I am trying to auto-archive active database table to archive database table using stored procedure and event in MariaDB10. These are the steps I am following:
- Create new table everyday just before midnight in archive database.
- copy rows from active table to archive table.
- delete all rows from active table.
This seems to work mostly except one issue. PLC is writing to active database table every second. When the above mentioned process is taking place, there is a gap of 2 mins between last entry of archive table and first entry of active table (meaning active table is loosing 2 mins worth of data i.e 120 rows). As per my understanding this 2 mins gap is when rows are copied over to arch table and deleted from active table. There are approximately 87K rows(256MB)generated in a day.
Question is how can I reduce this 2 mins gap (loss of rows/data)? Any help or pointers would be really helpful.
I just noticed that for step 2, I am using INSERT INTO with SELECT, probably this is locking the rows of active table hence PLC is not able to insert new rows to the active table thus loosing the 2 mins of data/rows. IT is innoDB engine. Is this thinking correct? If yes, any way to get around it?
PS: I have instrumentation engineering background (and minimal experience of DBA) and I have inherited this PLC-MariaDB setup. Original DB is not indexed, also, there is no auto-archiving taking place. Thus DB is growing in size and affecting the performance when doing any queries on DB. I have indexed the DB now and performing auto-archiving.