June 18, 2013

Comment: Benchmarking Percona Server TokuDB vs InnoDB

May 7, 2013 By 32 Comments

… is indexes. If you add multiple multi-column indexes the difference with InnoDB will be even more notable. Also it allows multiple clustering indexes… 3.x and 4.x). It really shines on large tables and index scan like queries.

Filed Under: Benchmarks, MySQL, Percona Server Tagged With: , , ,

Post: Galera Flow Control in Percona XtraDB Cluster for MySQL

May 2, 2013 By 5 Comments

… transactions that have been certified but not yet applied, so multi-node writing will not lead to inconsistencies, but that is… lookups into the certification index, which is a hash table.  A small fc_limit does however keep the certification index smaller in memory… the slaves with no writes coming from them. However, with multi-node writing, larger queues will make certification more expensive replication…

Filed Under: Insight for DBAs, Percona Live, XtraDB Cluster Tagged With: , , ,

Post: Is Synchronous Replication right for your app?

May 14, 2013 By 18 Comments

…a single row (well, the PRIMARY KEY index entry for that row).  This means typically…are maintained in separate tables and there also exists a users_groups table to define the relationship between…This is not implemented for full BEGIN … COMMIT multi-statement transactions since it cannot be assumed…

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Post: Multi Column indexes vs Index Merge

September 19, 2009 By 31 Comments

… combined multi-column index on (AGE,STATE). Lets see why it is the case. MySQL indexes are (with few exceptions) BTREE indexes – this index type… compared to single index only but it is by far better to use multi column indexes. But the problems with Index Merge do not… intersection) on values it gets from the single table. I have reverted table to have i1 and i2 as independent columns in…

Filed Under: Insight for DBAs, MySQL Tagged With:

Post: Sphinx search performance optimization: multi-threaded search

January 16, 2013 By 10 Comments

…): source src1 { type = mysql sql_query = SELECT id, text FROM table } index idx1 { type = plain source = src1 } searchd { dist_threads = 0 # default… table WHERE id % 3 = 2; } index idx1_template { type = plain source = src1 } index idx1p0 : idx1_template { source = src1p0 } index idx1p1 : idx1_template { source = src1p1 } index…

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Post: Performance Schema tables stats

May 2, 2011 By 2 Comments

… memory workload and against single tables. Now after adding multi-tables support to sysbench, it …table with statistic per index: mysql> select * from table_io_waits_summary_by_index_usage where OBJECT_NAME=’sbtest55′G *************************** 1. row *************************** OBJECT_TYPE: TABLE…

Filed Under: MySQL

Post: 3 ways MySQL uses indexes

September 12, 2009 By 28 Comments

… see how many index parts are actually used for row lookup. Very common problem I see is multi column indexes which are used… on the table. In such case you would see “Index” type in explain which correspond to scanning (potentially) complete table in the index order. It is very important to understand in which conditions index can be used to…

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Post: Sysbench with support of multi-tables workload

April 29, 2011 By 4 Comments

… select insert delete update_index update_non_index to support different OLTP modes. Most interesting: all scripts support –oltp-tables-count=N ( default 1), in this case N sbtest tables…

Filed Under: MySQL

Post: Multi Range Read (MRR) in MySQL 5.6 and MariaDB 5.5

March 21, 2012 By 10 Comments

…. Multi Range Read With traditional secondary index lookups, if the columns that are being fetched do not belong to the secondary index definition…. Suppose you have the following query executed on the InnoDB table: SELECT non_key_column FROM tbl WHERE key_column=x… traditional index lookup (for non-index-only columns) involves, reading an index record, and then using the PK column value in the index record…

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Post: Why MySQL could be slow with large tables ?

June 9, 2006 By 141 Comments

… (ie old and rarely accessed data stored in different servers), multi-server partitioning to use combined memory and a lot of… to work with in temporary table etc. Prefer full table scans to index accesses – For large data sets full table scans are often faster than range scans and other types of index…

Filed Under: Insight for DBAs Tagged With: ,
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