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Jim_UK Board Member
Joined: 19 Nov 2008
Posts: 656 Location: North West UK
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Posted: Fri Jun 12, 2015 9:13 am Post subject: Table crash |
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For the very first time I have just experienced my database crash. This was a single table in the database (sessions table)
What would be the most likely cause of a table such as "sessions" crashing or is it just one of those things and I have been lucky up to now?
The whole server had been down for unknown reason and had just been rebooted. Could that be the cause?
Jim _________________ The truth is out there.
Unfortunately they will not let you anywhere near it! |
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StarWolf3000 Board Member
Joined: 10 Jun 2010
Posts: 175 Location: Germany
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Posted: Sun Jun 14, 2015 4:54 am Post subject: Re: Table crash |
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Is your sessions table using the default MyISAM engine? In most cases MEMORY would be the better storage engine (you can change it with ALTER TABLE prefix_sessions ENGINE=MEMORY; ).
This stores the structure of the table on disk, but it's contents in RAM of the server (make sure your server has enough RAM and MySQL enough assigned), emptying the table when MySQL is stopped/restarted.
To repair the sessions table:
REPAIR TABLE prefix_sessions;
If your server rebooted without a MySQL clean shutdown, this can lead to a problem with tables, when data is written to the disk during that moment. Normally, MySQL autochecks most databases and tables on startup and tries to repair them on its own (or prompting the user to do that, only with shell access), but there can always be some lost or corrupted data.
A lot of database related problems in phpBB 2.x origin of corrupted sessions tables. |
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Jim_UK Board Member
Joined: 19 Nov 2008
Posts: 656 Location: North West UK
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Posted: Sun Jun 14, 2015 5:02 am Post subject: Re: Table crash |
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Thanks for the info. I shall monitor it for a while before deciding whether to make any change. That is the first table crash in 10 years.
Jim _________________ The truth is out there.
Unfortunately they will not let you anywhere near it! |
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Matuse Board Member
Joined: 18 Apr 2017
Posts: 1
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Posted: Sat Apr 22, 2017 3:24 am Post subject: Re: Table crash |
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Jim_UKe wrote: | Thanks for the info. I shall monitor it for a while before deciding whether to make any change. That is the first table crash in 10 years.
Jim |
I've had one of those rare occasional crashes after years of running perfectly recently, just like yourself. |
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Jim_UK Board Member
Joined: 19 Nov 2008
Posts: 656 Location: North West UK
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Posted: Sat Apr 22, 2017 3:30 am Post subject: Re: Table crash |
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We have had no problems since that incident.
Have you run a repair on your database tables?
Jim _________________ The truth is out there.
Unfortunately they will not let you anywhere near it! |
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DanielBenford Board Member
Joined: 19 Jul 2018
Posts: 1
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Posted: Thu Jul 19, 2018 10:47 pm Post subject: Re: Table crash |
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Matuse wrote: | Jim_UKe wrote: | Thanks for the info. I shall try over the counter phentermine first and monitor it for a while before will make any change. That is the first table crash in 10 years.
Jim |
I've had one of those rare occasional crashes after years of running perfectly recently, just like yourself. |
I've also experienced a crash once after 5-6 years of running with no problem. One table got corrupted, but backups helped. No problem experienced since then. |
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Jim_UK Board Member
Joined: 19 Nov 2008
Posts: 656 Location: North West UK
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Posted: Fri Jul 20, 2018 5:01 am Post subject: Re: Table crash |
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Still just had the one table crash and now at 14 years.
I do of course do regular database backups "just in case"
Jim _________________ The truth is out there.
Unfortunately they will not let you anywhere near it! |
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JLA Board Member
Joined: 30 Apr 2009
Posts: 451 Location: U.S.A
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Posted: Mon Jul 23, 2018 4:32 pm Post subject: Re: Table crash |
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We've found it helpful to run scheduled optimize and repairs on tables. Also for INNODB it has been helpful to have each table have its own file.... _________________ http://www.jlaforums.com |
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Manuelm Board Member
Joined: 02 Aug 2018
Posts: 1
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Posted: Thu Aug 02, 2018 5:40 am Post subject: Re: Table crash |
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Matuse wrote: | Jim_UKe wrote: | Thanks for the info. I shall try the Yoga Burn monitor it for a while before deciding whether to make any change. That is the first table crash in 10 years.
Jim |
I've had one of those rare occasional crashes after years of running perfectly recently, just like yourself. |
I had my first one the other day after 8 years of perfect running. I've been doing backups since the start and I can tell you, all of that extra time backing things up did pay off in the end |
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Jim_UK Board Member
Joined: 19 Nov 2008
Posts: 656 Location: North West UK
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Posted: Thu Aug 02, 2018 7:01 am Post subject: Re: Table crash |
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I used to do a daily backup using Msqldumper but have reduced it to about once a week.
Daily is better of course.
Jim _________________ The truth is out there.
Unfortunately they will not let you anywhere near it! |
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Jim_UK Board Member
Joined: 19 Nov 2008
Posts: 656 Location: North West UK
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Posted: Sat Feb 16, 2019 11:32 am Post subject: Re: Table crash |
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Jim_UK wrote: | For the very first time I have just experienced my database crash. This was a single table in the database (sessions table)
Jim |
Well I have just had my second one and once again it is the sessions table. Could it be that of all the tables this is the one most likely to develop problems. Fortunately I happened to be on line at the moment the sessions table crashed so it was fixed in just a couple of minutes.
Jim _________________ The truth is out there.
Unfortunately they will not let you anywhere near it! |
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lumpy burgertushie Board Member
Joined: 18 Nov 2008
Posts: 266
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Posted: Sun Feb 17, 2019 1:28 pm Post subject: Re: Table crash |
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so, once ever 4 years the sessions table gets sideways. I would say that is not too bad.
are you truncating the table when you fix it? if not, do that. all that will happen is that it will log out anyone logged in at the time and everyone will have to log in next time they visit.
maybe the table just can't handle as many records as it has after 4 years.
robert |
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Jim_UK Board Member
Joined: 19 Nov 2008
Posts: 656 Location: North West UK
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Posted: Sun Feb 17, 2019 1:36 pm Post subject: Re: Table crash |
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Hi Robert
Rarely more than about 7 or 8 on line at anyone time.
I don't truncate it - just run a repair on it and that cures the problem.
First indication there was a problem was when I tried to do a search for "posts since last visit".
That threw up an error message on the screen indication a sessions table error.
I didn't do a screen shot but was something to do with a duplicate entry in sessions table.
Problem solved - I just wondered if the sessions table was prone to this sort of thing.
Jim _________________ The truth is out there.
Unfortunately they will not let you anywhere near it! |
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StarWolf3000 Board Member
Joined: 10 Jun 2010
Posts: 175 Location: Germany
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Posted: Mon Feb 18, 2019 3:28 am Post subject: Re: Table crash |
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I'm just wondering: phpBB2 already includes a clean-up routine for the sessions, so I don't really get it why the table gets full or damaged. Even though its not of type MEMORY by default, it should not become "full", since the key is not an integer (that might overflow), but a 32 chars string.
If its type is MyISAM, then you have a row limit of 4,294,967,296 (2^32), unless MySQL has been built with the --with-big-tables option, for which the row limit is 18,446,744,073,709,551,616 (2^64).
If it gets full, then you're probably hitting the 4 billion something mark. |
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Jim_UK Board Member
Joined: 19 Nov 2008
Posts: 656 Location: North West UK
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Posted: Mon Feb 18, 2019 6:29 am Post subject: Re: Table crash |
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The error message was something about a duplicate entry. I should have done a screen grab but first thing on my mind was get rid of the problem before I start getting emails/phone calls from members telling me there was a problem.
Jim _________________ The truth is out there.
Unfortunately they will not let you anywhere near it! |
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