Java SQLite JDBC“ SELECT”语句非常慢

Question

From an API i get ~9000 entries which i have to insert into a table. Detailed data for every of these entries is stored in another table with ~45000 entries

Now i am trying to insert these 9000 entries into a new table and getting the needed information about these entries from the other table.

The SELECT statement for the data in the table with 45000 entries takes something between 30-90ms each time.

The code for the select is as follows (Repeated 9000 times):

                long startTime = System.nanoTime();

                PreparedStatement selectDB = cStatic.prepareStatement("SELECT column1, column2, column3, column4 FROM DB WHERE ID = ?");
                selectDB.setInt(1, rsIDs.getInt(3));

                ResultSet rsDB = selectDB.executeQuery();

                long endTime = System.nanoTime();

                long duration = (startTime - endTime) / 1000000;

From the whole process (collecting information, iserting) the SELECT + ResultSet alone take 95% of the processing time, i'd like to know how i can speed this up

Since i already searched for solutions i am already using indexes for "getInt/getString" from result set and also only call the needed columns of the table instead of the full row, but only a very minor improvement.

Every other statement (UPDATE , INSERT, DELETE) hardly even uses 1ms, why is SELECT needing so much time?

EDIT:

Didn't really speed up the SELECT , but i was rebuilding the code to only use the SELECT once and store every important data into an array , now it's done in 2-3 seconds instead of 5 minutes.

Thanks to Rahul i tried giving the columns an index and it helped a bit too:

ALTER TABLE table_name ADD INDEX idx_id ( ID );

Answer 1

30ms shouldn't be counted as slow though, you may want to make sure that you have a index created or index in place for the ID column since you are using that column in your WHERE condition as WHERE ID = ?

No I mean create an unique index on ID column if you don't have already by saying below which will eventually speed up your query by performing an index scan.

ALTER TABLE table_name ADD INDEX `idx_id` (`ID`);