merge: Add support for trace writing

This pull request extends the trace API to support writing new traces.

- Unify columns of different tables 
- Support column lookup via index
- Use index lookup in trace loader 
- Add property for describing partition keys
- Simplify TraceFormat SPI interface
- Add support for writing traces

**Breaking API Changes**

- `TraceFormat` SPI interface has been redesigned.

1 files changed, 8 insertions, 6 deletions

diff --git a/opendc-trace/opendc-trace-api/src/main/kotlin/org/opendc/trace/Table.kt b/opendc-trace/opendc-trace-api/src/main/kotlin/org/opendc/trace/Table.kt
index 6aca2051..b0181cbc 100644
--- a/opendc-trace/opendc-trace-api/src/main/kotlin/org/opendc/trace/Table.kt
+++ b/opendc-trace/opendc-trace-api/src/main/kotlin/org/opendc/trace/Table.kt
@@ -32,14 +32,14 @@ public interface Table {
     public val name: String
 
     /**
-     * A flag to indicate that the table is synthetic (derived from another table).
+     * The list of columns supported in this table.
      */
-    public val isSynthetic: Boolean
+    public val columns: List<TableColumn<*>>
 
     /**
-     * The list of columns supported in this table.
+     * The columns by which the table is partitioned.
      */
-    public val columns: List<TableColumn<*>>
+    public val partitionKeys: List<TableColumn<*>>
 
     /**
      * Open a [TableReader] for this table.
@@ -47,7 +47,9 @@ public interface Table {
     public fun newReader(): TableReader
 
     /**
-     * Open a [TableReader] for [partition] of the table.
+     * Open a [TableWriter] for this table.
+     *
+     * @throws UnsupportedOperationException if writing is not supported by the table.
      */
-    public fun newReader(partition: String): TableReader
+    public fun newWriter(): TableWriter
 }