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2009
geonetadmin

Analyze This!

Posted by geonetadmin Dec 31, 2009
analyze this

Hello, this is Sigmund Frodo…er…Jim W., Geodata Analyst at ESRI Support Services in Charlotte, NC with some thoughts that might help to ‘enlighten’ you on the inner life of your relational database management system (RDBMS). Just as some humans will visit a psychiatrist to help them understand the inner workings of their minds, databases have been known to benefit from the help of a qualified professional practitioner who can give meaning to the vast number of disassociated bits and bytes that swirl around deep within their digital brains. Regular ‘analysis’ of a database can be a good thing and can help to maintain an optimum level of equilibrium necessary for quickly answering the ‘BIG’ queries of life, such as, “Where can I find a good burger?”

Now, geodatabases have been known to have a ‘spatial’ complex, and periodically analyzing them will keep them grounded in reality, thereby improving overall performance. But first, we digress with a brief interlude into the realm of statistics…

Analyzing a database involves collecting statistics that help us to get a handle on the nature of the data that is contained within the database.  These statistical facts about objects such as tables, columns, and indexes are then stored internally within the RDBMS’s data dictionary tables. They help the database optimizer to determine the optimum path to data, ensuring the fastest response time for queries, while at the same time minimizing the cost of database resources. For example, getting a count of how many rows of data are contained in each table may help the database optimizer determine whether or not to use an index, or how best to join two tables when selecting the best execution plan for a given SQL statement.

What kinds of statistics are gathered?  Analyzing a table can retrieve and store metadata such as the number of rows in each table, the average row length in bytes, the average column length, the minimum and maximum values contained in each column, and the number of null values in a column.  Other statistics can describe the data by looking at the number of distinct values contained in a column (known as its cardinality), as well as by constructing histograms that give an idea of how the data is distributed (whether the data is evenly distributed throughout its range, or is it clumped together with a large number of rows containing similar values). Clinical terms such as platykurtosis, leptokurtosis, and skewness come fondly to mind, but that’s another story for another time…

So, you may ask, "Just how are statistics collected?"  It can be as simple as pointing and clicking on an individual feature class in ArcCatalog and then analyzing.  You could also use an ArcSDE command line tool called sdetable, or the Analyze geoprocessing tool available in ArcToolbox.  Or, you might even want to set up an automated scheduled task using the tools to gather statistics provided by the specific RDBMS that you’re using.

For a more in-depth look at analyzing a geodatabase and collecting statistics, most of what you’ll need to get started is located at: About updating geodatabase statistics.

Just remember, since data can be dynamic and ever changing, it’s a good idea to frequently analyze in order to pick up any changes that may occur in the database. In a healthy geodatabase, where numerous edits may occur on a daily basis, it could be wise to schedule frequent analysis sessions. Regular analysis can help improve the display time of versioned feature classes, as well as speed up other edit processes where fast query response times are required to keep you from waiting. And best of all, there’s no charge!

- Jim W., Support Analyst - Geodata Unit, ESRI Support Services, Charlotte, NC.



 

In a previous blog post, we stated that several users were calling into ESRI reporting an issue that Raster Catalogs and Feature Classes with Raster Fields stored in ArcSDE for SQL Server do not display after applying the 9.3.1 Service Pack 1.


 

There is now a patch available that resolves this issue: ArcSDE 9.3.1 SP1 SQL Server Raster Catalog and Raster Field Patch.


 

This patch fixes the following bugs:


 

·         NIM052174 - Raster Catalogs and Feature Classes with raster fields stored in ArcSDE for SQL Server do not display after applying the 9.3.1 Service Pack 1.


 

ESRI apologizes for any inconvenience this may have caused you. If you have any issues installing the patch, please contact ESRI Support Services.


 

-Eric R., Development Tech Lead – UAG, ESRI Support Services


 

Several users have called in to ESRI Support Services in the last few days and reported the following issue: after installing ArcGIS Desktop 9.3.1 Service Pack 1 when direct connections are used or after installing ArcSDE 9.3.1 Service Pack 1 when application server connections are used, Raster catalogs are not displaying in ArcMap. This issue also impacts Raster Fields stored in Microsoft SQL Server. If you have Raster fields on your feature class, you will not be able to access that information after applying 9.3.1 Service Pack 1.

ESRI is aware of this issue, and is currently working on a resolution to this problem. We appreciate your patience and understanding, and are sorry for any inconvenience this may have caused you.

The following Bug reports are currently being investigated for a possible solution:

  • NIM052174: ArcSDE Raster catalogs do not display using ArcMap 9.3.1 Service Pack 1

If you have not installed ArcSDE 9.3.1 Service Pack 1, please wait to install it until this issue has been resolved.

For further information, please refer to knowledge base article 37463.

We will keep you posted via this blog post for further updates as they become available.

- Eric R., Development Tech Lead – User Advocacy Group, ESRI Support Services



When creating an Online Support Incident, it is often cumbersome to fully document exactly what you are doing. Whether you don’t know the correct terminology or don’t feel like sending an e-mail that rivals epic novels such as War and Peace and Horton Hears a Who!, the Problems Steps Recorder is here to help you. This very helpful feature was added to the Windows 7 operating system and will soon become your best friend!

To open the Problems Steps Recorder, follow the steps below:

1.       Click on the ‘Start’ button.

2.       In the search dialog type ‘psr’ and press ‘Enter’.

Launching the psr.exe opens a new toolbar that appears on the desktop.

 

This easy-to-use tool allows you to begin recording screen shots as soon as you click ‘Start Record’. Once the recording has begun, navigate through the issue you would like to report. When you are done, click ‘Stop Record’ on the Problem Steps Recorder toolbar. After clicking the ‘Stop Record’ button on the toolbar, you will be prompted to name the .zip file that will contain your screen captures.  The next step will be to include this .zip file when you create your new ESRI Support Services request online.

*Note there is a 10 megabyte file size limitation on uploads. If the file is larger than 10 MB, simply ask the Support Analyst you work with for instructions on using the FTP site.

- Andrew S., Server Support Analyst, ESRI Support Services



We are pleased to announce that ArcGIS 9.3.1 Service Pack 1 was released today. With Service Pack 1 now available, there is an accompanying list of the issues that were addressed within the new service pack. You can check out the entire list by going to the Issues addressed with Service Pack 1 Webpage on the ESRI Support Center Web site. Many of these issues came directly from customers reporting them to ESRI Support Services and were prioritized to be included in this service pack.

For details on each individual product’s service pack, the issues addressed, instructions on how to install the service pack and other information, see each product’s link below:

If you run into any issues with the installation of this service pack or have feedback, please contact ESRI Technical Support at 1-888-377-4575. International sites, please contact your local ESRI software distributor.

- Collin W., SCN Blog Content manager, ESRI Support Services



geonetadmin

Be Prepared!!

Posted by geonetadmin Dec 11, 2009

Have you ever had that sinking feeling in your stomach when you realize your data has become corrupt, and you must now perform a restore from your database backup…wait, what backup?? The only time you recall backing up was in your car when you left your house this morning.

Picture this: You finally decide to take a vacation, so you have left your database running in the good hands of your co-workers. Just as you sit back in your lounge chair on the beach, your cell phone rings. The disk drive has crashed, and even though you have performed scheduled backups, you aren’t in the office to actually perform this urgent restore, and only you know the steps to take. This can mean only one thing: manually walking your co-workers through a database restore process over a costly phone call, thousands of miles away, while your vacation time quickly slips by, …oh the dread.

Hello, this is Elaine, a Support Analyst within the Geodata unit at ESRI Support Services located in Charlotte, NC. I have been with ESRI for almost nine years working as an Instructor and Technical Analyst within ESRI’s Professional Services division and now as a Support Analyst within ESRI’s Support Services. Over the years, I have heard of many stomach-wrenching scenarios from clients who have run into various backup and restore situations such as the ones listed above, and I have a few tips that I would like to pass on to you to in order to be prepared!

  1. Backup, Backup, Backup!! - When analyzing your backup strategy, the most important question to ask yourself is, "What can I afford to lose?" The data that is utilized within your company's GIS is the most valuable asset, and without data, the software alone isn’t going to help much. It is vital when storing your data within an ArcSDE database to perform regular and scheduled backups that fit your company’s GIS needs. There are many variations of backups depending on the RDBMS that is being utilized. Determining the frequency of your backup is largely based on the volume of edits that are taking place on the data.
    For example, when using SQL Server in a GIS environment involving medium to high write frequency to the data, you might consider establishing a combination of a Full Database backup weekly, a Differential Database backup daily, and a Transaction Log backup every four hours.
    To access additional information pertaining to creating backups and restoring databases for each DBMS, review the following links:

    SQL Server:
    SQL Server backups
    Recovery models for SQL Server

    ORACLE:
    Oracle backups
    Recovery models for Oracle

    DB2:
    DB2 backups
    Recovery models for DB2

    Informix:
    Informix backups
    Recovery models for Informix

    PostgreSQL:
    PostgreSQL backups
    Recovery models for PostgreSQL

  2. Test your backup!! - Having a backup isn’t going to do much good if you have never tested the process of actually restoring your database from backup: knowing how a restore works, what the steps and procedures are that would need to be executed, and whether or not the current backup plan is going to provide the best restore with the least amount of data loss. Again, keep in mind the question: What can you afford to lose? For additional information, please review the following link on ESRI’s Desktop Help: About database backup and recovery.


  3. Finally, put together your own Emergency Operating Procedures Manual that is easily accessible and is written with the highest level of detail. So, if you happen to be on vacation and the only person in the office when a restore must be performed is your newly-hired GIS intern, you can simply say, “Open the EOP Manual to page 1, follow all the steps outlined, and call me if you run into any issues”.

Knowing that you have already accounted for every possible step and potential question, you can quickly get back to soaking up the sun on your lounge chair on the beach!

- Elaine E., Support Analyst - Geodata Unit, ESRI Support Services, Charlotte, NC.


wiki.gis.com logo

Merriam-Webster defines community as “a body of individuals organized into a unit or manifesting usually with awareness some unifying trait”.

With this definition in mind, it can be said that wiki.GIS.com is developing a community. Our “unifying trait” is GIS or knowledge and awareness of GIS and its many uses.

With an increase in users comes the creation and editing of wiki pages. By looking at the recent changes to wiki.GIS.com, you can see that the creation and editing processes have involved some collaboration amongst users. Collaboration and a wiki go hand-in-hand, so it is good to see a community formulating and collaborating within wiki.GIS.com.

Upon the launch of wiki.GIS.com, GIS Lounge posted a blog with an approximation of the number of content pages at that time and an invite to add your knowledge of GIS to wiki.GIS.com. It is always great to see the community get involved with spreading the word and creating some chatter.

Since the launch of wiki.GIS.com there have been about 75 content pages added and a few new users are creating accounts every day. As I have found out through browsing, adding to and editing the wiki, it can be fun and it is always a learning experience. Jump in head first and see what or how you can contribute to wiki.GIS.com.

- Collin W., SCN Blog Content manager, ESRI Support Services



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