CODEWITHSUNDEEP
javamongodb
Joyo Waseem
Joyo Waseem

Reputation: 680

Regex query MongoDB Performance issue

i have Mongodb collection which contains single field , each day i am receiving 31000 documents and in the collection i have almost 6 months data

Here is how my data looks like in database 

 {
"_id" : ObjectId("59202aa3f32dfba00d0773c3"),
"Data" : "20-05-2017 18:38:13 SYSTEM_000_00_SAVING ",
"__v" : 0
 }
 {
"_id" : ObjectId("59202aa3f32dfba00d0773c4"),
"Data" : "20-05-2017 18:38:13 SyTime_000_09_00:00 ",
"__v" : 0
}

here is my code for query

 DBObject query = new BasicDBObject();
 Pattern regex = Pattern.compile("20-05-2017"); 
 query.put("Data", regex);

i have created index but its still slow 

                   [
                {
                    "v" : 1,
                    "key" : {
                        "_id" : 1
                    },
                    "name" : "_id_",
                    "ns" : "NOB_SRB.fdevices"
                },
                {
                    "v" : 1,
                    "unique" : true,
                    "key" : {
                        "Data" : 1.0
                    },
                    "name" : "Data_1",
                    "ns" : "NOB_SRB.fdevices"
                }
            ]

Upvotes: 4

Views: 164

Answers (1)

Bohemian
Bohemian

Reputation: 425198

Add a start of input anchor ^ to the start of the regex:

Pattern regex = Pattern.compile("^20-05-2017");

Because your regex does not have an anchor, the entire field is searched for the date anywhere in it, which requires every character in the field to be compared.

Upvotes: 1

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