fixes #283

Signed-off-by: Sean Corfield <sean@corfield.org>

CHANGELOG.md

@@ -3,6 +3,7 @@
 Only accretive/fixative changes will be made from now on.
 
 * 1.3.next in progress
+  * Address [#283](https://github.com/seancorfield/next-jdbc/issues/283) by adding a note in the documentation, linking to the PostgreSQL bug report about `ANY(array)`.
   * Address [#269](https://github.com/seancorfield/next-jdbc/issues/269) by adding `:name-fn` as an option (primarily for the SQL builder functions, but also for result set processing); the default is `clojure.core/name` but you can now use `next.jdbc.sql.builder/qualified-name` to preserve the qualifier.
   * Update testing deps.
 

doc/tips-and-tricks.md

@@ -247,7 +247,11 @@ method is called for each query. If you want to avoid those extra queries,
 and you can live with unqualified column names, you can use `as-unqualified-maps`
 as the result set builder instead.
 
-If you have a query where you want to select where a column is `IN` a sequence of values, you can use `col = ANY(?)` with a native array of the values instead of `IN (?,?,?,,,?)` and a sequence of values.
+If you have a query where you want to select where a column is `IN` a sequence of values, you can use `col = ANY(?)` with a native array of the values instead of `IN (?,?,?,,,?)` and a sequence of values. **Be aware of
+[PostgreSQL bug 17822](https://www.postgresql.org/message-id/flat/17922-1e2e0aeedd294424%40postgresql.org)
+which can cause pathological performance when the array has a single element!**
+If you think you might have a single-element array, consider using `UNNEST` and
+`IN` instead.
 
 What does this mean for your use of `next.jdbc`? In `plan`, `execute!`, and `execute-one!`, you can use `col = ANY(?)` in the SQL string and a single primitive array parameter, such as `(int-array [1 2 3 4])`. That means that in `next.jdbc.sql`'s functions that take a where clause (`find-by-keys`, `update!`, and `delete!`) you can specify `["col = ANY(?)" (int-array data)]` for what would be a `col IN (?,?,?,,,?)` where clause for other databases and require multiple values.