if there are three fields in the table: id, date, gender if sometimes the query is (id, date, gender) , sometimes the query is (id, gender) is it possible to create a (id, date) joint index because gender is not highly differentiated does not need to...
The index of numeric type is b-tree tree, but what about string type? Is it possible to map a numeric value to each string and arrange it according to the b-tree tree? ...
problem description 1. A certain field of a table has a high degree of repetition, so how much repetition is it not suitable for indexing? 2. If a table does not build an index other than the primary key, how old will the table be, such as a slow que...
Hello, everyone. I have a question to ask you. I have a string s: = "ts_flow " and then I want to take the first index. I used to use python, just say python is s [1]. But take it out and it s a number. I want to make the judgment of if s [1] = " " an...
query statement as follows: select * from table where index column in (xx,yy,zz,.) expect it to trigger the index, but sometimes the index cannot be triggered when there are too many elements. what is the reason for this? ...
or answer my question directly: when a sql of select has a primary key and an index, what is the order of its execution? is there a big god to find it first from the primary key or from the index? ...
problem description the environmental background of the problems and what methods you have tried The execution plan with the btree index added to the field still seems to sweep the table related codes Please paste the code text below (do ...
I check in the background that there are multiple indexes of a table in the database I have rebuilt a table. Is there any way to add all the indexes to ...
when using Lucene to build an index, the IndexWriter object is too large to lead to memory overflow, but my IndexWriter has been created by declaring temporary variables, but after each execution of the IndexWriter.addDocument () method, the size of the ...
Let s say that there are three fields in the Table table, which are all high-frequency queries for Filter conditions. If you set up a composite index (An and B), some query combinations will cause the index to fail, so why not build an index on all thre...
now there are several completely different statistical data structures for a city, which are obtained from parsing tables. If you put dozens of type, under an index in the mapping of ES, there are probably dozens of type, under different Index or all und...
The index is a data structure in which the leaf node of the b + tree holds pointers to the actual rows. what about clustered indexes? what does InnoDB s clustered index mean by storing B+Tree indexes and data rows in the same structure? Does mean that...
when you look at the error prompt, it feels like there is not enough space, but it is not. 5 machines each have 20T disks, each with 8T left. But every time the index is created for about a day or so, an error will be reported. error log is as follows...
select * from test_table where a=xx1 and b=xx2 and c=xx3 group by dailxx4; ask the bosses, this kind of query condition, so how to build it? Do you want to build a single index or a composite index? Answers and reasons. I hope the bosses can mention an...
has the following array [ {name: , age: 15}, {name: , age: 14}, {name: , age: 13}, {name: , age: 22}, {name: , age: 16}, {name: , age: 18}, ] can we use regular and findIndex-like methods to match all index? with ...
Writing code in pycharm in ubuntu cannot connect to the oracle database, but the tools included in pycharm can connect, and you can connect normally in shell. In the end, you can t find the reason why you keep reporting that it is a 64-bit client, but a...
when you click manually, you can copy the specified content to the pasteboard, and add an automatic loading page on this basis, how to achieve it? < hr > <body> <input type="text" id="inputText" value="444" ...
see a shopping item in github. All user orders create a schema1 to store all user orders. User personal information creates schema2,schema2. In addition to basic information, there is a personal order: [] to store personal orders. there is a question....
how do you realize that a registration page needs to switch between individual registration and institutional registration? ...
I have two sites, and after they log in, they will generate a token, to determine whether the authentication is successful. The next API request can be made with token, or only if it is required. but how can I achieve token sharing between the two sit...