Given that indexing is so important as your data set increases in size, can someone explain how indexing works at a database-agnostic level?
For information on queries to index a field, check out How do I index a database column.
Is there a way to see a list of indices on a collection in mongodb in shell? i read through http://www.mongodb.org/display/DOCS/Indexes but i dont see anything
Imagine a table with multiple columns, say, id, a, b, c, d, e. I usually select by id, however, there are multiple queries in the client app that uses various conditions over subsets of the columns.
When MySQL executes a query on a single table with…
Say, we have something like this:
add_column :users, :single, :boolean
add_index :users, :single
and then later we do
rename_column :users, :single, :married
Will ActiveRecord and/or the database handle the renaming of the index as well or do I…
I have a table that has one boolean column.
productid integer
isactive boolean
When I execute the query
SELECT productid
FROM
product
WHERE ispublish
LIMIT 15 OFFSET 0
After that, I created an index for the ispublish…
I could not reach any conclusive answers reading some of the existing posts on this topic.
I have certain data at 100 locations the for past 10 years. The table has about 800 million rows. I need to primarily generate yearly statistics for each…
I have a simple query to join two tables that's being really slow. I found out that the query plan does a seq scan on the large table email_activities (~10m rows) while I think using indexes doing nested loops will actually be faster.
I rewrote the…
I create indexes without the USING BTREE clause. Is there any advantage of using BTREE index?
CREATE INDEX `SomeName` USING BTREE ON `tbl_Name`(`column_name`);
A field on a model, foo = models.ForeignKey(Foo) will automatically add a database index for the column, in order to make look-ups faster. That's good and well, but Django's docs don't state whether the fields in a model-meta's unique_together…
I have read in the latest release that super columns are not desirable due to "performance issues", but no where is this explained.
Then I read articles such as this one that give wonderful indexing patterns using super columns.
This leave me with…
I have a query of such like
$query = "SELECT * FROM tbl_comments WHERE id=222 ORDER BY comment_time";
Do I need to add an index on the comment_time field?
Also, if I want to get the data between two dates then how should I build the index?
In docs for various ORMs they always provide a way to create indexes, etc. They always mention to be sure to create the appropriate indexes for efficiency, as if that is inherent knowledge to a non-hand-written-SQLer who needs to use an ORM. My…
I'm undecided whether it's better, performance-wise, to use a very commonly shared column value (like Country) as partition key for a compound primary key or a rather unique column value (like Last_Name).
Looking at Cassandra 1.2's documentation…
I am creating a new Neo4j database. I have a type of node called User and I would like an index on the properties of user Identifier and EmailAddress. How does one go setting up an index when the database is new? I have noticed in the…
I've never really understood the difference between these two indexes, can someone please explain what the difference is (performance-wise, how the index structure will look like in db, storage-wise etc)?
Included index
CREATE NONCLUSTERED INDEX…
