_id: "MongoDB id"
userid: "user id" (int)
mobile: "users mobile number" (int)
transaction: "transaction id" (int)
sms: "message sent to user mobile" (text)
created_dt: "unix timestamp of the transaction"

{
    mobile:<users mobile number>
}

{
    "cursor" : "BasicCursor",
    "nscanned" : 37145516,
    "nscannedObjects" : 37145516,
    "n" : 37145516,
    "millis" : 296040,
    "nYields" : 1343,
    "nChunkSkips" : 0,
    "isMultiKey" : false,
    "indexOnly" : false,
    "indexBounds" : {
    }
}

insert  query update delete getmore command flushes mapped  vsize    res faults locked % idx miss %     qr|qw   ar|aw  netIn netOut  conn       time
    13      2      0      0       0       1       0   168g   336g  6.86g      1        1          0       0|0     1|0    21k     1k    19   11:30:04
    16      0      0      0       0       1       0   168g   336g  6.88g      0      0.1          0       0|0     1|0    21k     1k    19   11:30:05
    14      0      0      0       0       1       0   168g   336g  6.86g      0        0          0       0|0     1|0    29k     1k    19   11:30:06
    10      0      0      0       0       1       0   168g   336g  6.86g      0        0          0       0|0     1|0    19k     1k    19   11:30:07
    16      0      0      0       0       1       0   168g   336g  6.88g      0      0.1          0       0|0     1|0    21k     1k    19   11:30:08
     9      0      0      0       0       1       0   168g   336g  6.89g      0        0          0       0|0     1|0    13k     1k    19   11:30:09
    19      0      0      0       0       1       0   168g   336g  6.89g      0        0          0       0|0     1|0    27k     1k    19   11:30:10
    12      0      0      0       0       1       0   168g   336g  6.89g      1      1.2          0       0|0     1|0    24k     1k    19   11:30:11
    17      0      0      0       0       1       0   168g   336g  6.89g      1      1.7          0       0|0     1|0    31k     1k    19   11:30:12
    15      0      0      0       0       1       0   168g   336g  6.89g      0        0          0       0|0     1|0    19k     1k    19   11:30:13

[
{
    "v" : 1,
    "key" : {
        "_id" : 1
    },
    "ns" : "mymongodb.transaction_sms_details",
    "name" : "_id_"
},
{
    "v" : 1,
    "key" : {
        "_transaction_mobile_" : 1
    },
    "ns" : "mymongodb.transaction_sms_details",
    "background" : 1,
    "name" : "mobile"
},
{
    "v" : 1,
    "key" : {
        "_transaction_transaction_" : 1
    },
    "ns" : "mymongodb.transaction_sms_details",
    "background" : 1,
    "name" : "transaction"
}
]

"_transaction_mobile_" : 1
    "_transaction_transtion_" : 1

db.xxx.dropIndexes();
db.xxx.ensureIndex({mobile: 1});
db.xxx.ensureIndex({transaction: 1});