Re: Divide table raw into chunks - Mailing list pgsql-novice

From Miguel Beltran R.
Subject Re: Divide table raw into chunks
Date
Msg-id CAEc04crky=ZtOYkzYJ64+vieUdogaXBPxaHMCkqT49MDMcNmzA@mail.gmail.com
Whole thread Raw
In response to Divide table raw into chunks  (Shmagi Kavtaradze <kavtaradze.s@gmail.com>)
Responses Re: Divide table raw into chunks  ("David G. Johnston" <david.g.johnston@gmail.com>)
List pgsql-novice
I not sure but proably with a recursive CTE (common table expression)

somethink like

with R as (
   select send_id, 4 as len, 1 as chunk
   , substring(bow from 1 for 4) as bow_ok, substring (bow for 4 +1) as bow_2
   from bow1
   union all
      select send_id, len, chunk+1 as chunk
     , substring(bow_2 from 1 for 4) as bow_ok, substring (bow from 4 +1) as bow_2
      where char_length((bow_2) >0
     from R
)
select * from r

2016-02-28 5:39 GMT-06:00 Shmagi Kavtaradze <kavtaradze.s@gmail.com>:
I have a table with too long entries with 1s and 0s. For example I have table :

| Sent id.|   BoW.   |
|---------|----------|
|    1    | 10100101 |
|    2    | 00011110 |
|    3    | 10101111 |
I want to create new table which will divide column BoW. entries into some arbitrary length and assigns chunk number. 

| Sent id.| Chunk No. | BoW. |
|---------|-----------|------|
|    1    |     1     | 1010 |
|    1    |     2     | 0101 |
|    2    |     1     | 0001 |
|    2    |     2     | 1110 |
|    3    |     1     | 1010 |
|    3    |     2     | 1111 |
I am beginner, tried to search in documentation, but without success. Maybe something like this, but with proper function:

select b.sent_id, chunk, substring(bow from (chunk - 1) * 4 + 1 for 4)
from (select b.sent_id, generate_series(1, 1 + floor(length(bow) - 1 / 4) ) as chunk     from bow1 b    ) b;

I have 4623 Sent ids (sentences) and each is 10,000 characters long. I want to divide them into 32-40 character long chunks. 




--
________________________________________
Lo bueno de vivir un dia mas
es saber que nos queda un dia menos de vida

pgsql-novice by date:

Previous
From: Tom Lane
Date:
Subject: Re: Inspecting generated PlannerInfo
Next
From: "David G. Johnston"
Date:
Subject: Re: Divide table raw into chunks