Still celebrating National IT Professionals Day with 3 months of free Premium Membership. Use Code ITDAY17

x
?
Solved

Sybase IQ Questions

Posted on 2013-01-28
4
Medium Priority
?
740 Views
Last Modified: 2013-02-07
Hi

It would be a great help if anybody knows the answer for the following queries :

1. In a Sybase IQ Multiplex environment, which process synchronize the secondary nodes using TLV log.

2. In a column with FP index, where and how  the row ids are maintained?   How about in column with LF index?

3. Does the LF index  get rebuilt after loading the data?

thanks
CS
0
Comment
Question by:CHAN
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 2
  • 2
4 Comments
 
LVL 24

Expert Comment

by:Joe Woodhouse
ID: 38830498
1) Every write server (if there is more than one) is in charge of distributing its writes through Table Level Versioning (TLV) Log. This lets the secondary servers know about table versions. Remember IQ effectively locks a table snapshot (although it doesn't copy the whole table, just the changed blocks). TLV in Multiplex is just like the Lock Manager in any traditional RDBMS. You get one of these per writer node.

2) The data is the FP index. There is always an FP on every column because that's where the column's data lives. The ROWID on every column is just the array entry. Remember IQ stores everything in columns, there is actually no real "row" anywhere. "Row #10" just means "the 10th entry in the FP array of column1 + the 10th entry in the FP array of column2" and so on. Is that making sense? The ROWID is not stored anywhere, just as the number of each array entry is also not stored anywhere, it is the data structure.

3) Every index is rebuilt during loads. Unlike traditional RDBMS, it is faster to index an empty table then load it than the other way around. Test it and see. :)
0
 

Author Comment

by:CHAN
ID: 38838166
Thanks Joe.

Whenever the failed secondary nodes comes back online, there is an internal process which will read TLV log from IQ store and sync the catalog store of that secondary node. Am I right?

Now I understand the ROWID concept in FP index . What about in LF index, is the ROWID attached to LF index column values?

Regards
CS
0
 
LVL 24

Accepted Solution

by:
Joe Woodhouse earned 1500 total points
ID: 38839219
TLV doesn't sync Catalog Store, that holds database schema and the coordinating server syncs that to all other nodes.

TLV is only for table versions, i.e. locking... and after a complete failure or shutdown there are no locking issues to deal with because nothing is running.

If only one node has failed, TLV Log makes sure every node understands which tables are versioned in the writer(s). So yes, automatic, but nothing to do with Catalog Store.

ROWID is only part of the FP index because only the FP has the actual data. LF (and every other index type) does not store the actual data, just additional index structures. That said yes there has to be some kind of internal address associating all the column entries belonging to the same row - maybe they use ROWID, I don't know, but it doesn't make sense to talk about ROWID stored anywhere but in the FP but that's the only place data is stored.

I hope that's making sense, IQ is a bit topsy-turvy. :)
0
 

Author Comment

by:CHAN
ID: 38863256
Thanks Joe.

Regards
CS
0

Featured Post

Learn how to optimize MySQL for your business need

With the increasing importance of apps & networks in both business & personal interconnections, perfor. has become one of the key metrics of successful communication. This ebook is a hands-on business-case-driven guide to understanding MySQL query parameter tuning & database perf

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

A while back, I ran into a situation where I was trying to use the calculated columns feature in SharePoint 2013 to do some simple math using values in two lists. Between certain data types not being accessible, and also with trying to make a one to…
The core idea of this article is to make you acquainted with the best way in which you can export Exchange mailbox to PST format.
Video by: ITPro.TV
In this episode Don builds upon the troubleshooting techniques by demonstrating how to properly monitor a vSphere deployment to detect problems before they occur. He begins the show using tools found within the vSphere suite as ends the show demonst…
Do you want to know how to make a graph with Microsoft Access? First, create a query with the data for the chart. Then make a blank form and add a chart control. This video also shows how to change what data is displayed on the graph as well as form…

721 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question