MongoDB Notes Part II

Insert Documents

Insert a document into a collection.

MongoDB provides a Bulk( ) API that you can use to perform multiple write operations in bulk.

• initialize the operation builder
• 
• add insert operation
• 
• execute
• 

Query Documents

Select all document in a collection.

Specify equality condition

• use { <field> : <value> }

Specify conditions using query operators 

Specify AND condition

Specify OR condition

Exact Match on the Embedded Document

Equality Match on Fields within an Embedded Document

Exact Match on an Array

• Match every element in the array, including the order

Match an Array Element

• The array contains at least one element with the specified value.

Match a Specify Element of an Array

• Match at a particular position in the array

Single Element Satisfies the Criteria

• Use $elemMatch to specify multiple criteria on the elements of an array such that at least one element in the array satisfies all criteria.

Combination of Elements Satisfies the Criteria

Matching a Field in the Embedded Document Using the Array Index

Match a Field Without Specifying Array Index

• Select the document where the ‘memos’ field contains an array that at least one embedded document contains the field ‘by’ with ‘shipping’. 

Single Element Satisfies the Criteria

Combination of Elements Satisfies the Criteria

Modify Documents

Use update operators to change field values.

Update an embedded field.

• Use dot notation

Update multiple documents

• Use the multi option in update

Replace a document.

Specify upsert: true for the update replacement operation.

Specify uperst: true for the update specific fields operation.

• If no document matches, a new document would be inserted.

Remove Documents

Remove All Documents

Remove Documents that Match a Condition

Remove a Single Document that Matches a Condition

Limit Fields to Return from a Query

You can not combine inclusion and exclusion semantics in a single projection with the exception of _id.

Iterate a Cursor

Use toArray( ) to convert the cursor into an array. It will consume all the cursor. 

Query with Index

Two Phase Commit

http://docs.mongodb.org/manual/tutorial/perform-two-phase-commits/

Create an Auto-Incrementing Sequence Field

• Use Counters Collection
• • use a collection to hold the last id, use a function to get and update the id from this counter collection.
• Optimistic Loop
• • calculates the incremented _id value and attempts to insert a document with the calculated _id until the insertion is successful.

All pictures are from http://docs.mongodb.org/manual/