Use the term "Batch Sorted Merge" in EXPLAIN

Currently it says "sorted merge append" and that's the only remnant of
the old name.

tsl/src/nodes/decompress_chunk/decompress_chunk.c

@@ -825,7 +825,7 @@ ts_decompress_chunk_generate_paths(PlannerInfo *root, RelOptInfo *chunk_rel, Hyp
 		path = (Path *) decompress_chunk_path_create(root, compression_info, 0, compressed_path);
 
 		/*
-		 * Create a path for the sorted merge append optimization. This optimization performs a
+		 * Create a path for the batch sorted merge optimization. This optimization performs a
 		 * merge append of the involved batches by using a binary heap and preserving the
 		 * compression order. This optimization is only taken into consideration if we can't push
 		 * down the sort to the compressed chunk. If we can push down the sort, the batches can be

tsl/src/nodes/decompress_chunk/exec.c

@@ -79,7 +79,7 @@ static const struct BatchQueueFunctions BatchQueueFunctionsHeap = {
 /*
  * Build the sortkeys data structure from the list structure in the
  * custom_private field of the custom scan. This sort info is used to sort
- * binary heap used for sorted merge append.
+ * binary heap used for batch sorted merge.
  */
 static void
 build_batch_sorted_merge_info(DecompressChunkState *chunk_state)
@@ -892,7 +892,7 @@ decompress_chunk_explain(CustomScanState *node, List *ancestors, ExplainState *e
 	{
 		if (chunk_state->batch_sorted_merge)
 		{
-			ExplainPropertyBool("Sorted merge append", chunk_state->batch_sorted_merge, es);
+			ExplainPropertyBool("Batch Sorted Merge", chunk_state->batch_sorted_merge, es);
 		}
 
 		if (es->analyze && (es->verbose || es->format != EXPLAIN_FORMAT_TEXT))

tsl/test/sql/compression.sql

@@ -1032,11 +1032,11 @@ ANALYZE sensor_data_compressed;
 
 SELECT * FROM sensor_data_compressed ORDER BY time DESC LIMIT 5;
 
--- Only the first chunks should be accessed (sorted merge append is enabled)
+-- Only the first chunks should be accessed (batch sorted merge is enabled)
 :PREFIX
 SELECT * FROM sensor_data_compressed ORDER BY time DESC LIMIT 5;
 
--- Only the first chunks should be accessed (sorted merge append is disabled)
+-- Only the first chunks should be accessed (batch sorted merge is disabled)
 SET timescaledb.enable_decompression_sorted_merge = FALSE;
 :PREFIX
 SELECT * FROM sensor_data_compressed ORDER BY time DESC LIMIT 5;
@@ -1047,11 +1047,11 @@ SELECT compress_chunk(ch, if_not_compressed => true) FROM show_chunks('sensor_da
 
 SELECT * FROM sensor_data_compressed ORDER BY time DESC LIMIT 5;
 
--- Only the first chunks should be accessed (sorted merge append is enabled)
+-- Only the first chunks should be accessed (batch sorted merge is enabled)
 :PREFIX
 SELECT * FROM sensor_data_compressed ORDER BY time DESC LIMIT 5;
 
--- Only the first chunks should be accessed (sorted merge append is disabled)
+-- Only the first chunks should be accessed (batch sorted merge is disabled)
 SET timescaledb.enable_decompression_sorted_merge = FALSE;
 :PREFIX
 SELECT * FROM sensor_data_compressed ORDER BY time DESC LIMIT 5;
@@ -1061,11 +1061,11 @@ RESET timescaledb.enable_decompression_sorted_merge;
 INSERT INTO sensor_data_compressed (time, sensor_id, cpu, temperature)
    VALUES ('1980-01-02 01:00:00-00', 2, 4, 14.0);
 
--- Only the first chunks should be accessed (sorted merge append is enabled)
+-- Only the first chunks should be accessed (batch sorted merge is enabled)
 :PREFIX
 SELECT * FROM sensor_data_compressed ORDER BY time DESC LIMIT 5;
 
--- Only the first chunks should be accessed (sorted merge append is disabled)
+-- Only the first chunks should be accessed (batch sorted merge is disabled)
 SET timescaledb.enable_decompression_sorted_merge = FALSE;
 :PREFIX
 SELECT * FROM sensor_data_compressed ORDER BY time DESC LIMIT 5;