chore: disable ttl for write cache by default (#4595)

* chore: remove default write cache ttl

* docs: update example config

* chore: fix ci

config/config.md

@@ -116,11 +116,12 @@
 | `region_engine.mito.global_write_buffer_reject_size` | String | `2GB` | Global write buffer size threshold to reject write requests. If not set, it's default to 2 times of `global_write_buffer_size` |
 | `region_engine.mito.sst_meta_cache_size` | String | `128MB` | Cache size for SST metadata. Setting it to 0 to disable the cache.<br/>If not set, it's default to 1/32 of OS memory with a max limitation of 128MB. |
 | `region_engine.mito.vector_cache_size` | String | `512MB` | Cache size for vectors and arrow arrays. Setting it to 0 to disable the cache.<br/>If not set, it's default to 1/16 of OS memory with a max limitation of 512MB. |
-| `region_engine.mito.page_cache_size` | String | `512MB` | Cache size for pages of SST row groups. Setting it to 0 to disable the cache.<br/>If not set, it's default to 1/16 of OS memory with a max limitation of 512MB. |
+| `region_engine.mito.page_cache_size` | String | `512MB` | Cache size for pages of SST row groups. Setting it to 0 to disable the cache.<br/>If not set, it's default to 1/8 of OS memory. |
+| `region_engine.mito.selector_result_cache_size` | String | `512MB` | Cache size for time series selector (e.g. `last_value()`). Setting it to 0 to disable the cache.<br/>If not set, it's default to 1/16 of OS memory with a max limitation of 512MB. |
 | `region_engine.mito.enable_experimental_write_cache` | Bool | `false` | Whether to enable the experimental write cache. |
 | `region_engine.mito.experimental_write_cache_path` | String | `""` | File system path for write cache, defaults to `{data_home}/write_cache`. |
 | `region_engine.mito.experimental_write_cache_size` | String | `512MB` | Capacity for write cache. |
-| `region_engine.mito.experimental_write_cache_ttl` | String | `1h` | TTL for write cache. |
+| `region_engine.mito.experimental_write_cache_ttl` | String | `None` | TTL for write cache. |
 | `region_engine.mito.sst_write_buffer_size` | String | `8MB` | Buffer size for SST writing. |
 | `region_engine.mito.scan_parallelism` | Integer | `0` | Parallelism to scan a region (default: 1/4 of cpu cores).<br/>- `0`: using the default value (1/4 of cpu cores).<br/>- `1`: scan in current thread.<br/>- `n`: scan in parallelism n. |
 | `region_engine.mito.parallel_scan_channel_size` | Integer | `32` | Capacity of the channel to send data from parallel scan tasks to the main task. |
@@ -408,11 +409,12 @@
 | `region_engine.mito.global_write_buffer_reject_size` | String | `2GB` | Global write buffer size threshold to reject write requests. If not set, it's default to 2 times of `global_write_buffer_size` |
 | `region_engine.mito.sst_meta_cache_size` | String | `128MB` | Cache size for SST metadata. Setting it to 0 to disable the cache.<br/>If not set, it's default to 1/32 of OS memory with a max limitation of 128MB. |
 | `region_engine.mito.vector_cache_size` | String | `512MB` | Cache size for vectors and arrow arrays. Setting it to 0 to disable the cache.<br/>If not set, it's default to 1/16 of OS memory with a max limitation of 512MB. |
-| `region_engine.mito.page_cache_size` | String | `512MB` | Cache size for pages of SST row groups. Setting it to 0 to disable the cache.<br/>If not set, it's default to 1/16 of OS memory with a max limitation of 512MB. |
+| `region_engine.mito.page_cache_size` | String | `512MB` | Cache size for pages of SST row groups. Setting it to 0 to disable the cache.<br/>If not set, it's default to 1/8 of OS memory. |
+| `region_engine.mito.selector_result_cache_size` | String | `512MB` | Cache size for time series selector (e.g. `last_value()`). Setting it to 0 to disable the cache.<br/>If not set, it's default to 1/16 of OS memory with a max limitation of 512MB. |
 | `region_engine.mito.enable_experimental_write_cache` | Bool | `false` | Whether to enable the experimental write cache. |
 | `region_engine.mito.experimental_write_cache_path` | String | `""` | File system path for write cache, defaults to `{data_home}/write_cache`. |
 | `region_engine.mito.experimental_write_cache_size` | String | `512MB` | Capacity for write cache. |
-| `region_engine.mito.experimental_write_cache_ttl` | String | `1h` | TTL for write cache. |
+| `region_engine.mito.experimental_write_cache_ttl` | String | `None` | TTL for write cache. |
 | `region_engine.mito.sst_write_buffer_size` | String | `8MB` | Buffer size for SST writing. |
 | `region_engine.mito.scan_parallelism` | Integer | `0` | Parallelism to scan a region (default: 1/4 of cpu cores).<br/>- `0`: using the default value (1/4 of cpu cores).<br/>- `1`: scan in current thread.<br/>- `n`: scan in parallelism n. |
 | `region_engine.mito.parallel_scan_channel_size` | Integer | `32` | Capacity of the channel to send data from parallel scan tasks to the main task. |

config/datanode.example.toml

@@ -394,9 +394,13 @@ sst_meta_cache_size = "128MB"
 vector_cache_size = "512MB"
 
 ## Cache size for pages of SST row groups. Setting it to 0 to disable the cache.
-## If not set, it's default to 1/16 of OS memory with a max limitation of 512MB.
+## If not set, it's default to 1/8 of OS memory.
 page_cache_size = "512MB"
 
+## Cache size for time series selector (e.g. `last_value()`). Setting it to 0 to disable the cache.
+## If not set, it's default to 1/16 of OS memory with a max limitation of 512MB.
+selector_result_cache_size = "512MB"
+
 ## Whether to enable the experimental write cache.
 enable_experimental_write_cache = false
 
@@ -407,7 +411,8 @@ experimental_write_cache_path = ""
 experimental_write_cache_size = "512MB"
 
 ## TTL for write cache.
-experimental_write_cache_ttl = "1h"
+## +toml2docs:none-default
+experimental_write_cache_ttl = "8h"
 
 ## Buffer size for SST writing.
 sst_write_buffer_size = "8MB"

config/standalone.example.toml

@@ -431,9 +431,13 @@ sst_meta_cache_size = "128MB"
 vector_cache_size = "512MB"
 
 ## Cache size for pages of SST row groups. Setting it to 0 to disable the cache.
-## If not set, it's default to 1/16 of OS memory with a max limitation of 512MB.
+## If not set, it's default to 1/8 of OS memory.
 page_cache_size = "512MB"
 
+## Cache size for time series selector (e.g. `last_value()`). Setting it to 0 to disable the cache.
+## If not set, it's default to 1/16 of OS memory with a max limitation of 512MB.
+selector_result_cache_size = "512MB"
+
 ## Whether to enable the experimental write cache.
 enable_experimental_write_cache = false
 
@@ -444,7 +448,8 @@ experimental_write_cache_path = ""
 experimental_write_cache_size = "512MB"
 
 ## TTL for write cache.
-experimental_write_cache_ttl = "1h"
+## +toml2docs:none-default
+experimental_write_cache_ttl = "8h"
 
 ## Buffer size for SST writing.
 sst_write_buffer_size = "8MB"

src/cmd/tests/load_config_test.rs

@@ -82,6 +82,7 @@ fn test_load_datanode_example_config() {
                     vector_cache_size: ReadableSize::mb(512),
                     page_cache_size: ReadableSize::mb(512),
                     max_background_jobs: 4,
+                    experimental_write_cache_ttl: Some(Duration::from_secs(60 * 60 * 8)),
                     ..Default::default()
                 }),
                 RegionEngineConfig::File(EngineConfig {}),
@@ -218,6 +219,7 @@ fn test_load_standalone_example_config() {
                     vector_cache_size: ReadableSize::mb(512),
                     page_cache_size: ReadableSize::mb(512),
                     max_background_jobs: 4,
+                    experimental_write_cache_ttl: Some(Duration::from_secs(60 * 60 * 8)),
                     ..Default::default()
                 }),
                 RegionEngineConfig::File(EngineConfig {}),

src/mito2/src/config.rs

@@ -143,7 +143,7 @@ impl Default for MitoConfig {
             enable_experimental_write_cache: false,
             experimental_write_cache_path: String::new(),
             experimental_write_cache_size: ReadableSize::mb(512),
-            experimental_write_cache_ttl: Some(Duration::from_secs(60 * 60)),
+            experimental_write_cache_ttl: None,
             sst_write_buffer_size: DEFAULT_WRITE_BUFFER_SIZE,
             scan_parallelism: divide_num_cpus(4),
             parallel_scan_channel_size: DEFAULT_SCAN_CHANNEL_SIZE,

tests-integration/tests/http.rs

@@ -836,7 +836,6 @@ auto_flush_interval = "30m"
 enable_experimental_write_cache = false
 experimental_write_cache_path = ""
 experimental_write_cache_size = "512MiB"
-experimental_write_cache_ttl = "1h"
 sst_write_buffer_size = "8MiB"
 parallel_scan_channel_size = 32
 allow_stale_entries = false