When using Redis, we can use the LASTSAVE command to get the Unix time of the last DB save.
More specifically, LASTSAVE returns the Unix time of the last DB save executed with success.
NoSQL
Install Redis on a Mac with Homebrew
Below are the steps that I used to install Redis on my M1 Mac. The M1 Mac (and M2) uses the ARM64 architecture, but this is not a problem, as Redis versions 4.0 and above support the ARM architecture.
3 Ways to Convert a String to a Date in MongoDB
If you have a MongoDB collection with dates stored as strings, you can convert those into the Date BSON type if required.
Below are three ways to convert a string into a Date in MongoDB.
Remove Duplicates when using $unionWith in MongoDB
In MongoDB, the $unionWith aggregation pipeline stage performs a union of two collections, and it includes duplicates.
This behaves in a similar way to SQL’s UNION ALL, which also includes duplicates. By contrast, using just UNION (i.e. without the ALL)in SQL removes duplicates.
In MongoDB, we don’t have the option of specifying $unionWith ALL or similar, so we need to reduce duplicates in another way.
In MongoDB, we can remove duplicates by using the $group stage.
3 Ways to Return a Random Sample of Documents from a MongoDB Collection
If you need to return a small sample of random documents from a collection, here are three approaches you can try using the aggregation pipeline.
MongoDB Aggregation Operators for Returning Date Parts
This article lists the various aggregation pipeline operators that can be used to return individual date parts from a Date object in MongoDB.
2 Ways to Unhide an Index in MongoDB
If you have a hidden index in MongoDB, you can use the unhideIndex() method or the collMod administration command to unhide it.
$strLenBytes vs $strLenCP in MongoDB: What’s the Difference?
MongoDB includes the $strLenBytes and $strLenCP operators in its aggregation pipeline framework. These operators do a similar but slightly different thing. In some cases, both will return exactly the same result, while in other cases the results will differ.
Here’s a quick overview of the difference between these two operators.
2 Ways to Get a Document’s Size in MongoDB
If you need to return the size of a document in MongoDB, you can use the following:
- The
$bsonSizeaggregation pipeline operator - The
Object.bsonSize()method
Below are examples of each approach.