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MySQL: What are the pros and cons of running with engine=Memory vs on a memory-mapped filesystem?

What is the difference (in terms of read and write perf, alter tables, backup and recoverability and consistency) of running a MySQL database on a memory-mapped filesystem vs with ENGINE=MEMORY
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1answer
129 views

Table Data Space Used Confusion

I have a heap table with around 700k rows. The rowsize is 34 bytes: (1x BIGINT, 2x SMALLINT, 2x BIT, 4X INT, 1x SMALLDATETIME). Why does Data Space Used say this table is taking up nearly 4000000KB ...
0
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1answer
139 views

Moving a heap between filegroups

I would like to move the tables in my database from one filegroup (Primary) to a another (a new one). I can find lots of advice on this concerning tables with clustered indexes but all these tables in ...
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2answers
898 views

What are valid usage scenarios for HEAP tables?

I am currently doing some data imports into a legacy system and discovered that this system does not use a single clustered index. A quick Google search introduced me to the concept of HEAP tables and ...
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1answer
361 views

How do I automate converting heaps into clustered indexes?

I have around 40 tables in one of our production databases that, for varying reasons, where not created with a clustered index. What is the best automated method for converting these heaps? Since ...
3
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2answers
357 views

Heap size too large for data present

A SQL Server 2008 R2 Standard Edition database has a staging table with no indexes, eight varchar(50) and one varchar(255) columns, and 162,676 rows. I'd expect that this table shouldn't be much over ...
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1answer
756 views

Are there any performance benefits to using a hash table with no clustered index?

I have this table: CREATE TABLE [dbo].[relatea] ( [mid] [varchar](16) NOT NULL, [sid] [varchar](16) NOT NULL ) It stores hash matches. Is there any benefit to having this as a heap? It has ...
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1answer
118 views

SQL Server - is it ok to store link table as a heap?

I'm trying to understand if it's a good practice to have non-clustered PK on link table: CREATE TABLE table1_table2(table1_id INT NOT NULL, table2_id INT NOT NULL, CONSTRAINT PK_T1_T2 PRIMARY KEY ...
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3answers
347 views

Are heaps considered an index structure or are they strictly a table structure without index?

Inspired by this post: https://twitter.com/#!/SQLChicken/status/102930436795285505 Heaps: Are they considered an index structure or are they strictly a table structure without index?