Return TEXT instead of VARCHAR columns #583
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In DuckDB the canonical name for an unlimited size text column is `VARCHAR`[1], in Postgres this is `TEXT`[2]. In DuckDB `TEXT` is simply an alias for `VARCHAR` type, and there's no way to know what was provided by the user. In Postgres these types are actually distinct, although behave exactly the same for unlimited length. Basically everyone uses `TEXT` instead of `VARCHAR`. Currently we convert the DuckDB type to a Postgres `VARCHAR`. In many cases this doesn't really matter, because pretty much all clients handle VARCHAR and TEXT the same too. There's one place where this leaks through though: DDL coming from a query. For example if you do a CTAS with a DuckDB query the resulting table columns will be of type `character varying` instead of `text`[3]. [1]: https://duckdb.org/docs/sql/data_types/text.html [2]: https://www.postgresql.org/docs/current/datatype-character.html [3]: #556 (comment)
JelteF
commented
Feb 11, 2025
| @@ -1,4 +1,4 @@ | |||
| CREATE TABLE t(a INT, b VARCHAR); | |||
| CREATE TABLE t(a INT, b TEXT); | |||
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There seems to be some bug when creating materialized views. Without changing this type we'd get an error like this:
+ERROR: SELECT rule's target entry 2 has different type from column "b"
+DETAIL: SELECT target entry has type character varying, but column has type text.
That shouldn't happen, the type should be detected as text everywhere.
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In DuckDB the canonical name for an unlimited size text column is
VARCHAR1, in Postgres this isTEXT2. In DuckDBTEXTis simplyan alias for
VARCHARtype, and there's no way to know what wasprovided by the user. In Postgres these types are actually distinct,
although behave exactly the same for unlimited length. Basically
everyone uses
TEXTinstead ofVARCHAR.Currently we convert the DuckDB type to a Postgres
VARCHAR. In manycases this doesn't really matter, because pretty much all clients handle
VARCHAR and TEXT the same too. There's one place where this leaks
through though: DDL coming from a query. For example if you do a CTAS
with a DuckDB query the resulting table columns will be of type
character varyinginstead oftext3.TODO: