Postgres Pro
Downloads
Home   >   mailing lists

Thread: Adding Indexes to Functions

Adding Indexes to Functions

From
Jeff MacDonald
Date:
Hi,

I have a table, where one of the columns "extradata" is a gob of XML.
I'd like to be able to create an index on this function.. so i tried
this


CREATE INDEX actitemsXML_idx ON act_items
(pgxml_xpath(extradata,'//RequestInfo/refund_id/text()','',''));

And i got this nice little error

ERROR:  parser: parse error at or near
"'//RequestInfo/refund_id/text()'" at character 66

I tried escaping the single quotes.. that basically leaves me at a psql
prompt with a ', meaning i need to close my quote, but they're all
escaped.

If anyone has any input for adding index's on functions that have single
quotes in them, that would be great.

Thanks.

Jeff.

Re: Adding Indexes to Functions

From
Bruno Wolff III
Date:
On Mon, Oct 06, 2003 at 11:15:06 -0300,
  Jeff MacDonald <info@bignose.ca> wrote:
> Hi,
>
> I have a table, where one of the columns "extradata" is a gob of XML.
> I'd like to be able to create an index on this function.. so i tried
> this
>
>
> CREATE INDEX actitemsXML_idx ON act_items
> (pgxml_xpath(extradata,'//RequestInfo/refund_id/text()','',''));

I don't think that you can create indexes on functions that had expressions
or constants for parameter values in 7.3 and earlier. You might want to
try this with the 7.4 beta and see if it works there. There will probably
be a 7.4 release candidate this week, so you may be able to consider
7.4 for production soon.

Re: Adding Indexes to Functions

From
Stephan Szabo
Date:
On Mon, 6 Oct 2003, Jeff MacDonald wrote:

> I have a table, where one of the columns "extradata" is a gob of XML.
> I'd like to be able to create an index on this function.. so i tried
> this
>
> CREATE INDEX actitemsXML_idx ON act_items
> (pgxml_xpath(extradata,'//RequestInfo/refund_id/text()','',''));
>
> And i got this nice little error
>
> ERROR:  parser: parse error at or near
> "'//RequestInfo/refund_id/text()'" at character 66
>
> I tried escaping the single quotes.. that basically leaves me at a psql
> prompt with a ', meaning i need to close my quote, but they're all
> escaped.
>
> If anyone has any input for adding index's on functions that have single
> quotes in them, that would be great.

In 7.3 (and earlier), functional indexes must be defined on a function
over columns in the table.  You cannot put fixed parameters in the call.
You can generally hack around this by making a function on only the
columns that calls the function with the constant arguments.