Re: Doing better at HINTing an appropriate column within errorMissingColumn()

On Wed, Nov 19, 2014 at 10:33 AM, Peter Geoghegan <pg(at)heroku(dot)com> wrote:
> Maybe you'd prefer if there was a more gradual ramp-up to requiring a
> distance of no greater than 50% of the string size (normalized to take
> account of my non-default costings)

I made this modification:

diff --git a/src/backend/parser/parse_relation.c
b/src/backend/parser/parse_relation.c
index 40c69d7..cca075f 100644
--- a/src/backend/parser/parse_relation.c
+++ b/src/backend/parser/parse_relation.c
@@ -929,7 +929,8 @@ searchRangeTableForCol(ParseState *pstate, const
char *alias, char *colname,
* seen when 6 deletions are required against actual attribute
name, or 3
* insertions/substitutions.
*/
- if (state->distance > 6 && state->distance > strlen(colname) / 2)
+ if ((state->distance > 3 && state->distance > strlen(colname)) ||
+ (state->distance > 6 && state->distance > strlen(colname) / 2))
{
state->rsecond = state->rfirst = NULL;
state->second = state->first = InvalidAttrNumber;

When I run the regression tests now, then all the cases that you found
objectionable in the regression tests' previous expected output
disappear, while all the cases I think are useful that were previously
removed by applying a broad 50% standard remain. While I'm not 100%
sure that this exact formulation is the best one, I think that we can
reach a compromise on this point, that allows the costing to remain
the same without offering particularly bad suggestions for short
strings.

--
Peter Geoghegan