Raise default global-dict retained budget 1GB -> 2GB (#303 finding 2)

writer/src/main/java/io/github/dfa1/vortex/writer/WriteOptions.java

@@ -37,12 +37,15 @@ public record WriteOptions(
         boolean enableZstd,
         long globalDictMaxRetainedBytes
 ) {
-    /// Default aggregate retention budget (1 GB) for the buffered per-chunk code arrays of global
+    /// Default aggregate retention budget (2 GB) for the buffered per-chunk code arrays of global
     /// -dictionary candidate columns. Raised from 256 MB when buffering became cardinality-bounded
-    /// (ADR 0021): codes are ~35–45× smaller than the raw values the old budget guarded, so a 1 GB
-    /// default bounds the same pathological many-wide-columns risk while letting normal wide,
-    /// low-cardinality files (e.g. NYC 311, ~38 string columns) keep all their shared dictionaries.
-    private static final long DEFAULT_GLOBAL_DICT_MAX_RETAINED_BYTES = 1024L * 1024 * 1024;
+    /// (ADR 0021), then from 1 GB (#303): a wide, high-cardinality file (NYC 311, ~30 admitted string
+    /// columns × ~37 MB of buffered codes ≈ 1.15 GB) crossed the 1 GB budget and evicted its
+    /// highest-cardinality columns to per-chunk dictionaries, repeating their values pool each chunk
+    /// (~35 MB larger). 2 GB fits that file with headroom while still bounding the pathological
+    /// many-wide-columns risk. Constrained-heap writers can lower it via
+    /// [#withGlobalDictMaxRetainedBytes(long)].
+    private static final long DEFAULT_GLOBAL_DICT_MAX_RETAINED_BYTES = 2L * 1024 * 1024 * 1024;
 
     /// Default options: global dictionary encoding enabled, no cascading compression, Zstd disabled.
     ///

writer/src/test/java/io/github/dfa1/vortex/writer/WriteOptionsTest.java

@@ -7,14 +7,14 @@
 /// Unit tests for [WriteOptions] factories and copy-methods.
 class WriteOptionsTest {
 
-    // The hardcoded default; both factories must keep supplying it so the budget stays 1 GB unless a
+    // The hardcoded default; both factories must keep supplying it so the budget stays 2 GB unless a
     // caller overrides it via withGlobalDictMaxRetainedBytes(...). Raised from 256 MB when buffering
-    // became cardinality-bounded (ADR 0021): the budget now guards ~2 B/row code arrays, not raw
-    // values, so a larger budget bounds the same risk while keeping wide low-cardinality files dicted.
-    private static final long DEFAULT_BUDGET = 1024L * 1024 * 1024;
+    // became cardinality-bounded (ADR 0021), then from 1 GB (#303) so wide high-cardinality files
+    // keep their high-cardinality columns globally dictionaried instead of evicting them to per-chunk.
+    private static final long DEFAULT_BUDGET = 2L * 1024 * 1024 * 1024;
 
     @Test
-    void defaults_globalDictMaxRetainedBytes_is1Gb() {
+    void defaults_globalDictMaxRetainedBytes_is2Gb() {
         // Given / When
         WriteOptions result = WriteOptions.defaults();
 
@@ -23,7 +23,7 @@ void defaults_globalDictMaxRetainedBytes_is1Gb() {
     }
 
     @Test
-    void cascading_globalDictMaxRetainedBytes_is1Gb() {
+    void cascading_globalDictMaxRetainedBytes_is2Gb() {
         // Given / When
         WriteOptions result = WriteOptions.cascading(3);