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13 votes

Does AWS RDS support MEMORY storage engine?

This answer applies to AWS Aurora not straight MySQL RDS. Just because SHOW ENGINES says the database has the MEMORY storage engine doesn't mean you can actually use it. We have found that in AWS ...
Barry Coleman's user avatar
9 votes

What is the stride of a GAM interval

sources This has been documented in a bunch of places for a long time. The first place I saw it written about was in this blog post from 2012: Breaking Down TempDB Contention (part 2) GAM: Page ID = ...
Erik Darling's user avatar
  • 42.1k
9 votes
Accepted

What is the stride of a GAM interval

I have available a TB-sized database. There should be plenty of GAM pages to find. Let's first examine the strides from those documents. 4GB is 524,288 pages. Adding this offset to 2 for the 1st page, ...
Michael Green's user avatar
9 votes
Accepted

Understanding IAM Pages: extent intervals

You can see by the red arrow what seems to be 16 pages related to the same extent. How is that possible? The red arrow points to an entry showing that extents starting at 1:176 and 1:184 are ...
Paul White's user avatar
  • 87.1k
7 votes
Accepted

Does AWS RDS support MEMORY storage engine?

Yes, it does. How come ? Run this query in the RDS Instance: mysql> select * from information_schema.engines where engine='MEMORY'\G *************************** 1. row *************************** ...
RolandoMySQLDBA's user avatar
6 votes
Accepted

What page type is page 516855552?

On a newly-created SQL Server 2022 database, the script below shows page 516855552 is a PFS page and 516855553 is a GAM page. USE master; DROP DATABASE IF EXISTS GAMTest; CREATE DATABASE GAMTest ON ...
6 votes
Accepted

MongoDB - Unable to change mongodb storage engine to WiredTiger

Based on the warning message included in your description, you are already using the WiredTiger storage engine but your dbPath is using the ext file system (in theory ext4, but the Linux filesystem ...
Stennie's user avatar
  • 10.3k
4 votes

MongoDB MMAPv1 vs WiredTiger storage engines

We shifted to WiredTiger from MMAPv1 on the lure of 7x to 10x performance gain. We had to revert back to MMAPv1 as MongoDB would lock up when the WiredTiger cache would hit 100%. We've documented our ...
Anand's user avatar
  • 41
4 votes
Accepted

Disable database tables for writes but report writes as successful

MySQL, and friends, i.e. MariaDB and Percona, have a rather unusual storage mechanism called the Black Hole engine - it might help with your particular request (see the fiddle here). For example, if ...
Vérace's user avatar
  • 30.3k
4 votes

Kafka Internal Data structure vs LSM tree

No, Kafka does not use LSM trees or any tree based data structure for data representation. It relies upon Sequential IO so that it is not relying upon JVM to maintain cache which would then be ...
Jim's user avatar
  • 41
4 votes

What is the stride of a GAM interval

This info can can also be gleaned in newer versions from sys.dm_db_page_info. Here's a brute-force method on a test database: SELECT page_info.* FROM sys.database_files AS df CROSS APPLY ...
3 votes
Accepted

Disabling Aria INSERT log in MariaDB

After lots of experimentations, I found out that the problem was not TRANSACTIONAL, but PAGE_CHECKSUM. The default behaviour of Aria is PAGE_CHECKSUM=1 for which Aria keeps a copy of the inserting ...
Googlebot's user avatar
  • 4,531
3 votes

howto read/interpret "show engine innodb mutex" output?

(Sorry for the delay; there are some important issues.) The following things won't explain your mutex questions, but may improve performance such that the questions go away. Observations: Version: ...
Rick James's user avatar
  • 78.6k
2 votes

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

The other disadvantage of the MEMORY-based tables is that they can't be referred multiple times in the same query. At least that behaviour was found till the v5.4. How with CTEs (since v8.x) there is ...
Kondybas's user avatar
  • 4,556
2 votes

Migrate Jira to MySql - Unknown system variable 'storage_engine'

If using Mysql 7 and Jira 7 change the connection string in the mysql.properties file. sudo vi ${JIRA_APPLICATION_DIR}/atlassian-jira/WEB-INF/classes/database-defaults/mysql.properties Find the ...
sweetfa's user avatar
  • 188
2 votes
Accepted

DBCC PAGE read page from buffer pool or directly from the file system?

We know that SQL Server always read pages from disk to memory for all its operations. The pages are asked for from memory like most things in SQL Server. The same process applies for DBCC PAGE as it ...
Sean Gallardy's user avatar
2 votes

MariaDB not starting in windows 10 after crash

Step 1: Locate the configuration file Win + R (shortcut for 'run'), type services.msc, Enter Find the entry named 'MariaDB', right click on it, select properties You should see something like "F:...
sariDon's user avatar
  • 121
2 votes
Accepted

WiredTiger Page Size

The parameter I was looking for is referred to as the allocation_size It's WiredTiger parameter. From the documentation A component of WiredTiger called the Block Manager divides the on-disk pages ...
Pavel Sapezhko's user avatar
1 vote

Disabling Aria INSERT log in MariaDB

Many of the system tables in the information_schema, mysql and sys databases use the Aria storage engine, and some of these have transactional=1. So even if you create a table with transactional=0, ...
dbdemon's user avatar
  • 6,381
1 vote
Accepted

How to add sphinx engine to mysql 5.7?

Install MariaDB which will run on top of a MySQL-5.7 data directory. This has SphinxSE included in every mariadb-server package on Ubuntu. You will need to install the plugin: INSTALL SONAME '...
danblack's user avatar
  • 7,819
1 vote
Accepted

Primary File Organization in DBMS - Files of ordered records (sorted files)

I think it's just a sloppy turn of the phrase by the book authors. Clearly, if you don't do raw I/O (which, as you say, few modern databases do), you have limited control over how your records are ...
mustaccio's user avatar
  • 26.4k
1 vote
Accepted

What MariaDB storage engine should i use?

Your only real choice here is between InnoDB and Percona's XtraDB engines - see this page. Coincidentally, I wrote an answer to Change all table ENGINE at once from "MyISAM" to "InnoDB&...
1 vote

Does any MariaDB engine have the option to declaratively or configuratively abstract highly-redundant data?

In any RDBMS, "normalization" is an explicit task that the programmer does. Having stuff buried inside JSON strings makes that task more difficult.
Rick James's user avatar
  • 78.6k
1 vote
Accepted

SQL SERVER Database IO performance impact of splitting database tables into FileGroups and multiple Files per filegroup

Talk with your SAN administrator. That's the source that should be able to explain you with detailed information what kind of SAN you've got and what it is capable of. Have you got MPIO? What's the ...
1 vote

MongoDB - Unable to change mongodb storage engine to WiredTiger

To change Storage Engine in Mongo DB on Ubuntu Linux from WiredTiger to MMAPv1 (or vice versa) Assuming you don't have data that needs backing up, as you've run into this issue you probably have an ...
Leigh Mathieson's user avatar
1 vote
Accepted

mongodb inMemory engine available in the community edition?

As at MongoDB 3.4, no plans have been announced to make the In Memory Storage Engine available in the MongoDB Community Edition. I suspect this is likely to remain as an Enterprise-only feature for ...
Stennie's user avatar
  • 10.3k
1 vote
Accepted

Sync two MySQL servers data, while changing the Engine in the slave

This should not a problem, provided you do not execute any DDL related to the Storage Engine on the Master. I have written about this many times Jun 01, 2011 : What can we do in MySQL 5.0 Replication ...
RolandoMySQLDBA's user avatar
1 vote
Accepted

Mysql read only engine type and indexes

If you solve it by adding a secondary index then imho MyISAM or InnoDB won't matter much, as both use B-Tree indexes. Append both additional columns to the index: (col3, col1, col2) or (col3, col2, ...
jkavalik's user avatar
  • 5,130
1 vote

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

In addition to the previous answers. straight from the MySQL 5.7 manual: "MEMORY performance is constrained by contention resulting from single-thread execution and table lock overhead when ...
Eljuan's user avatar
  • 182
1 vote

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

MEMORY tables are not intended for persistent storage, particularly of large subsets of data or anything where retention is critical. Their best purpose from my experience is to house transient ...
mopsyd's user avatar
  • 111

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