How to create an effective Index with this query?
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table: CREATE TABLE `deal` ( `id` int(11) NOT NULL default '0', `site` int(11) NOT NULL default '0', `time` bigint(13) NOT NULL default '0', PRIMARY KEY (`id`), KEY `site` (`site`), KEY `time` (`time`,`site`) ) TYPE=MyISAM sql query: select * from `deal` where time>0 && site=8 I create index:time for this query, but why this query always using index: site? explain select * from `deal` where time>0 && site=8 output: table type possible_keys key key_len ref rows Extra...
Answer:
You need to create composite index site + time (yes, order matters). So delete both indexes site and...
Zenofo at Stack Overflow Mark as irrelevant Undo
Other solutions
Answer:
You control the indexes that are created, so you control the space used. Compare MongoDB to a Key/Value...
Gaëtan Voyer-Perrault at Quora Mark as irrelevant Undo
Howdy, Can I ask a Cassandra data model question here about time series data and timeline query? Materialized Views or Index CF, which way is better to handle 20 single column indexes in one table? We have a book table with 20 columns, 300 million rows...
Answer:
Short answer - Use IndexCF. You will have to hit cassandra twice to get full object but thats a tradeoff...
Sarang Anajwala at Quora Mark as irrelevant Undo
If we create the following index: { a: 1, b: 1, c: 1, d: 1 } Will the following query and sort operations use the index? db.collection.find({a:5,f:7,h:9).sort( { a:1 } )
Answer:
cursor.explain() provides an information about the query plan. Just append ".explain()" to...
Michael Spector at Quora Mark as irrelevant Undo
I have an oracle database (8.1.7) ... it has two columns that i want to context index title and subtitle I want to run a query like this when i'm finished select isbn,title,subtitle from MASTER where contains (concat, 'Cheeses',1) > 0 and get results...
Answer:
Hi Brian, From your question, there appears to be multiple ways to solve your problem. Essentially...
chiefarcher-ga at Google Answers Mark as irrelevant Undo
I have an .mdb database. I created a query. I exported it to excel. That's all fine and dandy... but now I have to help hundreds of others do the same thing. I made a cute little instruction sheet on how to do it step by step, copy/pasting the SQL code...
Answer:
one idea to think about...instead of exporting from Access to Excel, why not just "import"...
Steven at Yahoo! Answers Mark as irrelevant Undo
I also want to compare the beta of these stock indices with HFN Asset Based Lending Index.
Answer:
As a data source, you can usually tap into the historical prices of the financial information platforms...
Lutz Enke at Quora Mark as irrelevant Undo
In some data mining scenarios, I have a MongoDB collection whose records are heterogenous (i.e. they can have different keys). I often query for "which records have a field with a given key", as in db.coll.find({"fieldname":{$exists...
Answer:
In MongoDB 1.8 $exists doesn't use indexes. In 1.9 it does[1]. 1.9 is the unstable development release...
David Mytton at Quora Mark as irrelevant Undo
i have two columns in a sql table that i need to perform math on (qty max - min onhand) during a query and display the calculated results in a field with the query results. i am using microsoft sql server management studio express to complete this. I...
Kevin K at Yahoo! Answers Mark as irrelevant Undo
SurveyResearchFilter: Creating an index when response items are on different (and somewhat non-sensical) scales. I am working with a large survey data set. There are several questions that are of interest to me and these questions hang quite well together...
Answer:
Transform the weird ones (a, dis, dep) to (a, dep, dis), do principal components (which you already...
proj at Ask.Metafilter.Com Mark as irrelevant Undo
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