problem description There are two indexes in mongo, the first is a single-field index of the {_ id} field, and the second index is a composite index composed of {chat_id, _ id}. When I use the query db.collection.find ({ "chat_id ": ObjectId ( "* ")...
raceback (most recent call last): File " home shenjianlin .local lib python3.4 site-packages twisted internet defer.py", line 653, in _runCallbacks current.result = callback(current.result, *args, **kw) File " home shenjianlin my_pr...
in java, mongodb is operated by multiple threads. uses mongoTemplate as an operation. then, there are more than five hundred threads to operate on the mongodb. then, it was found that none of the 500-plus threads had to create a new mongodb connection...
how can I delete the files under the journal file of mongodb? produced a lot of tables before, so some were deleted, but this folder still has more than 60 gigabytes, which is much larger than the size of the existing tables. how to clean it up? ...
case: a table has at least 30 million pieces of data per day. There are thousands of types. Can you now quickly read the maximum values of the day for thousands of types at a time, that is, the last record time of the day? Maybe 15:00. Maybe 23:00. I m...
I currently have a query using mongodb3.4, that needs to be paged. Paging needs to return the total number and number of pages. but that s the problem. Paging queries are fast, but counting is slow . The count statement is as follows: db.message.fin...
(?!) Zero width negative antecedent assertion, attempts to match always fail because there is no suffix expression how to understand this sentence. If you can give an example. ...
see a sentence from a blog: selectorDOMpseudo-class DOM csspseudo-class. I have never felt much about this passage, let alone understand it. Recently, I learned pseudo-elements and read an example and suddenly had an epiphany. The example is very l...
how hexo embeds a demo code tool like jsfiddle ...
install the Ambari2.6.2 version, the HDP2.6.4 version, which comes with hbase version 1.2. Now if I want to install the hbase2.0 version, all I can think of is to customize a service, and put the 2.0 version hbase; in the custom service. But I think the ...
this is the case with multiple tasks created. After clicking run, it will always be stuck in the active state and will not grab the data. It can be run before, but it can t be restarted now ...