Understanding streamPosition

[MoeE]

Hi guys,

I'd like to understand how streamPosition can be used to determine the order of events in a transaction. 

For example I have 00000035.e15132e0.00000001.0000.01.0000:2837.339472.16 which was a streamPosition generated for an Event Hubs message. Can you explain how SCN is extracted from this and how order is determined? Can you please break down for me what each part means? The source is Oracle.

Thanks.

Kind Regards,

Mohmmed

[Arun_Arasu · Accepted solution]

Hello @MoeE ,

Thanks for reaching out to Qlik Support , please find the below split up

00000035.e15132e0.00000001.0000.01.0000:2837.339472.16

SCN- 00000035.e15132e0
Thread- 00000001
0000- Serial Number inside current SCN
01 - serial of current vector inside REDO event
0000 - serial number in the multiple insert even
2837- REDO LOG Sequence number
339472- Block Number in REDO Log
16- not used

Hope this answers your question.

Thanks & Regards

Arun

[Alan_Wang]

Hi @MoeE 

Note that the SCN from the stream position is in hexadecimal format. Oracles databases present your SCN in decimal format. Any hexadecimal to decimal converters can be used to convert the SCN back to a decimal format so you can check with your archive logs to see when the SCN occurred.

Should you need to start any tasks with a specific SCN, please refer to this article.

https://community.qlik.com/t5/Official-Support-Articles/How-to-start-a-Replicate-task-with-Oracle-so...

[MoeE]

Hi @Arun_Arasu @Alan_Wang ,

Thanks for the replies, they are helpful.

Kind regards,

Mohammed

[MoeE]

Hi @Arun_Arasu,

What is the "Serial Number inside current SCN" and the "serial number in the multiple insert even". 

Can they be used to order changes in the scenario where there are multiple changes within the same SCN?

For example, say I am replicating to a change table. If 3 update records have the same SCN, can the "serial number in the multiple insert event" value be used to determine the exact order of changes within the source?

Thank you!

Regards,

Mohammed

[DesmondWOO]

Hi @MoeE ,

From my understanding, this serial number allows you to distinguish between multiple changes that occur at the same SCN timestamp.

Regards,
Desmond