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What is RSS and VSZ in Linux memory management
...g work? and in particular that the OS can allocate virtual memory via page tables / its internal memory book keeping (VSZ virtual memory) before it actually has a backing storage on RAM or disk (RSS resident memory).
Now to observe this in action, let's create a program that:
allocates more RAM t...
Why can't a text column have a default value in MySQL?
If you try to create a TEXT column on a table, and give it a default value in MySQL, you get an error (on Windows at least). I cannot see any reason why a text column should not have a default value. No explanation is given by the MySQL documentation. It seems illogical to me (and somewhat frustrati...
How to delete the top 1000 rows from a table using Sql Server 2008?
I have a table in SQL Server. I would like to delete the top 1000 rows from it. However, I tried this, but I instead of just deleting the top 1000 rows it deleted all the rows in the table.
...
Using varchar(MAX) vs TEXT on SQL Server
...hould use a Full Text Index.
LIKE is simpler to implement and is often suitable for small amounts of data, but it has extremely poor performance with large data due to its inability to use an index.
share
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Random row from Linq to Sql
...dom()
select row).FirstOrDefault();
Note that this is only suitable for small-to-mid-size tables; for huge tables, it will have a performance impact at the server, and it will be more efficient to find the number of rows (Count), then pick one at random (Skip/First).
for count approa...
Generate full SQL script from EF 5 Code First Migrations
... Does this create an exact copy of the database? Including the table contents?
– Multitut
Mar 20 '15 at 14:36
2
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What is the best Distributed Brute Force countermeasure?
...nd since it still beats being locked out of your account, it would be acceptable.
(Also, note that none of this happens if the attack is any less sophisticated than the nasty distributed version I've described here. If the attack is coming from just a few IPs or only hitting a few usernames, it wi...
Easiest way to rename a model using Django/South?
...
To answer your first question, the simple model/table rename is pretty straightforward. Run the command:
./manage.py schemamigration yourapp rename_foo_to_bar --empty
(Update 2: try --auto instead of --empty to avoid the warning below. Thanks to @KFB for the tip.)
If ...
Rails: Using greater than/less than with a where statement
...non discrete values or columns where you can't use the + 1 strategy.
Arel table
If you want to get fancy you can make use of the Arel::Table.
User.where(User.arel_table[:id].gt(200))
will generate the SQL
"SELECT `users`.* FROM `users` WHERE (`users`.`id` > 200)"
The specifics are as foll...
How to get a list of user accounts using the command line in MySQL?
...
Use this query:
SELECT User FROM mysql.user;
Which will output a table like this:
+-------+
| User |
+-------+
| root |
+-------+
| user2 |
+-------+
As Matthew Scharley points out in the comments on this answer, you can group by the User column if you'd only like to see unique userna...