… sure I understand why InnoDB used 210 GB for 234M rows when loaded in PK order. What am I doing wrong…-row metadata overhead in PK rows * PK index pages are 15/16 full as they are loaded in order * 7 bytes per-row metadata overhead…
Post: Follow these basics when migrating to Percona XtraDB Cluster for MySQL
May 1, 2013 By 10 Comments
…, it would be good if your async master can use ROW based binlog format as well to achieve better consistency, if… PK imposes an additional overhead, and because cluster performance is somewhat dependent on the slowest node – this overhead can easily become visible… is because because synchronous replication inside PXC has an additional overhead, this means the SQL_THREAD will not be able to…
Post: More on MySQL transaction descriptors optimization
April 26, 2013 By Leave a Comment
… round, since reportedly Dimitri was using 8 tables with 1M rows each (about 2.1GB) for his tests, while in our… we used a much larger one, 16 tables with 5M rows each (about 23GB). So it makes sense to check if… in read-only transactions, start suffering from the trx_list overhead created by concurrent updates. Once we step away from this…
Comment: Is Synchronous Replication right for your app?
May 16, 2013 By 18 Comments
… sets of events in a single transaction to reduce the overhead of the RTT. I was just trying to think of… not sure how useful it is to update the same row multiple times in a single transaction.”
Comment: Is Synchronous Replication right for your app?
May 15, 2013 By 18 Comments
…, I can think of a scenario where you update a row multiple times before committing: Your apps send frequent updates into… otherwise everything goes through synchronous replication, then it mitigates the overhead of the RTT. The events in the MQ may not…
Post: How much overhead is caused by on disk temporary tables
August 16, 2007 By 26 Comments
…| table | type | possible_keys | key | key_len | ref | rows | Extra | +—-+————-+——-+——+—————+——+———+——+———+—————–+ | 1 | SIMPLE | gt | ALL | NULL | NULL | NULL …on tmpfs as this should avoid write overhead we’ve observing (and which is indeed…
Post: How many partitions can you have ?
December 5, 2009 By 19 Comments
… – is this the “setup” overhead of statement opening all partitions for execution or is this “per row” overhead. To check this I ran the statements with different number of rows in the batch. With 100 rows per batch… with 10000 rows per batch performance was not significantly different from 1000 rows per batch so I conclude this is per row overhead. This…
Post: Efficient Boolean value storage for Innodb Tables
April 23, 2008 By 6 Comments
… for boolean flag storage in Innodb (not accounting for standard row overhead) if we use BIT(1), TINYINT or ENUM types but… is modest space savings of course but considering large per row overhead Innodb has this will transform to much larger savings if…: NULL Create_options: Comment: *************************** 3. row *************************** Name: tbool Engine: MyISAM Version: 10 Row_format: Fixed Rows: 2097152 Avg_row_length: 11 Data_length: 23068672…
Post: Using CHAR keys for joins, how much is the overhead ?
June 18, 2007 By 18 Comments
….i+t2.j+length(t2.c)+t1.j) | +———————————-+ | 10239901336 | +———————————-+ 1 row in set (1.70 sec) Here is explain if someone…_keys: NULL key: NULL key_len: NULL ref: NULL rows: 262144 Extra: *************************** 2. row *************************** id: 1 select_type: SIMPLE table: t2 type…: j key_len: 4 ref: test.t1.i rows: 26 Extra: 2 rows in set (0.00 sec) So what about Innodb…
Post: MySQL File System Fragmentation Benchmarks
March 21, 2008 By 28 Comments
….7170957877sec. tables: 1000; total records: 10000000; write rows per sec: 5180.4069362984 , reads rows per sec: 1346.7226581156sec. tables: 10000; total records… was created without dir_index option which should add significant overhead for insert with many tables. The read performance, which is…
