Should the column used to order results be included in the index of a postgresql table?

I am creating indexes for a PostgreSQL database. I would like to know whether the column(s) used to order results in a PostgreSQL statement should be included in the index. Assume I have created a …

Using two single-column indexes in where and orderby clause

I have googled a lot and couldn’t find a clear answer to my question assume we have this query SELECT * WHERE user_id = x ORDER BY date_created If we have a single column index on user_id and another …

Is there a way to use MySQL fulltext to search related tables?

I have a table called persons which contains data about, well, people. It also contains foreign keys to another table. I’d like to make a fulltext index that is able to search the related tables for …

Does DB2 implement multi-table indexes?

I’m afraid this functionality may not exist [yet]. I wanted to use an index that spans multiple tables in DB2. I know Oracle and SQL server implement them (with more or less options) and that …

Best approach to index a PostgreSQL database with plain html content?

I have a database with a few million posts, each with a column “content” that contains the post content in plain HTML.

<a href="http://…

Index and hasmap

In order to ask my question I first need to explain my understanding of both concepts. Actually, my understanding is very vague, so stop me if I’m wrong. Index (btree in SQL): An index is helpful …

query for trunc(date) on a view that already filters for date

We’re accessing a view from another team’s database and to make it a lot simpler, the view looks a bit like this: create view x_view as select x.exec_time, … from stuff x where x.exec_time &…

How to build an index that is best for this SQL?

I’m querying database by a simple SQL like: SELECT DISTINCT label FROM Document WHERE folderId=123 I need a best index for it. There are two way to implement this. (1) create two indexes CREATE …

Why query is still so fast when I operate a non-indexing column?

I am learning indexing of database. here are indexings of a table. And this table has 330k records. mysql> show index from employee; +———-+————+————-+————–+———…

Optimize MySQL InnoDB query for max, count

I have an MySQL InnoDB table with 5.7M rows and 1.9GB size: +——————-+———+——+—–+———+—————-+ | Field | Type | Null | Key | Default | Extra …