…column. No matter what I did – forced it to use key, forced a different join order, it did not want to…ORDER BY tb1.title ASC LIMIT 4\G *************************** 1. row *************************** id: 1 select_type: SIMPLE … is converted to its equivalent binary string form; if you want to avoid …
Post: Faster Point In Time Recovery with LVM2 Snaphots and Binary Logs
February 23, 2012 By 3 Comments
… LSize Origin Snap% Move Log Copy% Convert lv_root VolGroup -wi-ao 5.54g…rows affected (0.49 sec) mysql> alter table employees add column age smallint unsigned not null default 0; Query OK, 300024 rows…can use `lvmsnap.sh snapshot` to create snapshots. The restore…
Comment: Air traffic queries in MyISAM and Tokutek (TokuDB)
November 6, 2009 By 26 Comments
… latest version – row-based and column-based. I suspect that fastest compression option (similar to gzip -1) should be used to save CPU time during loading. Don’t know which one is better (row-based or column-based) but it seems really easy to convert…
Post: MySQL Prepared Statements
August 2, 2006 By 21 Comments
… also can bind direct variables to return columns – which means not only data does not need to be converted back and forth but you also save extra data copying from row structure to your variables. So…
Post: Finding out largest tables on MySQL Server
February 4, 2008 By 27 Comments
… | +————————————-+——–+——–+——–+————+———+ 10 rows in set (2 min 29.19 sec) I do some converting and rounding to see number of rows in millions… on counting zeros. The last column shows how much does the index take compared to the data which is mainly…
Post: When is MIN(DATE) != MIN(DATE) ?
September 4, 2012 By 5 Comments
……. INDEX `uid` (uid, update_time), INDEX `bar` (some_other_columns) …. ) ENGINE=InnoDB; When he ran this query: SELECT … of zero, whereas doing a CAST() or a CONVERT() on the update_time field first (so that … 00:00:00. But then I decided to move my bogus rows around by changing their PK, and …
Post: Implementing efficient counters with MySQL
July 1, 2007 By 16 Comments
…are implemented the most trivial way – they convert read load to write load. When you would simply … to do in this case ? First separate them into special counter table, having say “id” and “counter” columns…course the fact you update short rows also helps. The next problem to deal with is log flushes…
Comment: Fixing column encoding mess in MySQL
December 18, 2007 By 32 Comments
Right. I’ve just tested changing the column charset to binary and UTF-8 and can confirm it works fine. … MySQL thinks there’s some other encoding, use CHANGE COLUMN to binary and back to proper encoding. (This is the case that jrabbit… itself is not OK, or if you only need to fix several rows, use CONVERT() tricks. (This is the case which I had…
Post: INSERT ON DUPLICATE KEY UPDATE and summary counters.
May 29, 2006 By 48 Comments
…ntoa functions which can convert IP address strings to integers and back. This allows to save on field … in insert clause but this would require to specify list of columns which we skipped for sake of…UPDATE could be different, depending on number of new rows and data set size. 30% speedup should be…
Post: Find unused indexes
June 30, 2012 By Leave a Comment
…-usage uses EXPLAIN and User Statistics number of rows read for every index. So we’re …-index-usage tries to convert non-SELECT queries to SELECT queries and is not always possible to get a perfect…but your application may need them to avoid duplicates on the column. Take in account that depending on…
