Tag Archives: Java

MongoException multi update only works with $ operators

It is quite possible for the first MongoDB Official Logotime when you are working with Multiple documents update in MongoDB you might see this exception.
Exception in thread “main” com.mongodb.MongoException: multi update only works with $ operators Continue reading MongoException multi update only works with $ operators

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Update Multiple Documents MongoDB Java Example

This post will talk about Update Multiple Documents MongoDB Java Example.
In the last few examples MongoDB Official Logowe have seen that, we are using the default version of update() method , where it takes 2 arguments i.e. search criteria object and modified object. Whenever this version of update() method is executed it updates only Continue reading Update Multiple Documents MongoDB Java Example

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Upsert MongoDB Java Example

This post will talk about upsert mongodb java example.
Consider a scenario where we have to MongoDB Official Logo
write the logic such that – we will
search for a record in the database
and if it is available in database we
will update it else we will insert a
new record with same information.
Conventional solution for this type of problem is first you will try to find the record in MongoDB either using findOne() or find() , and on Continue reading Upsert MongoDB Java Example

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Can’t serialize class – MongoDB Illegal Argument Exception

While working on the array modifiers example MongoDb
, I was trying to use the $sort
modifier with $each and $push modifier
.In that example I added
an array of books to my original
document and was trying to sort it on the basis of one of the fields.As soon as I executed that method,i got our infamous IllegalArgumentException : Exception in thread “main” java.lang.IllegalArgumentException: can’t serialize class com.lotusmedia.mongo.models.Book (Can’t serialize class – MongoDB). Continue reading Can’t serialize class – MongoDB Illegal Argument Exception

Array Modifiers Update MongoDB Java Example

This post is in continuation of our Update MongoDB Java Example series.

In the previous post we have Logical Querying MongoDB Java Exampleseen some of the Atomic update modifiers provided by MongoDB with the help of a Java example ,that can be used to
update and add new key to a
document. Now we will move one step ahead and will look into the Array modifiers available in MongoDB. Below are the following Array Modifiers that we are going to cover in this post.

  • $push
  • $each
  • $slice

Continue reading Array Modifiers Update MongoDB Java Example

Atomic Update MongoDB Java Example

In the previous post i.e Document Logical Querying MongoDB Java Example
Replacement in MongoDB
we have
seen how we were updating the
document – first by getting the
document using findOne() , then
updating its values and finally
putting it back in the collection.
We can also achieve the same task
in a single step i.e skipping findOne() invocation and by using atomic update modifiers provided by mongodb. This post will focus on update mongodb java example. Continue reading Atomic Update MongoDB Java Example

Document Replacement using update MongoDB Java

In the previous posts we have seen examples Logical Querying MongoDB Java Example
on how we can query a MongoDB using Java. We have seen different ways in which we can invoke find() method and how to do comparison querying and logical querying. This post will focus
on updating of our existing documents present in our mongo database using Java.

Update MongoDB Java Example :

Here also, we will continue with the same example that we have used in our previous posts. Continue reading Document Replacement using update MongoDB Java

Logical Querying MongoDB Java Example

This post will focus on the logical Logical Querying MongoDB Java Example
operators that are available in
momgodb.I will use Java for the
illustration purpose of these
operators. You can use any of
the language for which mongo
driver is available. For the comparison operators you can refer the previous post here.
There are 4 logical operators that have been documented in mongodb specs.
We will continue with the same example that we have seen in the previous post. Continue reading Logical Querying MongoDB Java Example

Metaspace in Java8

Metaspace in Java8One of the new features that we will see in Java8 is the introduction of Metaspace. Metaspace is nothing but a replacement of our old friend PermGen (Permanent Generation) space.

What is PermGen?
The permanent Generation is part of your heap space that is actually used to store meta-data information for the classes created by users and prior to Java 7, it is also used to store interned Strings (interned strings – used to remove String duplicates by internalizing them to reduce memory consumption). As of Java 7, intern strings also moved as a part of heap space to make the more space available in Continue reading Metaspace in Java8