Rob <postgre...@mintsoft.net> writes: > Basically, if a table exists with a PK which is CHAR(n) and a query is > sent with VARCHAR or CHAR then it uses an Index Scan. If the query is > sent with TEXT as the type then postgresql casts the column to TEXT > (rather than the value to CHAR) and it does a Seq Scan.
Yeah, this is an artifact of the fact that text is considered a "preferred type" so it wins out in the parser's choice of which type to promote to. See https://www.postgresql.org/docs/current/typeconv-oper.html > I guess the root question is: is TEXT supposed to be identical to > VARCHAR in all scenarios? It's not for this purpose, because varchar isn't a preferred type. FWIW, my recommendation for this sort of thing is almost always to not use CHAR(n). The use-case for that datatype pretty much disappeared with the last IBM Model 029 card punch. regards, tom lane
