Invalidating query cache entries mysql
For example, the position is 999 and I want to analyze the previous five events. Q: We are having issues with inconsistencies over time.
We also have a lot of “waiting for table lock” statuses during high volume usage.
That's what my searching online has found, I don't know if that's true though or if I should be regularly reseting the cache.
Queries that happened a month ago are probably no longer useful now.
Regarding data consistency between the master and slave, you need to use row-based replication.
If I understand correctly, every insert or update will clear the cache for that table?
So if it's storing those query results then it's completely worthless because chances are no one is going to run that same exact query again.
I ran SHOW STATUS LIKE "Qcache%" and the results were: Qcache_free_blocks 6941 Qcache_free_memory 23490288 Qcache_hits 253269763 Qcache_inserts 368937684 Qcache_lowmem_prunes 57410566 Qcache_not_cached 9872266 Qcache_queries_in_cache 35275 Qcache_total_blocks 84877 I don't really know what those things mean or if they are even useful in determining whether or not I need to reset the cache. The manual didn't lie to you, any queries which alter data in a table invalidate any cache entries that reference that table. If your data is updated so often that queries would never last in the cache, or the same query is run so infrequently that it's not useful to cache it, then you're just wasting huge amounts of memory and CPU time checking and invalidating cache entries on every Is there a way to turn off the query cache just for selected tables?
To avoid this issue, you need to keep the query cache small (not larger than 512 MB) and de-fragment it from time to time using the FLUSH QUERY CACHE command.
Q: Sometimes when IO is slow and during lag we see info: Reading event from the relay log “Waiting for master to send event” — How do we troubleshoot to get more details.
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If there is no error message, or if the message doesn’t provide enough information to solve the issue, use the network troubleshooting methods discussed in the “Troubleshooting hardware resource usage” webinar.