Mysql slave invalidating query cache entries

16-Aug-2017 03:59

to complete Your long_query_time seems to be fine BINARY UPDATE LOG The binary update log is NOT enabled. MEMORY USAGE Max Memory Ever Allocated : 650 M Configured Max Per-thread Buffers : 2.70 G Configured Max Global Buffers : 320 M Configured Max Memory Limit : 3.02 G Physical Memory : 2.00 G Max memory limit exceeds 90% of physical memory KEY BUFFER Current My ISAM index space = 52 M Current key_buffer_size = 256 M Key cache miss rate is 1 : 1710 Key buffer free ratio = 74 % Your key_buffer_size seems to be fine QUERY CACHE Query cache is enabled Current query_cache_size = 64 M Current query_cache_used = 29 M Current query_cache_limit = 1 M Current Query cache Memory fill ratio = 45.79 % Current query_cache_min_res_unit = 4 K My SQL won't cache query results that are larger than query_cache_limit in size SORT OPERATIONS Current sort_buffer_size = 2 M Current read_rnd_buffer_size = 12 M Sort buffer seems to be fine JOINS Current join_buffer_size = 132.00 K You have had 225 queries where a join could not use an index properly You should enable "log-queries-not-using-indexes" Then look for non indexed joins in the slow query log.You will not be able to do point in time recovery See THREADS Current thread_cache_size = 8 Current threads_cached = 7 Current threads_per_sec = 0 Historic threads_per_sec = 0 Your thread_cache_size is fine MAX CONNECTIONS Current max_connections = 151 Current threads_connected = 1 Historic max_used_connections = 18 The number of used connections is 11% of the configured maximum. If you are unable to optimize your queries you may want to increase your join_buffer_size to accommodate larger joins in one pass. This script will still suggest raising the join_buffer_size when ANY joins not using indexes are found.In today’s post, we’ll set up Proxy SQL to work in a My SQL Replication environment managed by Cluster Control.We will take a look at the metrics it provides to a DBA, and how this data can be used to ensure smooth operations.In a situation like this, the query cache can mask performance problems caused by missing indexes, which makes it helpful for novice users.The query cache has been disabled-by-default since My SQL 5.6 (2013) as it is known to not scale with high-throughput workloads on multi-core machines.Rene confirmed this in his post yesterday, but it has also previously been mentioned by Stewart Smith, Domas Mituzas (update: and Kristian Koehntopp).Assuming that scalability could be improved, the limiting factor of the query cache is that since only queries that hit the cache will see improvement; it is unlikely to improve We concur with the research performed by Jiamin Huang, Barzan Mozafari, Grant Schoenebeck, Thomas F. We considered what improvements we could make to query cache versus optimizations that we could make which provide improvements to .

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In a previous blog post, we discussed the installation of Proxy SQL and its configuration system.

OPEN FILES LIMIT Current open_files_limit = 1561 files The open_files_limit should typically be set to at least 2x-3x that of table_cache if you have heavy My ISAM usage.

This is indeed something we have observed in the My SQL team for a while.

I suspect the performance impact is even higher on My SQL 5.7. A single global mutex just doesn’t scale to 4 cores, let alone 24 cores at 8 threads per core.

My SQL のレプリケーションは、安定稼働やバックアップ、負荷分散などの目的に利用できる優れた機能です。 bin-log (バイナリログ) を利用して Master サーバから Slave サーバに更新を伝播させ、データの複製を行います。Slave サーバでは、2 つのスレッドが動作しています。 IO_THREAD – Master から送られてきたデータを受け取り、relay-log (リレーログ) として書き出す SQL_THREAD – relay-log を読み出し、DB を更新するshow slave status \G *************************** 1.

Hopefully this threat can grow and be useful to others in the future. In any case, output of recent is included here for your viewing enjoyment...