StartsWith on citext column does not return results

[jcachat]

I am having an issue trying to do a StartsWith() on a "citext" column. When the case of the search value doesn't match the data, I don't get the correct results returned.

The condition that is being generated is something like this

WHERE ("ec"."Name" LIKE ($1 || '%') AND (LEFT("ec"."Name", LENGTH($1)) = $1))

The problem seems to be caused by the LEFT/LENGTH part. LEFT seems to be returning the value as a normal "text" string and not a "citext" value so it's not doing a case insensitive comparison.

In my searches, I came across this discussion which I assume is why that condition was added.

I can workaround it with a .ToLower() on the column but that defeats the purpose of the citext. Can anything be done about this?

[roji]

I'll take a look at this. Can you please say which version you're using?

[jcachat]

Sorry, I meant to include that and forgot. I'm using version 2.0.1 (the latest) and running 10.1 of PostgreSQL.

[roji]

Your analysis is correct. PostgreSQL's LEFT() unfortunately returns a text when given a citext (i.e. there's no citext overload. LEFT() is used to implement StartsWith() in order to chop the beginning part of the string for comparison (LIKE is used first to use any existing index).

I pushed a commit that will specifically check for citext and cast the result of LEFT() to a citext, so that comparison is case-insensitive. This is somewhat hacky but it works. It will be released with 2.1.0-preview2.

[chrisckc]

This appears to have regressed in 3.1
see: #388