Planet MySQL Planet MySQL: Meta Deutsch Español Français Italiano 日本語 Русский Português 中文
Showing entries 1 to 5

Displaying posts with tag: statement (reset)

Temporary Tables and Replication
+2 Vote Up -0Vote Down

I recently wrote about non-deterministic queries in the replication stream. That’s resolved by using either MIXED or ROW based replication rather than STATEMENT based.

Another thing that’s not fully handled by STATEMENT based replication is temporary tables. Imagine the following:

  1. Master: CREATE TEMPORARY TABLE rpltmpbreak (i INT);
  2. Wait for slave to replicate this statement, then stop and start mysqld (not just STOP/START SLAVE)
  3. Master: INSERT INTO rpltmpbreak VALUES (1);
  4. Slave: SHOW SLAVE STATUS \G
  [Read more...]
Non-Deterministic Query in Replication Stream
+0 Vote Up -0Vote Down

You might find a warning like the below in your error log:

130522 17:54:18 [Warning] Unsafe statement written to the binary log using statement format since BINLOG_FORMAT = STATEMENT. Statements writing to a table with an auto-increment column after selecting from another table are unsafe because the order in which rows are retrieved determines what (if any) rows will be written. This order cannot be predicted and may differ on master and the slave.
Statement: INSERT INTO tbl2 SELECT * FROM tbl1 WHERE col IN (417,523)

What do MariaDB and MySQL mean with this warning? The server can’t guarantee that this exact …


  [Read more...]
Temporary files, binlog_cache_size, and row-based binary logging
+20 Vote Up -0Vote Down

Even when the output of EXPLAIN doesn’t show “using temporary”, a temporary file may still be used in certain cases.

That’s not to say the query needs the temporary file to actually resolve the query (like what you’d see from the need for a derived table). But rather, the temporary file I’m speaking of is due to binary logging.

In particular, you can see this easily if using InnoDB, (most commonly) row-based binary logging, and you issue a large transaction, say a large …

  [Read more...]
Using short if statement in programming
+0 Vote Up -0Vote Down

In many programing languages it is possible to shorten if statements using what’s called the ternary operator. It is sometimes referred as the “one line if statement” or the “short if statement”. This can help at times to produce cleaner code, however use this operator wisely as it is not always best to be used for more complicated statements.

PHP Example of an if statement

1
2
3
4
5
6
7
8
if($nFoo > 0)
{
   echo "I'm at the work.";
}
else
{
   echo "I'm at home.";
}
  [Read more...]
Will you use row-based replication by default?
+0 Vote Up -0Vote Down



MySQL 5.1 introduces row based replication, a way of replicating data that fixes many inconsistencies of the statement based replication, the standard method used by MySQL so far.


The good: row based replication solves some problems when replicating the result of non deterministic functions, such as …





  [Read more...]
Showing entries 1 to 5

Planet MySQL © 1995, 2014, Oracle Corporation and/or its affiliates   Legal Policies | Your Privacy Rights | Terms of Use

Content reproduced on this site is the property of the respective copyright holders. It is not reviewed in advance by Oracle and does not necessarily represent the opinion of Oracle or any other party.