I have annotation-driven hibernate capabilies on my project.
Now I want to create an index over a column. My current column definition is
@NotNull
@Column(name = "hash")
private String hash;
and I add @Index annotation here.
@NotNull
@Column(name =…
I have a query of such like
$query = "SELECT * FROM tbl_comments WHERE id=222 ORDER BY comment_time";
Do I need to add an index on the comment_time field?
Also, if I want to get the data between two dates then how should I build the index?
Is it possible in PostgreSQL to create a deferrable unique constraint on a character column, but case-insensitive?
Let's assume the following basic table:
CREATE TABLE sample_table (
my_column VARCHAR(100)
);
If deferrable constraint is not…
I have found out that there's two versions of SQL Server types that are very different in terms of pricing...
The Web version from my host provider costs about 13$ per 2 core packs, whereas the Standard edition is right around 200$.
From my…
I have a User model that looks like this:
class User < ApplicationRecord
belongs_to :organization
belongs_to :department
end
The users table in the database has the two foreign keys organization_id and department_id. How can I make these two…
When searching on Google for join table indexes, I got this question.
Now, I believe that it is giving some false information in the accepted answer, or I do not understand how everything works.
Given the following tables (running on PostGreSQL…
I am trying to reproduce the first example of index intersection instruction (http://docs.mongodb.org/manual/core/index-intersection/) but facing a problem: mongo doesn't uses both indexes
My steps:
Download mongo (3.0.3) and install it
Run mongod:…
I use NHibernate and SQL Server 2005 and I have an index on a computed column in one of my tables.
My problem is that when I insert a record to that table I get the following error:
INSERT failed because the following SET options have incorrect…
I have a column Column which is declared to be NULL DEFAULT(GETUTCDATE()) and there's a non-clustered index that includes this column. I want to change this column to be NOT NULL DEFAULT(GETUTCDATE()) and when I run ALTER TABLE ALTER COLUMN…
I am trying to compile a list of non-system-specific database indexes. I've looked at Oracle, DB2, MySQL, Postgres and Sybase, and almost every resource has a different list. So far I have seen:
clustered, multi-dimensional clustered, unclustered,…
Description :
Here is the sample demonstration of the performance issue.
We first created two tables , enabled row level security and created policy as well .
Table definition:
create table sample_schema.sample_table1(ID numeric(38) PRIMARY KEY NOT…
In my schema.rb I have the following line:
add_index "users", ["email"], name: "index_users_on_email", unique: true, using: :btree
When I run \di in psql I get:
Schema | Name | Type | Owner |…
I have big table with 22 millions records.
I want to execute next query:
select auto_alerts from alerts_stat where endDate > "2012-12-01"
To improve performance I added BTREE index for endData field:
CREATE INDEX endDate_index USING BTREE ON…
I know how binary search works but I wanted to know practical uses for binary search...
I searched through the internet and I found that the main use is data base indexing, but I couldn't understand how binary search could help in data base…
So I always thought that seeing "Using Where" in the Extra column was a good thing. However, I was planning a brown bag lunch for my coworkers on intepreting EXPLAIN and now I'm not so sure. The MySQL doc says this in the notes about "Using…
