Does findAndModify effectively lock the document to prevent read conflicts?

Question

Assume there is document's structure like below:
{_id:"session-01", status:"free"}

And there are 2 concurrent operations that perform the findAndModify operation below: db.collection.findAndModify({query:{status:"free"}, update:{status:"occupied"}, new:true})

What I want to achieve is only one operation can get the "free" one, and perform lock on it, so the other operation must be getting null. Is that what the findAndModify does?

score 16 · Accepted Answer · answered Nov 10 '14 at 14:56

16

According to official docs, MongoDB does provide isolated update and return.
Here is the mongoDB official doc link: Why findAndModify is Atomic.
Here is a superbly illustrated example of how findAndModify works in mongoDB : How findAndModify works

Note - I usually do not enjoy posting links but I did not want to discredit the content owners.

answered Nov 10 '14 at 14:56

vmr

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The second link's explanation makes me more confidence. Thanks for the answer :D – Agung Pratama Nov 10 '14 at 15:13
@vmr So, the OP's understanding is correct? in concurrent operation, others will receive no data? – Suresh Prajapati Aug 13 '20 at 12:37

Does findAndModify effectively lock the document to prevent read conflicts?

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