MySQL Proxy, reverse mode + source

The MySQL proxy got some final touches to make it ready for the first release:

  • a command-line interface
  • some more mode descriptions for the different modes of operation

You can choose between three modes for now:

  • pseudo server
  • injection proxy

injection proxy * replication client

replication client

For the future we plan:

  • connection pooling

connection pooling * replication ...

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Trees in SQL

The problem of how to handle trees in SQL has been talked about alot. The basic 3 ways are:

  • store the full path for each entry
  • store the parent for each node
  • use nested tree

Nested tree is good for read-many-write-less applications where the tree doesn't check over time ...

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Analyzing complex queries

When you ask someone how to optimize SQL queries you will always get the answer

  • enable the slow query log
  • set the long-query-time to 1-2 seconds
  • enable the logging of query which aren't using an index
  • run EXPLAIN on the queries that are shown and optimize them with proper ...
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groupwise max

... or "How to solve the same problem in 10 different ways".

One of the common problems to solve in SQL is "Get row with the group-wise maximum". Getting just the maximum for the group is simple, getting the full row which is belonging to the maximum is the interesting step ...

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ORDER BY RAND()

If you read the MySQL manual you might have seen the ORDER BY RAND() to randomize the the rows and using the LIMIT 1 to just take one of the rows.

SELECT name
  FROM random
 ORDER BY RAND()
 LIMIT 1;

This example works fine and is fast if you only ...

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