length

Number of key-value pairs in the data cache

Syntax

num = length(c)

num = length(c,location)

Description

num = length(c) returns the total number of key-value pairs in the data cache c.

num = length(c,location) returns the numbers of key-value pairs in the data cache c stored remotely or locally as specified by location.

Examples

Count the Number of Key-Value Pairs

Start a persistence service that uses Redis™ as the persistence provider. The service requires a connection name and an open port. Once the service is running, you can connect to the service using the connection name and create a cache.

ctrl = mps.cache.control('myRedisConnection','Redis','Port',4519);
start(ctrl)
c = mps.cache.connect('myCache', 'Connection', 'myRedisConnection');

Retain a few keys locally.

retain(c, {'keyOne','keyTwo'})

Add keys and values to the cache.

put(c,'keyOne',10,'keyTwo',20,'keyThree',30,'keyFour',[400 500],'keyFive',magic(5))

Count the number of keys-value pairs.

numTotal = length(c)
numRemote = length(c,'Remote')
numLocal = length(c,'Local')

numTotal =

  int64

   5

numRemote =

  int64

   3

numLocal =

  int64

   2

Since keyOne and keyTwo were retained before being written to the cache, they were never written to the persistence service. They are stored locally until flushed or purged to the persistence service.

Input Arguments

c — Data cache

persistence provider specific data cache object

A data cache represented by a persistence provider specific data cache object.

Currently, Redis and MATLAB^® are the only supported persistence providers. Therefore, the cache objects will be of type mps.cache.RedisCache or mps.cache.MATFileCache.

Example: c

location — Location name

'Remote' | 'Local'

Location of keys specified as an enumerated member of the class mps.cache.Location. The valid location options are either 'Remote' or 'Local'.

Example: 'Remote'

Output Arguments

num — Number of keys

integer

Total number of key-value pairs in the data cache or the number stored remotely or locally, returned as an integer.

Version History

Introduced in R2018b