Cara menggunakan mongodb update ttl index

Question

This document provides an introduction to MongoDB's "time to live" or collection feature. TTL collections make it possible to store data in MongoDB and have the automatically remove data after a specified number of seconds or at a specific clock time.

Table of Contents Show

Expire Documents after a Specified Number of Seconds
Expire Documents at a Specific Clock Time
Indexes Configured Using NaN
Identify misconfigured indexes.
Correct misconfigured indexes.

Data expiration is useful for some classes of information, including machine generated event data, logs, and session information that only need to persist for a limited period of time.

A special TTL index property supports the implementation of TTL collections. The TTL feature relies on a background thread in that reads the date-typed values in the index and removes expired from the collection.

Procedures

To create a , use the method with the expireAfterSeconds option on a field whose value is either a or an array that contains

Note

The TTL index is a single field index. Compound indexes do not support the TTL property. For more information on TTL indexes, see TTL Indexes.

You can modify the expireAfterSeconds of an existing TTL index using the command.

Expire Documents after a Specified Number of Seconds

To expire data after a specified number of seconds has passed since the indexed field, create a TTL index on a field that holds values of BSON date type or an array of BSON date-typed objects and specify a positive non-zero value in the expireAfterSeconds field. A document will expire when the number of seconds in the expireAfterSeconds field has passed since the time specified in its indexed field.

For example, the following operation creates an index on the

db.log_events.insertOne( {
   "createdAt": new Date(),
   "logEvent": 2,
   "logMessage": "Success!"
} )

3 collection's

db.log_events.insertOne( {
   "createdAt": new Date(),
   "logEvent": 2,
   "logMessage": "Success!"
} )

4 field and specifies the expireAfterSeconds value of

db.log_events.insertOne( {
   "createdAt": new Date(),
   "logEvent": 2,
   "logMessage": "Success!"
} )

6 to set the expiration time to be ten seconds after the time specified by

db.log_events.insertOne( {
   "createdAt": new Date(),
   "logEvent": 2,
   "logMessage": "Success!"
} )

4.

db.log_events.createIndex( { "createdAt": 1 }, { expireAfterSeconds: 10 } )

When adding documents to the

db.log_events.insertOne( {
   "createdAt": new Date(),
   "logEvent": 2,
   "logMessage": "Success!"
} )

3 collection, set the

db.log_events.insertOne( {
   "createdAt": new Date(),
   "logEvent": 2,
   "logMessage": "Success!"
} )

4 field to the current time:

db.log_events.insertOne( {
   "createdAt": new Date(),
   "logEvent": 2,
   "logMessage": "Success!"
} )

MongoDB will automatically delete documents from the

db.log_events.insertOne( {
   "createdAt": new Date(),
   "logEvent": 2,
   "logMessage": "Success!"
} )

3 collection when the document's

db.log_events.insertOne( {
   "createdAt": new Date(),
   "logEvent": 2,
   "logMessage": "Success!"
} )

4 value is older than the number of seconds specified in expireAfterSeconds.

[1](, ) If the field contains an array of BSON date-typed objects, data expires if at least one of BSON date-typed object is older than the number of seconds specified in expireAfterSeconds.

Expire Documents at a Specific Clock Time

To expire documents at a specific clock time, begin by creating a TTL index on a field that holds values of BSON date type or an array of BSON date-typed objects and specify an expireAfterSeconds value of

db.log_events.createIndex( { "expireAt": 1 }, { expireAfterSeconds: 0 } )

5. For each document in the collection, set the indexed date field to a value corresponding to the time the document should expire. If the indexed date field contains a date in the past, MongoDB considers the document expired.

For example, the following operation creates an index on the

db.log_events.insertOne( {
   "createdAt": new Date(),
   "logEvent": 2,
   "logMessage": "Success!"
} )

3 collection's

db.log_events.createIndex( { "expireAt": 1 }, { expireAfterSeconds: 0 } )

7 field and specifies the expireAfterSeconds value of

db.log_events.createIndex( { "expireAt": 1 }, { expireAfterSeconds: 0 } )

5:

db.log_events.createIndex( { "expireAt": 1 }, { expireAfterSeconds: 0 } )

For each document, set the value of

db.log_events.createIndex( { "expireAt": 1 }, { expireAfterSeconds: 0 } )

7 to correspond to the time the document should expire. For example, the following operation adds a document that expires at

db.log_events.insertOne( {
   "expireAt": new Date('July 22, 2013 14:00:00'),
   "logEvent": 2,
   "logMessage": "Success!"
} )

2.

db.log_events.insertOne( {
   "expireAt": new Date('July 22, 2013 14:00:00'),
   "logEvent": 2,
   "logMessage": "Success!"
} )

MongoDB will automatically delete documents from the

db.log_events.insertOne( {
   "createdAt": new Date(),
   "logEvent": 2,
   "logMessage": "Success!"
} )

3 collection when the documents'

db.log_events.createIndex( { "expireAt": 1 }, { expireAfterSeconds: 0 } )

7 value is older than the number of seconds specified in expireAfterSeconds, i.e.

db.log_events.createIndex( { "expireAt": 1 }, { expireAfterSeconds: 0 } )

5 seconds older in this case. As such, the data expires at the specified

db.log_events.createIndex( { "expireAt": 1 }, { expireAfterSeconds: 0 } )

7 value.

Indexes Configured Using NaN

Warning

Possible Data Loss

When a TTL index has expireAfterSeconds set to

db.log_events.insertOne( {
   "expireAt": new Date('July 22, 2013 14:00:00'),
   "logEvent": 2,
   "logMessage": "Success!"
} )

9, upgrade, downgrade, and certain syncing operations can lead to unexpected behavior and possible data loss.

Do not set expireAfterSeconds to

db.log_events.insertOne( {
   "expireAt": new Date('July 22, 2013 14:00:00'),
   "logEvent": 2,
   "logMessage": "Success!"
} )

9 in your TTL index configuration.

Prior to MongoDB 5.0, when a TTL index has expireAfterSeconds set to

db.log_events.insertOne( {
   "expireAt": new Date('July 22, 2013 14:00:00'),
   "logEvent": 2,
   "logMessage": "Success!"
} )

9, MongoDB logs an error and does not remove any records.

From MongoDB 5.0.0 - 5.0.13 (and 6.0.0 - 6.0.1),

db.log_events.insertOne( {
   "expireAt": new Date('July 22, 2013 14:00:00'),
   "logEvent": 2,
   "logMessage": "Success!"
} )

9 is treated as

db.log_events.createIndex( { "expireAt": 1 }, { expireAfterSeconds: 0 } )

5. If a TTL index is configured with expireAfterSeconds set to

db.log_events.insertOne( {
   "expireAt": new Date('July 22, 2013 14:00:00'),
   "logEvent": 2,
   "logMessage": "Success!"
} )

9, all TTL-indexed documents expire immediately.

Starting in MongoDB 5.0.14 (and 6.0.2), the server will not use TTL indexes that have expireAfterSeconds set to

db.log_events.insertOne( {
   "expireAt": new Date('July 22, 2013 14:00:00'),
   "logEvent": 2,
   "logMessage": "Success!"
} )

9.

However, there are still some situations which may result in unexpected behavior. Documents may expire:

During an initial sync to an earlier version from MongoDB 5.0.0 - 5.0.13 (or 6.0.0 - 6.0.1).
When upgrading from an earlier version to MongoDB 5.0.0 - 5.0.13.
When restoring a collection from a pre-5.0

into a MongoDB 5.0.0 - 5.0.13 (or 6.0.0 - 6.0.1) instance.

To avoid problems, either drop or correct any misconfigured TTL indexes.

1

Identify misconfigured indexes.

Run the following script in the shell. The script does not work in the legacy mongod2 shell.

function getNaNIndexes() {
  const nan_index = [];
  const dbs = db.adminCommand({ listDatabases: 1 }).databases;
  dbs.forEach((d) => {
    const listCollCursor = db
      .getSiblingDB(d.name)
      .runCommand({ listCollections: 1 }).cursor;
    const collDetails = {
      db: listCollCursor.ns.split(".$cmd")[0],
      colls: listCollCursor.firstBatch.map((c) => c.name),
    };
    collDetails.colls.forEach((c) =>
      db
        .getSiblingDB(collDetails.db)
        .getCollection(c)
        .getIndexes()
        .forEach((entry) => {
          if (Object.is(entry.expireAfterSeconds, NaN)) {
            nan_index.push({ ns: `${collDetails.db}.${c}`, index: entry });
          }
        })
    );
  });
  return nan_index;
};
getNaNIndexes();