Problem in ExecEvalExpr function

On Tue, Oct 18, 2005 at 02:38:39PM +0530, sandeep satpal wrote:

Hi,

I have some doubts related to ExecEvalExpr functions which is used to
executing the expression.

Since they are operators, they go through ExecEvalOper. However, after
the first call they go through ExecMakeFunctionResult. The operator has
an oid which is used to find the function and it is eventually called
using FunctionCallInvoke.

Note, ExecEvalExpr is a macro, so you can't break on it.

Here we are finding the subexpression recursively.
But I am not able to find it out that where exactly the comparison taking
place.
For eg.
relation A
id name age
relation B
name age status

if query is
select id , name , age , status from A , B where A.name = B.name and A.age
= B.age.

Note that if the operator appears in the OPERATOR CLASS and the
optimizer has determined that it can use an index, it won't go through
this code at all, instead using the compare function in _bt_compare.

Then parser find this "and" condition and divide this into two expression.
But I am not getting in which function exactly these comparison between
tupleslot taking place.

FunctionCallInvoke will be calling the function for operator =.

Have a nice day,
--
Martijn van Oosterhout <kleptog@svana.org> http://svana.org/kleptog/

Sandeep,

You seem to be having a lot of trouble understanding the evaluation code
which isn't that complex. Are you still trying to do that case-insensitive
comparison? If so, I seriously recommend that you just look at the citext
project on gborg and stop messing around in the backend, it's just going to
get ya into trouble.

On 10/18/05, Martijn van Oosterhout <kleptog@svana.org> wrote:

On Tue, Oct 18, 2005 at 02:38:39PM +0530, sandeep satpal wrote:

Hi,

I have some doubts related to ExecEvalExpr functions which is used to
executing the expression.

Since they are operators, they go through ExecEvalOper. However, after
the first call they go through ExecMakeFunctionResult. The operator has
an oid which is used to find the function and it is eventually called
using FunctionCallInvoke.

Note, ExecEvalExpr is a macro, so you can't break on it.

Here we are finding the subexpression recursively.
But I am not able to find it out that where exactly the comparison

taking

place.
For eg.
relation A
id name age
relation B
name age status

if query is
select id , name , age , status from A , B where A.name <http://A.name&gt;=

B.name <http://B.name&gt; and A.age

= B.age.

Note that if the operator appears in the OPERATOR CLASS and the
optimizer has determined that it can use an index, it won't go through
this code at all, instead using the compare function in _bt_compare.

Then parser find this "and" condition and divide this into two

expression.

But I am not getting in which function exactly these comparison between
tupleslot taking place.

FunctionCallInvoke will be calling the function for operator =.

Have a nice day,
--
Martijn van Oosterhout <kleptog@svana.org> http://svana.org/kleptog/

Patent. n. Genius is 5% inspiration and 95% perspiration. A patent is a
tool for doing 5% of the work and then sitting around waiting for

someone

else to do the other 95% so you can sue them.

--
Respectfully,

Jonah H. Harris, Database Internals Architect
EnterpriseDB Corporation
http://www.enterprisedb.com/