From MongoDB 4.4, it’s possible to hide an index from the query planner. This allows you to evaluate the potential impact of dropping an index without actually dropping the index.
You can use the getIndexes() method to check whether or not an index is hidden. If an index is hidden, that index will display a hidden field as having a value of true (i.e. "hidden" : true).
If you’re using a T-SQL function such as OPENJSON(), JSON_QUERY(), or JSON_VALUE(), you might be wary of any non-alphanumeric characters that might be in the JSON document that you’re working with. Especially if those special characters are in the key names, and you need to reference those key names.
Starting from MongoDB 4.4, we can now hide indexes from the query plan. This enables us to evaluate the potential impact of dropping an index without actually dropping the index.
If hiding it has a negative impact, we can unhide the index. This saves us from having to drop the index, then recreate it again.
Below are 3 ways to hide an index in MongoDB.
Continue readingDistinct values are those values with redundant duplicates removed. In other words, distinct values are unique values.
In MongoDB there are a few ways we can return distinct values in a query. This article presents 3 ways to return distinct values in the mongo shell.
Continue readingThis article demonstrates how to use T-SQL to change the password for a SQL Server login.
You can change the password for another login (assuming you have the appropriate permissions), or you can change it for your own login. This article outlines both of these scenarios.
Continue readingMongoDB provides several ways to drop an index or indexes.
To drop a single index, you can use the dropIndex() method.
To drop multiple indexes, you can use either the dropIndexes() method or the dropIndexes administration command.
If you connect to MariaDB using the command line interface, you might sometimes find that your query results are too wide, due to the number of columns being returned, and the data they contain.
Continue readingSometimes you might find that the amount of text returned in a database column is too long. You might just want to return a short snippet of that text, followed by an ellipsis or three dots.
Fortunately, this is relatively easy to do in MariaDB.
Continue readingWhen you run a query against a MariaDB database, MariaDB uses a bunch of system variables to determine which character set and collation to use whenever queries are run. If the client uses a different character set to the server, then MariaDB can translate it into an appropriate character set and collation.
When sending the query results back to the client, MariaDB can translate these results back to a different character set altogether if required. MariaDB uses system variables to determine which character sets and collations to use at each of these steps.
Here are three ways to show the connection collation in MariaDB.
Continue readingYou can use the T-SQL code below to convert a month number to its corresponding name in SQL Server.
This is for times where you don’t actually have the full date – when all you have is the month number. If you do have the date, then here’s how to get the month name from a date.
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