Databases
StackOverflow2013
Postsdbo
PO
 

Note that there are some explanatory texts on larger screens.

plurals
  1. PO
    primarykey
    data
    text
    <p>The first time I read this it was very helpful to me. Thank you.</p> <p>Since then I gained some insight about the downside of creating indexes: if you write into a table (<code>UPDATE</code> or <code>INSERT</code>) with one index, you have actually two writing operations in the file system. One for the table data and another one for the index data (and the resorting of it (and - if clustered - the resorting of the table data)). If table and index are located on the same hard disk this costs more time. Thus a table without an index (a heap) , would allow for quicker write operations. (if you had two indexes you would end up with three write operations, and so on)</p> <p>However, defining two different locations on two different hard disks for index data and table data can decrease/eliminate the problem of increased cost of time. This requires definition of additional file groups with according files on the desired hard disks and definition of table/index location as desired.</p> <p>Another problem with indexes is their fragmentation over time as data is inserted. <code>REORGANIZE</code> helps, you must write routines to have it done.</p> <p>In certain scenarios a heap is more helpful than a table with indexes, </p> <p>e.g:- If you have lots of rivalling writes but only one nightly read outside business hours for reporting.</p> <p>Also, a differentiation between clustered and non-clustered indexes is rather important. </p> <p>Helped me:- <a href="https://stackoverflow.com/questions/1251636/what-do-clustered-and-non-clustered-index-actually-mean">What do Clustered and Non clustered index actually mean?</a></p>
    singulars
    1. This table or related slice is empty.
    1. POHow does database indexing work?
      singulars
      1. PTQuestion
    1. PTAnswer
    1. USCommunity
    1. USDer U
    plurals
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTUpMod
    2. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTUpMod
    3. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTUpMod
    1. This table or related slice is empty.
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload