optimizing a Slow MySQL query using EXPLAIN output
The database was running on RDS with pretty high QPS (spikes up to 200). On average that caused 50 IOP/s to disk. Changing instance storage type from magnetic to Generic SSD solved the issue.
Slow mysql query with LEFT-JOIN
mysql,sql,join,left-join,explain
You are comparing category.catid varchar(16) with items.catid int(11) will be more faster if you compare int = int deducing that catid is just numbers you can try alter the catid column in category table alter table category modify column catid int(11) NOT NULL; test this code above. NOTE: if you...
EXPLAIN in postgresql not working
sql,postgresql,syntax,syntax-error,explain
It should not work - DDL statements has no plan - so EXPLAIN has nothing to show.
MySQL - How can I know my query is tuned?
Except for trivial queries, there is no way to know if you have the optimal query & indexes. Nor can you get a metric for how well designed the schema and application are. 3 seconds on a cold system for a 3-way JOIN with "Rows" of 409, 45, 1 is...
db2 explain stored procedure
If I have understood your requirements correctly you have a procedure where you would like to explain the plan for a query inside that procedure. I'll invent some bogus stuff to explain my thoughts: create table t ( x int not null primary key , y int not null) @...
Reduce row scan of update query without using index
mysql,sql-update,innodb,explain
Yes. You want an index on H_M_SAMP(M_ID): create index idx_h_m_sampe_1 on h_m_sampe(m_id); ...
fix Using index, Using temporary, Using filesort
ORDER BY `t`.`position`,`st`.`position`,`n`.`position` ASC You can't eliminate the temp table and filesort in this query, given the tables you have, because you're sorting on columns from multiple tables. Optimizing sorting means using an index so that the query fetches rows in the order you want them. But there's no way...