maria-discuss team mailing list archive

[Rhys Campbell <Rhys.Campbell@xxxxxxxxxxxxxxxxx>]

Hi All,

I've been playing with the innodb buffer pool save / load feature in MariaDB 10.0.14. I initially thought it wasn't working but I've since identified the cause of my confusion

The buffer pool was being populated with the correct number of pages but no table/index name values were given in information_schema. INNODB_BUFFER_PAGE. These details are populated as soon as the database has been access. Steps to repeat.


1.       Ensure buffer pool save/load is on.

2.       Record the SPACE & PAGE_NUMBER details of a page in information_schema.INNODB_BUFFER_PAGE for one of your databases.

3.       Stop MariaDB.

4.       Start MariaDB

5.       Allow time for buffer pool to load...

6.       SELECT *  FROM information_schema.INNODB_BUFFER_PAGE WHERE SPACE = 157 AND PAGE_NUMBER = 99212; <- NULL values for TABLE_NAME / INDEX_NAME

7.       Execute USE <db_name> # Where db_name is the database containing the above page.

8.       Repeat above select and TABLE_NAME and INDEX_NAME will be populated correctly.

Now, on a busy database this wouldn't be an issue but it did throw me for a while on my dev box. I have found a MySQL bug report...

http://lists.mysql.com/announce/847

"When running a query on INFORMATION_SCHEMA.INNODB_BUFFER_PAGE
        that requested table_name and index_name values, query results
        would include index pages without table_name or index_name
        values. (Bug #14529666)"


But the bug has been deleted so I can't check the full details to see if this is resolved or still an issue.

As an aside the logging for the buffer pool loading feature appears to use a different datetime format...

150217 18:03:37 [Note] InnoDB:  Percona XtraDB (http://www.percona.com) 5.6.20-68.0 started; log sequence number 103721589973
2015-02-17 18:03:37 7f53285f8700 InnoDB: Loading buffer pool(s) from /log/file/path/...


Rhys Campbell
Database Administrator
TradingScreen, Inc.
23 York House, 5th Floor
London WC2B 6UJ
Email: rhys.james.campbell@xxxxxxxxxxxxxx<mailto:rhys.james.campbell@xxxxxxxxxxxxxx>

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