This blog is mostly eliminated in MySQL 8.0 with the advent of the following function: Even on a beefy system, this limits you to a few hundred INSERTs per second. Once the index is too big to be cached, most INSERTs involve a disk hit. Therefore, INSERTing into an index means jumping around a lot.
GUIDs/UUIDs (Globally/Universally Unique Identifiers) are very random.
#GENERATE UUID MYSQL MAC#
And the v1() calls are very similar but just slightly different because it's based on the computer's MAC address and the current time. The v4() UUIDs are always entirely different because they are (pseudo)random. The same goes for the v5() function which is always supplied a null URL. V4 UUID: 12a940c7-0f3f-46a1-bb5f-bdd602e10654Īs you can see, the calls to v3() always return the same UUID because the same URL parameter, "abc", is always supplied. Here's a simple class illustrating the proper usage (note that if php5-uuid is not installed on your system, each function call will just return false):Įcho "V3 UUID of URL='abc': ". this is the value that is to be hashed (MD5 for v3, SHA-1 for v5) it may be any string or even null The fourth argument to uuid_make() is: $url this is a secondary resource created with uuid_create() it is apparently used to generate an internal UUID, which is used as the namespace of the output UUID The third argument to uuid_make() is: $namespace The first two arguments have been demonstrated below and are straightforward, so I'll skip to the as-yet non-described arguments. The uuid_make() function takes two arguments when generating v1 or v4, but four arguments are required when generating v3 or v5.
#GENERATE UUID MYSQL CODE#
The php5-uuid functions could definitely use some documentation to clarify how they should be used, but here's what I've gleaned by examining the OSSP source code (found here: ). UUIDs generated below validates using OSSP UUID Tool, and output for named-based UUIDs are exactly the same.
Given the same namespace and name, the output is always the same. They require a namespace (another valid UUID) and a value (the name).
The following class generates VALID RFC 4211 COMPLIANT Universally Unique IDentifiers (UUID) version 3, 4 and 5. Here's an example of why:Īs you can see, using it w/ a DB can cause the creation of documents with repeated ID's.
#GENERATE UUID MYSQL ARCHIVE#
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