diff --git a/tslib/storage/src/journal.ts b/tslib/storage/src/journal.ts
index 79a746d1..05c0779d 100644
--- a/tslib/storage/src/journal.ts
+++ b/tslib/storage/src/journal.ts
@@ -139,6 +139,8 @@ class JournalStorage {
       const unionUserAttrs: Set<string> = new Set()
       const unionSearchSpace: Set<string> = new Set()
       let intersectionSearchSpace: string[] = []
+      const nameToSearchSpaceItem: Map<string, Optuna.SearchSpaceItem> =
+        new Map()
 
       study.trials.forEach((trial, index) => {
         for (const userAttr of trial.user_attrs) {
@@ -146,6 +148,12 @@ class JournalStorage {
         }
         for (const param of trial.params) {
           unionSearchSpace.add(param.name)
+          if (!nameToSearchSpaceItem.has(param.name)) {
+            nameToSearchSpaceItem.set(param.name, {
+              name: param.name,
+              distribution: param.distribution,
+            })
+          }
         }
         if (index === 0) {
           intersectionSearchSpace = Array.from(unionSearchSpace)
@@ -162,14 +170,10 @@ class JournalStorage {
         }
       })
       study.union_search_space = Array.from(unionSearchSpace).map((name) => {
-        return {
-          name: name,
-        }
+        return nameToSearchSpaceItem.get(name) as Optuna.SearchSpaceItem
       })
       study.intersection_search_space = intersectionSearchSpace.map((name) => {
-        return {
-          name: name,
-        }
+        return nameToSearchSpaceItem.get(name) as Optuna.SearchSpaceItem
       })
     }
 
diff --git a/tslib/storage/src/sqlite.ts b/tslib/storage/src/sqlite.ts
index cb4be1ff..11912ac2 100644
--- a/tslib/storage/src/sqlite.ts
+++ b/tslib/storage/src/sqlite.ts
@@ -165,24 +165,35 @@ const getStudy = (
     }
 
     const params = getTrialParams(db, trial.trial_id)
-    const param_names = new Set<string>()
+    const paramNames = new Set<string>()
+    const paramNameToSearchSpaceItem = new Map<string, Optuna.SearchSpaceItem>()
     for (const param of params) {
-      param_names.add(param.name)
+      paramNames.add(param.name)
+      if (paramNameToSearchSpaceItem.has(param.name)) {
+        paramNameToSearchSpaceItem.set(param.name, {
+          name: param.name,
+          distribution: param.distribution,
+        })
+      }
       if (
         study.union_search_space.findIndex((s) => s.name === param.name) === -1
       ) {
-        study.union_search_space.push({ name: param.name })
+        study.union_search_space.push({
+          name: param.name,
+          distribution: param.distribution,
+        })
       }
     }
     if (intersection_search_space.size === 0) {
-      // biome-ignore lint/complexity/noForEach: <explanation>
-      param_names.forEach((s) => {
-        intersection_search_space.add({ name: s })
-      })
+      for (const s of paramNames) {
+        intersection_search_space.add(
+          paramNameToSearchSpaceItem.get(s) as Optuna.SearchSpaceItem
+        )
+      }
     } else {
       intersection_search_space = new Set(
         Array.from(intersection_search_space).filter((s) =>
-          param_names.has(s.name)
+          paramNames.has(s.name)
         )
       )
     }