Thread: Creating partial index on a relation

Hello

I am doing a small project in Postgress where i have to achieve the
following:

Suppose i know the index name(lets say index1) and the relation(table1) on
which partial index to has to be build. 

I was looking through the code and found that IndexStmt-->whereClause is the
one that i need to populate manually . 

As of know i am successful in creating index by giving a call to Method
DefineIndex of indexcmds.c that creates a index on the relation, but this
index is not an partial index.

I found that DefineIndex takes *Expr *predicate* as an parameter which
specifies that partial index has to be built. This predicate is nothing but 
*IndexStmt-->whereClause *

So is there a way to populate manually IndexStmt-->whereClause 

An example of partial index that i need is if my My table1 schema is (a int
,b int ,c int) 

index on c where a is null, b is null and c is not null

Thanks in advance



Regards



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naman.iitb <naman.bbps@gmail.com> wrote:

> An example of partial index that i need is if my My table1 schema
> is (a int ,b int ,c int)
>
> index on c where a is null, b is null and c is not null

Your question is not very clear, but perhaps you are looking for
something like this:

CREATE INDEX index1 ON table1 (c)
  WHERE a IS NULL AND b IS NULL AND c IS NOT NULL;

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On 10/29/2013 04:15 PM, naman.iitb wrote:
> So is there a way to populate manually IndexStmt-->whereClause 

Unless you have an _extremely_ compelling reason, you should probably
just use the SPI routines to execute a CREATE INDEX command.

-- Craig Ringer                   http://www.2ndQuadrant.com/PostgreSQL Development, 24x7 Support, Training & Services