Use old-style SPSS compression by default for .sav (SPSS) files, sinc…

…e almost nobody uses the inefficient uncompressed format. The newer ZCompressed format (compress=TRUE) is even better, but is much less used and less supported by third-party tools.

NEWS.md

@@ -11,6 +11,10 @@
 * Updated to ReadStat 1.1.5. Most importantly this includes support for
   SAS binary compression.
 
+* `write_sav(..., compress=FALSE)` now uses SPSS Bytecode compression instead
+  of the rarely-used uncompressed mode.  `compress=TRUE` continues to use the new
+  (and not universally supported, but more compact) ZLIB format. (@oliverbock, #544)
+
 # haven 2.3.1
 
 * Add missing methods so `median()`, `quantile()` and `summary()` work

R/haven.R

@@ -217,7 +217,7 @@ read_por <- function(file, user_na = FALSE, col_select = NULL, skip = 0, n_max =
 #' @export
 #' @rdname read_spss
 #' @param compress If `TRUE`, will compress the file, resulting in a `.zsav`
-#'   file.
+#'   file.  Otherwise the `.sav` file will be bytecode compressed.
 write_sav <- function(data, path, compress = FALSE) {
   validate_sav(data)
   write_sav_(data, normalizePath(path, mustWork = FALSE), compress = compress)

src/DfWriter.cpp

@@ -382,6 +382,8 @@ void write_sav_(cpp11::list data, cpp11::strings path, bool compress) {
   Writer writer(HAVEN_SAV, data, path);
   if (compress)
     writer.setCompression(READSTAT_COMPRESS_BINARY);
+  else
+    writer.setCompression(READSTAT_COMPRESS_ROWS);
   writer.write();
 }