Questions tagged [buffer-pool]

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1answer
46 views

Big Amount of <free_space_in_bytes> in Buffer Pool's Database Pages

We were viewing sys.dm_os_buffer_descriptors using below query select d.[name] [Database_Name], (count(file_id) * 8) / 1024 [...
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0answers
24 views

MySQL 5.7 isn't using new innodb buffer pool settings

I have a very tiny VM which keeps running out of memory. I believe this is due to the buffer pool size. Default appears to be 128M for innodb_buffer_pool_size and innodb_buffer_pool_chunk_size. So I'...
0
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1answer
21 views

Amount of used cache / free cache

I need to find out how much cache is used, and if there is free cache available. Background: Queries on a production server take a lot of time when the server is under heavy load. I suspect that ...
0
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1answer
17 views

Least recently used replacement strategy - where is pin count stored?

I am reading a book on databases and a chapter in it talks about buffer manager and it's replacement strategies. The two popular replacement startegies mentioned are least recently used - LRU and ...
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1answer
28 views

Direct database interaction with memory - how it works?

I am reading a book on databases and a chapter in it talks about buffer manager and it's replacement strategies. I've noticed that the DBMS interacts directly with memory, as opposed to asking OS to ...
8
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1answer
172 views

Database Cache Memory in Performance Monitor drops down significantly after DBCC CheckDB

We have been monitoring some SQLServer: Memory Manager's metrics, and noticed that after DBCC CheckDB job, metric Database Cache Memory (KB) drops down significantly. If to be exact, it dropped ...
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0answers
25 views

SQL Server Resource Governor for Buffer Pool [duplicate]

We plan to have multiple databases on a Server Instance. Does Resource Governor allow buffer pool to be allocated for each database in SQL Server 2017?
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19 views

How can I reproduce InnoDB buffer pool 'warm-up' time? What am I doing wrong with sysbench?

I've found that a large production DB experiences a severe degradation in performance, after a restart. It makes sense that this is because after a restart, the innoDB buffer pool isn't yet warmed up ...
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0answers
204 views

buffer overflow detected in mariadb 10.3.11

We are getting Assertion failure every time memory usage of MySQL spikes up to the overall system's memory. Example: InnoDB: Assertion failure in file /home/buildbot/buildbot/build/mariadb-10.3....
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0answers
194 views

SQL Server buffer cache smaller after reboot with same workload [closed]

We are hosting a SQL Server 2014 SP2 CU16 in a Windows Server 2016 64-bit environment for a customer. Performance has been fine for a long while. On March 31 at midnight, the database server ...
0
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1answer
53 views

Does Lazy Writer spend resources on flushing out pages from the buffer pool?

In MS SQL Server, does Lazy Writer spend resources to make pages out of the buffer pool after periodically checking free buffer list and marking some clean pages as free? Or free marked clean pages ...
1
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1answer
97 views

How does SQL Server determine how much memory to allocate to Data cache

SQL Server Standard Edition has a limit to how much memory it can use for the data cache. With that in mind, how does Enterprise Edition decide how much memory it can use for the data cache? Lets ...
0
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1answer
82 views

innodb cache duplication due to os page cache and buffer pool

We have set our innodb buffer pool 80% of total memory. Mysql page allocation gets stalled sometimes when page cache is occupying memory. Now since mysql is caching table rows and indexes and follows ...
0
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1answer
238 views

How does MySQL evict pages from the buffer pool?

I am trying to understand the internals of MySQL. I do know that MySQL's buffer pool management has an old/young page list as shows here. And I do know about the flushing of old dirty pages, such as ...
1
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1answer
137 views

Cannot set innodb_buffer_pool_size above 1023M in my.ini

Windows server 2012 R2 with 64GB RAM, MySQL 8. The Database is about 5GB. I am using a buffer pool of 1023M, as shown below: innodb_buffer_pool_size=1023M If I enter anything above 1023M e.g. 1024M ...
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0answers
156 views

MySQL connection timeout issues

We have a PXC environment with three nodes, and each node has 8GB of total RAM, with half of that (4G) dedicated to SWAP, and 3GB configured for Innodb-buffer_pool_size. Our developers have reported ...
0
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2answers
69 views

In Full recovery mode, when does the buffer/transaction log changes get applied to the database data pages?

When a change is to be made, the data page is fetched from the database data file into the buffer and changes are made to the buffer page and are also written to the transaction log. Write ahead ...
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0answers
34 views

MySQL Queries Truncate Causing Connection Spikes

We have a MySQL Master Instance & Read (failover only) on AWS. MySQL 5.6 Aurora running Magento. Performance is great, and better than standard MySQL (we have high traffic site so see the benefits)...
2
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3answers
2k views

Would my MySQL database benefit from increasing the InnoDB buffer pool size?

Of course, the answer is pretty much always "yes", but I'm interested in my specific situation. This is similar to Making sense of INNODB buffer pool stats but, IMO, a little more specific. First of ...
1
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1answer
595 views

getting innodb buffer usage

I am running MySQL 5.5.52 I am trying to see how much of my innodb buffer pool is used. If I run 'show engine innodb status' I see this: ---------------------- BUFFER POOL AND MEMORY -----------------...
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0answers
401 views

SQL Buffer Pool and Plan cache

Does SQL Buffer Pool size = Max server memory.? I have been trying to find out the reason why plan cache in my SQL server 2016 gets cleared every few hours. I have 128 GB Physical Memory. Earlier i ...
8
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4answers
22k views

Memory Usage by SQL Server

How do i check memory usage by my SQL server in production box. I am using SQL Server 2016.When ever i check task manager,it shows above 90%. I don't think that is the real memory usage by sql server. ...
0
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1answer
45 views

Querying MySQL InnoDB to find if the Record is in its Buffer Pool

For us, it is very important to get high response time for our website php script which queries a large database. It is essentially getting user information for the user who visited the page. There ...
5
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1answer
241 views

Dump the buffer pool to disk so it can be loaded after a restart

Is there a way to preserve the buffer pool cache so that is can be loaded in after a restart? My research suggests that other DB servers can do this but SQL Server is not one of them. I'm looking for ...
3
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2answers
788 views

MySQL `innodb_log_file_size`: how big is too big?

In many answers, discussions, and comments, the prevailing wisdom seems to be to "set innodb_log_file_size to be 25% of the inndb_buffer_pool_size. What about fairly large buffer pools? For example, ...
2
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1answer
36 views

SQL Server Buffer Pool Extension in FullText Index Population

I have a server that has 32GB of RAM and SQL Server 2014 Enterprise installed over it. I want to try the impact of Buffer Pool Extension (BPE) on Full Text Population. I created a table and populated ...
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0answers
61 views

Why are pages being removed from the buffer cache

I have an test environment with SQL Server 2016 SP1 installed. My machine has 32GB of RAM and I give 30GB to SQL Server. I have 2 databases in my server - BGD and, BGD_Mem. The second one contains ...
3
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1answer
7k views

SQL Server 2012/2014 insufficient memory available in the buffer pool [closed]

We have bunch of SQL Server 2012 Standard and SQL Server 2014 Standard database instances running on Windows 2012, each have different storage and memory. We are getting: Error Code: 802; There is ...
1
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1answer
34 views

What is the purpose of a buffer and a buffer manager?

In a database system, what is the purpose of a buffer and a buffer manager? This concept currently came up in my class and am very interested to learn more.
2
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1answer
83 views

If a query reads more pages than the InnoDB buffer can hold, are all the previous pages evicted?

If I have some (hot) pages in the InnoDB buffer, and I perform a query which reads an amount of data larger than the buffer itself, will the hot pages be necessarily evicted?
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1answer
1k views

Data Synchronization process in Database Mirroring and Alwayson Groups SQL Server

I have few questions on Database Mirroring and Alwayson, i am reading about always on and i found below data synchronization process from primary replica to secondary replica in msdn, Quesitions: ...
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0answers
23 views

MySQL optimizing buffer_pool_size among buffer_pool_instances - where is the trade off? [duplicate]

I'm looking to optimize MySQL INNODB by tuning buffer pool individual instances. According to the MySQL documentation: "The total size you specify is divided among all the buffer pools. For ...
3
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2answers
82 views

Why are certain objects loaded into Buffer?

I have been experimenting on my test environment with clearing buffer cache via DBCC DROPCLEANBUFFERS Before any work is done or operational queries run the buffer is instantly starting to ...
1
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1answer
2k views

Mysql innodb_log_buffer_size change

I'm new to Mysql, and i'm reading this in a book: "A large log buffer allows large transactions to run without a need to write the log to disk before the transactions commit. Thus, if you have big ...
10
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3answers
3k views

How does SQL Server handle the data for a query where there is not enough room in the buffer cache?

My question is how does SQL Server handle a query that needs to pull more volume of data into the buffer cache than there is space available? This query would contain multiple joins, so the result set ...
1
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3answers
64 views

Identify cached data for a specific query in data cache

I'm trying to identify, if possible, how long it takes for data being cached by a stored procedure to be taken out of the cache. I know there is the PLE counter in sys.dm_os_performance_counters, but ...
3
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1answer
447 views

select data which is bigger than buffer pool size

Imagine we have a table which has 100 Million rows and 80 GB size. Every rows has Text column and multiply integer columns. we set Innodb_buffer_pool_size to 40G I executing this Query: select ...
1
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1answer
2k views

What are the different ways to Warmup InnoDB Buffer Pool in MySQL 5.6?

Warming up a cold MySQL instance is moving all data or the data with the highest probability of getting used to main memory. And, yes, by main memory, I mean InnoDB Buffer Pool. The Buffer Pool is ...
0
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1answer
284 views

Innodb_buffer_pool_bytes_data increases day by day even after delete the data

We have MySQL server V5.7.11 in which the Innodb_buffer_pool_bytes_data is getting increasing day by day. Initially we have set innodb_buffer_pool_size to 8G but we got error of max connection reached,...
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3answers
7k views

Page life expectancy very low on certain time?

Everyday we receive an alert on a specific period (03:00 AM - 04:00 AM) indicating that Page life expectancy is too low : SCOM :Alert: SQL DB 2008 Engine Page Life Expectancy is too low We have ...
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1answer
2k views

memory leaks in innodb

I have MySQL server 5.6 and I use stress test to evaluate the performance of it. after the test the result of mysqltuner.pl was like below : root@master-1:/home/debian# perl mysqltuner.pl Please ...
0
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1answer
363 views

MySQL 5.7 not accepting values of innodb_buffer_pool_instances greater than 1

I've been tweaking the values of the buffer pool size (innodb_buffer_pool_size) and the number of buffer pool instances (innodb_buffer_pool_instances) in the my.ini initialization file to optimize ...
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2answers
459 views

MySql not using Buffer Pool

I'm checking into a buffer pool issue on a MySql database. According to the query to get database size shown here, the total database size is about 11GB. Unfortunately I know I have much less RAM than ...
0
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1answer
318 views

Does innodb_data_reads include reads from the buffer pool?

We have set up some monitoring on many of our databases that serve many different applications. It seems that they all report back more writes than reads when in reality that is very unlikely. I ...
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0answers
427 views

Does “CREATE INDEX WITH DROP_EXISTING” use the bufferpool for the recreated index?

We have recreate our 4TB clustered index in ouor SQL Server. Even thought we have 1.5TB of memory we still run into the following error message: "Msg 802, Level 17, State 2, Line 30 There is ...
6
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4answers
942 views

How can I Debug a Buffer Issue?

I have a production "Microsoft SQL Server 2012 (SP1) - 11.0.3128.0 (X64)" that is showing weird buffer and page life expectancy (PLE) symptoms. I am running this every minute on my server (to track ...
11
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4answers
24k views

Optimal Number of MySQL InnoDB Buffer Pool Instances

Server Characteristics Total system RAM: 8GB (running MySQL + other stuff than MySQL on it i.e. not dedicated to MySQL) Number of CPU Cores: 6 I have data in the db amounting to about 2GB I have ...
6
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2answers
2k views

Buffer Size Changing?

I have a production database that is experiencing wildly fluctuating Page Life Expectancy (PLE) issues. (It crashes to zero at random times.) I have been researching the PLE issue and have found ...
4
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2answers
1k views

Sudden MySQL freeze, with spike in dirty pages, but without obvious write queries

I'm systematically (1/2 times per day) experiencing a freeze in the DB server. Suddenly, all the COMMITs get stuck in 'init' state; they pile up (up to 20/30), an almost no other queries are executed ...
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0answers
84 views

AlwaysOn AG Live Migration

A couple of thoughts on AlwaysOn AG migrations: Is there a reason why Microsoft didn't implement similar technology to Hyper-V Live Migration to AlwaysOn AGs so that the buffer pool and cache are ...