Bits...Understanding Bits bit more

Wed, 25 Nov 2020 16:16:04 GMT

All,

I have recently read an article "Symbol Tables and Bit-Stuffed Pointers" recently ( referred by Marcus Sommer).. It really opened by eye broadly to see qlik from its another side..I have some questions.. ( but it may be silly from an expert point of view)

How this bit concept will be applied to VARCHAR fields?

Say for example, I have a table with 3 fields as below...

Create Table Employee

(

Eno INT Primary Key,

Ename VARCHAR(100) NOT NULL,

Email_Address VARCHAR(100) NOT NULL

Company_Name VARCHAR(250) NOT NULL

)

Sample Data:

1,Karthik, karth_qw@xyz.com, ABC Pvt Ltd

2,Sean, sean@xyz.com, ABC Pvt Ltd

3,Karthik, karthi_82@abc.com, XYZ Pvt Ltd

4,Raj, Raj@qtp.com, ABC Pvt Ltd

5,Karthikeyan Masilamani,km@fd.com, FD Pvt Ltd

6,Ganapathi, gana_84@bs.com, BS Pvt Ltd

7,Raghu, Raghu11@fd.com, FD Pvt Ltd

My Questions are...

1) How many BITS will be assigned for each column? Please provide the calculation here to understand.

2) is it fine to use Database Sequence number as it is in qlik or the internal AutoNumber(), Recno(), RowNo() qlik function is fine for this purpose as these will not occupy any bits in symbol table? Correct my understanding if it is wrong...

3) what would be structure of Symbol table & Data Table for this example? Please explain it in detail.

4) How 'NULL' and 'NOT NULL' columns will be treated in qlikview?

5) How CHAR() & VARCHAR() will be treated in qlikview? any additional storage required for VARCHAR fields?

I have another table and there is a relationship between these two table. say for example "Emp_Investments" and it has "Eno" columns, it acts as the common key.

6) What about the design of Symbol table for this table ?

7) how the bit relationship will be common for both the table ? which process will take care it?

😎 What compression algorithm is used in qlikview? is it RLE ? i saw this somewhere in any article here?

9) Will this symbol table & Data table generation done at the time of script execution ?

If i think little bit outside box,

10) How to get the list of symbol table & data table created from a project perspective?

11) what is the maximum limit of this count? is there any aging concept (like MRU & LRU in database) available in qlikview?

12) In SQL, sysobjects will hold an entry for all the objects created in database. is there any such table available in qlikview to get the list of qvw files, qvd files, symbol tables, data tables and its creation time something like below..

ID ObjectName ObjectType CreatedOn UsedIn

1 sales.qvw qvw 01/01/2017 < some report>

2 customer.qvd qvd 02/02/2017 <some qvw file name>

3 xyz.symbol symbol 03/02/2017

4 xyz.data data 03/02/2017

13) if there is no such table, i want to know xyz qvd file is used in how many places. How ?

14) what is the extension of symbol table & data table ?

15) Please explain more on naming standard used for symbol & data table. is it something like below

employee table ( database)

employee.symbol ( symbol table)

employee.data ( data table)

16) Is it possible to view symbol table data?

17) is the same concept ( symbol table & data table) used in other BI's like POWER BI, WEBFOCUS, TABLEAU and legacy COGNOS ?

I think it should be the special of qlikview..although i just want to ask this question to get the opinion of others...

18) is qlikview comes with file or database based repository? How to allocate memory for Repository ? is there any relationship between REPOSITORY memory and RAM memory?

Inputs are welcome!

Re: Bits...Understanding Bits bit more

Mon, 13 Mar 2017 17:31:19 GMT

any inputs please ?

Re: Bits...Understanding Bits bit more

Tue, 14 Mar 2017 03:49:25 GMT

It would be helpful if experts share their thoughts...

Re: Bits...Understanding Bits bit more

jonathandienst — Tue, 14 Mar 2017 04:57:19 GMT

I suggest you ask a few questions at a time, rather than sending a detailed questionnaire.

Qlikview has a different view to datatypes than SQL. The bit lengths have no relationship to the SQL type definitions -- they are determined by the number of distinct values for that field after loading (or when storing a QVD); sufficient bits to identify each distinct value.

Re: Bits...Understanding Bits bit more

Thu, 16 Mar 2017 17:47:50 GMT

Sure Jonathan. Going forward I will split my questions..

But this time..can i get answer for these questions....

topic Re: Bits...Understanding Bits bit more in QlikView

Bits...Understanding Bits bit more

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Re: Bits...Understanding Bits bit more

Re: Bits...Understanding Bits bit more

Re: Bits...Understanding Bits bit more