Sunday, July 19, 2015

2015-07-19 Sunday - MySQL Federated Engine

I'm doing some research this weekend on MySQL's Federated Engine.  This posting is placeholder for collecting various information I find that might be of interest to others.

  • FEDERATED table does not support indexes in the usual sense; because access to the table data is handled remotely, it is actually the remote table that makes use of indexes. This means that, for a query that cannot use any indexes and so requires a full table scan, the server fetches all rows from the remote table and filters them locally. This occurs regardless of any WHERE or LIMIT used with this SELECT statement; these clauses are applied locally to the returned rows
  • Queries that fail to use indexes can thus cause poor performance and network overload. In addition, since returned rows must be stored in memory, such a query can also lead to the local server swapping, or even hanging.

  • "a number of limitations and due to network latency are rarely used...not enabled by default and is no longer maintained by Oracle and it's use is discouraged"

Saturday, July 11, 2015

2015-07-11 Saturday - Seattle Code Camp 2015 (9.12.15)

I've submitted an idea for a talk at this year's 2015 Seattle Code Camp
"Often when invited into an organization as a consultant, every new environment/situation offers numerous new challenges: symptoms of inefficiencies and performance concerns...that span systems, people, processes, infrastructure, and organizational culture. This talk will focus on sharing lessons learned from years of experience - across many different technical platforms, many different industries - and hopefully provide you with a useful, holistic, conceptual framework to help you quickly assess, diagnose, triage, and begin treatment of the system-as-patient."

2015-07-11 Saturday - DNS configuration

In my normal day-to-day architecture role, I seldom need to perform hands-on System Admin and Network Configuration tasks. However, I need to be more deeply involved in reviewing many aspects of infrastructure and network design details for a current client engagement. So today I'm doing some background reading on DNS configuration as part of a new cloud architecture design effort - and deployment planning.

Saturday, July 04, 2015

2015-07-04 Saturday - SaaS Performance Tuning Notes

When exploring possible SaaS performance issues, there are a couple of possible questions/concerns that might be worth examining as possible contributing factors:
  • Is there possible saturation of server CPU % utilization?
  • Is there possible saturation of server Memory % utilization?
  • Is there possible saturation of server Disk % utilization?
  • Is there possible saturation of the available network bandwidth?
    • Check the NIC % utilization on all servers, particularly for the database
    • What is the average response time within the data center network?
  • Is there possible database thread starvation occurring?
  • Are there inefficient SQL queries excessively consuming resources?
  • Does the application leverage any SQL query caching?
  • Is there lock contention occurring on database operations?
  • Would a Master-Slave configuration help distribute some database I/O 
    • Write against Master
    • Read from Slave (need to understand latency of Master to Slave replication)
  • Is there possible excessive session management overhead being incurred?
    • How much data is being stored in session management for an average user?
  • Is there possible File I/O contention for read/write of session data files?
  • Is there possible excessive overhead being incurred for static content delivery?
    • Is static content being served up by the same domain for which cookies are specified?
    • If so, cookies will be sent for each GET of a static content file can be instrumental in helping isolate problems - as well as additional monitoring tools (e.g. such as Ganglia, SolarWinds, etc.)

In a recent experiment, moving two static content files to an externally hosted Content Delivery Network (CDN) appeared to suggest a possible 66% reduction in page load time.

2015-07-04 Saturday - R Programming Language (v3.2.1)

Experimenting today with the newest 2015-06-18 release of the R programming language (3.2.1)

exploring The R Manuals

As well as the 3.4.2 StateET for R Eclipse plugin

 ...In the new Eclipse 4.5 Mars release