… that writes dynamic SQL. And it only takes one SQL injection vulnerability to cause a big problem. Your …an input data string, followed by invalid SQL syntax: http://example.com/page.php?param=string’ TEST …be protected again if you use query results in a subsequent SQL query, then you should be …
Post: Are larger buffers always better ?
June 6, 2006 By 9 Comments
…=MyISAM DEFAULT CHARSET=utf8 select sql_no_cache count(*) from t1 where c in (select sql_big_result count(*) from t1 where d=50… ahead and set them to 64M ? Not really – this could result in nasty suprises with full table scan LIMIT queries as… away the rest. These are some examples I’m quite sure there are others. For example too large table_cache may slow…
Post: MySQL Session variables and Hints
December 28, 2006 By 2 Comments
… as SQL_BIG_RESULT, STRAIGHT_JOIN, FORCE INDEX etc. You place these directly into the query to change how query is executed for example… query is executed, so I could do something like: SELECT SQL_SORT_BUFFER_SIZE=50000000 NAME FROM LARGE_TABLE ORDER BY…
Comment: Why MySQL could be slow with large tables ?
June 19, 2006 By 141 Comments
… which you need to consider – for example if you do GROUP BY and number of resulting rows is large you might get pretty poor speed because temporary table is used and it grows large. Using SQL_BIG_RESULT…
Post: New SpecJAppServer results at MySQL and Sun.
November 12, 2008 By Leave a Comment
… It would be very interesting to see for example results on the same hardware just running PostgreSQL …in /etc/my.cnf (included in FDA) [mysqld] sql-mode = IGNORE_SPACE transaction-isolation = READ-COMMITTED …_cache_size = 0M – query cache disabled. Not a big surprise though as this is default value …
Post: Checking for a live database connection considered harmful
May 5, 2010 By 38 Comments
…function query_database(connection, sql, retries=1) while true try result=connection.execute(sql) return result catch InactiveConnectionException e if…these issues, because it’d be a big help to apps when they grow. It…a sore thumb. (Edit) Here’s another example of the impact of these silly queries: #…
Post: A case for MariaDB's Hash Joins
May 31, 2012 By Leave a Comment
… the results of executing benchmarks for different queries and explain the results so … hash tables would be created. For example if the left operand has “n”…clause on an indexed column The SQL used for this test together …non-indexed column. They also provide big improvement in query response time …
Post: High-Performance Click Analysis with MySQL
December 22, 2008 By 13 Comments
…so ETL jobs written to rely on SQL tend to get really bogged down.Â…ranges of values for various attributes, for example; or the presence or absence of values…work on a slave, then piping the results back up to the master with …joins are not all that fast on big joins; the query optimizer can sometimes…
Post: Updated msl (microslow) patch, installation walk-through!
April 20, 2008 By 17 Comments
…example-storage-engine’ ‘–with-federated-storage-engine’ ‘–without-bench’ ‘–with-zlib-dir=bundled’ ‘–with-big…sql/sql_cache.cc patching file sql/sql_class.cc patching file sql/sql_class.h patching file sql/sql_parse.cc patching file sql/sql_select.cc patching file sql/sql… intermediate results  
Post: Four ways to optimize paginated displays
September 24, 2008 By 27 Comments
… results pages, leaderboards, and most-popular lists are good examples. You know the design pattern: display 20 results in…and the total count, you either a) use SQL_CALC_FOUND_ROWS (see our post on this…-organizing data, or query optimizations, there are two big things you can do. One is caching …
