Thread

1. Print b-tree tuples

   Samuel Vogel <s@muel-vogel.de> — 2013-01-03T16:48:26Z

   Hello,
   
   I'm trying to print out the tuples in the b-tree nodes for analysis, but 
   when iterate over more than the first entry of the tuples (scanKey++), I 
   strangely get the error below on query execution:
   ERROR:  relation "simpletest" does not exist
   LINE 1: SELECT * FROM simpletest WHERE id = 50;
   
   Any help with reviewing my my small attached patch would be greatly 
   appreciated!
   
   Regards,
   Samuel Vogel
   

2. Re: Print b-tree tuples

   Samuel Vogel <s@muel-vogel.de> — 2013-01-04T12:00:21Z

   Hello,
   
   > I'm trying to print out the tuples in the b-tree nodes for analysis, 
   > but when iterate over more than the first entry of the tuples 
   > (scanKey++), I strangely get the error below on query execution:
   > ERROR:  relation "simpletest" does not exist
   > LINE 1: SELECT * FROM simpletest WHERE id = 50;
   I was able to get around this by only printing byval attributes:
   
   if (!itupdesc->attrs[i-1]->attbyval)
                break;
   
   I would still like to know why my code screws up though. The relnames 
   are not byval, but I should still be able to print the address, right?
   
   Regards,
   Samuel
   

3. Re: Print b-tree tuples

   Tom Lane <tgl@sss.pgh.pa.us> — 2013-01-04T20:26:02Z

   Samuel Vogel <s@muel-vogel.de> writes:
   > I'm trying to print out the tuples in the b-tree nodes for analysis, but 
   > when iterate over more than the first entry of the tuples (scanKey++), I 
   > strangely get the error below on query execution:
   > ERROR:  relation "simpletest" does not exist
   > LINE 1: SELECT * FROM simpletest WHERE id = 50;
   
   Is this patch the only thing you changed?  The only obvious explanation
   for the above error (other than "you fat-fingered the query") seems to
   be that you caused index searches in pg_class to fail, but I don't see
   how this patch could be affecting the result of _bt_binsrch.
   
   			regards, tom lane
   
   
   

4. Re: Print b-tree tuples

   Samuel Vogel <s@muel-vogel.de> — 2013-01-11T15:33:01Z

   Am 04.01.13 21:26, schrieb Tom Lane:
   > Samuel Vogel <s@muel-vogel.de> writes:
   >> I'm trying to print out the tuples in the b-tree nodes for analysis, but
   >> when iterate over more than the first entry of the tuples (scanKey++), I
   >> strangely get the error below on query execution:
   >> ERROR:  relation "simpletest" does not exist
   >> LINE 1: SELECT * FROM simpletest WHERE id = 50;
   > Is this patch the only thing you changed?  The only obvious explanation
   > for the above error (other than "you fat-fingered the query") seems to
   > be that you caused index searches in pg_class to fail, but I don't see
   > how this patch could be affecting the result of _bt_binsrch.
   Yes, I've switched to a clean master and only applied this patch. If I 
   put the the break, the query works, so it's fine as well.
   
   BTW: I just had a discussion if it would make sense, to recreate my test 
   table with a different order, as a b-tree is always dependent on 
   insertion order. But as the b-tree index is newly created in memory 
   after each restart, two different insertion orders (same values) would 
   give me the same b-tree at least after a restart, right?
   
   Regards,
   Samuel