College Writing – Between Research and Outline – The Five Ps of Snapshot Text

I’m sure you know about the ‘Thesis Statement,” we all learn that one in Middle School. Thesis Statement is one kind of Snapshot Text, but by no means the ONLY one. Choosing a firm, usable snapshot will make the structuring and final writing much more efficient.

1 – Promise Snapshot

An article that is intended to give information, like this one for instance, would use a Promise. One intention of the Promise is to let the casual reader know quickly if it holds something of particular use. Another is to reference the assignment given and show how the information fulfills it.

The Promise Snapshot is usually a single sentence that gives a specific promise of what will be found- for instance, a recipe, a checklist or links to useful web sites. It would be placed in an introductory first paragraph that described the usefulness of the information. It might, in some cases, be preceded or followed by a statement of the author’s ‘credentials’ or background as an expert.

2 – Process Snapshot

Like the Promise, the Process Snapshot generally heads up an informational piece. It describes exactly what process will follow. For instance:

“5 steps to bone a duck” or “Step-by-step manicure”

In an academic setting this Snapshot might be used in a description of research method or experimental procedure. With some small adaptation, it would lead well to a timeline approach.

3 – Pinpoint Snapshot

This rather academic introductory paragraph describes the area of research undertaken. It should also Pinpoint the tighter research question, or research focus. Specific research sources should not be referenced here, unless an illustrative quote opens the paragraph. It needs no particular author credentials since the expertise of the sources is relied on for the piece.

Make very sure that your Pinpoint answers the requirements of the assignment!

4 – Position Snapshot

This is the Thesis Statement from Middle School. Use it to take a stand in a debate/discussion. Be obvious:

“The City Council should…” or “This essay will demonstrate that…”

It is preceded by a survey of the topic, often including a ‘nod’ to the dissenting argument. However, MORE important, it is followed by a preview of the argument/examples to follow.

5 – Placard Snapshot

Think of this like a ‘Headline’ or ‘Teaser’ or ‘Hook’. Unlike the other types, this is the first sentence or two of the piece. Its purpose is to entice a reader to continue. It might be a question, a quotation, an interesting fact or statistic

One of the other types of Snapshots might follow it or not.

A Placard should be used with caution in any academic writing other than a persuasive essay assignment. There, it would be a good start if followed by the Position Snapshot later in the introduction.

Once you have designed your snapshot, take a minute or two. Would your audience [instructor/general public/friends/whoever] want to read THAT article or paper? Will it satisfy the assignment? Does it strike the appropriate level of academic formality? Do you have the research or knowledge to back it up?

Is that the piece you want to write?

If you can answer ‘yes’ to most or all of those questions you are ready to go!

SQL Server Snapshot – How it Works

SQL Servers have been growing in business exponentially since they were created in the 1970’s. First created by IBM in San Jose, California, SQL did not become a standard computer language until the mid-1980s. Since that time, during its growth, there have been many upgrades and changes to the SQL relational database management systems, one such upgrade is the SQL server snapshot.

A SQL server snapshot is essentially what it sounds like, it is a snapshot of the system that is stored and used as a primary system. When a snapshot occurs, the information is stored in the main drive and then further information created after the snapshot occurs is stored in a new data is stored in what is called a sparse file. A snapshot creates a backup of the system at that time, and uses 90% less drive space than backing up the system does. This information is stored for as long as the user requires it, and can be dropped when no longer needed.

The purposes of a SQL server snapshot vary depending on the needs of the user. In some cases, it is used simply to back up the system without having to use so much drive space during the working day. In other situations, it is created when data is perceived as “ideal” and any new data needs to be compared to the data that was previously acquired. This information can be stored indefinitely and new snapshots can be created at any point to continue tracking specific data. When saving the user should simply take the name of the data and add a time stamp to it. This will ensure that there is no confusion when accessing the information as to what its purpose is.

When a SQL server snapshot is dropped, the new information and the previous information join to form a completely new set of information. The information from the snapshot is no longer available and cannot be referenced for projects or projections. When the decision is made to drop it, it is vital that the project manager or user understands that it will become irretrievable.

While some business may never drop a SQL server snapshot, others may find that they simply want to test their data against studies that may have been conducted or to simply experiment with different ways of looking at their data. Once the information is retrieved the SQL snapshot is dropped in favor of new testing, or they return to their regular data consumption. Companies that track long-term data may never drop a snapshot, and the SQL servers are designed to function either way.

Database Snapshots in SQL Server

Ever wanted to make a read-only point-in-time copy of a database, and wondered which technique to use? Microsoft SQL Server 2005 provides a plethora of ways to do this, including database backup/restore, database detach/re-attach, log-shipping, replication, mirroring, and so forth. However, one method available in the Enterprise edition, the Database Snapshot, is new to SQL Server 2005, and is worth taking a closer look.

Why are Database Snapshots Useful?
There are many applications where a point-in-time snapshot is useful. Microsoft suggest the following use cases:

  • Reporting up to a specific time period, ignoring later data
  • Reporting against mirror or standby databases that are otherwise unavailable
  • Insuring against user or administrator error, providing a quick way to revert to an older version of the database
  • Managing test databases, particularly during rapid feature and schema development

Of course, these needs could be served by a database backup or attached copy of a database, but the key benefit of choosing a snapshot over one of the other methods is simple: creating a database snapshot is fast.

Creating and Using Database Snapshots
Creating database snapshots is easy – it’s a CREATE DATABASE statement, specifying only the logical and physical filenames. Remember it’s a read-only snapshot, so we don’t need to add autogrowth or transaction log settings. Here’s the code:

CREATE DATABASE AdventureWorks_Snapshot_Monday ON 
(

NAME=AdventureWorks_Data,

FILENAME='C:SnapshotsAD2K_Monday.ss' ) AS SNAPSHOT OF AdventureWorks

Snapshot creation is not supported by the Object Explorer interface in Management Studio; you must use a CREATE DATABASE statement as above, with the AS SNAPSHOT OF clause indicating the source database. Also, note that only the Enterprise edition of SQL Server 2005 supports database snapshots.

The snapshot contains a version of the data as it existed at its creation, having rolled back uncommitted transactions. This means that otherwise unavailable databases, such as mirrors and standby servers, can be used to create snapshots.

Having created a snapshot, you can now use it as you would any other read-only database; all objects are exposed in exactly the same way, via Object Explorer, scripts, or reporting tools.

Reverting a database to the version stored in the snapshot is similarly easy:

RESTORE DATABASE AdventureWorks FROM

DATABASE_SNAPSHOT='AdventureWorks_Snapshot_Monday'

This returns the database to the state it was in when the snapshot was created, minus any uncommitted transactions – remember that a snapshot is transactionally consistent at its creation. Note that restoring from a snapshot renders all other snapshots unusable – they should be deleted and re-created if required.

How do Database Snapshots work?
A Database Snapshot looks like an ordinary read-only database, from the user’s point of view; it can be accessed with a USE statement, and can be browsed from within Management Studio. However, it initially occupies almost no disk space, and so can be created almost instantly. This magic is achieved via an NTFS feature, sparse files. A sparse file is a file that may appear to be large, but in fact only occupies a portion of the physical space allocated to it.

Now, because a database snapshot presents a read-only view of your source database, it need not store a copy of every page. Instead, SQL Server performs a copy-on-write operation; in the source database, the first time a data page changes after the creation of a snapshot, a copy of the original page is placed in the sparse file. The snapshot serves data from the snapshot copies where source data has changed, and the original source pages when they are unchanged.

Best Practices
Sometimes you will choose a copy of a backup over a snapshot, sometimes it’ll be a detached copy of the data file. However, for many situations your best bet is a database snapshot, so it’s worth keeping some points in mind. In particular:

  • The file size will look considerably larger than the space it consumes on disk, and should be clearly marked as a snapshot for this reason. Use explicit naming conventions to make it clear to administrators.
  • Snapshots are at their best when young and fresh, and don’t take up too much space. If you need to keep a snapshot for any length of time, consider using another method to create your read-only copies.
  • As snapshots persist until deleted, you will need to explicitly rotate snapshots, either manually or with a script.
  • Performing index operations such as defragmentation or index rebuilding will modify so many pages that the snapshot will likely contain a complete copy of the source data for that index. The more snapshots there are, the more copies will exist.
  • If the disk containing a snapshot fills up, and a page write fails, the snapshot will become useless, as it will not contain all necessary pages. Make sure the disk can’t fill up!

Database snapshots are a worthwhile addition to the arsenal of any SQL Server DBA, and fit well with other techniques, particularly when you may need to quickly revert a database, or if you need to maintain rolling snapshots. Remember the key advantages: high speed and low physical size. But also remember that these advantages diminish as the snapshot ages and grows, and if the number of snapshots increases.

Above all, database snapshots are fast and easy to use; it won’t cost you anything to try them out, and you will probably find them very useful indeed. If all you need to do with a point-in-time copy is select from it, or possibly revert to it, then a database snapshot is likely the best choice available.