When used in the context of databases, memory refers to RAM directly addressable by the CPU as opposed to going through the I/O subsystem.

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35
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4answers
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On a dedicated database server, how much memory to reserve for the OS?

Assuming you have a dedicated server explicitly for database functions -- how much memory should you reserve for the operating system? I realize this will probably vary somewhat depending on the ...
32
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5answers
19k views

Why would I NOT use the SQL Server option “optimize for ad hoc workloads”?

I've been reading some great articles regarding SQL Server plan caching by Kimberly Tripp such as this one: http://www.sqlskills.com/blogs/kimberly/plan-cache-and-optimizing-for-adhoc-workloads/ Why ...
26
votes
3answers
3k views

Excessive sort memory grant

Why is this simple query granted so much memory? -- Demo table CREATE TABLE dbo.Test ( TID integer IDENTITY NOT NULL, FilterMe integer NOT NULL, SortMe integer NOT NULL, Unused ...
26
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3answers
21k views

Is the SQL Server Express memory and CPU limit per instance?

If I have 8GB of RAM in a server and I run 4 instances of SQL Server Express, will the total memory limit used by SQL Server be 1GB or 4GB? Would it be advisable to run multiple instances like this ...
21
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3answers
20k views

What are reasons *not* to use the MEMORY storage engine in MySQL?

I recently discovered that MySQL has a "memory" engine that I wasn't aware of (most of my database work is for hobby projects so I learn what I need as I go). It seems like this option should give me ...
20
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3answers
47k views

Recommended page file size for SQL 2008R2 on Windows 2008R2

This Microsoft article - How to determine the appropriate page file size for 64-bit versions of Windows Server 2008 and or Windows 2008 R2 provides guidance for calculating the page file size for 64 ...
19
votes
3answers
25k views

What is the default order of records for a SELECT statement in MySQL?

Suppose you have the following table and data: create table t(k int, v int,index k(k)) engine=memory; insert into t values(10, 1), (10, 2), (10, 3); When issuing select * from t where k = 10 with ...
18
votes
3answers
335 views

Does CPU utilization affect the cost of foreign NUMA access?

Scenario Let's assume I have a SQL Server with 4 sockets with each 1 NUMA node. Each socket has 4 physical cores. There is 512 GB of memory total so each NUMA node has 128 GB of RAM. A key table is ...
18
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1answer
3k views

SQL Server - Anyone use SUMA, trace flag 8048, or trace flag 8015?

Recently included SQL Server startup Trace Flag 8048 to resolve a serious spinlock contention issue in a SQL Server 2008 R2 system. Interested to hear from others who have found usage cases where ...
17
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6answers
15k views

PostgreSQL: Force data into memory

Is there a systematic way to force PostgreSQL to load a specific table into memory, or at least read it from disk so that it will be cached by the system?
17
votes
2answers
34k views

How do I shrink the innodb file ibdata1 without dumping all databases?

InnoDB stores all tables in one big file ibdata1. After dropping a big table, the file is keeping its size no matter how big the table was. How can I shrink that file without having to dump and re-...
16
votes
4answers
26k views

tuning postgresql for large amounts of ram

I have two identical servers (in terms of hardware), they are both standard installations of windows server 2008 r2, with minimal software installed (basically my code and required stuff like jvm etc)....
14
votes
4answers
13k views

SQL Server Max Memory not limiting use of RAM

I would like your input on this. I have a sql server 2008r2 Ent. Ed. 64bit with 16 cores and 64GB RAM. There is one instance of SQL server patched fully as of 20111014. The max ram is set to 60000MB. ...
14
votes
1answer
504 views

Plan cache size and reserved memory

When running a query including the Actual Execution Plan, the root operator (SELECT) tells me that the Cached Plan Size is 32KB. A query that joins sys.dm_exec_cached_plans and sys....
12
votes
3answers
8k views

SQL Server 2008 R2 “Ghost Memory”?

We have a dedicated SQL Server 2008 R2 machine that is experiencing some strange memory issues.. The machine itself has plenty of resources including two quad-core processors, 16gb of RAM and 64bit ...
10
votes
5answers
64k views

Why is SQL Server consuming more server memory?

Sqlserver is consuming 87.5 % of my server Ram. This recently causes alot of performance bottleneck such as slowness.I Research on this issue. One common solution i could find on the internet is to ...
10
votes
2answers
21k views

Why is MySQL is creating so many temporary tables on disk?

Can any configuration mistake lead to creating too many temp tables by mysql..mysql tuner shows Current max_heap_table_size = 200 M Current tmp_table_size = 200 M Of 17158 temp tables, 30% were ...
10
votes
3answers
509 views

Configure RAM for SQL Server and NUMA

Accidental DB admin here. Question: Would you still manually limit max RAM for SQL Server even though the sole purpose of that server is to serve SQL Server database engine only? I have Microsoft ...
9
votes
3answers
16k views

How to see what is cached in memory in SQL server 2008?

Is there a way how to find out what is cached in SQL Server 2008 R2? I have found the following nice article: http://blog.sqlauthority.com/2010/06/17/sql-server-data-pages-in-buffer-pool-data-stored-...
9
votes
3answers
16k views

How to use insert delay with the InnoDB engine and use less connection for insert statements?

I'm working on an application which involves a lot of database writes, approximately ~70% inserts and 30% reads. This ratio would also include updates which I consider to be one read and one write. ...
9
votes
2answers
4k views

View Postgresql Memory Usage

I'm running Postgresql on a Ubuntu server and need to be able to monitor its memory usage. Currently I have scripts running in a one-minute cron job that monitor/log various statistics and need to ...
9
votes
2answers
1k views

Increased RAM, Worse Performance

Setup: Windows Server 2008 R2 SQL Server 2008 R2 SP1 240GB RAM TempDB is 8x16GB data files w/out auto-grow (128GB total) Physical/Stand-alone Server This server is used for ETL processing. We ...
8
votes
1answer
803 views

SQL Server not using available memory

SQL Server 2008 R2 Standard Edition (64-bit) on Windows 2008R2 Enterprise Server has over 300 GB of memory but total memory use in control panel never goes over 86 GB Have SQL configured to use ...
8
votes
3answers
10k views

How to free SQL Server memory?

I have a SQL Server sandbox installation on my local computer. I have set the memory SQL Server instance can use to 1000 mb. When running an intensive operation, memory usage rises up to 1000 mb. When ...
8
votes
1answer
5k views

Can SQL Server's Page Life Expectancy be too high?

I've read several articles about SQL Server's Page Life Expectancy and what it means and what kind of information you can glean from it. In most of these articles that I've read, a common, healthy PLE ...
8
votes
3answers
2k views

I am using the MEMORY storage engine but MySQL still writes to my disk…Why?

I am using the MEMORY Engine for all tables associated with a particular MYSQL query because speed of access is paramount to my project. For some reason, I have noticed that a large amount of disk ...
8
votes
4answers
26k views

Why does MySQL say I'm out of memory?

I was trying to execute a fairly large INSERT...SELECT in MySQL with JDBC, and I got the following exception: Exception in thread "main" java.sql.SQLException: Out of memory (Needed 1073741824 bytes) ...
8
votes
4answers
5k views

MySQL Cluster RAM requirement

From MySQL 5.1, the data doesn't need to be entirely in memory anymore. I've read that the indexed columns (I think the entire index structure) must still be in memory (MySQL High Availability, 2010, ...
8
votes
3answers
5k views

ORA-04031: unable to allocate bytes of shared memory (“”,“”,“”,“”)

I am receiving this error in a development database. It happens on some specific queries (simple inserts and deletes via .NET application). The database is used by one user, and error happens ...
7
votes
2answers
23k views

Quick look at how much RAM is allocated to SQL Server?

With SQL Server 2005, you could look at the Task Manager and, at least, get a cursory look at how much memory is allocated to SQL Server. With SQL Server 2008, the Working Set or Commit Size never ...
7
votes
2answers
20k views

SQL Server becomes slower over time until we have to restart it

We have a database with a mixed OLAP/OLTP workload. The queries are quite ad-hoc and are dynamically created in the mid-tier application server. When we start the server, the performance is quite ...
7
votes
2answers
1k views

Why is SQL Server 2014 consuming so much RAM with no active data stored?

I'm running SQL Server 2014 on my laptop along with a ton of other installed applications, from Visual Studio to video games. This is obviously not a production server, but for development and ...
7
votes
2answers
1k views

What does Page Life Expectancy say about the instance?

I have installed monitoring software on a few SQL Server instances in the environment. I am trying to find bottlenecks and fix some performance issues. I want to find out if some servers need more ...
7
votes
2answers
326 views

SQL Server not using all memory

I have SQL Server 2014 with max memory set to 6GB (physical memory is 8GB). The Target Server Memory is sometimes 6GB and then drops back to Total Server Memory (approx 5.3GB, never reaches 6GB). I ...
7
votes
2answers
5k views

SQL Server 2012 memory consumption outside the buffer pool

I've got an instance of SQL Server 2012 SP2 Enterprise Edition consuming ~20GB of memory higher than the max. memory limit. The instance is limited to 65GB but the physical memory in use from the ...
7
votes
2answers
6k views

Is it bad to create many mysql temporary tables simultaneously?

I need to make heavy statistical analysis to deliver some data to users. Currently, I catch the data from mysql and process them via PHP arrays. However, mysql temporary tables are quite better (...
7
votes
3answers
29k views

How long will a temporary MEMORY table persist if I don't drop it (MySQL)

I'm using a recursive stored procedure in MySQL to generate a temporary table called id_list, but I must use the results of that procedure in a follow up select query, so I can't DROP the temporary ...
7
votes
1answer
1k views

SQL Server 2012 x64 - cannot safely allocate more than 50% RAM

We're running SQL Server 2012 SP1 CU4 on a 64-bit 12-core, 2 socket server using NUMA architecture server. OS is Windows Server 2008 R2 x64. Whenever we allocate more than 50% of the physical RAM to ...
7
votes
1answer
813 views

How much memory is a table taking up?

Is there a way to find out how much memory a table is taking up in SQL Server (2005 and greater)? For example, suppose I have a table with 30 million records. I'd like to know how many pages ...
7
votes
1answer
9k views

How do you increase MySQL performance using current server resources?

I have a MySQL database and some of my queries became slow. Query time is not stable. Most of the queries are fast, but some of them (may be that reads and returns less data) take long time. I know ...
7
votes
1answer
4k views

MongoDB Not Using All Available RAM

I have something around 200 GB worth data stored in a mongo cluster. The physical memory on one of the instances which runs mongo is 8GB. Nothing else of any consequence runs on this instance. As near ...
6
votes
2answers
11k views

How should I tune Postgresql for 20 GB of RAM?

I've been fortunate enough to have the use of a 20GB Linode instance running Ubuntu 64 bit. I want to try to optimize PostGres for this service, but I don't know what I should prioritize changing. I ...
6
votes
2answers
822 views

Query Plans not retained insufficient memory errors

We have been experiencing memory issues with SQL Server. We first realised we had a problem when we started getting timeouts and login errors: A connection was successfully established with the ...
6
votes
3answers
5k views

How much memory will a MEMORY table take up?

Let's say I have a MyISAM table with a data length of 4.8GB and an index length of 6.2GB. So, a total data size of eleven gig. How much memory would this require, were I to convert it to a MEMORY ...
6
votes
2answers
3k views

sql server max memory includes SSIS?

I have installed 2 instances of sql server plus SSIS on the following server. Note the amount of RAM is nearly 384 GB And this is the max and min memory settings that I have applied to my 2 ...
6
votes
1answer
13k views

SQL Server Maximum and Minimum memory configuration

What are the correct settings for min-memory and max-memory in this use case? The server has 8GB ram, dual Intel Xeon processors, running Windows Server 2008 R2 / Sql Server 2008 Standard Edition. It'...
6
votes
1answer
802 views

PostgreSQL could not fork autovacuum worker process: Cannot allocate memory

Running into some issues every few days with postgres crashing and entering recovery mode. The logs from postgres look like so ... Lots of this for 5-10minutes 2015-09-24 10:07:27 GMT LOG: could ...
6
votes
2answers
11k views

Redis takes up all the Memory and Crashes

A redis server v2.8.4 is running on a Ubuntu 14.04 VPS with 8 GB RAM and 16 GB swap space (on SSDs). However htop shows that redis alone is taking up 22.4 G of memory! redis-server eventually crashed ...
6
votes
1answer
580 views

SQL Server instance using only a few hundred MB. Well below the minimum server memory setting

I've got two SQL Server 2012 instances running on a server with 32GB of RAM and running little else. One instance is behaving normally. Its working set memory is running close to its commit which is ...
6
votes
1answer
10k views

SQL Server - How to determine ideal memory for instance?

We have some virtual machines that have X memory allocated to them. This amount of memory is somewhat random. It was allocated to the machine because that was the amount of memory the physical ...