of this post is to describe what covering indexes are and how they can be used to improve the performance of queries. People mostly use indexes to filter or sort the results but not much thought is given to actually reduce the disk reads by using proper indexes. So I will show you how to reduce disk reads and hence improve the performance of queries by utilizing indexes properly.

Optimizing UPDATE and DELETE statements

While most people look at performance optimizations for SELECT statements, UPDATE and DELETE statements are often overlooked. These can benefit from the principles of analyzing the Query Execution Plan (QEP). You can only run an EXPLAIN on a SELECT statement, however it’s possible to rewrite an UPDATE or DELETE statement to perform like a SELECT statement.

To optimize an UPDATE, look at the WHERE clause. If you are using the PRIMARY KEY, no further analysis is necessary. If you are not, it is of benefit to rewrite your UPDATE statement as a SELECT statement and obtain a QEP as previously detailed to ensure optimal indexes are used. For example:

UPDATE t
SET     c1 = ‘x’, c2 = ‘y’, c3 = 100
WHERE c1 = ‘x’
AND     d = CURDATE()

You can rewrite this UPDATE statement as a SELECT statement for using EXPLAIN:

EXPLAIN SELECT c1, c2, c3 FROM  t WHERE c1 = ‘x’ AND    d = CURDATE()

You should …

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Statement-based vs Row-based Replication

Replication as most people know it, has mostly been SQL statement propagation from master to slave. This is known as "statement-based" replication. But there is also another kind of replication that is available, "the row-based replication" and that has quite a lot of benefits. In this post I intend on highlighting the advantages and disadvantages of both the types of replication to help you choose the best one. I also follow up with my own recommendation.

Find friends of friends using MySQL

In a previous article, I've already talked about an optimized way to connect locations in a geographic point of view by using MySQL. In this manner, locations of pubs, drugstores, barbers or even users can be obtained. Communities, or perhaps I should use the newer term Social Networks, make use of the buddy network of indiviual members in addition to the geographical mapping. This has many psychological advantages, because new members can be integrated in an established network very easily and I'm more willing to become involved when I already know some of the members.

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Find friends of friends using MySQL

In a previous article, I've already talked about an optimized way to connect locations in a geographic point of view by using MySQL. In this manner, locations of pubs, drugstores, barbers or even users can be obtained. Communities, or perhaps I should use the newer term Social Networks, make use of the buddy network of indiviual members in addition to the geographical mapping. This has many psychological advantages, because new members can be integrated in an established network very easily and I'm more willing to become involved when I already know some of the members.

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Is it possible to avoid query parsing inside of MySQL?

I've just started learning MySQL's internals but I've got an idea which I want to convert to a question here, to ask people who are already deeper in it. Is it a bad idea to completeley avoid query parsing on the server side and use a binary protocol instead? This way the client parses the query and could cache the statement structure for further usage or another client API uses a NoSQL approach to send the request data to the server.

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Tech Messages | 2010-12-21

A special extended edition of Tech Messages for 2010-12-14 through 2010-12-21:

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