[GitHub] [iceberg] rdblue commented on a change in pull request #3959: Disable metrics for very wide tables to reduce metadata size

[GitBox <gi...@apache.org>]

rdblue commented on a change in pull request #3959:
URL: https://github.com/apache/iceberg/pull/3959#discussion_r805435487



##########
File path: core/src/main/java/org/apache/iceberg/MetricsConfig.java
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@@ -94,15 +96,21 @@ public static MetricsConfig getDefault() {
    **/
   @Deprecated
   public static MetricsConfig fromProperties(Map<String, String> props) {
-    return from(props, null);
+    return from(props, null, DEFAULT_WRITE_METRICS_MODE_DEFAULT);
   }
 
   /**
    * Creates a metrics config from a table.
    * @param table iceberg table
    */
   public static MetricsConfig forTable(Table table) {
-    return from(table.properties(), table.sortOrder());
+    String defaultMode;
+    if (table.schema().columns().size() <= MAX_COLUMNS) {

Review comment:
       I think we may already have what we need to do this. Right now, the default metrics mode is set by `write.metadata.metrics.default`. I'd propose the following:
   * If `write.metadata.metrics.default` explicitly set in table properties, always use it
   * If `write.metadata.metrics.default` is not set, check the number of columns
       * If `numCols < 32` then use `truncate[16]`, the current default
       * If `numCols >= 32` then use `none`
   
   That seems like a reasonable way to make this customizable.




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