-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 Dan,
On 1/19/15 11:46 AM, Daniel Mikusa wrote: > On Mon, Jan 19, 2015 at 11:05 AM, Christopher Schultz < > ch...@christopherschultz.net> wrote: >> >> Some things [memcached] cannot do: >> >> 1. Replicate to other nodes. You can do sharding, but it's >> pretty low-brow and the shards don't actually know about each >> other. All of the smarts are in the client. The server doesn't do >> any of this. Evidently, there are some flavors of memcached that >> have been hacked to provide replication to other nodes, but it's >> not part of the main distribution and didn't seem ... safe. >> >> > I believe the situation with Redis is similar. There some ways to > do this with the stable 2.x release, but those have their are > drawbacks. There's official clustering support in 3.0, which is > still beta, though. It's supposed to resolve these issues. Interesting. I also considered Voldemort, but honestly I was looking for something that was likely to be higher-performing than a Java hash map :) (/This/ from a Java programmer!) >> 2. Dump its database to disk. If you restart, you lose >> everything. >> >> > You can save state with Redis. It's pretty flexible about how you > configure it too, giving you different trade-offs between > durability and performance. Cool. >> 3. Allow you to browse. Basically, if you know an item's key, you >> can fetch its value. If you don't, you are out of luck. You can't >> just poke around looking for things. There is no equivalent of >> "SELECT * LIMIT 5" just to see what's in there. >> > > I think you'd be looking for the "KEYS" command. Yeah, memcached does not have that. There are ways to hack-out some keys but there is no command to list anything. > http://redis.io/commands/keys > > This is off topic, but it's really why I like Redis so I'm going to > share. With Redis, not only can a key point to a value, but it can > also point to other data structures like sets, lists, hashes and > sorted sets. Something I've found to be very handy. Well, in memcached values are binary, so you can stuff anything you want in there. You can serialize a whole object tree if that's what you want to do. I can imagine that memcached + JSON is a popular combination. We just put plain-old binary values in as keys at this point, but assuming you can serialize to bytes (like always!), you can store anything you want in memcached. But it's not like a formal column-store like Cassandra, etc. where the storage mechanism understands a bit about the structures being stored. It's basically an implementation of Map<byte[],byte[]> and we treat it like it's Map<byte[],Integer> because we are not really even using the values themselves; just the keys for quick lookup. - -chris -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 Comment: GPGTools - http://gpgtools.org iQIcBAEBCAAGBQJUvVnRAAoJEBzwKT+lPKRYi9wQAJJ6rYClvss+i4/sGGaCQQXZ MJbVpI7tkcIaz/PFOcK7o5yJXl5F+trdMnfkIM2VGV21fvbRBe28u1c6EeA8yd8P mmuXeLjZnOSPmKngR6LgtxSC8/IAba18DeuiDBkQ/Jgw207BXBZul8ELzm1H0ihF B8GtWv5BgvASIl7r+8MX793rfBc2qDmyfV5f56EhyodZKPuBQ+nYBwZZWoNOZN38 NxC3bs9U5+MCimVPqU8CF11m+gJXaV/sK1wqrDFJP0watHHyLJ7kHpN35RU4TeSF mYTYbQUxPKPaIZ+dPeo2yJZJadHZ4K3IX3vC9cgIz5sayTTl6esTMclzYCGMrFBI BRj9EywYCSWdgo7ZG6p3lZPjmXSe/oEEAt00YolpnR/jyjkyzMT/k+GoS4+1n81A QmV0U95i3i+D6E2RCR9YGa2O1yFhk5H9BuTYq+E831vrVP+XICP6vugICYdy5KUv IPghVDlYoUuKSe7KDDNKvKnoLKC755OHg18spjlBRsTESVm1Ht1+yscaAtlbEwWB TeZDfLsezIns6rp/9/qt6vB9g1zTZSNvepYB3cNKBabhj7lMd0K6Zdu4bvEpxLOO dnrEXFzByG8vQ0mi/NAWcBBZJfcDMo4IHngqi3MDFUITHukxOg1TKa2238Rxi6If 3o5leMJ4BUfBBhnfKGn0 =JnfC -----END PGP SIGNATURE----- --------------------------------------------------------------------- To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org For additional commands, e-mail: users-h...@tomcat.apache.org
