11-30-2011
If you need to improve the performance of the above statement you may try to index the date column
(in certain cases, for example Oracle (not sure for MySQL, you may check wit explain <your_statement_here>),
may try to use the index in order to avoid the costly sorting operation -
because the optimizer is aware that the data in the index is already sorted).
BTW: thanks for providing the necessary code in order to set up a test case!
Last edited by radoulov; 11-30-2011 at 06:39 PM..
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LEARN ABOUT DEBIAN
alzabo::runtime::index
Alzabo::Runtime::Index(3pm) User Contributed Perl Documentation Alzabo::Runtime::Index(3pm)
NAME
Alzabo::Runtime::Index - Index objects
SYNOPSIS
use Alzabo::Runtime::Index;
DESCRIPTION
This object represents an index on a table. Indexes consist of columns and optional prefixes for each column. The prefix specifies how
many characters of the columns should be indexes (the first X chars). Some RDBMS's do not have a concept of index prefixes. Not all col-
umn types are likely to allow prefixes though this depends on the RDBMS. The order of the columns is significant.
INHERITS FROM
"Alzabo::Index"
Note: all relevant documentation from the superclass has been merged into this document.
METHODS
columns
Returns an ordered list of the "Alzabo::Runtime::Column" objects that are being indexed.
prefix ("Alzabo::Runtime::Column" object)
A column prefix is, to the best of my knowledge, a MySQL specific concept, and as such cannot be set when using an RDBMSRules module for a
different RDBMS. However, it is important enough for MySQL to have the functionality be present. It allows you to specify that the index
should only look at a certain portion of a field (the first N characters). This prefix is required to index any sort of BLOB column in
MySQL.
This method returns the prefix for the column in the index. If there is no prefix for this column in the index, then it returns undef.
unique
Returns a boolean value indicating whether the index is a unique index.
fulltext
Returns a boolean value indicating whether the index is a fulltext index.
function
For function indexes, this returns the function being indexed.
id
The id is generated from the table, column and prefix information for the index. This is useful as a canonical name for a hash key, for
example.
Returns a string that is the id which uniquely identifies the index in this schema.
table
Returns the "Alzabo::Runtime::Table" object to which the index belongs.
AUTHOR
Dave Rolsky, <autarch@urth.org>
perl v5.8.8 2007-12-23 Alzabo::Runtime::Index(3pm)