pebbleDB: experiment 2, sentry-01 changes

Author: marcello33

ethdb/pebble/pebble.go

@@ -299,7 +299,8 @@ func New(file string, cache int, handles int, namespace string, readonly bool) (
 		// buffers are taken from this too. Assign all available
 		// memory allowance for cache.
 		Cache:        pebble.NewCache(int64(cache * 1024 * 1024)),
-		MaxOpenFiles: handles,
+		MaxOpenFiles:  handles,
+		BytesPerSync: 1 * 1024 * 1024, // G: was 512 KB implicit default — fewer, larger syncs during compaction
 
 		// The size of memory table(as well as the write buffer).
 		// Note, there may have more than two memory tables in the system.
@@ -319,13 +320,13 @@ func New(file string, cache int, handles int, namespace string, readonly bool) (
 		// Per-level options. Options for at least one level must be specified. The
 		// options for the last level are used for all subsequent levels.
 		Levels: []pebble.LevelOptions{
-			{TargetFileSize: 2 * 1024 * 1024, FilterPolicy: bloom.FilterPolicy(10)},
-			{TargetFileSize: 4 * 1024 * 1024, FilterPolicy: bloom.FilterPolicy(10)},
-			{TargetFileSize: 8 * 1024 * 1024, FilterPolicy: bloom.FilterPolicy(10)},
-			{TargetFileSize: 16 * 1024 * 1024, FilterPolicy: bloom.FilterPolicy(10)},
-			{TargetFileSize: 32 * 1024 * 1024, FilterPolicy: bloom.FilterPolicy(10)},
-			{TargetFileSize: 64 * 1024 * 1024, FilterPolicy: bloom.FilterPolicy(10)},
-			{TargetFileSize: 128 * 1024 * 1024, FilterPolicy: bloom.FilterPolicy(10)},
+			{TargetFileSize: 2 * 1024 * 1024, FilterPolicy: bloom.FilterPolicy(10), Compression: pebble.NoCompression},                                  // E: no compression on hot data
+			{TargetFileSize: 4 * 1024 * 1024, FilterPolicy: bloom.FilterPolicy(10), Compression: pebble.NoCompression},                                  // E: no compression on hot data
+			{TargetFileSize: 8 * 1024 * 1024, FilterPolicy: bloom.FilterPolicy(10)},                                                                     // Snappy (default)
+			{TargetFileSize: 16 * 1024 * 1024, FilterPolicy: bloom.FilterPolicy(10)},                                                                    // Snappy (default)
+			{TargetFileSize: 32 * 1024 * 1024, FilterPolicy: bloom.FilterPolicy(10), BlockSize: 32 * 1024},                                              // F: larger blocks for deep levels
+			{TargetFileSize: 64 * 1024 * 1024, FilterPolicy: bloom.FilterPolicy(10), BlockSize: 32 * 1024, Compression: pebble.ZstdCompression},          // E+F: Zstd on cold data, larger blocks
+			{TargetFileSize: 128 * 1024 * 1024, FilterPolicy: bloom.FilterPolicy(10), BlockSize: 32 * 1024, Compression: pebble.ZstdCompression},         // E+F: Zstd on cold data, larger blocks
 		},
 		ReadOnly: readonly,
 		EventListener: &pebble.EventListener{