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-2
votes
1answer
27 views

How does InnoDB store tables in ibdata file? [closed]

There are two tables and their default engine is InnoDB. I want know the following What's inside the ibdata file ? How does InnoDB store these two tables ?
5
votes
2answers
91 views

PostgreSQL, integer arrays, index for equality

I have a huge list of integer arrays (300,000,000 records) stored in Postgres 9.2 DB. I want to efficiently search these records for an exact match (equality only). I have heard of the intarray module ...
1
vote
1answer
89 views

what is the structure of a Mysql multi-column index? [closed]

For example: CREATE TABLE test( col_1 INT, col_2 INT, col_3 VARCHAR(11), col_4 VARCHAR(11) )ENGINE = INNODB; CREATE INDEX mul ON test(col_2,col_3,col_4); Sorry,my English is not good,I mean ...
1
vote
1answer
55 views

When is the index actually created?

I have noticed that even on huge tables with millions of records when I do a CREATE INDEX the index is created immediately (I get the console back in nsecs). Why is this? Doesn't it create the B-Tree ...
1
vote
1answer
101 views

In MySQL if column X has unique values what's the difference between UNIQUE index and B-Tree index

Let's assume that I have table data: CREATE TABLE `test`.`data` ( `row_id` INT NOT NULL , `data_id` INT NOT NULL , PRIMARY KEY (`row_id`) ); Now, let's assume that data_id has unique values. Is ...
5
votes
1answer
190 views

Walking a BTREE index as far as possible in MySQL

Suppose one has a column of words on which one builds a BTREE index: CREATE TABLE myTable ( words VARCHAR(25), INDEX USING BTREE (words) ); LOAD DATA LOCAL INFILE '/usr/share/dict/words' INTO ...
3
votes
3answers
1k views

Optimizing DELETE Query on MySQL MEMORY Table

I run a large forum which maintains a MySQL database for backend data storage. The 'session' table tracks logged in users & guests. It is currently about 100k records, so not really that large. ...
3
votes
4answers
1k views

Benefits of BTREE in MySQL

What are the pros and cons of using a BTREE index in MySQL, regarding query speed, disk storage and memory usage? Does BTREE provide easier iteration in increasing order ? What kind of queries would ...