… select statements on this and other tables …. UPDATE assets SET x=1, y=2, z=3 WHERE asset.id=12 Transaction-2… that the deadlock is occurring because Transaction-1 is upgrading from a S to an X lock but Transaction 2 is already waiting for an X lock on assets since it came in between the SELECT and UPDATE statements in Transaction-1 and hence…
Comment: GROUP_CONCAT useful GROUP BY extension
November 13, 2012 By 49 Comments
i have below loop for($x=$c;$x!=1;$x–){ $sql1=”select l2tpCDR.iccid as ic, sum(l2tpCDR.data) as ….ICCID=l2tpCDR.iccid where StatementID=0 and sim.simID=’” . $b[$x] . “‘ group by ic”; $result1=mysql_query($sql1); mysql_error(); $row1…
Post: Fast storage: 8 SSD Intel X-25M 80GB benchmarks
January 18, 2010 By 15 Comments
…. He granted me access to servers with 8 attached Intel X-25M 80GB MLC cards. The cards attached to 2 Adaptec… 4 cards per controller. The cost of setup is 8 x 260$ (X-25M) + 2×500$ (Adaptec 5805) = ~3000$. Available space varies in… to note (beside SSD is doing much worse than FusionIO). 1. Something is wrong with scaling random writes in this setup…
Comment: Improved spam blocking solution for our blog
May 18, 2010 By 4 Comments
I found a simple challenge X+X, where X={1..9}, to be sufficient to ellimate all bot spam. Drop me a line I can send u a WP plugin its very simple.
Post: Getting around optimizer limitations with an IN() list
January 9, 2010 By 9 Comments
…_keys | key | key_len | ref | rows | Extra | +—-+————-+————-+——-+—————+———–+———+——+——+————-+ | 1 | SIMPLE | coordinates | range | x_y_col_a | x_y_col_a | 38 | NULL | 4032 | Using…_keys | key | key_len | ref | rows | Extra | +—-+————-+————-+——-+—————+———–+———+——+——+————-+ | 1 | SIMPLE | coordinates | range | x_y_col_a | x_y_col_a | 3 | NULL | 4032 | Using…
Post: Eventual Consistency in MySQL
November 18, 2011 By 8 Comments
…_SCHEMA: test TABLE_NAME: Bar COLUMN_NAME: X ORDINAL_POSITION: 1 POSITION_IN_UNIQUE_CONSTRAINT: 1 REFERENCED_TABLE_SCHEMA: test REFERENCED_TABLE_NAME… OUTER JOIN test.Foo AS Foo ON (Bar_ibfk_1.X,Bar_ibfk_1.Y) = (Foo.A,Foo.B) WHERE Foo.B IS… OUTER JOIN test.Foo AS Foo ON (Bar_ibfk_1.X,Bar_ibfk_1.Y) = (Foo.A,Foo.B) WHERE Foo.B IS…
Post: Implications of Metadata Locking Changes in MySQL 5.5
February 1, 2013 By 9 Comments
… (0.00 sec) session1 > select * from test where id=1; +—-+——+ | id | x | +—-+——+ | 1 | foo | +—-+——+ 1 row in set (0.00 sec) session2 > ALTER TABLE… test; session10 > select * from test_2 order by id; +—-+——+ | id | x | +—-+——+ | 1 | foo | | 2 | bar | +—-+——+ 2 rows in set (0.00 sec…
Post: New distribution of random generator for sysbench - Zipf
May 9, 2012 By 3 Comments
… 3^θ less, …, row X is accessed X^θ less times. Say θ=1.1, then if row 1 accessed 1,000,000 times, then row 2 is : 1,000,000/(2^1.1…,000^1.1) = 39 times. Obviously with θ=0 we are getting uniform distribution – each row is accessed equal times ( for row X: 1/(X…
Post: Some fun with R visualization
February 23, 2012 By 5 Comments
… me remind how I do measurements. I run benchmark for 1 hours, with measurements every 10 seconds. So we have 360…
Post: Moving Subtrees in Closure Table Hierarchies
February 14, 2011 By 18 Comments
… a.descendant = d.descendant LEFT JOIN TreePaths AS x ON x.ancestor = d.ancestor AND x.descendant = a.ancestor WHERE d.ancestor = ‘D’ AND x.ancestor IS NULL; That deletes paths that terminate within the …, length) SELECT supertree.ancestor, subtree.descendant, supertree.length+subtree.length+1 FROM TreePaths AS supertree JOIN TreePaths AS subtree WHERE subtree…
