Add zstd with low compression quality

libs/pageserver_api/src/models.rs

@@ -469,6 +469,7 @@ pub enum CompactionAlgorithm {
 )]
 #[strum(serialize_all = "kebab-case")]
 pub enum ImageCompressionAlgorithm {
+    ZstdLow,
     Zstd,
     ZstdHigh,
     LZ4,

pageserver/src/tenant/blob_io.rs

@@ -266,10 +266,16 @@ impl<const BUFFERED: bool> BlobWriter<BUFFERED> {
                 const UNCOMPRESSED: u8 = 0x80;
                 const ZSTD: u8 = UNCOMPRESSED | 0x10;
                 const LZ4: u8 = UNCOMPRESSED | 0x20;
+                use ImageCompressionAlgorithm::*;
                 let (high_bit_mask, len_written, srcbuf) = match algorithm {
-                    Some(ImageCompressionAlgorithm::Zstd | ImageCompressionAlgorithm::ZstdHigh) => {
+                    Some(ZstdLow | Zstd | ZstdHigh) => {
                         let mut encoder =
-                            if matches!(algorithm, Some(ImageCompressionAlgorithm::ZstdHigh)) {
+                            if matches!(algorithm, Some(ZstdLow)) {
+                                async_compression::tokio::write::ZstdEncoder::with_quality(
+                                    Vec::new(),
+                                    Level::Precise(1),
+                                )
+                            } else if matches!(algorithm, Some(ZstdHigh)) {
                                 async_compression::tokio::write::ZstdEncoder::with_quality(
                                     Vec::new(),
                                     Level::Precise(6),

pageserver/src/tenant/storage_layer/image_layer.rs

@@ -381,6 +381,7 @@ impl ImageLayer {
         }
         let image_compressions = [
             None,
+            Some(ImageCompressionAlgorithm::ZstdLow),
             Some(ImageCompressionAlgorithm::Zstd),
             Some(ImageCompressionAlgorithm::ZstdHigh),
             Some(ImageCompressionAlgorithm::LZ4),