Where are `KEYS`, `SCAN`, `FLUSHDB`, `FLUSHALL` ?
Where are `KEYS`, `SCAN`, `FLUSHDB` etc?
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Some very common recurring questions are:
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@@ -14,15 +14,16 @@ The key word here, oddly enough, is the last one: database. Because StackExchang
-`KEYS` / `SCAN`
-`FLUSHDB` / `FLUSHALL`
-`RANDOMKEY`
-`CLIENT *`
-`CLUSTER *`
-`CONFIG` / `INFO` / `TIME`
-`CLIENT`
-`CLUSTER`
-`CONFIG *` / `INFO` / `TIME`
-`SLAVEOF`
-`SAVE` / `BGSAVE` / `LASTSAVE`
-`SCRIPT` (not to be confused with `EVAL` / `EVALSHA`)
-`SHUTDOWN`
-`SLOWLOG`
-`PUBSUB *` (not to be confused with `PUBLISH` / `SUBSCRIBE` / etc)
-`PUBSUB` (not to be confused with `PUBLISH` / `SUBSCRIBE` / etc)
- some `DEBUG` operations
(I've probably missed at least one) Most of these will seem pretty obvious, but the first 3 rows are not so obvious:
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@@ -33,7 +34,7 @@ The key word here, oddly enough, is the last one: database. Because StackExchang
Actually, StackExchange.Redis spoofs the `RANDOMKEY` one on the `IDatabase` API by simply selecting a target server at random, but this is not possible for the others.
So how do I use them?
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Simple: start from a server, not a database.
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@@ -48,6 +49,6 @@ Note that unlike the `IDatabase` API (where the target database has already been
The `Keys(...)` method deserves special mention: it is unusual in that it does not have an `*Async` counterpart. The reason for this is that behind the scenes, the system will determine the most appropriate method to use (`KEYS` vs `SCAN`, based on the server version), and if possible will use the `SCAN` approach to hand you back an `IEnumerable<RedisKey>` that does all the paging internally - so you never need to see the implementation details of the cursor operations. If `SCAN` is not available, it will use `KEYS`, which can cause blockages at the server. Either way, both `SCAN` and `KEYS` will need to sweep the entire keyspace, so should be avoided on production servers - or at least, targeted at slaves.
So I need to remember which server I connected to? That sucks!
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No, not quite. You can use `conn.GetEndPoints()` to list the endpoints (either all known, or the ones specified in the original configuration - these are not necessarily the same thing), and iterate with `GetServer()` to find the server you want (for example, selecting a slave).
