One of my MySQL tables has been truncated by accident and I'd like to undo it so the data is returned. Is there a log anywhere I can view the data truncated or possibly get back the data?
I've read about MySQL binary log, where are they stored? The last backup I have is from 3rd of may but I'd like to get back the data that has been truncated if possible.
How do I solve: binary logs?
mysql_query("SHOW BINARY LOGS");
How do I view binary logs?
You can use the mysqlbinlog utility to view the content of the binary log if binary logging is enabled for your MySQL Server instance. It will dump the binary log as a SQL script.
You may still not be able to recover your data, as binary logs are sometimes a little tricky and contain just a few days of history.
I suggest that you read the documentation of the mysqlbinlog utility before attempting anything: https://dev.mysql.com/doc/refman/5.6/en/point-in-time-recovery.html
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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.
I want to get mysqldump after certain checkpoint e.g. if i take the mysqldump now then next time when i will take the dump it should give me only the commands which executed between this time interval. is there anyway to get this using mysqldump.
One more thing how to show the commands delete, update in the mysqldump files.
Thanks
I dont think this is possible from a MySQLdump, however that feature exists as part of MySQL core - its called Binlogging or binary logging.
The binary log contains “events” that describe database changes such as table creation operations or changes to table data. It also contains events for statements that potentially could have made changes (for example, a DELETE which matched no rows). The binary log also contains information about how long each statement took that updated data
Check this out http://dev.mysql.com/doc/refman/5.0/en/binary-log.html
Word of warning, binlogs can slow down the performance of your server.
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
There are times when a table / database is dropped unintentionally.
I have to check the date-time of the start position from the binary when the backup was taken.
I do also have to check the date-time of the position where the "drop" statement is found. I do run the mysqlbinlog statement with those parameters.
I can not use start-position and stop-position parameters because the binaries are spread across different files. Is there any better way to handle such human mistakes?
every time you take a backup, you should be using FLUSH TABLES WITH READ LOCK to force all of the tables in to a consistent state, followed by FLUSH LOGS to close the current binary log. then, when you apply the backup, all you have to do is replay one binary log.
I've set mysql parameter innodb_flush_log_at_trx_commit=0. It means that mysql flushes transactions to HDD 1 time per second. Is it true that if mysql will fail with this flush (because of power off) i will lose my data from these transactions. Or mysql will save them in data file (ibdata1) after each transaction regardless of binlog flush?
Thanks.
The binary log contains “events” that describe database changes such as table creation operations or changes to table data. It also contains events for statements that potentially could have made changes (for example, a DELETE which matched no rows), unless row-based logging is used. The binary log also contains information about how long each statement took that updated data. The binary log has two important purposes:
For replication, the binary log on a primary replication server provides a record of the data changes to be sent to secondary servers. The primary server sends the events contained in its binary log to its secondaries, which execute those events to make the same data changes that were made on the primary.
Certain data recovery operations require the use of the binary log. After a backup has been restored, the events in the binary log that were recorded after the backup was made are re-executed. These events bring databases up to date from the point of the backup
The binary log is not used for statements such as SELECT or SHOW that do not modify data.
https://dev.mysql.com/doc/refman/8.0/en/binary-log.html
Here is the entry in the MySQL reference manual for innodb_flush_log_at_trx_commit. You can lose the last second of transactions with the value set to 0.
Note that the binlog is actually something different that is independent of innodb and is used for all storage engines. Here is the chapter on the binary log in the MySQL reference manual.