Solved

Sybase IQ Questions

Posted on 2013-01-28
4
716 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:ncshome170
[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:ncshome170
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 500 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:ncshome170
ID: 38863256
Thanks Joe.

Regards
CS
0

Featured Post

Announcing the Most Valuable Experts of 2016

MVEs are more concerned with the satisfaction of those they help than with the considerable points they can earn. They are the types of people you feel privileged to call colleagues. Join us in honoring this amazing group of Experts.

Question has a verified solution.

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

Suggested Solutions

Title # Comments Views Activity
Agreggate sums in sql 1 528
Generating a Format File in Sybase ASE BCP 1 1,271
SQL Syntax 2 458
InterSystems Caché OPEN QUERY 4 547
This article describes how to import an Outlook PST file to Office 365 using a third party product to avoid Microsoft's Azure command line tool, saving you time.
Dramatic changes are revolutionizing how we build and use technology. Every company is automating, digitizing, and modernizing operations. We need a better, more connected way to work together as teams so we can harness the insights from our system…
I've attached the XLSM Excel spreadsheet I used in the video and also text files containing the macros used below. https://filedb.experts-exchange.com/incoming/2017/03_w12/1151775/Permutations.txt https://filedb.experts-exchange.com/incoming/201…
Attackers love to prey on accounts that have privileges. Reducing privileged accounts and protecting privileged accounts therefore is paramount. Users, groups, and service accounts need to be protected to help protect the entire Active Directory …
Suggested Courses

738 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