Recently on my local test database, some of the tables got droped unfortunately by mistake.
I enables binary logging for that database.
I would like to get the data of those specific tables from the bindary logs.
how can i do this...?
I know that binary log will consist all the writes activty. but how to get the writes of that specifictable...? binary logs are of huge size(5GB each).
plese tell me if someone knows a better approach here..
The best possible approach is to create a blackhole replication setup for the table you require.
It will log statements related to that table only.
In case of recovery you can simply use the binary logs of blackhole server to recover the data of that given table.
Related
I have to create a dashboard based on a table in mysql, and only on today datas
This db is used on a service with a massive data quantity, and continous read and write data, so I'd like to replicate in a "slave" instance part of this table (only today data).
Is it possible to do it in Mysql, without scripting?
Thanks
MySQL has no built-in feature to replicate a subset of rows. There are replication filters to replicate a subset of schemas or tables, but not rows.
One workaround could be to replicate fully to the replica, then on the replica delete any data that is more than one day old.
But this would work only for a database that is INSERT-only. If you also have UPDATE and DELETE operations replicated, they might find that they are trying to change rows that are missing. If you use ROW-based binary logs, this would result in a replication error when it can't find the row, and replication would stop.
It might work if you only use STATEMENT-based binary logs, but I've never tried it so I can't predict what other problems might occur. Also, you can't fully prevent ROW-based binary logs from occurring, because individual sessions can change their binary log format.
I think you're going to need a bespoke solution no matter what. Probably not using replication, but just an ETL job to query the current day's data and import it into another MySQL instance (not a replica).
I just dropped my company's table and realized that the SQL backup I made was for STRUCTURE not DATA. I need to restore the data immediately.... is there anyway to do this? I'm using PHPMyAdmin and all i've done so far is
DROP TABLE USEFUL_TABLE
AND
CREATE TABLE IF NOT EXISTS USEFUL_TABLE
AND (IN DESPERATION)
ROLLBACK
Is there anyway to get the data records back?
Edit
Thanks for the comments, and thank God above that I found an obscure backup somewhere that I was able to restore! Just as a tip for anyone as hasty and careless as myself, BEFORE any backup/export operations, always make sure you've selected the Dump all rows option when exporting data for a backup. I didn't, and I didn't even check to confirm that the SQL had the rows dumped.
DDL commands can't be rolled back in MySQL. You need to restore from a backup.
If you need to recover data that was committed since the latest backup, perform point in time recovery with binary logs. But this depends on having binary logging enabled, and having a continuous set of binary logs since the date of the last full backup.
We have a MySQL database based on InnoDB. We are looking to build an Analytics system for this data. We are thinking to create a cloned database that denormalizes the data to prevent join and uses MyIsam for faster querying. This second database will also facilitate avoiding extra load on the main database to which the data will be written.
Apart from this, we are also creating some extra tables that will store aggregated numbers to avoid recalculation.
I am wondering how can I sync these tables once every day to keep them updated. It looks similar to Master-slave config of MySQL which uses binary log. But in our case, the second database is not an exact slave. Are there any open-source reliable tools or any other ideas which I can use to write an 'update mechanism'?
Thanks in advance.
Is there any methods to retrieve deleted records from a mysql database?
No.
Deleted records are gone (or munged so badly you can't recover them). If you have autocommit turned on, the system commits each statement as you complete it (if you have auto commit turned off, then do a rollback NOW - phew, you're saved -- but you are running with autocommit, aren't you?).
One other approach is to reply the activity that created the missing records - can you do that? You can either re-run whatever programs did the updates, or replay them from a binary log (if you still have the binary log). That may not be possible, of course.
So you need to recover the data from somewhere - either a backup of your db (made using mysqldump) or of your file system (the data files of MyISAM tables are all simply structured and on the disk - recovering InnoDB tables are complicated by the shared use of ibdata files).
There is a possible way to retrieve deleted records (depending upon your situation). Please check here:
https://stackoverflow.com/a/72303235/2546381
How to fetch the data from binary log file and insert in our desired table in MySQL?
I am on my way of scripting a PHP code for Audit Trail, in this I encountered a situation that if there will be new table created then I will not be available with triggers for that new table and hence no tracking could be done for that, so if I code it to create three new triggers for this new table, then how will get the last change done in this table? Hence I found that Binary Log File can be helpfull for me in this case, to fetch the last change for this new table and insert it in tracking table... BUT HOW????
If you're talking about the MySQL binary log file (mysql-bin), it wasn't designed to be read by anything other than MySQL - it's a transaction log file. The data in the log file will most of the time already be in your database by the time you read it.
Perhaps if you edit your answer to provide more information about what it is you're trying to achieve, you may get a better answer and solution.
EDIT:
Parsing the binary log file is going to give you more headaches - it's an internal file for MySQL and is known to change between releases. It also changes format depending on how the server is configured (row-based/statement-based/mixed format.) Server administrators can also disable binary logging completely.
If you can take the performance hit, you may be better off logging all queries - you can have these written to a file, or even to a database table (although in early versions of MySQL 5.1 there were severe performance hits for this; it may still be the case.) This logs all SQL queries received from clients, so you can check for the CREATE TABLE query and all statements amending data in this table.
http://dev.mysql.com/doc/refman/5.1/en/query-log.html