任何人都知道regionserver队列大小是什么意思？
根据doc的定义:
9.2.5.hbase.regionserver.compactionQueueSize压缩队列的大小.这是该区域中已实现压缩的商店数量.
这是区域服务器的Store(或商店文件？我听过它的两个版本)需要主要压缩的数量.
我有一个使用顺序密钥(非分布式)以热点样式编写数据的工作.我在公制历史中看到发现它一次发生了一个compaction-queue-size = 4.这在理论上是不可能的,因为我在任何时候都只有一个Store(顺序键).
然后我深入了解日志,发现有任何关于队列大小> 0的提示:每个主要的压缩说 "这个选择在队列中0秒"
013-11-26 12:28:00,778 INFO [regionserver60020-smallCompactions-1385440028938] regionserver.HStore:完成了myTable.key.md5 ....的f1中3个文件的主要压缩到md5 ....( size = 607.8 M),存储的总大小为645.8 M. 此选择在队列中持续0秒,并执行了39秒.
更令人困惑的是:在早期版本中是不是启用了多线程,只是将每个压缩作业分配给一个线程,这就是为什么存在压缩队列？
太糟糕了,hbase doc中没有详细说明.
我目前正在研究一个非常大的表(约1亿行,35列),它目前存储在SQL db中,但我正在运行的查询(它们各种各样)运行得非常非常慢..所以我得到了我应该转移到NoSQL db.问题是:
如何判断哪个(NoSQL)数据库最适合我？
如何将当前的SQL表移动到新的NoSQL方案？
或者我应该留在SQL中并进行微调？
更多细节:不会添加/删除行,这是历史数据,所有分析都将在该表上完成.计划对其进行各种查询.数据是数字的.
使用cassandra,我想在列族中存储2000万个行键.
我的问题是:
long和utf8 rowKey键之间是否存在真正的性能差异？
任何,行密钥存储大小问题？
我的userkey看起来像这样
rowKey=>112512462152451
rowKey=>135431354354343
rowKey=>145646546546463
rowKey=>154354354354354
rowKey=>156454343435435
rowKey=>154435435435745
我怎样才能编写过滤器,这会导致今天创建的文档.我知道ObjectId有时间戳.我试过这个:
db.doc.find({_id : { $gte : ObjectId().getTimestamp().getTime() }}
我能写吗？
db.doc.find({'_id.getTimestamp().getTime()' : { $gte : ObjectId().getTimestamp().getTime() }}
这是我第一次使用NoSQL数据库,所以我真的很困惑.我真的很感激我能得到的任何帮助.
我想在我的表格中存储包含公告的数据.基本上,每个公告都有ID,日期和文本.
例如,公告可能具有ID为1,日期为2014/02/26,以及"这是示例公告"的文本.较新的公告总是具有比旧公告更大的ID值,因为它们稍后会添加到表中.
我想在此表上运行两种类型的查询:
所以我设置了具有以下属性的表:ID(数字)作为主键,日期(字符串)作为范围
这适合我的用例吗？如果是这样,我应该运行什么样的查询/读取/请求/扫描/其他(我真的对这里的术语感到困惑)来完成我想要的两种类型的查询？
任何帮助将非常感谢.谢谢!
是否可以以任何方式将函数存储在IndexedDB数据存储区中？我做了一些搜索,没有发现IndexedDB支持的数据类型.我尝试将函数和函数实例添加到对象存储中,如下所示,但它不起作用.
var myclass = function () {
self = this;
self.name = 'Sam';
self.hello = function () {
console.log('Hello ' + self.name);
};
}
var transaction = db.transaction(['codeobject'], 'readwrite');
var store = transaction.objectStore('codeobject');
var request = store.put({ 'classname': 'someclass', 'object': myclass });
我试过了.
var request = store.put({ 'classname': someclass', 'object': new myclass() });
我真的想要在对象db中存储一个类.即使我必须将它存储为某种类型的blob,然后将其序列化为一个函数.
谢谢
Google Apps Engine将Google Datastore作为唯一的NoSQL数据库提供(我认为它基于BigTable).
在我的应用程序中,我有一个类似社交的数据结构,我想像在图形数据库中那样对其进行建模.我的应用程序必须保存异构对象(用户,文件,...)和它们之间的关系(例如user1 OWNS file2,user2 FOLLOWS user3等).
我正在寻找一种模拟这种典型情况的好方法,我想到了两个解决方案系列:
基于列表的解决方案:任何对象都包含其他相关对象的列表,列表中的对象存在本身就是这种关系(正如Google在JDO部分中所说的那样https://developers.google.com/appengine/docs/java/datastore/jdo/relationships).
基于图形的解决方案:节点和关系都是对象.对象独立于关系存在,而每个关系包含对两个(或更多)连接对象的引用.
这两种方法的优点和缺点是什么？
关于方法1:这是一个人们可以想到的更简单的方法,它也出现在官方文档中,但是:
关于方法2:每个关系可以具有更高级别的特征(它是一个对象,它可以具有属性).我认为内存大小不是Google的问题,但是:
你能帮助我找到两种方法的其他重点,以这种方式选择最佳模型吗？
首先:我已经根据MongoDB查询性能阅读了很多帖子,但我没有找到任何好的解决方案.
在集合内部,文档结构如下所示:
{
"_id" : ObjectId("535c4f1984af556ae798d629"),
"point" : [
-4.372925494081455,
41.367710205649544
],
"location" : [
{
"x" : -7.87297955453618,
"y" : 73.3680160842939
},
{
"x" : -5.87287143362673,
"y" : 73.3674043270052
}
],
"timestamp" : NumberLong("1781389600000")
}
我的收藏已经有一个索引:
db.collection.ensureIndex({timestamp:-1})
查询看起来像:
db.collection.find({ "timestamp" : { "$gte" : 1380520800000 , "$lte" : 1380546000000}})
尽管如此,响应时间太长,大约20-30秒(这个时间取决于指定的查询参数)
任何帮助都很有用!
提前致谢.
编辑:我更改了查找参数,用实际数据替换了这些参数.
上面的查询需要46秒,这是explain()函数给出的信息:
{
"cursor" : "BtreeCursor timestamp_1",
"isMultiKey" : false,
"n" : 124494,
"nscannedObjects" : 124494,
"nscanned" : 124494,
"nscannedObjectsAllPlans" : 124494,
"nscannedAllPlans" : 124494,
"scanAndOrder" : …我有一组文件,每个文件中有20个以上的密钥,密钥因文档而异.某些密钥可能不存在于所有文档中.我正在尝试使用聚合框架运行MongoDB组操作.查询看起来像这样 -
db.collection.aggregate([{'$group': {'count': {'$sum': 1}, '_id': {'location': '$location', 'type': '$type', 'language': '$language'}}}])
在理想情况下,它应该返回应该存在3个键的文档,并对它们执行"分组"操作.但结果看起来像这样 -
{
"result" : [
{
"_id" : {
"location" : "abc",
"type" : "456"
},
"count" : 5
},
{
"_id" : {
"type" : "123",
"language" : "english"
},
"count" : 1
},
{
"_id" : {
"location" : "ghi",
"type" : "9876",
"language" : "latin"
},
"count" : 2
},
{
"_id" : {
"language" : "hebrew",
"type" : "9434"
},
"count" : …快速提问,但有没有人知道为什么MongoDB不会保存以下文件？我在NodeJS中使用MongoJS连接到MongoDB并使用以下代码行进行保存(在我的JS文件中,函数调用位于变量定义下面).保存功能不保存,但会自动转到回调功能.
有什么想法吗？非常感谢 :).
编辑:将错误日志添加到回调后,我收到以下错误:
{ [MongoError: error parsing element 0 of field documents :: caused by :: wrong type for '0' field, expected object, found 0: "{"Word":"Count","read":1,"letter":1,"wh":1,"urging":2,"swift":1,"approval":1,"add'l":1,"lease":1,"space":1,"fayetteville":1,"vamc":1,"vets":2,"care":1..."]
name: 'MongoError',
ok: 0,
errmsg: 'error parsing element 0 of field documents :: caused by :: wrong type for \'0\' field, expected object, found 0: "{"Word":"Count","read":1,"letter":1,"wh":1,"urging":2,"swift":1,"approval":1,"add\'l":1,"lease":1,"space":1,"fayetteville":1,"vamc":1,"vets":2,"care":1..."',
code: 9 }
db.collection.save(json_buffer, function() {
console.log("Complete");
});
var json_buffer = {"Word":"Count","read":1,"letter":1,"wh":1,"urging":2,"swift":1,"approval":1,"add'l":1,"lease":1,"space":1,"fayetteville":1,"vamc":1,"vets":2,"care":1,"@gnip":3,"--":3,"delivering":3,"data":3,"happy":3,"customers":3,"outrageous":1,"france":1,"sell":1,"warships":1,"putin":1,"@senatorkirk":1,"@repkinzinger":1,"@usrepkeating":1,"&":5,"urge":1,"strong":1,"action":3,"polling":1,"shows":1,"race":1,"close":1,"pitch":1,"pre-primary":1,"deadline":1,"goal":2,"joining":1,"@teamcavuto":1,"shortly":1,"discuss":1,"can’t":1,"continue":1,"punt":1,"debt":2,"crisis":1,"road":1,"watch":1,"opening":1,"remarks":1,"today’s":1,"senate":1,"committee":1,"hearing":1,"mcdonald":1,"nomination":1,"urged":1,"passage":1,"#summermealsact":2,"yesterday":1,"#monticello":1,"#ny--so":1,"impt":1,"expand":1,"@usda's":1,"summer":2,"nutrition":1,"program":1,"great":2,"catch":1,"high":1,"school":2,"friend":1,"john":1,"choate":1,"today":7,"family":1,"capitol":1,"hill":1,"child":1,"america":1,"wake":1,"day":1,"wondering":1,"eat":1,"nebraska":1,"communities":1,"access":1,"local":1,"tv":1,"programming":1,"introduced":1,"bill":4,"work":2,"past":1,"time":2,"congress":1,"meaningful":1,"reduce":1,"threat":1,"cyber":1,"attacks":1,"@mercnews":1,"op-ed":1,"fitting":1,"@us_sfrc":1,"passed":1,"#crpd":1,"bob":1,"dole's":1,"bday":1,"#disabilitytreaty":1,"advocate":1,"beginning":1,"#isupportcrpd":1,"senator":1,"mcconnell":2,"co-sponsors":1,"protect":2,"correctional":1,"officers":2,"daily":1,"independent":2,"#ashland":1,"#kentucky":1,"millions":1,"children":2,"recv":1,"free":1,"reduced":1,"meals":1,"year":1,"left":1,"hungry":1,"months":1,"unacceptable":1,"rt":5,"@aterkel":1,"record":1,"phone":1,"@senschumer":1,"…":1,"good":1,"meeting":1,"anne":1,"rung":1,"nominee":1,"@ombpress":1,"office":2,"fed":1,"procurement":1,"policy":1,"cc":1,"@senatehsgac":1,"@federalreserve":1,"divert":1,"leftover":1,"funds":1,"foreclosure":1,"review":1,"hardest":1,"hit":1,"fund":1,"#ri":1,"supports":1,"corrections":1,"prisons":1,"manchester":1,"pine":1,"knot":1,"ashland":1,"inez":1,"lex":1,"miami":1,"valley":1,"well-run":1,"base":1,"makes":1,"wright-patt":1,"#1":1,"airmen":1,"@gopoversight":1,"release":1,"#irs":2,"needed":1,"days":1,"confirm":1,"lerner":1,"hard":2,"drive":1,"crash":2,"provide":1,"support":3,"runaway":1,"homeless":1,"youth":1,"victims":1,"trafficking":1,"@housefloor":1,"tomorrow":1,"glad":1,"signature":1,"industry":1,"@kydistillers":1,"@repandybarr":1,"obama":1,"meant":1,"flexibility":1,"re-elected":1,"thoughts":1,"prayers":1,"affected":1,"fires":1,"tooele":1,"pray":1,"staying":1,"safe":1,"#utpol":1,"hr":1,"passes":1,"house":1,"@repderekkilmer":1,"modernize":1,"labs":1,"fyi":1,"fun":1,"activities":1,"hosted":1,"google":1,"young":1,"inventors":1,"age":1,"13+":1,"choose":1,"projects":1,"virtual":1,"field":1,"trips":1,"joined":1,"nyc":1,"workforce":2,"development":2,"hosting":1,"roundtable":1,"#bronx":1,"failure":1,"disclose":1,"timely":1,"manner":1,"destroyed":1,"critical":1,"evidence":1,"reason":2,"special":1,"prosecutor":1,"26%":1,"texas":1,"live":1,"poverty":1,"#raisethewage":1,"#honorflightact":2,"codify":1,"process":1,"tsa":1,"expedited":1,"dignified":1,"screening":1,"veterans":1,"visiting":1,"war":1,"memorials":1,"humbled":1,"join":2,"medal":1,"honor":1,"recipient":1,"staff":1,"sergeant":1,"ryan":1,"pitts":1,"nashua":1,"ceremony":1,"pentagon":1,"icymi":1,"statement":1,"halbig":1,"burwell":1,"@ecpzachevans":1,"save":1,"date":1,"mt":1,"@shrinersfest":1,"dates":1,"announced":1,"shrinersfest":1,"june":1,"25-28":1,"feat":1,"@blueangels":1,"htt…":1,"unleash":1,"america's":1,"energy":2,"abundance":1,"create":1,"#jobs":1,"economic":1,"growth":1,"affordable":1,"#yes2energy":1,"marks":1,"#100days":1,"nigerian":1,"schoolgirls":1,"kidnapping":1,"forgotten":1,"#bringbackourgirls":1,"pleased":1,"mayor":1,"@rahmemanuel":1,"taking":1,"@fly2ohare":1,"noise":1,"measure":1,"seeks":1,"pay":1,"gratitude":1,"group":1,"americans":1,"make":1,"ultimate":1,"sacrifice":1,"stopped":1,"dutch":1,"embassy":1,"offer":1,"condolences":1,"lost":1,"loved":1,"#mh17":1,"#obamafailures":1,"min":1,"#131":1,"odds":1,"drives":1,"irs":1,"claims":1,"win":1,"fl":1,"lottery":1,"times":1,"#tcot":1}