$tsSecond (expression operator)

Definition

$tsSecond

New in version 5.1.

Returns the seconds from a timestamp as a long.

$tsSecond syntax:

{ $tsSecond: <expression> }

The expression must resolve to a timestamp.

Tip

Behavior

$tsSecond returns:

Null if the input expression evaluates to null or refers to a field that is missing.
An error if the input expression does not evaluate to a timestamp.

Examples

Obtain the Number of Seconds from a Timestamp Field

Create a stockSales collection that contains company stock financial market sales:

db.stockSales.insertMany( [   { _id: 0, symbol: "MDB", saleTimestamp: Timestamp(1622731060, 1) },   { _id: 1, symbol: "MDB", saleTimestamp: Timestamp(1622731060, 2) },   { _id: 2, symbol: "MSFT", saleTimestamp: Timestamp(1714124193, 1) },   { _id: 3, symbol: "MSFT", saleTimestamp: Timestamp(1714124193, 2) },   { _id: 4, symbol: "MSFT", saleTimestamp: Timestamp(1714124193, 3) }] )

In the timestamp constructor, the:

First value is the number of seconds after the Unix epoch.
Second value is the incrementing ordinal. When multiple events happen within the same second, the incrementing ordinal uniquely identifies each event.

The following example uses $tsSecond in a $project pipeline stage to return the seconds from the stock sales saleTimestamp field:

db.stockSales.aggregate( [   {      $project:      {         _id: 0, saleTimestamp: 1, saleSeconds: { $tsSecond: "$saleTimestamp" }      }   }] )

Example output:

{  saleTimestamp: Timestamp({ t: 1622731060, i: 1 }),  saleSeconds: Long("1622731060")},{  saleTimestamp: Timestamp({ t: 1622731060, i: 2 }),  saleSeconds: Long("1622731060")},{  saleTimestamp: Timestamp({ t: 1714124193, i: 1 }),  saleSeconds: Long("1714124193")},{  saleTimestamp: Timestamp({ t: 1714124193, i: 2 }),  saleSeconds: Long("1714124193")},{  saleTimestamp: Timestamp({ t: 1714124193, i: 3 }),  saleSeconds: Long("1714124193")}

Use `$tsSecond` in a Change Stream Cursor to Monitor Collection Changes

The example in this section uses $tsSecond in a change stream cursor to monitor changes to a collection.

Create a change stream cursor on a collection named cakeSales that you will see later in this section:

cakeSalesCursor = db.cakeSales.watch( [   {      $addFields: {         clusterTimeSeconds: { $tsSecond: "$clusterTime" }      }   }] )

In the example, the:

db.collection.watch() method creates a change stream cursor for the cakeSales collection and stores the cursor in cakeSalesCursor.
$addFields stage adds a field named clusterTimeSeconds to cakeSalesCursor.
- $clusterTime is the timestamp from the oplog entry for the cakeSales collection change. See Command Response.
- $tsSecond returns the seconds from $clusterTime, which is stored in clusterTimeSeconds.

Create a cakeSales collection that contains cake sales in the states of California (CA) and Washington (WA):

db.cakeSales.insertMany( [   { _id: 0, type: "chocolate", orderDate: new Date("2020-05-18T14:10:30Z"),     state: "CA", price: 13, quantity: 120 },   { _id: 1, type: "chocolate", orderDate: new Date("2021-03-20T11:30:05Z"),     state: "WA", price: 14, quantity: 140 },   { _id: 2, type: "vanilla", orderDate: new Date("2021-01-11T06:31:15Z"),     state: "CA", price: 12, quantity: 145 },   { _id: 3, type: "vanilla", orderDate: new Date("2020-02-08T13:13:23Z"),     state: "WA", price: 13, quantity: 104 },   { _id: 4, type: "strawberry", orderDate: new Date("2019-05-18T16:09:01Z"),     state: "CA", price: 41, quantity: 162 },   { _id: 5, type: "strawberry", orderDate: new Date("2019-01-08T06:12:03Z"),     state: "WA", price: 43, quantity: 134 }] )

To monitor the cakeSales collection changes, use cakeSalesCursor. For example, to obtain the next document from cakeSalesCursor, use the next() method:

cakeSalesCursor.next()

The following example output shows the insert details for the first document added to the cakeSales collection. The clusterTimeSeconds field contains the seconds from the clusterTime field.

_id: {  _data: '82613A4A51000000032B022C0100296E5A100495189B4131584C56AC8BA9D540799F23461E5F696400290004'},operationType: 'insert',clusterTime: Timestamp({ t: 1631210065, i: 3 }),fullDocument: {  _id: 0,  type: 'chocolate',  orderDate: ISODate("2020-05-18T14:10:30.000Z"),  state: 'CA',  price: 13,  quantity: 120},ns: { db: 'test', coll: 'cakeSales' },documentKey: { _id: 0 },clusterTimeSeconds: 1631210065

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