Linked Questions

17
votes
3answers
2k views

Is a weekly rebuild of indexes a good idea? [duplicate]

We had a SQL expert suggest rebuilding our table indexes weekly. We're currently doing this Saturday night and it causes lots of timeouts during the rebuild process. I'd like to avoid the timeouts ...
42
votes
2answers
91k views

When To Update Statistics?

I've inherited a Maintenance Plans that does the following: Cleanup old data Checks DB integrity Performs Database and Transaction Log Backups Reorganizes Our indexes Updates Statistics Delete old ...
27
votes
2answers
32k views

Why do we need to rebuild and reorganize Indexes in SQL Server

After searching the internet i couldn't find the reason for Why do we need to rebuild and reorganize indexes in SQL Server ? what does internally happens when we rebuild and reorganize ? An article ...
28
votes
1answer
7k views

Guidelines for full-text index maintenance

What guidelines should be considered for maintaining full-text indexes? Should I REBUILD or REORGANIZE the full-text catalog (see BOL)? What is a reasonable maintenance cadence? What heuristics (...
18
votes
3answers
6k views

Why might a table's data space take up 4x the size of the raw data?

I have a table with 490 M rows and 55 GB of table space, so about 167 bytes per row. The table has three columns: a VARCHAR(100), a DATETIME2(0), and a SMALLINT. The average length of the text in ...
4
votes
3answers
4k views

SQL Server Index Fragmentation

When should you rebuild an index? vs reorganize? What index fragmentation value is considered healthy?
4
votes
1answer
2k views

Why would the size of MySQL MyISAM table indexes (aka MYI file) not match after mysqldump import?

I've been archiving some MySQL (version 5.0.96) MyISAM tables locally and deleting from my server after checking the data. Every time the process has been pretty similar and comes off mostly without a ...
3
votes
1answer
2k views

Strange things with Avg_row_length

The data from one tables is dumped to file and inserted into calls_old table with load data infile it shows Avg_row_length 7366. Later I dumped table with mysqldump, droped table, then created again ...
2
votes
1answer
530 views

Why isn't the rows of an EXPLAIN accurate?

I have the following table: mysql> select count(*) from employees; +----------+ | count(*) | +----------+ | 10000 | +----------+ 1 row in set (0.03 sec) I do an EXPLAIN: mysql>...
2
votes
2answers
182 views

MySQL - SELECT on MyISAM Table on index - Does table size (rowcount) matter?

I was arguing with a coworker if SELECT * WHERE t BETWEEN ? AND ? on a MyIsam table where t is an index is significantly slower for huge tables. The hypothetically returned dataset is always the same,...
-1
votes
1answer
118 views

Reducing .mdf file size

I have a drive, :d, in my server where I have my .mdf file stored and now all of a sudden I notice that the drive :d has no space left. When I checked the .mdf file of the database demo1, it is 1.6TB ...
2
votes
2answers
49 views

Mysql used key changes between two consecutive EXPLAINs

I have a huge unmaintained innodb table (~1.5billion rows), I just started to try to query it. I write && instead of AND once; and surprise! it uses different key! EXPLAIN EXTENDED SELECT * ...