I would like to speed up the queries on my big table that contains lots of old data. I have a table named post that has the date column created_at. The table has over ~31 million rows and ~30 milli...

Though it may sound like a stupid question, sometimes it is necessary to show page numbers (and also the last page). What is the best way to calculate total row counts and also calculate page numbe...

I have statements like this that are timing out: DELETE FROM [table] WHERE [COL] IN ( '1', '2', '6', '12', '24', '7', '3', '5') I tried doing one at a time like this: DELETE FROM [table] WHERE ...

I'm learning how to optimize my database by re choosing the correct data types for the columns and I want to know how much size I will save if I choose MEDIUMINT (3 Bytes) instead of INT(4 Bytes) ...

I have a user table in mysql containing all user data (firstname, surname, address, etc) But should I store the authentication details in another table (username, password) and link the two tables...

I am running a batch operation over all rows in a database. This involves selecting every single model and doing something to it. It makes sense to split this into chunks and do it chunk by chunk. ...

I have the following table storing data about images: images - id (int) - sample_1_1 (int) - sample_1_2 (int) - sample_1_3 (int) - sample_2_1 (int) - sample_2_2 (int) - sample_2_3 (int) - ...

I have some innoDbs with only 2 int columns which are foreign keys to the primary keys of other tables. E.g one table is user_items, it has 2 columns, userId, itemId, both foreign keys to user and...

Evening, I'm going through the long process of importing data from a battered, 15-year-old, read-only data format into MySQL to build some smaller statistical tables from it. The largest table I ...

Firstly, I should point out I don't have much knowledge on SQL Server indexes. My situation is that I have an SQL Server 2008 database table that has a varchar(max) column usually filled with a lo...

I'd like to know, which option is the most expensive in terms of bandwith and overall efficiency. Let's say I have a class Client in my application and a table client in my database. Is it better...

I was once told that it is faster to just run an insert and let the insert fail than to check if a database entry exists and then inserting if it is missing. I was also told that that most databas...

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 My...

We have a query to remove some rows from the table based on an id field (primary key). It is a pretty straightforward query: delete all from OUR_TABLE where ID in (123, 345, ...) The problem is ...

I have two tables here: ITEMS ID| DETAILS| .....| OWNER USERS: ID| NAME|.... Where ITEMS.OWNER = USERS.ID I'm listing the items out with their respective owners names. For this I could use a j...

I need to fit in additional data into a database, and I have a choice between modifying an existing table (table_existing) or creating new tables. This is how table_existing looks like right now: ...

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...