Databases
StackOverflow2013
Postsdbo
PO
 

Note that there are some explanatory texts on larger screens.

plurals
  1. PO
    primarykey
    data
    text
    <p>One initial idea that might work would be to store a priority queue of all the unused IDs, sorted so that low IDs are dequeued before high IDs. Using a standard binary heap, this would make it possible to return an ID to the unused ID pool in O(log n) time and to find the next free ID in O(log n) time as well. This has the disadvantage that it requires you to explicitly store all of the IDs, which could be space-inefficient if there are a huge number of IDs.</p> <p>One potential space-saving optimization would be to try to coalesce consecutive ID values into ID ranges. For example, if you have free IDs 1, 3, 4, 5, 6, 8, 9, 10, and 12, you could just store the ranges 1, 3-6, 8-10, and 12. This would require you to change the underlying data structure a bit. Rather than using a binary heap, you could use a balanced binary search tree which stores the ranges. Since these ranges won't overlap, you can compare the ranges as less than, equal to, or greater than other ranges. Since BSTs are stored in sorted order, you can find the first free ID by taking the minimum element of the tree (in O(log n) time) and looking at the low end of its range. You would then update the range to exclude that first element, which might require you to remove an empty range from the the tree. When returning an ID to the pool of unused IDs, you could do a predecessor and successor search to determine the ranges that come immediately before and after the ID. If either one of them could be extended to include that ID, you can just extend the range. (You might need to merge two ranges as well). This also only takes O(log n) time.</p> <p>Hope this helps!</p>
    singulars
    1. This table or related slice is empty.
    1. POSearching for the first free index
      singulars
      1. PTQuestion
    1. PTAnswer
    1. This table or related slice is empty.
    1. UStemplatetypedef
    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. COThis is the same idea as a sequence object in a database. It works well.
      singulars
      1. PO
      1. USjim mcnamara
    2. COThanks for the detailed description, I need to implement the approach you mentioned as the other approaches till Fenwwick tree to see which one can be done with the least complexity / space / time.
      singulars
      1. PO
      1. USRishabh Puri
 

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