![]() ![]() tTimer(config. ProcessRows(rowIterator) // this updates start_id so that the next query starts from somewhere else pollingHandler = id -> rows", rows.size()) I can't seem to understand how this is happening. When I replace ? in the query with the debug values and run the query in mysql console, it returns batch_size number of rows. The debug value for start_id remains the same after it was updated by the first call. The initial call does update start_id when I check the debug logs and therefore second call should return new batch of rows but it returns empty and so goes for the rest of the subsequent calls. I can't seem to understand why it's returning an empty RowSet. The logs are filled with Processing 0 records when I debug. But the subsequent scheduled calls all return 0 rows. In code, only the first call works and returns the right number of rows, and after finished processing start_id is updated for the next scheduled call. In code, only the first call works and returns the right number of rows, and after finished processing startid is updated for the next scheduled call. When I copy the query FETCH_SAMPLE_DATA_QUERY with various valid parameters of start_id and batch_size and use it in mysql console, it works. When I copy the query FETCHSAMPLEDATAQUERY with various valid parameters of startid and batchsize and use it in mysql console, it works. ![]() I have this property in the class private static Handler pollingHandler and initialize it as below and call it for the first time. I am using vertx setTimer to do the periodic scheduling (so that one starts after the previous has ended). It simply queries a certain table and based on the row values processes them (i have to maintain the polling, can't change to CDC like debezium). You could create this as a function and return the SelectStatement, if that's more convenient for your environment.I'm porting an old java program that polls the db every few minutes. I added a linebreak (CHAR(10)) to each subsidiary "SELECT.UNION" statement, for convenience in viewing or editing the statement. Very similar to the first procedure in concept. # TableName RowCount for all tables in the current database. # SELECT.UNION statement that, if used as a View, will output # Outputs a single row and column, containing a (possibly lengthy) That is useful if you want to join the row counts to some other per-table info from another table. So, it is still useful to be able to quickly produce, without manual editing, the separate SELECT.UNION statement that can be used as a View. However, despite returning a result set, so far as I am aware it can't be referenced in another View or Query, presumably because MySQL is unable to determine, before running it, what result sets it produces, let alone what columns they have. The above procedure is useful for a quick look in an admin environment like Navicat, or on the command line. ![]() Sets the group_concat_max_len variable in order to allow a long enough result string from GROUP_CONCAT. The SELECT.INTO creates the necessary query, and the PREPARE. 'SELECT ''',table_name,''' as TableName, COUNT(*) as RowCount FROM ', SET SESSION group_concat_max_len = 1000000 # Outputs a result set listing all tables and their row counts The first example code here is a stored procedure which performs the entire process in one step, so far as the user is concerned. It's not rocket science, but it's convenient to have it spelled out. I had not seen this turned into a single step, so below I post that answer. One query to create a result set with rows containing the individual select count(*) statements, followed by a textediting procedure to turn that into the actual statement that can produce the desired output. for each table.Īcross many repetitions of this question on stackoverflow, there are numerous answers that involve a two-step process. Hence it's necessary to compose a method that does an explicit SELECT Count(*). The MySQL TABLES table in the information_schema database provides a table_rows field: SELECT table_name, table_rowsīut table_rows is only valid for some database engines, whereas for INNODB it is either NULL or not accurate. When reviewing a database, it's highly useful to get an overview of all the tables, including their row counts: TableName Count
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