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How to find a hash key containing a matching value
....9 and greater:
hash.key(value) => key
Ruby 1.8:
You could use hash.index
hsh.index(value) => key
Returns the key for a given value. If
not found, returns nil.
h = { "a" => 100, "b" => 200 }
h.index(200) #=> "b"
h.index(999) #=> nil
So to get "oran...
Rails 3: Get Random Record
... big tables but more sql-style
UPD. You can use the following trick on an indexed column (PostgreSQL syntax):
select *
from my_table
where id >= trunc(
random() * (select max(id) from my_table) + 1
)
order by id
limit 1;
...
How can I make SQL case sensitive string comparison on MySQL?
...
@adjwilli If the column was a part of an index, you will suffer a performance hit on queries reliant on that index. To maintain performance, you need to actually alter the table.
– dshin
Sep 19 '13 at 18:50
...
How to use the 'main' parameter in package.json?
...meter in your package.json if the entry point to your package differs from index.js in its root folder. For example, people often put the entry point to lib/index.js or lib/<packagename>.js, in this case the corresponding script must be described as main in package.json.
You can't have two scr...
how do I insert a column at a specific column index in pandas?
Can I insert a column at a specific column index in pandas?
4 Answers
4
...
Fastest way to determine if record exists
... If it is not the PK, I would also suggest making sure there is an index on that column. Otherwise, the query will have to do a table scan instead of a faster table seek.
– CD Jorgensen
Aug 7 '13 at 22:23
...
Error: No default engine was specified and no extension was provided
...ch (program.template) {
case 'ejs':
write(path + '/views/index.ejs', ejsIndex);
break;
case 'jade':
write(path + '/views/layout.jade', jadeLayout);
write(path + '/views/index.jade', jadeIndex);
break;
case 'jshtml':
...
ElasticSearch, Sphinx, Lucene, Solr, Xapian. Which fits for which usage? [closed]
...essly expressed through JSON DSL.
Solr is also a solution for exposing an indexing/search server over HTTP, but I would argue that ElasticSearch provides a much superior distributed model and ease of use (though currently lacking on some of the search features, but not for long, and in any case, th...
Choosing a stand-alone full-text search server: Sphinx or SOLR? [closed]
... and Sphinx satisfy all of your requirements. They're fast and designed to index and search large bodies of data efficiently.
Both have a long list of high-traffic sites using them (Solr, Sphinx)
Both offer commercial support. (Solr, Sphinx)
Both offer client API bindings for several platforms/langu...
How to drop rows of Pandas DataFrame whose value in a certain column is NaN
...
Is there any advantage to indexing and copying over dropping?
– Robert Muil
Jul 31 '15 at 8:15
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