ttl

问题 When using the redis expire commands like SETEXP & TTL , there are scenarios in which there is no need for the key to hold a value at all, because the time to live acts as such. However, redis requires any key to have a value. What would be the most reasonable value to use - if you don't ever want to read it? 回答1: Who said that you should actually store anything in redis key? Empty string "" is a perfectly valid value for a redis key, and it's a shortest possible one: > SET foo "" OK > GET

问题 I'm trying to send a UDP packet to a router with a time to live of 1, to then receive an ICMP time exceeded reply. So far I'm able to send the packet, but when my program gets to the recv part of the execution, it just hangs. I have an error check for recvfrom, but it doesn't even get to that. My computer is receiving the request. I know this because I run Wireshark when I run the program and I filter for ICMP requests. Every time I run the program, I receive the reply. What am I doing wrong

问题 I know that there are TTLs on columns in Cassandra. But is it also possible to set a TTL on a row? Setting a TTL on each column doesn't solve my problem as can be seen in the following usecase: At some point a process wants to delete a complete row with a TTL (let's say row "A" with TTL 1 week). It could do this by replacing all existing columns with the same content but with a TTL of 1 week. But there may be another process running concurrently on that row "A" which inserts new columns or

问题 I have a requirement for setting a TTL on a collection of Docs in my app but also need those docs to be referenced by another collection and am unsure how this would work? Does setting a TTL on a document remove that document from all other reference docs when it is expired or would I have to write a backend process myself and not use mongoDb's TTL indexes? An example schema of the functionality I would want : var mongoose = require('mongoose') , Schema = mongoose.Schema var personSchema =

问题 I have so many records in aerospike, i want to fetch the records whose ttl is -1 please provide solution 回答1: Just to clarify, setting a TTL of -1 in the client means never expire (equivalent to a default-ttl of 0 in the server's aerospike.conf file), while setting a TTL of 0 in the client means inherit the default-ttl for this namespace . With Predicate Filtering: If you're using the Java, C, C# and Go clients the easiest way to identify the records with a void time of 0 would be to use a

问题 I have a little confusing about arduino uno. I use Serial.print("hi") code then it "hi" appears on the serial monitor. I also use rs232/ttl converter which are connected pin 1 and 0 on the arduino properly. Then I realize that when serial.print("hi") working the data first is going through usb cable. But I want the data has to go through tx rx pins which are 1 and 0. But when I enter some data from serial monitor , rs232/ttl will work and some data will be sended ? I do not understand the

问题 I am having problem during compilation. Can you help to figure out the problem please? ` public static void main(String[] args) throws IOException { File dir = new File("C:data\\test"); String[] fileNames = dir.list(); FileWriter outFile = new FileWriter("out.ttl"); RDFWriter writer = org.eclipse.rdf4j.rio.Rio.createWriter(RDFFormat.TURTLE, outFile ); writer.startRDF(); for (String fileName : fileNames) { System.out.println("Reading from " + fileName); File f = new File(dir, fileName); Model

问题 I need to merge 1000+ .ttl files into one file database. How can I merge them with filtering the data in the source files and keep only the data needed in the target file? Thanks 回答1: There's a number of options, but the simplest way is probably to have use a Turtle parser to read all the files, and let that parser pass its output to a handler which does the filtering before in turn passing the data to a Turtle writer. Something like this would probably work (using RDF4J): RDFWriter writer =

问题 As far as I can figure this seems to be the way to set up Memcached and set the TTL and Namespace but they have no effect in the cache. The key is not prefixed with a namespace and the expire is infinite. $MemcachedOptions = new \Zend\Cache\Storage\Adapter\MemcachedOptions(); $MemcachedResourceManager = new \Zend\Cache\Storage\Adapter\MemcachedResourceManager(1, new \Zend\Cache\Storage\Adapter\Memcached()); $MemcachedResourceManager->addServer(1, array('localhost', 11211)); $MemcachedOptions-

问题 How to expire each element of a collection by setting an individual time-to-live (TTL) property in Cassandra? the documentation is here, but I cannot find an example. (https://docs.datastax.com/en/cql/3.3/cql/cql_using/useExpire.html) 回答1: If you want to have different TTL in a same column collection (set, list, map) of cassandra. Do like in this example: There is a table -> tableName whih one column (col1) primary key of text type A column(col2) of type set <long> UPDATE tableName USING TTL