Update NEWS.md

NEWS.md

@@ -743,10 +743,8 @@ rowwiseDT(
 
 27. `as.data.frame(DT)`, `setDF(DT)` and `as.list(DT)` now remove the `"index"` attribute which contains any indices (a.k.a. secondary keys), as they already did for other `data.table`-only attributes such as the primary key stored in the `"sorted"` attribute. When indices were left intact, a subsequent subset, assign, or reorder of the `data.frame` by `data.frame`-code in base R or other packages would not update the indices, causing incorrect results if then converted back to `data.table`, [#4889](https://github.com/Rdatatable/data.table/issues/4889). Thanks @OfekShilon for the report and the PR.
 
-28. `dplyr::arrange(DT)` uses `vctrs::vec_slice` which retains `data.table`'s class but uses C to bypass `[` method dispatch and does not adjust `data.table`'s attributes containing the index row numbers, [#5042](https://github.com/Rdatatable/data.table/issues/5042). `data.table`'s long-standing `.internal.selfref` Refer to [internal.selfref](../man/internal.selfref.Rd) for additional information.
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-
- mechanism to detect such operations by other packages was not being checked by `data.table` when using indexes, causing `data.table` filters and joins to use invalid indexes and return incorrect results after a `dplyr::arrange(DT)`. Thanks to @Waldi73 for reporting; @avimallu, @tlapak, @MichaelChirico, @jangorecki and @hadley for investigating and suggestions; and @mattdowle for the PR. The intended way to use `data.table` is `data.table::setkey(DT, col1, col2, ...)` which reorders `DT` by reference in parallel, sets the primary key for automatic use by subsequent `data.table` queries, and permits rowname-like usage such as `DT["foo",]` which returns the now-contiguous-in-memory block of rows where the first column of `DT`'s key contains `"foo"`. Multi-column-rownames (i.e. a primary key of more than one column) can be looked up using `DT[.("foo",20210728L), ]`. Using `==` in `i` is also optimized to use the key or indices, if you prefer using column names explicitly and `==`. An alternative to `setkey(DT)` is returning a new ordered result using `DT[order(col1, col2, ...), ]`.
+28. `dplyr::arrange(DT)` uses `vctrs::vec_slice` which retains `data.table`'s class but uses C to bypass `[` method dispatch and does not adjust `data.table`'s attributes containing the index row numbers, [#5042](https://github.com/Rdatatable/data.table/issues/5042). `data.table`'s long-standing `.internal.selfref` mechanism to detect such operations by other packages was not being checked by `data.table` when using indexes, causing `data.table` filters and joins to use invalid indexes and return incorrect results after a `dplyr::arrange(DT)`. Thanks to @Waldi73 for reporting; @avimallu, @tlapak, @MichaelChirico, @jangorecki and @hadley for investigating and suggestions; and @mattdowle for the PR. The intended way to use `data.table` is `data.table::setkey(DT, col1, col2, ...)` which reorders `DT` by reference in parallel, sets the primary key for automatic use by subsequent `data.table` queries, and permits rowname-like usage such as `DT["foo",]` which returns the now-contiguous-in-memory block of rows where the first column of `DT`'s key contains `"foo"`. Multi-column-rownames (i.e. a primary key of more than one column) can be looked up using `DT[.("foo",20210728L), ]`. Using `==` in `i` is also optimized to use the key or indices, if you prefer using column names explicitly and `==`. An alternative to `setkey(DT)` is returning a new ordered result using `DT[order(col1, col2, ...), ]`.
+Refer to [internal.selfref](../man/internal.selfref.Rd) for additional information.
 
 29. A segfault occurred when `nrow/throttle < nthread`, [#5077](https://github.com/Rdatatable/data.table/issues/5077). With the default throttle of 1024 rows (see `?setDTthreads`), at least 64 threads would be needed to trigger the segfault since there needed to be more than 65,535 rows too. It occurred on a server with 256 logical cores where `data.table` uses 128 threads by default. Thanks to Bennet Becker for reporting, debugging at C level, and fixing. It also occurred when the throttle was increased so as to use fewer threads; e.g. at the limit `setDTthreads(throttle=nrow(DT))`.