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Re: Performace issue with insert


Am 31.01.2016 um 09:09 schrieb Sergei Golubchik:
Hi, Reindl!

On Jan 30, Reindl Harald wrote:

Am 30.01.2016 um 21:07 schrieb walter harms:
Aktualy I do now some profiling now we want to see the differences
when switching 31-1.  We used myISAM since the biggest problem is
speed and immoDB showed to be crash sensitive.  We store long time
series data so the system is writing data all the time.

for "writing data all the time" MyISAM is for sure a completly wrong
decision because the performance strength of MyISAM was always on
most-read workloads

MyISAM *always* does a *complete table lock* for writes and don't allow
concurrent writes without locking - that don't scale when you write all
day long and there are table locks all day long

MyISAM should perform very good if inserts are *append only* (no updates
or deletes). In this case MyISAM will not use an exclusive table lock
and concurrent reads will be allowed

but only if you do *nothing else*

i had servers going down by 50% append and 50% update a key-field after mail-confirmation and so 50% insert / 50 % updates + locked reads for display the page

solution was to create a second table, append and update there and every 15 minutes via cron batch-insert into the main table

in that case InnoDB was no option because the only table out of 6000 on that machine which woul dhave needed it and i hate this stupid global tablespace which exists even with files_per_table

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